understanding microcapsule properties for developing ... zhang... · understanding microcapsule...
Post on 28-Mar-2018
228 Views
Preview:
TRANSCRIPT
-
Understanding Microcapsule Properties for Developing Consumer Products
Professor Zhibing Zhang School of Chemical Engineering University of Birmingham, UK Tel: 0121 414 5334 Email: Z.Zhang@bham.ac.uk
-
Biological and Non-biological Materials (1mm - 1mm)
animal cells yeasts Bacteria fungal hyphae plant cells cell and debris flocs skin cells and
chondrocytes starch granules pollen grains biofilms and food fouling
deposits
microcapsules (encapsulates)
microspheres agglomerates granules textile fibres ice crystals bubbles structured liquids
-
Formulation and Characterisation of functional microcapsules
Pressure-sensitive materials (e.g melamine
formaldehyde perfume capsules; capsules for self healing materials)
Carriers of speciality chemicals (e.g. peroxide, antimicrobial agents, herbicide)
Drugs (water soluble, non-soluble, protein) Probiotic cells (bacteria and yeast) Nutraceutical enzyme (Nattokinase)
-
http://www.scienceinthebox.com/laundry-perfumes-provide-fresh-scents
-
Properties of Capsules
Core and wall chemical compositions Morphology, size and wall thickness Mechanical strength Pore size, structure of wall materials and
release rate Surface charge Adhesion on surface Functionality of active ingredient
-
Formation of a melamine formaldehyde (M-F) wall on the surfaces of oil droplets . Sun and Zhang (2001) J Microencapsulation
M-F wall
Oil droplet
-
352 nm
1m 1m
Transmission electron microscopy (TEM) image of melamine formaldehyde microcapsules. Long, Preece, York and Zhang (2009) J. Mat. Chem.
-
Schematic diagram of the micromanipulation rig
Zhang, Saunders & Thomas (1999) J Microencapsulation
-
-200
0
200
400
600
800
1000
1200
0 1 2 3 4 5 6 7 8 9 10
Probe moving distance, mm
Forc
e, m
N
A
B
C
D E
A: probe touching microcapsuleABC: microcapsule compressedB: pseudo yield pointCD: microcapsule burst and core material
l d
A'
Force versus displacement for compression of a microcapsule to rupture. Sun and Zhang (2001) J Microencapsulation
-
Mercad-Prieto et al (2011a) Chem. Eng. Sci.
-
Micromanipulation to measure the rupture force of single encapsulates and finite element modelling (FEM) to determine their intrinsic mechanical property parameters
20 m
-
FEM Elastic shell Determination of the Elastic Modulus (E): MF encapsulates are known to be elastic at small fractional deformations e < 0.15
The force profile depends on h/r at small fractional deformations
We can estimate h/r using the shape of the force profile
Mercade-Prieto et al. (2011a) Chem. Eng. Sci.
0
0.01
0.02
0.03
0.04
0.05
0.06
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16Fractional deformation
F/Er
h
0.33%1.84%3.23%5.5%7.7%11.1%13.67%
h/r h/r
e
-
Once h is known we can estimate Eh Compare experimental force curve with FEM results at
the appropriate h/r
FEM Elastic shell Estimate Eh
-0.10
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0% 2% 4% 6% 8% 10% 12% 14%h/r
coef
icie
nt b
and
c
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
coef
icie
nt a
bcacba
ErhF
++= ee 2
FEA results:
0.03 < e < 0.1
The experimental Eh is calculated at different fractional deformations
cbarFEh
++=
eee
e 2
-
MF Encapsulates Elastic shell Estimate Eh
150
200
250
300
350
400
450
500
5 10 15 20 25 30 35Capsule size (m)
Eh (N
/m)
Eh is independent of the encapsulate size.
Eh ~355 60 N/m h ~0.2 m
E ~1.8 0.3 GPa
1m
-
MF microcapsules Elastic perfectly-plastic shell
At high deformations (e.g. e > 0.1), MF microcapsules deform plastically
Consider the simplest plasticity scenario: Perfect plasticity
strain
Stre
ss Yield Stress
(Y)
Youngs Modulus (E)
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.0 0.1 0.2 0.3 0.4 0.5Fractional deformation
F/E
rh
FullyElastic
0.035
0.029
0.024
0.021
E / EsY / E
e
Mercad-Prieto et al. (2011b) Chem. Eng. Sci.
-
FEM Determination of rupture parameters
0.0
0.1
0.2
0.3
0.4
0.5
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7Fractional deformation
F/E
rh
sY
0.022 0.49
T ~1 GPa
0.33
E ~7 GPa
~165 MPa
Strain
Stre
sssB~325 MPa
sY
0.022 0.49
T ~1 GPa
0.33
E ~7 GPa
~165 MPa
Strain
Stre
sssB~325 MPa
Mercad-Prieto et al. (2012) AIChEJ
-
Manipulator Electron detector
Particle
Glass cantilever
Manipulator
Tip Slide
Schematic diagram of the nano-manipulation device in an ESEM Liu, Donald and Zhang (2005) Materials Sci. Technol.
-
Ren, Donald and Zhang (2007) Materials Sci. Technol.
-
ESEM (LHS) and TEM (RHS) images of the MF, ripened NP CaCO3 and double shell composite microcapsules Long, Vincent, York, Zhang and Preece (2010) Chem. Commun.
-
Percentage leakage of the core oil from the MF, ripened NP CaCO3 and double shell composite microcapsules over 24 hours
-
Schematic diagram of the release of the inner perfume oil through the microcapsule shell.
Mercad-Prieto et al. (2012) J. Microencapsulation
-
Saturation concentration (cs) of hexyl salicylate in different water-solvent solutions at 220C
-
The corresponding mean P/h values obtained using different cosolvents.
-
Is there any relationship between the fracture strength and oil release rate ?
The fracture strength is mainly determined by the macro-structure. The oil release rate is dominated by the fine structure, particularly for small molecules. ( ) ( )outin)s(out)s(in cch
PcchDJ -=-=
cbaErhF
++= ee 2 0.03 < e < 0.1
Shell thickness h affects both the fracture strength and oil leakage rate!
-
Cantilever and tip Sample surface
Laser diode
Photo detector
Computer and feedback
electronics
3-D Piezo electric stage
Schematic of an AFM set up.
-
SEM image showing an encapsulate (11.9 mm) was attached to a tipless cantilever Liu et al. (2013) J. Adhesion Sci. Technol.
-
Adhesion Investigation by AFM
29
50 m
Schematic representations of steps during a typical force interaction between an encapsulate and a cellulose film.
Encapsulate colloidal probe
Side view
Top view
He et al. (2014) J Microencapsulation
-
30
0
20
40
60
80
100
120
0 0.001% 0.01% 0.10%
Adhe
sion/
nN
Concentration (wt.%)
0.01S10S
Adhesion Force between encapsulates and Cellulose Films
Mean adhesion between 5 encapsulates and a cellulose film before and after being modified with chitosan solution.
-
Schematic Diagram of the Flow Chamber
Syringe Pump Flow Chamber
Computer Camera
-
Fabric Enhancers
Fabric care R&D in Procter & Gamble
Laundry UnitDose
Laundry Liquid Detergents (HDL)
-
Conclusions Perfume microcapsules are required to have non/low
permeability, strong adhesion on fabric surface and optimum mechanical strength.
Functional perfume capsules with different size, structure, surface property, mechanical strength and permeability have be prepared using various formulation and processing conditions to meet industrial needs.
Micromanipulation has been demonstrated to be a very powerful tool to characterise the mechanical properties of capsules and to infer their structure, and their mechanical strength can be used as a trigger to control the release of core materials, e.g. perfume.
-
Acknowledgements Prof. C. R. Thomas, J. Preece, D.
York, B. Vincent, W.E. Hennink and M. Adams
Dr G. Sun, R. Stenekes, W.A. Chan, E.S. Chan, J. T. Chung, Y. Ren, B. Huckle , Y. Long, J. Xue, Y. Yan, A. Fernandez, M. Liu, R. Mercade Prieto, R. Allen, Y. He, F. L. Tchuenbou-Magaia and Y. Zhang
Dr J. Smets, P. Justen, N. Young, M. Gifford and Mr T. Goodwin
-
Sponsors: EPSRC and BBSRC, UK; EU; TSB
The Royal Society K C Wong Foundation; The Royal Academy of Engineering
Arjo Wiggins Research and Development Ltd., UK;
Bayer, Germany; Bavarian Nordic, Germany; Merck Sharp & Dohme, UK; Procter & Gamble, UK, Belgium &
USA, China, Japan and Germany; Unilever, UK and The Netherlands; Probiotics International Ltd., UK; Tithebarn Ltd., UK; IAMS, USA; Roche, Switzerland; Phoqus Ltd., UK;
Rhodia, France; National Starch, USA; Firmenich, Switzerland; Givaudan Schweiz AG, Switzerland
and UK; Appleton Paper Inc. (Encapsys), USA Philips UK Lesaffre France International Favours and
Fragrances, USA DSM, Switzerland Cytec, UK Symrise AG, Germany Lexon, UK Guangzhou Municipal Government Syngenta, UK Mondelez, USA
Understanding Microcapsule Properties for Developing Consumer ProductsBiological and Non-biological Materials (1m - 1mm)Slide Number 3Slide Number 4Properties of CapsulesSlide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Is there any relationship between the fracture strength and oil release rate ?Slide Number 27Slide Number 28Adhesion Investigation by AFMAdhesion Force between encapsulates and Cellulose FilmsSchematic Diagram of the Flow ChamberSlide Number 32ConclusionsAcknowledgements Sponsors:
top related