Lena Ammosova

DissertationsDepartment of ChemistryUniversity of Eastern Finland

No. 144 (2017)

115/2012 MAKSIMAINEN Mirko: Structural studies of Trichoderma reesei, Aspergillus oryzae and Bacillus circulans sp. alkalophilus beta-galactosidases – Novel insights into a structure-function relationship116/2012 PÖLLÄNEN Maija: Morphological, thermal, mechanical, and tribological studies of polyethylene compositesreinforcedwithmicro–andnanofillers117/2013LAINEAnniina:Elementaryreactionsinmetallocene/methylaluminoxanecatalyzedpolyolefin synthesis118/2013TIMONENJuri:Synthesis,characterizationandanti-inflammatoryeffectsofsubstitutedcoumarin derivatives119/2013 TAKKUNEN Laura: Three-dimensional roughness analysis for multiscale textured surfaces: Quantitative characterization and simulation of micro- and nanoscale structures120/2014 STENBERG Henna: Studies of self-organizing layered coatings121/2014 KEKÄLÄINEN Timo: Characterization of petroleum and bio-oil samples by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry122/2014 BAZHENOV Andrey: Towards deeper atomic-level understanding of the structure of magnesium dichloride and its performance as a support in the Ziegler-Natta catalytic system123/2014 PIRINEN Sami: Studies on MgCl2/ether supports in Ziegler–Natta catalysts for ethylene polymerization124/2014 KORPELA Tarmo: Friction and wear of micro-structured polymer surfaces125/2014 HUOVINEN Eero: Fabrication of hierarchically structured polymer surfaces126/2014 EROLA Markus: Synthesis of colloidal gold and polymer particles and use of the particles in preparation of hierarchical structures with self-assembly127/2015 KOSKINEN Laura: Structural and computational studies on the coordinative nature of halogen bonding128/2015 TUIKKA Matti: Crystal engineering studies of barium bisphosphonates, iodine bridged ruthenium complexes, and copper chlorides129/2015JIANGYu:Modificationandapplicationsofmicro-structuredpolymersurfaces130/2015 TABERMAN Helena: Structure and function of carbohydrate-modifying enzymes 131/2015KUKLINMikhailS.:Towardsoptimizationofmetaloceneolefinpolymerizationcatalystsvia structuralmodifications:acomputationalapproach132/2015SALSTELAJanne:Influenceofsurfacestructuringonphysicalandmechanicalpropertiesof polymer-cellulosefibercompositesandmetal-polymercompositejoints133/2015 CHAUDRI Adil Maqsood: Tribological behavior of the polymers used in drug delivery devices134/2015 HILLI Yulia: The structure-activity relationship of Pd-Ni three-way catalysts for H2S suppression135/2016 SUN Linlin: The effects of structural and environmental factors on the swelling behavior of Montmorillonite-Beidellite smectics: a molecular dynamics approach136/2016 OFORI Albert: Inter- and intramolecular interactions in the stabilization and coordination of palladium and silver complexes: DFT and QTAIM studies137/2016 LAVIKAINEN Lasse: The structure and surfaces of 2:1 phyllosilicate clay minerals138/2016 MYLLER Antti T.: The effect of a coupling agent on the formation of area-selective monolayers of iron a-octabutoxy phthalocyanine on a nano-patterned titanium dioxide carrier139/2016KIRVESLAHTIAnna:Polymerwettabilityproperties:theirmodificationandinfluencesupon water movement140/2016 LAITAOJA Mikko: Structure-function studies of zinc proteins141/2017 NISSINEN Ville: The roles of multidentate ether and amine electron donors in the crystal structure formation of magnesium chloride supports 142/2017 SAFDAR Muhammad: Manganese oxide based catalyzed micromotors: synthesis, characterization and applications143/2017 DAU Thuy Minh: Luminescent coinage metal complexes based on multidentate phosphine ligands

Selective modification and controlled deposition on polymer surfaces

Lena Am

mosova: S

elective modification and controlled deposition on polym

er surfaces

144

Selective modification and controlled

deposition on polymer surfaces

Lena Ammosova

Department of Chemistry

University of Eastern Finland

Finland

Joensuu 2017

2

Lena Ammosova

Department of Chemistry, University of Eastern Finland

P.O. Box 111, FI-80101 Joensuu, Finland

Supervisors

Prof. Tapani A. Pakkanen, University of Eastern Finland, Joensuu

Prof. Mika Suvanto, University of Eastern Finland, Joensuu

Referees

Executive scientist, Suvi Haukka, ASM Microchemistry, Helsinki

Prof. Leena Hupa, Åbo Akademi University, Turku

Opponent

Assistant prof. Päivi Laaksonen, Aalto University, Espoo

To be presented with the permission of the Faculty of Science and Forestry of the

University of Eastern Finland for public criticism in Auditorium F100, Yliopistokatu 7,

Joensuu, on December 11th, 2017, at 12 o’clock noon.

Copyright © 2017 Lena Ammosova

ISBN: 978-952-61-2679-1

ISSN: 2242-1033

Grano Oy

Jyväskylä 2017

3

ABSTRACT Polymer materials have attracted growing interest from researchers and engineers

because of their low cost, lightweight, and easy processing. Moreover, other than

polymers bulk properties, their unique and fascinating surface properties have inspired

the scientific community to create novel functional polymer surfaces. Surface

functionalities are tailored at nano- and micro-scales by topographical modifications of

the surface. Likewise, the investigation of intelligent surfaces with site-selectivity and a

merging of those with complex geometries are in high demand for modern device

applications. Traditional photolithography methods for the preparation of functional

surfaces have been well studied, and yield polymer surfaces with advanced surface

properties. However, in the fabrication of complex multi-hierarchical or site-selective

multicomponent surfaces, traditional methods suffer from high costs and complex

preparation steps. Thus, this thesis focuses on designing affordable polymer substrates

with various nano- and micro-textures incorporated with site-selective chemical

modifications.

The study shows different fabrication methods for the generation of topographical

polymer surfaces, starting from simple nano- and micro-textures, which are developed

into hierarchical topographies. Replication from the mold insert in an injection molding

process and a direct, precise surface microstructuring gave various surface geometries.

Three-dimensional surface activation of the designed topographies with the aid of

confined photocatalytic oxidation and plasma treatment ensured the formation of

selective surface anisotropies. The three-dimensional wettability anisotropies assisted

the selective embedding of different polar filling liquids and served as a substrate for a

precise deposition of ink materials for potential applications.

We also demonstrate that the same microstructuring technique is not only able to

microstructure polymer surfaces, but also deposit ink variants onto the desired location

with precise control. The x, y, z- axis robotic control of the depositing needle enables

one to transfer ink material to specific areas, either on planar or complex topographies.

With the robotic technique, the targeted deposition of a metal nanoparticle ink precursor

gives metal patterns on polymer surfaces at low solidification temperatures.

Furthermore, we show that by combining both selective embedding within three-

dimensional chemical anisotropies and precise deposition of ink, it is possible to obtain

micro-nanohierarchical multicomponent substrates. The obtained micro-

nanohierarchical substrates consisting of the embedded self-assembled thin film together

with the deposited silver nanoparticles have proven to be effective in SERS applications.

In addition, polymer microstructures successfully operate as a protective environment

for the embedded components against mechanical wear.

4

LIST OF ORIGINAL PUBLICATIONS The thesis is based on data presented in the following articles, referred to by the Roman

numerals I – III and additional results included in the summary.

I. Ammosova L., Jiang Y., Suvanto M., Pakkanen T. A. Selective three-

dimensional hydrophilization of microstructured polymer surfaces through

confined photocatalytic oxidation. Appl. Surf. Sci. 2015 (329), 58-64.

II. Ammosova L., Jiang Y., Suvanto M., Pakkanen T. A. Precise micropatterning

of silver nanoparticles on plastic surfaces. Appl. Surf. Sci. 2017 (401), 353-361.

III. Ammosova L., Ankudze B., Philip A., Jiang Y., Pakkanen T. T., Pakkanen T.

A. Silver nanoparticle deposition on inverse opal SiO2 films embedded in

protective polypropylene micropits for SERS applications. Accepted for

publication in J. Micromech. Microeng. 2017.

AUTHOR’S CONTRIBUTION

The key ideas for the topics in Publications I- III derive from the author and discussions

and conversations between the author and co-authors. In Publication I the author has

been responsible for the experimental work with guidance from co-authors and prepared

the manuscript. The author played an essential role in the experimental part and

preparation of the manuscripts for Publication II and III.

5

TABLE OF CONTENTS ABSTRACT ................................................................................................................. 3 LIST OF ORIGINAL PUBLICATIONS ................................................................ 4 TABLE OF CONTENTS .......................................................................................... 5 ABBREVIATIONS ..................................................................................................... 6

1. INTRODUCTION ............................................................................................. 7

1.1. Topographical modification ......................................................................... 8 1.2. Selective chemical modification .................................................................. 8 1.3. Applications of surfaces ................................................................................ 9 1.4. Aims of the study ......................................................................................... 10

2. SURFACE STRUCTURING ....................................................................... 11 2.1. Topographical surface modification .......................................................... 11

2.1.1. One-level microstructures ................................................................... 11

2.1.2. Dual-level micro-microstructures ...................................................... 12

2.1.3. Nanostructures ...................................................................................... 13

2.2. Chemical surface modification .................................................................. 14

2.3. Topographical and chemical surface modification ................................. 16

3. CONTROLLED INK DEPOSITION .......................................................... 19 3.1. Ink deposition onto flat surfaces ................................................................ 19

3.1.1. Elastic needles in ink deposition ........................................................ 22

3.2. Ink deposition onto structured surfaces .................................................... 23

3.2.1. Ink deposition onto micro- and microstructures .............................. 24

3.2.2. Ink deposition onto nano- and micro-nanostructures ...................... 25

4. APPLICATIONS ............................................................................................ 27 4.1. Selective embedding.................................................................................... 27

4.2. Protective microenvironment ..................................................................... 29

4.3. SERS detection ............................................................................................ 30

5. CONCLUSIONS ............................................................................................ 33 ACKNOWLEDGEMENTS ..................................................................................... 34 REFERENCES ......................................................................................................... 35

6

ABBREVIATIONS 2D two-dimensional

3D three-dimensional

4D four-dimensional

4-ATP four-aminothiophenol

AAO anodic aluminum oxide

AFM atomic force microscope

ALD atomic layer deposition

APS ammonium persulfate solution

CA contact angle

CPO confined photocatalytic oxidation

EDS energy dispersive spectroscopy

HDPE high-density polyethylene

HMT hexamethylenetetramine

IO inverse opal

MMS micro-microstructures

MS microstructures

NS nanostructures

PDMS polymethylsiloxane

PEG polyethylene glycol

PLiPT pillars inside the pits

PLoPL pillars on top of the pillars

PP polypropylene

PS polystyrene

PTiPT pits inside the pits

SEM scanning electron microscopy

SERS surface enhanced Raman spectroscopy

UV ultraviolet

7

1. INTRODUCTION

Polymer materials are one of the important materials in our daily life. Starting from food

packages and household items, the fields of usage for polymers have expanded, for

example, as implants for medicine,1 in flexible electronic devices,2 or in sport

equipment.3 Driven by specific surface properties, like adhesion, wettability, and,

biocompatibility, in addition to bulk properties such as easy processing, being

lightweight and flexibility, polymeric materials have attracted great attention from many

researchers and engineers. Moreover, production and competition growth in a market,

together with economic pressures, inspire researchers to design affordable but yet

modern and functional polymer materials with advanced surface properties. Hence,

polymer surfaces with functional surface properties are becoming increasingly

sophisticated and require the development of state-of-the-art modification methods.

The best known surface topographical modifications have been inspired by nature, for

example micro-nanostructures of morpho wings which possess superhydrophobicity and

optical reflectance;4 and gecko toes which have unique adhesive properties.5 Using

exclusive examples inspired by nature, in recent years, various surface topography

modification methods were developed.6 The topographical modification methods, such

as photolithography,7 nanoimprint lithography,8 and molding,9 have proven themselves

as effective approaches for the creation of topographies on different substrates, including

plastics. Apart from topographical modifications, chemical modifications, like a coating

layer10 and grafting techniques,11 together with the direct deposition techniques,12 are

widening the variety of plastic materials applications. Furthermore, incorporating

topographical and chemical modification methods together exhibits a significant

advance towards the designing of new, even complicated, chemical and topographical

patterns.13,14,15,16

Figure 1. The hierarchical structures of (a) morpho butterfly wings and (d) gecko toe

represented in SEM images of (b, e, and f) microstructures and (c and g)

nanostructures.4,5

8

1.1. TOPOGRAPHICAL MODIFICATION

Topographical surface modification methods can proceed via top-down and bottom-up

approaches.17 The typical top-down surface structuration processes are laser cutting,18

micromilling,19 injection molding,20 and lithography processes,21 where topography on

the surfaces is forming directly on the surface. In a top-down approach the structures are

building down, meanwhile on the bottom-up approach, the surface topography is created

by building up small structures on the surfaces.22

Among the micro-nanofabrication methods to create surface topographies on plastics,

photolithography7 is widely used and well-known, due to resulting structures with high

fidelity. However, the method requires an additional preparation of a photomask, long

preparation time and typically needs a clean room environment. A simple and cost

effective method such as injection molding resembles the expensive and time-consuming

photolithography.7 The injection molding process yields different surfaces starting from

the flat surfaces and extending to multilevel surfaces by replicating the shape of the insert

mold.23,24 Obviously, the shape of the obtained polymer structures depends on the shape

of the insert mold. The mold can be textured with various techniques, such as anodic

aluminum oxide (AAO) anodization,25,26 a robotic technique,27,28,29 and laser cutting.30

However, when the more complex topographies are needed, the mold can meet

limitations in the preparation of complex structures. In this sense, the introduction of

additional direct structuring31 techniques may resolve the limitations.

1.2. SELECTIVE CHEMICAL MODIFICATION

Although the topographical modifications add advanced functionality to the surfaces,

they do not change the chemical properties of plastic material. From the perspective of

applicability, chemically modified surfaces have high-tech applications, which are

governed by ongoing interaction processes and reactions with various materials on the

interfaces and surfaces. Since plastics commonly have inert C-H bonds, the pristine

polymer surfaces and interfaces have low surface energy and low surface reactivity,

hence, poor adhesion. To improve the surface adhesion, surfaces can be activated by

physicochemical methods such as ultraviolet (UV) treatment32 and plasma33 treatment.

Chemical activation and transformation of abundant C-H bonds to C-OH or C-radicals

change the chemistry of the surface at the atomic level and open barriers for further

surface functionalization.34 With modification of the inert C-H bond to an active C-OH,

the surface energy improves adhesion for the attaching chemical compounds or

biomolecules.35,36,37 Meanwhile the bulk properties of the material remain unchanged.

Polymer surfaces can be functionalized with chemical variants such as metallic

nanoparticles, biological molecules, and other inorganic materials. The methods used to

functionalize the whole surface are, for example, dip coating38 and spin coating,39 and

9

deposition techniques like sputtering40,41 and atomic layer deposition (ALD).42

Furthermore, by incorporating together topographical modifications and deposition

techniques, it is possible to create area-selective chemical patterns onto the surfaces.43,44

New hybrid materials may contain synthetic polymer material with immobilized

inorganic material, such as metal nanoparticles45,46 or metal oxides.47,48 However, when

taking into account a commercialization of the final product, competitiveness in an

industrial market demands a minimization of the cost of fabrication process. Therefore,

investigation of other than complex and expensive conventional metal patterning

methods on plastic substrates is quite important. Apart from conventional

photolithography based methods of metals patterning onto plastic substrates, the

microworking robot needle ink printing method49 and inkjet printing50,51 are simple and

affordable methods to obtain solid metal patterns in a microscale resolution. The atomic

force microscope tip (AFM)52,53 patterning is similar with the robot needle patterning

method, yet, the method is at nanoscale.

1.3. APPLICATIONS OF SURFACES

Applications of the topographically structured surfaces are extensive. Depending on the

developed design, they meet applications starting from superhydrophobic self-

cleaning54,55 and anti-icing surfaces56 to that of their use in biomedicine57 and

photonics.58

Chemically modified surfaces serve as a platform that create new functional materials,

for example, surfaces with functionalized proteins and large biomolecules for biosensor

applications59 or coating layers.10

The metal patterned plastic surfaces are widely used in flexible devices towards creation

of new advanced functional materials.60 They meet applications in the high-volume

mass-productive nanoplasmonic61 and electronic devices,62 and biosensors.63 For

example, polymer substrates with the patterned surface enhanced Raman spectroscopy

(SERS)-active metal nanoparticles can be used for SERS sensing applications.64,65

Moreover, recently plastic surfaces exhibit significant advance towards designing

complex three-dimensional (3D) and four-dimensional (4D) structures for applications

in space confining for large biomolecule.66 For example, 3D micropatterns, could

provide 3D environment for cell media, mimicking of natural in vivo conditions for

bacteria capture, cells spatial localization, space confinement, and

differentiation,67,68,69,70 etc.

10

1.4. AIMS OF THE STUDY

The study summarized in this dissertation focused on the fabrication of selectively

modified polymer surfaces, obtained by combination of chemical and topographical

methods of surface modification. The specific objectives of the research were:

to create complex hierarchies on a polymer surface and to find an effective way

to modify the chemistry of the surface in selected locations of the hierarchical

levels.

to create in an affordable way chemical wettability anisotropies by combination

of structural modifications and selective chemical activation on polymer

surfaces.

to investigate a low temperature method for preparation of metallic

micropatterns onto the plastic substrates with a different hierarchy and variety

of chemicals for potential applications.

to create mechanically robust micro-nanohierarchical SERS substrates and to

examine unique properties of silver for applications in SERS sensitivity.

11

2. SURFACE STRUCTURING

2.1. TOPOGRAPHICAL SURFACE MODIFICATION

Surface structures, with various surface geometries, were manufactured, including

single-level micro and nanostructures, and dual-level micro-microstructures. Different

surface textures, like pillars, pits, and combined multilevel structures such as pits on top

of the pillars (PToPL), pillars inside the pits (PLiPT), and pits inside the pits (PTiPT),

were designed. The schematic representation of the fabrication process of various

surface geometries on PP surfaces is shown in Figure 2.

Figure 2. Schematic representation of manufacturing processes for different surface

types of topographies: (A) one-level micropits, (b) dual-level structures like pillars inside

the pits (PLiPT), and (C) nanopillars.25,26 (The scheme is not drawn to scale).

2.1.1. One-level microstructures

For preparation of one-level microstructures (MS), flat polymer discs with a thickness

of 1500 µm were fabricated by using injection molding with a DSM MIDI 2000 melt

compounder and a DSM microinjection molding machine. Polymer discs were directly

microstructured (Figure 2, A) with tungsten carbide needles with the aid of a computer

controlled RP-1AH microworking robot from Mitsubishi Electric, with a CR1 control

and a feedback unit, Delta Enterprise Ltd. Thermoplastic polymers, PP and HDPE, were

directly structured by using different needle sizes of 50, 70, 100, and 200 µm.

microstructures (MS)

micro-

microstructures

(MMS)

nanostructures (NS)

PP flat PP pits

PP flat PP pits Epoxy pillars Epoxy PToPL PP PLiPT

Al foil

AAO mold

PP nanopillars

direct robot structuring

A

B

C

direct robot structuring

cold mounting

injection molding

direct robot structuring

anodizationinjection molding

Al2O3 nanopores

12

Figure 3 shows the SEM images of the microstructured PP and HDPE surfaces, top-

views (Figure 3, a and b) and cross-sectional views (Figure 3, c).

Figure 3. SEM (a and b) top-view and (c) cross-section images and of (1) PP and (2)

HDPE micropits directly structured with a microworking robot needle. The size of the

needle is 100 µm.I,II

Upon the structuring microworking robot needle hits the surface, so that the surface had

microsized pits with the same size and shape as the needle (Figure 3). The micropits are

created as a consequence of the needle impact force applied onto the polymer surface.

The depth parameter is regulated by indirect scanning of the working surface via a

computer program and allows one to control the absolute depth of the employed needle.

The depth of the obtained micropits depends on not only parameters set with a computer,

but also the type of the polymers. For example, HDPE is plastic material, which is softer

than PP, and, hence, with the same parameter the depth of a HDPE micropit (Figure 3,

2) is deeper than that of a PP (Figure 3, 1).

2.1.2. Dual-level micro-microstructures

Dual-level PP micro-microstructures (MMS) of various complex topographies, such as

pits inside the pits (PTiPT) and pillars inside the pits (PLiPT)II (Figure 2, B) were

fabricated. Figure 4 shows optical and SEM images of fabricated hierarchical PP PTiPT

and PP PLiPT micro-microstructures.

13

Figure 4. (a) Optical top-view image of PP PTiPT micro-micropits and SEM images of

PP PLiPTII micro-micropillars, (b) top-view and (c) cross-section view.

For preparation of both PP PTiPT and PP PLiPT topographies, firstly the one-level PP

micropits were created. The fabrication of PP PTiPT micro-microstructures is simple

and quick. The process requires only a simple replacement of the needle with a smaller

sized needle and subsequent structuring the dual-level micropits within the one-level

micropits (Figure 4, a). To fabricate the more complicated PP PLiPT micro-

microstructures (Figure 4, b and c) the additional preparation step of the epoxy mold is

needed. The schematic representation of the PP PLiPT microstructures fabrication is

shown in Figure 2, B. The epoxy micropillars were replicated from one-level PP

micropits. The resulting epoxy substrate with micropillars was aligned in a robot

working area so that the micropillar coordinates match with coordinates, which were

previously used for one-level micropit structuring. Further, for structuration of the

second level on epoxy micropillars, the needle was replaced with the smaller sized

needle. Upon structuration, the epoxy was heated to avoid epoxy cracking and so that

the needle could easily hit the surface. After structuration, the resulted epoxy MMS were

pits on top of the pillars (PToPL). In order to fabricate final dual-level PP PLiPT

structures, the obtained epoxy PToPL substrates were used as a mold insert for the

injection molding process. Therefore, with the additional epoxy mold fabrication, it is

possible to fabricate not only the simple MMS with the dual-level pits, but also the more

complex MMS with the pillars incorporated with the pits.

2.1.3. Nanostructures

In order to fabricate nanostructures (NS) on PP surfaces, a beforehand electropolished

AAO membrane was employed as a mold insert for injection molding process. The AAO

membrane was manufactured by anodization of the aluminum foil by using Pt as a

counter electrode, subsequently placing it into oxalic acid and then into the phosphoric

acid to open the pores.25,26

Figure 5 shows the SEM images of the AAO foil (Figure 5, a) and the replicated PP

surfaces (Figure 5, b and c) after the injection molding at various mold temperatures.

The schematic representation of the fabrication process is shown in a Figure 2, C.

14

Figure 5. (a) SEM images of AAO mold and PP surface after injection molding with the

AAO mold at (b) 60 ºC and 80 ºC (c).

Replication of the nanopores onto the PP nanopillars gives various shapes of

nanostructures as shown in Figure 5, b and c. The shape and depth of the nanopores

dictate the shape and height of the replicated nanopillars. However, the mold temperature

has not less effect on the formation of the nanostructures geometry. The mold

temperature influences the degree of polymer filling within the nanopores, hence, shape

of the obtained nanostructures. Thus, with a mold temperature of 60 ºC, the polymer fills

the mold only partially, giving after solidification the nanopillared structures (Figure 5,

b). However, when the mold temperature was increased up to 80 ºC, the polymer

completely fills the nanopores, yielding elongated and randomly arranged nanostructures

(Figure 5, c). Therefore, the optimal conditions should be chosen according to the

desired for structures.

2.2. CHEMICAL SURFACE MODIFICATION

For chemical surface activation, UV phototransformation in the presence of a

photoinitiator I and plasma treatmentIII were employed. Figure 6 shows the schematic

representation of the conventional chemical surface modification with UV

phototransformation (Figure 6, A) and oxygen plasma treatment (Figure 6, B).

Figure 6. Schematic representation of the conventional (A) UV phototransformation

(CPO reaction) and (B) oxygen plasma treatment. (The scheme is not drawn to scale).

CPO

hydro-philization

Quartz plate

APS

Polymer substrate

Hydrophilized area

CPO treated area

UV

Top confining layer

Oxygen plasma

Plasma treated area

A

B

15

For the UV phototransformationI, ammonium persulfate solution (APS) was used as a

photoinitiator for UV phototransformation. APS initiates surface oxidation, which is

termed confined photocatalytic oxidation (CPO).31 Various polymer substrates were

tested, such as PP, HDPE, PS, and PDMS.

The idea of the CPO reaction is that during the UV irradiation the photosensitizer (~1

µl) is confined in a micrometer area between the polymer disc and the assisting polymer

disc. The assisting polymer disc confining the APS was of 300 µm thickness and

transparent to UV light. During the UV phototransformation, persulfates dissociate and

form sulfate anions on the polymer surface, which can then be transformed into hydroxyl

ions after subsequent hydrophilization at 50°C in deionized water for 16 hours.

Obviously, after oxidation the hydrophilicity increases. The changes in hydrophilicity

were measured with a water contact angle meter after 30 minutes, 2, and 3 hours of UV

irradiation. The CPO treated polymer substrates were characterized by the water contact

angle (CA) measurements. Table 1 shows the water CA values for different polymer

substrates after CPO reaction with corresponding values of pristine surfaces.

Table 1. The water CA values for different polymer substrates after CPO reaction and

corresponding values for pristine polymer substrates.

Irradiation time, min

pristine 30 120 180

PP 102° 83° ± 2.3° 83° ± 3.0° 81° ± 2.9°

HDPE 104° 82° ± 2.2° 57° ± 1.3° 65° ± 0.6°

PS 90° 64° ± 1.7° 67° ± 1.2° 68° ± 1.6°

PDMS 120° 118° ± 4.1° 116° ± 3.2° 112° ± 1.6°

Table 1 demonstrates that the water CA angle after CPO reaction significantly decreases

for PP, HDPE, and PS, while the water CA of PDMS substrate has no dramatic changes.

The differences in CA can be explained that with the PP, HDPE, and PS, polymer chains

can easily photodegrade, while the bonds of the polymer chains of PDMS are harder to

brake. For this reason, PDMS substrates were not studied for further research.

Furthermore, water droplets were captured both on pristine and CPO treated PP, HDPE,

and PS surfaces, illustrating changes in the water droplet shape and, hence, the

wettability changes caused by CPO reaction (Figure 7).

16

Figure 7. Water droplet images on (1) pristine and (2) CPO treated (a) PP, (b) HDPE,

and (c) PS surfaces. Irradiation time is 120 minutes.

In addition, the water CA measurements were repeated after 3 months and there was no

significant changes in the values. Therefore, the CPO treatment is permanent.

For the plasma surface activation,III oxygen plasma treatment with optimized pressure,

power, and treatment time was used. The water CA measurements results of the PP

substrate showed that after 3 min of oxygen plasma treatment, the water CA decreased

from 102° to 72°. Then, the stability check in three weeks showed that CA value from

72° increased up to 92°. Thus, while the CPO oxidation is permanent with time, plasma

treatment activation is temporary. Therefore, in the case of plasma treatment, the

chemical compounds should be functionalized immediately after the surface activation.

2.3. TOPOGRAPHICAL AND CHEMICAL SURFACE

MODIFICATION

First, the possibility of fabrication of the selectively chemically activated surfaces was

tested on flat samples. For that, the tape mesh with the 5 mm round shaped holes was

applied, and CPO process was followed with further hydrophilization. Further, while

conventional surface activation with CPO and plasma treatment operates only on a two-

dimensional surface area, we examine the possibility to create selective three-

dimensional anisotropies by incorporating both topographical and chemical

modifications of PP and HDPE surfaces.I

Figure 8 shows a schematic representation of the selective hydrophilization for both flat

surfaces (Figure 8, A) and micropits (Figure 8, B) with the aid of CPO processI and

plasma treatmentIII (Figure 8, C).

17

Figure 8. Schematic representation of the selective modifications with (A) UV

phototransformation with subsequent hydrophilization on flat surfaces,I (B) three-

dimensional UV phototransformation with subsequent hydrophilization,I and (C) three-

dimensional oxygen plasma treatment III (The scheme is not drawn to scale).

In the case of CPO treatment of the micropits, the selectivity was reached by protecting

the surface from contacting with the photosensitizer by the applied meshes, during the

UV process.I Three different meshes were tested, PDMS, tape and grease meshes. With

the applied meshes, only the area of the micropits, which is in contact with the APS

solution, was treated with the CPO process. Thus, the surface was modified not only on

the bottom but also on sidewalls of the micropits, facilitating creation of the wettability

anisotropies with the depth profiles. After the CPO process, hydrophilization was

followed.

Furthermore, selective three-dimensional activation was also performed with the aid of

plasma treatment (Figure 8, C). In this case, the three-dimensional chemical anisotropies

were succeeded using the tape mesh.III Similar to CPO process, the plasma activation

activated the PP surface only within the micropits.

To examine the wettability contrast between untreated and treated samples, a

luminescent compound ([Au6Cu2(C2C3H7O)6(PPh2C6H4PPh2)3][PF6]2),71 which is

dissolved in a water-acetone liquid mixture, was spin coated onto the CPO treated

surfaces (Figure 9). In comparison, the reference samples (flat and microstructured)

without CPO treatment were also tested.

CPO

CPO

hydro-philization

hydro-philization

UV

B

Quartz plate

APS

mesh

Polymer substrate

Hydrophilized area

CPO treated area

Top confining layer

C

A

UV

oxygenplazma

Plasma treated area

18

Figure 9. Optical images of spin coated with the luminescence compound (a and b)

smooth and (c and d) microstructured PP surfaces: (a and c) without CPO treatment and

(b and d) selectively CPO treated with further hydrophilization.I

Thus, it can be seen from Figure 9 that during the spin coating the luminescence

compound prefers to deposit onto the areas which are selectively hydrophilised (Figure

9, b and d) than on the chemically untreated ones (Figure 9, a and c). Therefore, the

obtained three-dimensional anisotropy facilitates the selective embedding of polar

solvents within the micropits, hence, opening the potential applications for embedding

for example, various inorganic materials.

19

3. CONTROLLED INK DEPOSITION

The computer controlled microworking robot is not able only to structure the surfaces

but also to deposit various viscous materials such as a PDMS precursor, ethylene glycols,

glycerin, and different ink nanoparticle precursors (silver, gold) on the surfaces. The key

idea is that the microworking needle first dips into the vessel containing the ink and then

transfers the attached ink onto the depositing surface. The ink deposition can be

performed on plastic surfaces, and also on various substrates, such as aluminum or paper.

For this study, PP discs were chosen as substrates for the ink deposition.

The ink transfer speed can be regulated and optimized. On the one hand, the ink transfer

should have a high enough speed to maximize the overall processing speed. However,

on the other hand, a low speed of transferring avoids ink leakage, which may arise due

to possible fluctuations. The robot deposition is in a contact mode and can be proceeded

at room temperature; therefore, liquid materials with a high viscosity are the ideal

candidate as ink material.

3.1. INK DEPOSITION ONTO FLAT SURFACES

Similar to surface direct structuring the ink deposition is controlled by an absolute depth

parameter set on the computer program. However, in case of the ink deposition, the

absolute depth is set so that the needle only gently touches the surface of the substrate.

Figure 10 shows the schematic representation of the viscous material deposition process

onto the flat surfaces and an example of the PDMS microarray deposited on PP surface

(insert, Figure 10).

Figure 10. Schematic representation of viscous material deposition on polymer surfaces

with further solidification process.I (The scheme is not drawn to scale). On the right side

is an example of optical microscope image of cured PDMS microarray.II

Various factors influence the deposition process, such as ink viscosity, the ink dipping

depth within the vessel, and the working distance between the needle and surface. The

PDMS ink should be used immediately after preparation because of the limited duration

20

of the curing time. The deposition can be repeated to increase the volume of the

depositing material.

Further, the wettability and surface chemistry of the substrate play an important role in

the formation of the shape and size of microarrays. Thus, a silver nanoparticle ink was

prepared by using the polyol method72 and deposited on both hydrophobic and

hydrophilic PP surfaces. II

Figure 11 shows the deposited silver nanoparticle microarray onto the pristine and CPO

treated PP surfaces (Figure 11, a and c) and silver nanoparticle micropatterns (Figure

11, b and d) after the solidification. Various depositing cycles of up to four times were

tested. In the polyol method, PEG was used as a reducing agent and also as an ink carrier

owing to its high viscosity. Thermal sintering was employed for solidification of the

silver nanoparticle ink microarray.

Figure 11. The optical microscope images of the (a and c) deposited silver nanoparticle

microarray on both unmodified and CPO hydrophilised PP surfaces and corresponding

images of silver nanoparticle micropatterns (b and d) after the thermal sintering process

with increasing deposition cycles.II

It can be seen from Figure 11,c that on the hydrophilic surfaces the ink volume adhered

onto the surface is much higher than that on the hydrophobic one (Figure 11, a). The

CPO treated surfaces possess active C-OH bonds, which facilitates increase in surface

hydrophilicity, hence, better adherence of the silver nanoparticle array on the PP surface.

Therefore, the wetting properties of the surface has an essential role for the size of the

microarray.

21

The microworking robot the dip painting method allows for the repetitive deposition of

the ink material, thereby, increasing the volume of the single microdot. The deposition

cycles can also effect the shape of the sintered microdot. Figure 12 shows the silver

nanoparticle microdot deposited on the CPO treated PP surface with a deposition cycle

of two and three.

Figure 12. The SEM images of the silver nanoparticle microdot deposited with different

deposition cycles of (a and b) one and (c and d) two onto CPO hydrophilised PP

surfaces.II

It can be seen from Figure 12 (a and b) that with the 2-cycle deposition, an uniform

silver nanoparticle microdot is formed, while with the 3-cycle deposition, the

nanoparticles tend to agglomerate, especially on the center of the microdot, forming

large clusters (Figure 12, c and d). It should be noted that during the solidification

process, the size of the ink microarray reduces. This size reduction and the nanoparticles

distribution can be explained with the liquid flow mechanism occurring during the

sessile drop evaporation.

Typically, upon drying of the sessile drop containing nanoparticles, the nanoparticles

tend to move from the droplet center to the edges, due to outward capillary flow arising

within the droplet. Since evaporation rate on the edges is faster than on the center of

droplet, the nanoparticles create a ring-like structure, and the phenomenon is called a

coffee ring effect.73 By addition, for example, highly viscous solvent,74 causing a surface

tension gradient within the droplet and, hence, appearance of the strong inward

Marangoni flow,75 it is possible to suppress the coffee ring effect. Thus, in the case of

the silver nanoparticle ink, where there is a mixture of two-different liquids water/PEG

solution, high surface tension gradient appears within the sessile drop, suppressing the

coffee ring effect.

22

3.1.1. Elastic needles in ink deposition

Since the tungsten carbide is very hard, it can give small scratches on the plastic surfaces

during ink deposition. The hard needles result in drawbacks, especially when patterning

continuous lines. To overcome the drawbacks, PDMS elastic needles were created

resembling a hard tungsten carbide needle. The PDMS elastic needles were fabricated

by the following steps. First, a PDMS mold was fabricated by replication of the

commercial tungsten needle. The prepared PDMS mold was hardened at 100 ºC

overnight for further fabrication steps. A new batch of PDMS precursor medium was

poured into the PDMS mold and cured at 50 ºC for 2 hours. The cured elastic needle can

be easily detached from the PDMS mold, repeating the shape of the mold.

Figure 13 shows the images of the fabricated needles (Figure 13 (a and b)) and example

of silver continuous lines patterned with the prepared elastic needles onto the CPO

treated PP surface (Figure 13, c).

Figure 13. Photographs of (a) elastic PDMS and tungsten carbide robot needles, (b)

elastic needle varieties, and (c) optical microscope image of silver continuous line

micropatterns on CPO treated PP surfaces painted with a 40 µm-sized elastic needle.

Different needles can be fabricated by replication of the tungsten carbide needle starting

from tip-type needles with various sizes, brush-type needles and also an array of

microneedles (Figure 13 (a and b)). With the elastic needle, continuous lines of ink

material can be painted without leaving any scratches on the surface upon the painting,

because of the needles bendability (Figure 13, c). Meanwhile, the drawback of the

method is that needle bendability causes enlargement of the pattern size compared to the

size of the painting needle. The fabricated microneedle array can be used for the printing

of the metallic conductive tracks applicable in microelectronics.76,77 Moreover, the

microarray of needles meets potential applications for localized drug reduction in

nanomedicine.78,79

23

3.2. INK DEPOSITION ONTO STRUCTURED SURFACES

Further, the main advantage of the microworking robot printing technique is the

patterning of materials with precise deposition. The x, y, z-axis control gives exceptional

transfer and deposition of different materials not only onto the planar surfaces, but also

within three-dimensional surfaces and even multileveled surfaces. Recently, the

development in fabrication of 3D-printed polymeric materials with complex geometries

has significantly increased. The addition of different chemical compounds other than

polymer material on such surfaces would improve the properties of materials for future

applications. However, when, for instance, ink depositing on those complex geometries

is needed, a precise z-axis control of the targeting point is required. Thus, with the z-axis

control of the microworking robot needle patterning, we can deposit different materials

onto the complex multi-level surfaces.

Figure 14 shows the schematic representation of the depositing silver ink nanoparticles

onto different hierarchical surfaces, one-level MS, dual-level MMS, NS, and the hybrid

complex structures containing inorganic inverse opal SiO2 nanostructures.

Figure 14. Schematic representation of the (1) transferring and (2) deposition ink

nanoparticle precursor on various structured polymer surfaces with further (3)

solidification. (The scheme is not drawn to scale).II, III

dipping

ink

(1) (2)

Z axis

Y axisX axis

3D polymer substrate, with cycle repeating

multileveled 3D polymer substrate, with cycle repeating

AAO polymer substrate, with cycle repeating

multileveled 3D polymer substrate containing inverse opals, with cycle repeating

dipping

ink

(3)

(3)

(3)

(3)

24

3.2.1. Ink deposition onto micro- and micro-microstructures

Figure 15 shows the optical microscope images of one-level PP micropit and dual-level

PLiPT PP with the deposited silver nanoparticle ink and corresponding images of those

substrates with solidified silver nanoparticles.

Figure 15. Optical images of the deposited silver nanoparticle ink array on a 3D and 3D

multilevel polypropylene surface before and after solidification processes.II

The deposition of the ink solution into the one-level micropit is similar to the

microstructuring of the dual-level structure with pits inside the pits (PTiPT). Thus, firstly

the micropits are structured on PP surfaces with large sized needle, and then the needle

is replaced with the smaller sized needle for further ink deposition within the structured

micropits. The coordinates should be adjusted so that the needle transfers and precisely

deposit the ink into the micropits, gently touching only the bottom part of the micropit.

Furthermore, it is very easy to obtain the ink microarray on even more complicated

pillars inside the pits (PLiPT) surface. With a simple changing of the absolute depth (z-

value), it is possible to deposit ink on the top of pillars of various heights. Figure 15

demonstrates that while depositing the ink with the needle, whose size corresponds to

the size of the micropillar, the silver ink overlaps the micropillar. Thus, the

microworking deposition technique is applicable when the overall surface of the

micropillar needs to be functionalized. On the other hand, with a needle, which is smaller

than the micropillar diameter, it is possible to deposit ink only on the top part of the

micropillar. However, some minor leak of the ink may occur arising from fluctuations

upon transferal to the oven for silver nanoparticles sintering process. The deposition

technique is applicable for deposition of an extra small volume of ink onto

microstructured surfaces under highly precise control.

25

Different metal inks were tested for the hierarchical patterning, such as gold and silver.

Figure 16 shows the SEM images and EDS spectras of the obtained particles on top of

the PLiPT PP structures.

Figure 16. The EDS spectrum and SEM images (inserts) of (a) silverII and (b) gold

nanoparticles formed after polyol reduction on the PP substrates.

Depending on the sintering conditions and the metal concentration in the ink precursor,

different shapes of the particles can be obtained. Thus, in the case of silver nanoparticles,

the round shape particles after thermal treatment are sintered together to form small

clusters (Figure 16, a). In the case of gold structures, single anisotropic gold

microparticles were obtained (Figure 16, b). The obtained rounds-shaped and the

anisotropic particles add an additional hierarchy level to the PLiPT topography.

3.2.2. Ink deposition onto nano- and micro-nanostructures

Figure 17 shows the optical image of silver nanoparticle micropatterns on the AAO

nanostructured PP substrate (Figure 17, a) and within the microstructured PP substrate

containing SiO2 inverse opal (IO) thin film (Figure 17, b).

Figure 17. The optical microscope image silver nanoparticle micropatterns (a) on the PP

nanostructures replicated from AAO mold and (b) within the PP micropits containing

SiO2 IO thin film.

26

One can see from (Figure 17, a) that the micropattern obtained on AAO nanostructured

PP substrate is similar to the micropatterns on flat surfaces (Figure 11). The deposition

process is also similar, because the differences between nanostructured and flat surfaces

are on a nanoscale and do not influence the dip-painting process.

Furthermore, the dip-painting is also applicable for painting within the micropits

containing different inorganic compounds. Thus, Figure 17, b illustrates the silver

nanoparticles deposited within the micropits containing SiO2 IO thin film. Since the SiO2

layer is on a nanoscale, the deposition of nanoparticles is similar to the deposition within

a one-level microstructure.

The dip-painting controlled deposition has proven to be a versatile method for placing

different components on specific locations, thus, overcoming the limitations of ink

patterning when precise patterning on complicated surfaces is needed. Moreover, with a

simple exchange of the needle it could be possible to create multi-component

hierarchical structures. This cheap and effective method opens new horizons for

fabrication of new functional flexible devices.

27

4. APPLICATIONS

4.1. SELECTIVE EMBEDDING

Selective three-dimensional chemical anisotropies were successfully fabricated within

topographically microstructured polymer surfaces with the aid of selective

hydrophilization. Enhanced hydrophilicity on both bottom and sidewalls of the micropits

provides three-dimensional anisotropic wetting and enables one to embed polar solvents

within the micropits. Figure 18 shows the embedded glycerin/water solution on PP and

HDPE chemical anisotropies created with a selective CPO hydrophilization process.

Figure 18. Optical microscope images of glycerin/water mixture filled on (a) pristine

microstructured (1) PP and (2) HDPE surfaces, and their (b) three-dimensional

wettability anisotropies obtained with a selective CPO process.I

One can see from Figure 18 that polar liquid tends to fill the micropits. Moreover, on

the pristine polymer surfaces the liquid mostly tends to have a convex shape (Figure 18,

a), while on the selectively hydrophilised the shape of the liquid is concave (Figure 18,

b). The differences on the liquid shape within pristine and hydrophilised micropits can

be attributed to the surface wetting properties of the micropit sidewall. Thus, on the

surfaces where selective hydrophilization did not take place, the liquid has a convex

shape due to the hydrophobic properties of the plastics and its high contact angle value.

While on hydrophilised surfaces, the liquid has a concave shape, revealing high

wettability. Therefore, on the hydrophilised surfaces liquid fully fills the micropits,

offering potential applications for lubricant retention.80

Selective embedment of the polar medium within three-dimensional anisotropies may

be a powerful tool for controlling the microenvironment of the media. Thus, the three-

dimensional chemical anisotropies were examined by spreading a NaCl solution onto

28

the microstructures, as an imitation of embedding the polar cell culture medium. For this,

the solution of NaCl was spread with a pipette onto the microstructures, leaving the

solidified NaCl crystals within the micropits. Figure 19 shows pristine and three-

dimensionally hydrophilised PP and HDPE surfaces filled with the NaCl crystals.

Figure 19. Optical microscope images of NaCl crystals spread onto the (a) pristine (1)

PP and (2) HDPE and (b) their three-dimensional anisotropies obtained with a selective

CPO process.I

It can be seen from Figure 19 that for both cases, the amount of NaCl crystals that filled

the micropits is larger on selectively hydrophilised surfaces (Figure 19, b1 and b2) than

on the pristine substrates (Figure 19, a1 and a2). Moreover, the amount of crystals on

the hydrophilised HDPE surface (Figure 19, b2) is larger compared to the hydrophilised

PP surface (Figure 19, b1). This can be explained by the fact that the water CA value of

HDPE surface is lower than that of the PP surface (Table 1).

The selective embedment of the polar medium within three-dimensional anisotropies

may possibly meet potential applications in cell culturing, shape confinement, and

crystal growth. Cells and other biomolecules, such as proteins and peptides, prefer to

adhere to surfaces that are hydrophilic. For example, Myllymaa et al. showed that a

hydrophilic coating on structurally modified polymer surfaces significantly improved

the adhesion, spread, and contact guidance of osteoblast type cells.81 Thus, the obtained

three-dimensional wettability anisotropies may serve as a platform for an in vitro

scaffold for cell culture, such as spreading, proliferation, and differentiation.

29

4.2. PROTECTIVE MICROENVIRONMENT

Activation of the inert C-H bonds facilitates surface functionalization with various

compounds, such as biomolecules, inorganic thin films, and particles. Conventionally

the inorganic materials such as SiOx82 and ZnO83 can be patterned on the substrates with

the aid of the photomask. Fabricated patterns have applications, for example, in gas

sensors84 and semiconductor devices.85 Although the adhesion at the solid-solid interface

is fair, it is very easy to damage the adhered brittle inorganic materials via mechanical

influences from the environment. Embedding the inorganic materials within the

micropits may protect brittle nanoparticles from such environmental action. Moreover,

3D structure of the micropits enlarges the surface area of the deposited material in

comparison to the 2D planar surfaces.

The inorganic materials have been successfully embedded within three-dimensional

anisotropies. Thus, SiO2 inverse opals (IO) were selectively embedded within three-

dimensional PP chemical anisotropiesIII with the use of polystyrene (PS) spheres as a

sacrificial template.86 Figure 20 shows SEM images of SiO2 selectively embedded

within the 3D micropits both on untreated and plasma activated PP surfaces.

Figure 20. SEM images SiO2 inverse opals (IO) selectively embedded within the (a)

pristine and (b) hydrophilised microstructured PP surfaces. (1) micropit bottom image

with the close-up images (inserts), (2) micropit wall image, and (3) cross-sectional view

of the SiO2 IO thin film layer.III

Figure 20 shows SiO2 IO covered both on micropit sidewalls and on the bottom of the

3D microstructured PP substrate. On the plasma treated surfaces, the coverage for the

SiO2 IO thin film is much larger than on the pristine PP surface. Moreover, on the plasma

treated surface SiO2 are hexagonally close-packed (Figure 20, b), while on the pristine

PP surfaces SiO2 IO are disordered (Figure 20, a). The better adhesion of SiO2 IO on

the plasma treated seems to be better on the hydrophilised surface than on the untreated

30

surfaces, which can be explained by formation of the active oxygen functional groups

on the plasma treated surface.87

Other than the SiO2 functional layer, ZnO was successfully selectively embedded within

PP micropits. For that, 3D CPO hydrophilised PP substrate together with the applied

grease mesh, was immersed into a solution of zinc nitrate and hexamethylenetetramine

(HMT) for hydrothermal growth88 at 90° C. Figure 21 shows resulting ZnO structures

selectively grown within the PP micropits.

Figure 21. SEM images of ZnO particles selectively embedded within the 3D chemical

PP anisotropies obtained via a selective CPO process.

It can be seen from Figure 21 that ZnO structures are vertically oriented on the bottom

and horizontally on the sidewall of the micropits. Therefore, in 3D microenvironment,

we were able to grow not only conventional vertical ZnO structures, but also laterally

aligned ZnO structures on the micropit sidewalls.

The developed PP micropits, containing metal oxide structures provide potential

applications in the fabrication of hierarchical hybrid inorganic/organic material for

potential sensing applications, for example, in SERS detection. Moreover, the

micropitted PP substrates form a protective microenvironment for brittle and fragile

inorganic compounds, paving a way for potential applications in mechanically robust

polymer hybrid functional materials. To prove this assumption, mechanical robustness

test with a pencil scratch test on the PP micropits compare to the flat PP substrates, both

containing inorganic compounds, was performed.III

4.3. SERS DETECTION

The SERS performance was successfully tested on the complex micro-nanohierarchical

substrate fabricated by combining the selective embedding of SiO2 IO thin film within

the PP micopits and the precise patterning of silver nanoparticles on the surface of the

embedded thin film (Figure 22).III Briefly, PP micropits were selectively hydrophilized

via plasma treatment and applied tape mesh. After that, mixture of a SiO2 precursor and

a PS template dissolved in ethanol was selectively embedded within the micropits. The

PS template was removed with the use of toluene leaving a SiO2 IO thin film layer86 on

31

the surface of the micropits. Further, the silver ink nanoparticle was precisely deposited

with the aid of a microworking robot needle on top of the SiO2 IO thin film.

Figure 22. Schematic representations and SEM images of silver nanoparticles

selectively embedded within the PP micropits containing a SiO2 IO thin film (Ag/SiO2

IO/PP).III

For SERS studies, the obtained micro-nanohierarchical substrate (Ag/SiO2 IO/PP) was

tested with the 4-aminotheophenol (4-ATP) as a probe molecule. As a reference, a flat

PP substrate with the deposited silver nanoparticle array (Ag/PP flat) and a micropitted

PP substrate with the deposited within the micropits silver nanoparticle array (Ag/PP

micropit) were used. Figure 23 shows the SERS spectra recorded on these substrates.

Figure 23. SERS spectra of 4-ATP (1×10-5 M) recorded from the various surfaces and

their schematic representations (the schemes are not to scale): (a) Ag/SiO2 IO/PP, (b)

Ag/PP micropits, (c) Ag/PP flat, and (d) all three substrates on the same axis for

comparison.III

32

The SERS studies showed that with the same concentration of the 4-ATP molecule, an

incubation time of three 3 minutes and an equal volume of deposited ink nanoparticles,

the signals of the probe molecule are at the same Raman shift. However, the intensity of

the 4-ATP signal at 1077 cm-1 decreases in the order Ag/SiO2 IO/PP micropits > Ag/PP

micropits > Ag/PP flat. The high intensity Raman signal on the Ag/SiO2 IO/PP micropits

substrate can be explained by the fact that nanoparticles tend to be distributed within the

SiO2 cavities, thus avoiding nanoparticle agglomerations, which cause a quenching of

the SERS hot spots. Moreover, the complex geometry of the micro-nanohierarchical

structure of the substrate impacts on the SERS signal. Thus, the spatial local

concentration of the analyte within the 3D space of the micropit rises, enhancing the

Raman signal. Further, the Ag/SiO2 IO/PP was studied for detection limit. Figure 24

represents the studies of the detection limit of the prepared micro-nanohierarchical

Ag/SiO2 IO/PP substrate. Different concentrations of the 4-ATP analyte molecule were

tested (1×10-5, 1×10-6, 1×10-7 M) for Raman measurements.

Figure 24. SERS spectra of 4-ATP molecule with different analyte concentrations

(1×10-5, 1×10-6, 1×10-7 M) recorded on micro-nanohierarchical Ag/SiO2 IO/PP

substrate.III

Figure 24 shows that the fabricated micro-nanohierarchical Ag/SiO2 IO/PP can detect a

4-ATP molecule at low concentrations (down to 1×10-7 M). Therefore, it can be suitable

for detection of analytes, which are not only in small volumes, but also in low

concentrations. In addition, the fabricated substrates showed sufficient enhancement

factor and good surface reproducibility.III

33

5. CONCLUSIONS

In this study, we introduced new cost-effective methods to texture polymer surfaces and

chemically modify the surfaces by selective modifications. Moreover, we combined both

topographical and chemical modifications together, for the preparation of functional

polymer substrates and demonstrated potential applications for the obtained substrates.

Different surface geometries were created, starting from single level structures to

complex geometries in nano- and microscales. The robotic surface structuring technique

allows one to directly structure the surface with high fidelity on the desired location and

facilitates creation of complex multilevel geometries. The designed topographical

surfaces were used as a substrate for further chemical modifications.

In order to introduce selective wetting properties into topographical polymer structures,

the designed polymer surfaces were selectively modified with the use of UV irradiation

and plasma treatment. To provide three-dimensional selectiveness control, different

meshes were applied during surface treatment. The obtained chemical anisotropies

ensured selective embedding of various polar liquids and functional chemical

compounds, like metal nanoparticles and metal oxides. The fabricated chemical

anisotropies could be used for production of multicomponent functional surfaces

applicable to bio medics and sensor devices.

In addition to surface structuring, the same surface patterning technique is able to change

surface chemistry, by subsequent precise deposition of the chemical compounds onto the

prefabricated surface structures. With the z-axis deposition control, the technique

provides ink deposition not only on flat but also on multilevel geometries. The

subsequent low temperature sintering of the metal ink precursor allowed one to create

metal micropatterns onto the plastic substrates. The demonstrated method may be used

for the fabrication of a multicomponent device with a complex topography.

The combination of the selective embedding together with ink deposition within the

complex topographies yielded micro-nanohierarchical substrates for SERS sensing

applications. Each individual level of the obtained micro-nanohierarchical substrates

influence the SERS sensitivity. Moreover, the confined micropit microenvironment

provides protection from the mechanical wear for the embedded components. The

fabricated substrates contain both organic and inorganic materials and offers a new

platform for fabrication of organic/inorganic hybrid devices.

34

ACKNOWLEDGEMENTS

This study was conducted between 2014-2017 at the Department of Chemistry,

University of Eastern Finland. The financial support provided by the Finnish Funding

Agency for Technology and Innovation (Tekes, Sliding Surfaces), the European

Union/European Regional Development Fund, and the University of Eastern Finland

(Tailored Materials, Organometallic Glow, and NAMBER projects) is very gratefully

acknowledged.

Firstly, I would like to thank my supervisors. I am deeply grateful to Prof. Tapani

Pakkanen for offering me a chance to start my Master’s studies and to continue that

research with my Doctoral studies in a fascinating field of surface chemistry. Your

experience and knowledge, advice and guidance, and talks about Yakutia inspired,

motivated, and helped me to persist throughout the research process. I also owe a debt

of gratitude to Prof. Mika Suvanto for your support, advice, and comments during the

research progress.

My research would have been impossible without the aid and support of Dr. Yu Jiang.

Your constant encouragements and advice helped me not only in research but also in

life. I was amazingly lucky to have such a wonderful colleague, mentor, and officemate!

I would also like to express my gratitude to Prof. Tuula Pakkanen, MSc. Bright Ankudze,

MSc. Anish Philip for their cooperation and creative discussions. I am deeply grateful to

the staff members of the Department of Chemistry, especially Dr. Sari Suvanto, Ms.

Taina Nivajärivi, Ms. Päivi Inkinen, Mr. Urpo Ratinen, Mr. Martti Lappalainen, Ms. Eija

Faari-Kapanen, and Ms. Mari Heiskanen for helping me to solve all the practical matters

and paper work I encountered during both my Master’s and PhD studies.

I owe my gratitude to people with luminescent coats, Kristina and Andrey, for fun times

inside and outside of the University walls, the black-skiing track and tasty lunches we

enjoyed together. I am also thankful for all my colleagues and Master degree students

for creating kind environment at the University. I owe my sincere gratitude to my lovely

friends, Julia, Anssi, Maya, and Varvara. Thank you for being with me throughout all

my ups and downs.

Lastly, but most importantly, words cannot express how grateful I am to my dad Kir,

sister Kira, grandmother Matryona, and my aunt Luidmila. Despite the numbers that

separate us, such as 9000 kilometers and 6 hours in time difference, your collective belief

in me encouraged me every single Finnish day!

Joensuu December 2017

Lena Ammosova

35

REFERENCES

1. L. Xu, C. Chen, G.-J. Zhong, J. Lei, J.-Z. Xu, B. S. Hsiao, Z.-M. Li, ACS Appl. Mater. Interfaces, 2012, 4 (3), 1521-1529

2. M. C. McAlpine, R. S. Friedman, S. Jin, K.-H. Lin, W. U. Wang, C. M. Lieber, Nano Letters, 2003, 3 (11), 1531-1535

3. J. Kaufmann, Procedia Eng, 2015, 112, 140-145

4. Y.-L. Zhang, Q.-D. Chen, Z. Jin, E. Kim, H.-B. Sun, 16, 2012, Nanoscale, 4858-

486

5. H. Gao, H. Yao, S. Gorb, E. Arzt, Mech. Mater, 2005, 37, 275-285

6. A. D. Campo, E. Arz, Chem. Rev. 2008, 108, 911−945

7. A. Vitale, M. Quaglio, S. L. Marasso, A. Chiodoni, M. Cocuzza, R. Bongiovanni, Langmuir, 2013, 15711-15718

8. M. C. McAlpine, R. S. Friedman, C. M. Lieber, Nano Lett., 2003, 3 (4), 443–445

9. R. M. McCormick, R. J. Nelson, M. G. Alonso-Amigo, D. J. Benvegnu, H. H.

Hooper, Anal. Chem., 1997, 69 (14), 2626-2630

10. Y. Wang, B. Bhushan, ACS Appl. Mater. Interfaces, 2015, 7, 743-755

11. M. Ciobanu, A. Siove, V. Gueguen, L. J. Gamble, D. G. Castner, V. Migonne, Biomacromolecules, 2006, 7 (3), 755-760

12. Y.-C. Liao, Z.-K. Kao, ACS Appl. Mater. Interfaces, 2012, 4, 5109-5113

13. S. Y. Lee, S.-H. Kim, M. P. Kim, H. C. Jeon, H. Kang, H. J. Kim, B. J. Kim, S.-M.

Yang, Chem. Mater. 2013, 25, 2421-2426

14. L. Peng, S. Zhou, B. Yang, M. Bao, G. Chen, X. Zhang, ACS Appl. Mater. Interfaces, 2017, 9, 24339-24347

15. K. Gerasopoulos, E. Pomerantseva, M. McCarthy, A. Brown, C. Wang, J. Culver,

R. Ghodssi, ACS Nano, 2012, 6 (7), 6422-6432

16. Y. Jiang, M. Suvanto, T. A. Pakkanen, J. Mater. Chem., 2012, 22(43), 22983-22988

17. D. Mijatovic, J. C. T. Eijkela , A. Berg, Lab Chip, 2005, 5, 492-500

18. J. Zhang, T. Zhou, L. Wen, A. Zhang, ACS Appl. Mater. Interfaces, 2016, 8, 33999-

34007

19. D. J. Guckenberger, T. E. Groot, A. M. D. Wan, David J. Beebea, E. W. K. Young, Lab Chip, 2015, 11

20. F. Dang, O. Tabata, M. Kurokawa, A. A. Ewis, L. Zhang, Y. Yamaoka, S.

Shinohara, Y. Shinohara, M. Ishikawa, Y. Baba. Anal. Chem. 2005, 77, 2140-2146

21. K. W. Kwon, J.-C. Choi, K.-Y. Suh, J. Doh, Langmuir, 2011, 27, 3238-3243

36

22. M. J. Madou, Fundamentals of Microfabrication. The Science of Miniaturization. 2nd ed., CRC Press, USA, 2002, 379-460

23. N. K. Andersen, R. Taboryski, Microelectron. Eng, 2015, 141, 211-214

24. T. Rasilainen, M. Suvanto, T. A. Pakkanen, Surf. Sci., 2009, 603, 14, 152240

25. E. Puukilainen, T. Rasilainen, M. Suvanto, T. A. Pakkanen, Langmuir, 2007, 23,

7263-7268

26. T. Rasilainen, A. Kirveslahti, P. Nevalainen, M. Suvanto, T. A. Pakkanen, Surf. Sci.,

2010, 604, 2036

27. T. Korpela, M. Suvanto, T. T. Pakkanen, Wear, 2015, 328–329, 262-269

28. E. Huovinen, L. Takkunen, M. Suvanto, T. A. Pakkanen, J. Micromech. Microeng.

2014, 24, 055017

29. E. Huovinen, J. T. Hirvi, M. Suvanto, T. A. Pakkanen, Langmuir, 2012, 28, 14747

30. B. Xu, X.-Y. Wu, S.-Q. Ling, F. Luo, C.-L. Du, X.-Q. Sun, J. Adv. Manuf. Technol.

2013, 66, 5-8, 601-609

31. P. Yang, W. Yang, Chem. Rev. 2013, 113 (7), 5547-5594

32. J. S. Mecomber, R. S. Murthy, S. Rajam, P. N. D. Singh, A. D. Gudmundsdottir, P.

A. Limbach, Langmuir, 2008, 24 (7), 3645-3653

33. H.Yasuda, M.Gazicki, Biomaterials, 1982, 3 (2), 68-77

34. P. Yang, W. Yang, ACS Appl. Mater. Interfaces. 2014, 6, 3759-3770

35. L. Cui, A. N. Ranade, M. A. Matos, G. Dubois, R. H. Dauskardt, ACS Appl. Mater. Interfaces, 2013, 5, 8495-8504

36. T. Shen,Y. Liu,Y. Zhu, D.-Q. Yang, E. Sacher, Appl. Surf. Sci. 2017, 411, 411-418

37. S. H. North, E. H. Lock, C. J. Cooper, J. B. Franek, C. R. Taitt, S. G. Walton, ACS

Appl. Mater. Interfaces, 2010, 2 (10), 2884-2891

38. A. K. Riau, D. Mondal, M. Setiawan, A. Palaniappan, G. H. F. Yam, B. Liedberg, S. S. Venkatraman, J. S. Mehta, ACS Appl. Mater. Interfaces, 2016, 8, 35565−35577

39. I. Yilgor, S. Bilgin, M. Isik, E. Yilgor, Langmuir, 2012, 28 (41), 14808-14814

40. S.C. Hamm, R. Shankaran, V. Korampally, S. Bok, S. Praharaj, G.A. Baker, J.D.

Robertson, B.D. Lee, S. Sengupta, K. Gangopadhyay, S. Gangopadhyay, ACS Appl. Mater. Interfaces. 2012, 4, 178-184

41. M. Schwartzkopf, A. Hinz, O. Polonskyi, T.Strunskus, F. C. Löhrer, V. Körstgens,

P. Müller-Buschbaum, F. Faupel, S. V. Roth, ACS Appl. Mater. Interfaces, 2017, 9, 5629-5637

42. S.M. George, Chem. Rev. 2010, 110, 111-131

43. C.E. Hendriks, P.J. Smith, J. Perelaer, A.M.J. Van den Berg, U.S. Schubert, Adv.

Funct. Mater. 2008, 18, 1031–1038.

37

44. A. Mahajan, W.J. Hyun, S.B. Walker, J.A. Lewis, L.F. Francis, C.D. Frisbie, ACS Appl. Mater. Interfaces. 2015, 7, 1841-1847

45. Y.-K. Liu, M.-T. Lee, ACS Appl. Mater. Interfaces, 2014, 6 (16), 14576-14582

46. Y. Chang, C. Yang, X.-Y. Zheng, D.-Y. Wang, Z.-G. Yang, ACS Appl. Mater.

Interfaces, 2014, 6 (2), 768-772

47. A. George, T. M. Stawski, S. Unnikrishnan, S. A. Veldhuis, J. E. Elsho, J. Mater. Chem, 2012, 22, 328-332

48. S. Cui, Z. Dai, Q. Tian, J. Liu, X. Xiao, C. Jiang, W. Wu, V. A.L. Roy, J. Mater.

Chem. C, 2016, 4, 6371-6379

49. L. Ammosova, Y. Jiang, M. Suvanto, T.A. Pakkanen, Appl. Surf. Sci. 2017, 401, 353-61

50. S. Ma, F. Ribeiro, K. Powell, J. Lutian, C. Møller, T. Large, J. Holbery, ACS Appl.

Mater. Interfaces. 2015, 7, 21628-21633

51. J.-T .Wu, S. L.-C. Hsu, M.-H. Tsai, W.-S. Hwang, J. Phys. Chem. C. 2011, 115, 10940-10945

52. S.D. Cronin, K. Sabolsky, E.M. Sabolsky, K.A. Sierros, Thin Solid Films. 2014,

552, 50-55

53. H. Nakashima, M.J. Higgins, C.O’Connell, K. Torimitsu, G.G. Wallace, Langmuir. 2012, 28, 804-811

54. S. Guldin, P. Kohn, M. Stefik, J. Song, G. Divitini, F. Ecarla, C. Ducati, U. Wiesner,

U. Steiner, Nano Lett., 2013, 13 (11), 5329-5335

55. M. Toma, G. Loget, R. M. Corn, ACS Appl. Mater. Interfaces, 2014, 6 (14), 11110-

11117

56. F. Wang, T. Shen, C. Li, Wen Li, G. Yan, Appl. Surf. Sci. 2014, 317, 1107–1112

57. X. Shi, Y. Wang, D. Li, L. Yuan, F. Zhou, Y. Wang, B. Song, Z. Wu, H. Chen, J.

L. Brash, Langmuir, 2012, 28 (49), 17011-17018

58. M. Leitgeb, D. Nees, S. Ruttloff, U. Palfinger, J. Götz, R.Liska, M. R. Belegratis, B. Stadlober, ACS Nano, 2016, 10 (5), 4926-4941

59. Q. Liu, C. Wu, H. Cai, N. Hu, J. Zhou, P. Wang, Chem. Rev., 2014, 114 (12), 6423-

6461

60. R. P. Gandhiraman, V. Jayan, J.-W. Han, B. Chen, J. E. Koehne, M. Meyyappan, ACS Appl. Mater. Interfaces, 2014, 6 (23), 20860-20867

61. L. Polavarapua, L. M. Liz-Marzan, Phys. Chem. Chem. Phys, 2013, 15, 5288

62. S. R. Forrest, Nature, 2004, 428, 911-918

63. F. J. Pavinatto, C. W.A. Paschoal, A.C. Arias, Biosens. Bioelectron, 2015, 67, 553-

559

64. W. Zhao, X. Liu, Y. Xu, S. Wang, T. Sun, S. Liu, X. Wu, Z. Xu, RSC Adv., 2016, 6, 35527-35531

38

65. H. Jiang, S. Alan, H.Shahbazbegian, J.N. Patel, B. Kaminska, ACS Nano, 2016, 10,

10544-10554

66. H. Tekin, J. G. Sanchez, C. Landeros, K. Dubbin, R. Langer, A. Khademhosseini, Adv Mater. 2012, 24(41), 5543-5542.

67. F. Ye, B. Ma, J. Gao, L. Xie, C. Wei, J. Jiang, J Biomed. Mater. Res. B Appl

Biomater. 2015, 103 (7), 1375-1380

68. H. J. Jeon, C. G. Simon Jr, G. H. Kim, J. Biomed. Mater. Res. B Appl. Biomater,

2014, 102 B, 7, 1580-1594

69. G. G. Giobbe, M. Zagallo , M. Riello, E. Serena, G. Masi, L. Barzon, B. Di Camillo,

N. Elvassore, Biotechnol Bioeng. 2012, 109 (12), 3119-3132

70. L. Kang, M. J. Hancock, M. D. Brigham, A. Khademhosseini, J. Biomed. Mater. Res. A. 2010; 93(2), 547-557

71. I. O. Koshevoy, C.-L. Lin, A.J. Karttunen, J. Janis, M. Haukka, S.P. Tunik, P.-T.

Chou, T.A. Pakkanen, Chem-a Eur. J. 2011, 17, 11456-11466

72. C. Luo, Y. Zhang, X. Zeng, Y. Zeng, Y. Wang, J. Coll. Interf. Sci. 2005, 288, 444-448

73. P.J. Yunker, T. Still, M.A. Lohr, A.G. Yodh, Nature, 2011, 476, 308-311

74. S. Karpitschka, F. Liebig, H. Riegler, Langmuir, 2017, 33, 4682-4687

75. H. Hu, R.G. Larson, J. Phys. Chem. B. 2006, 110, 7090-7094

76. S. H. Ko, H.C.P. Pan, C. P. Grigoropoulos, C. K. Luscombe, J. M. J. Fréchet, D.

Poulikakos, Nanotechnology, 2007, 18 (34)

77. M. A. Torres Arango, A. M. Cokeley, J. J. Beard, K. A. Sierros, Thin Solid Films, 2015, 596, 167–173

78. P. Dardano, A. Caliò, V. D. Palma, M. F. Bevilacqua, A. D. Matteo, L.D. Stefano, Materials, 2015, 8, 8661–8673

79. G. Arrabito, B. Pignataro, Anal. Chem. 2012, 84, 5450−5462

80. Y. Jiang, M. Suvanto, T. A. Pakkanen, Surf. Rev. Lett. 2016, 23, 1550097

81. K. Myllymaa, S. Myllymaa , H. Korhonen, M.J. Lammi, H. Saarenpää, M. Suvanto, T.A. Pakkanen, V. Tiitu, R. Lappalainen, J. Mater. Sci. Mater. Med. 2009, 20, 2337-47

82. S. Gan, P. Yang, W. Yang, Sci. China: Chem. 2010, 53, 173-182

83. P. Yang, S. Zou, W. Yang, Small, 2008, 4, 1527-1536

84. Y. Sun, J. A. Rogers, Adv. Mater. 2007, 19, 1897-1916

39

85. M. R. Alenezi, A. S. Alshammari, K. D. G. I. Jayawardena, M.J Beliatis, S. J. Henley, S. R. P. Silva, J. Phys. Chem. C, 2013, 117 (34), 17850-17858

86. M. O. A. Erola, A. Philip, T. Ahmed, S. Suvanto, T. T. Pakkanen, J. Solid State

Chem. 2015, 230, 209-217

87. Z. Zhou, Y. Zhao, Z. Cai, Appl. Surf. Sci. 2010, 256, 4724-4728

88. P. H. L. Aguiar, É. C. Oliveira, S. A. Cruz, Polym. Eng. Sci. 2013, 53 1065–72

Lena Ammosova

DissertationsDepartment of ChemistryUniversity of Eastern Finland

No. 144 (2017)

115/2012 MAKSIMAINEN Mirko: Structural studies of Trichoderma reesei, Aspergillus oryzae and Bacillus circulans sp. alkalophilus beta-galactosidases – Novel insights into a structure-function relationship116/2012 PÖLLÄNEN Maija: Morphological, thermal, mechanical, and tribological studies of polyethylene compositesreinforcedwithmicro–andnanofillers117/2013LAINEAnniina:Elementaryreactionsinmetallocene/methylaluminoxanecatalyzedpolyolefin synthesis118/2013TIMONENJuri:Synthesis,characterizationandanti-inflammatoryeffectsofsubstitutedcoumarin derivatives119/2013 TAKKUNEN Laura: Three-dimensional roughness analysis for multiscale textured surfaces: Quantitative characterization and simulation of micro- and nanoscale structures120/2014 STENBERG Henna: Studies of self-organizing layered coatings121/2014 KEKÄLÄINEN Timo: Characterization of petroleum and bio-oil samples by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry122/2014 BAZHENOV Andrey: Towards deeper atomic-level understanding of the structure of magnesium dichloride and its performance as a support in the Ziegler-Natta catalytic system123/2014 PIRINEN Sami: Studies on MgCl2/ether supports in Ziegler–Natta catalysts for ethylene polymerization124/2014 KORPELA Tarmo: Friction and wear of micro-structured polymer surfaces125/2014 HUOVINEN Eero: Fabrication of hierarchically structured polymer surfaces126/2014 EROLA Markus: Synthesis of colloidal gold and polymer particles and use of the particles in preparation of hierarchical structures with self-assembly127/2015 KOSKINEN Laura: Structural and computational studies on the coordinative nature of halogen bonding128/2015 TUIKKA Matti: Crystal engineering studies of barium bisphosphonates, iodine bridged ruthenium complexes, and copper chlorides129/2015JIANGYu:Modificationandapplicationsofmicro-structuredpolymersurfaces130/2015 TABERMAN Helena: Structure and function of carbohydrate-modifying enzymes 131/2015KUKLINMikhailS.:Towardsoptimizationofmetaloceneolefinpolymerizationcatalystsvia structuralmodifications:acomputationalapproach132/2015SALSTELAJanne:Influenceofsurfacestructuringonphysicalandmechanicalpropertiesof polymer-cellulosefibercompositesandmetal-polymercompositejoints133/2015 CHAUDRI Adil Maqsood: Tribological behavior of the polymers used in drug delivery devices134/2015 HILLI Yulia: The structure-activity relationship of Pd-Ni three-way catalysts for H2S suppression135/2016 SUN Linlin: The effects of structural and environmental factors on the swelling behavior of Montmorillonite-Beidellite smectics: a molecular dynamics approach136/2016 OFORI Albert: Inter- and intramolecular interactions in the stabilization and coordination of palladium and silver complexes: DFT and QTAIM studies137/2016 LAVIKAINEN Lasse: The structure and surfaces of 2:1 phyllosilicate clay minerals138/2016 MYLLER Antti T.: The effect of a coupling agent on the formation of area-selective monolayers of iron a-octabutoxy phthalocyanine on a nano-patterned titanium dioxide carrier139/2016KIRVESLAHTIAnna:Polymerwettabilityproperties:theirmodificationandinfluencesupon water movement140/2016 LAITAOJA Mikko: Structure-function studies of zinc proteins141/2017 NISSINEN Ville: The roles of multidentate ether and amine electron donors in the crystal structure formation of magnesium chloride supports 142/2017 SAFDAR Muhammad: Manganese oxide based catalyzed micromotors: synthesis, characterization and applications143/2017 DAU Thuy Minh: Luminescent coinage metal complexes based on multidentate phosphine ligands

Selective modification and controlled deposition on polymer surfaces

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