textiles 1
TRANSCRIPT
NANOTECHNOLOGY IN TEXTILES
INTRODUCTION•nanos (greek) means dwarf•technologies dealing with structures less than 100 nm•1 nm is a trillionth of 1 m (10-9 m)•surface properties play a more important role compared to•the volume properties - therefore:•Richard Phillips Feynman “There is plenty of room at the•Bottom” is considered to be the “father” of nanotechnolgy•interdisciplinary interaction of sciences (physics, chemistry)•therefore nanotechnology is called a convergent technology•nano materials are already of significance today
Nano Products Available in the Market
•pigments (most important)•up-to-date computer chips (nano lithography)•surface functionalisation with nano layers or composites
“self-cleaning” surfaces (“lotus-leaf effect”)•optically functional surfaces for antireflective coatings of displays (“moth-eye effect”)•chemical nano-products already exist for a long time:
like TiO2 or ZnO nanoparticles in sunscreens
•textile research focuses on new functional properties:soil-repellence, UV-protection, abrasion resistance, drug delivery...
SOME APPLICATIONS OF NANOTECHNOLOGY IN TEXTILES
1) Ag (antimicrobial activity)
2) SiO2 (sol-gel, ceramic layers)
3) TiO2 (UV-protection, photocatalysis)
4) bionics: shark-skin effect, self-cleaning surfaces
FUNCTIONAL/INTELLIGENT MATERIALS
functional materials(on the market)
• waterproof, wind-tight, breathable,humidity transportetc.
• optimized materialpropertiese.g. color fastness,tensile and abrasionresistance, heat-proof, cold-resistant
smart materials(in the market)
• smell release orodor control
• advanced wearingcomfort and heatinsulation
• individuallyadjustable heatinsulation
• microcapsules withphase changematerials (PCM)
• reflection materials• EM field protection• UV protection
intelligent materials(under development)
• developments withnew raw materials
• development withadditional electronicfunctions
Antimicrobial Fiber Modification(biochemical effect with nano silver)
antimicrobial body wear
• caused by increasing customerawareness of hygiene
• odor control
• medical applications
• silver nanoparticles in the fiber
• silver nano coating
• high washing fastness• done by electrospinning microfiber
cross section
braced silvercoating on thefiber surface
silver coating
Micro fiber
Ceramic Coating (Sol-Gel-Process)
• matrix-precursor (SiO2 nanoparticles with cross-linking silicium organic compounds)
• functional additives
LyogelSol
Properties:
mechanical: reinforcing, scratch-resistant, antistatic, anti-adhesive
optical: interference colors, UV protection, IR absorption
biological: antimicrobial, medical applications
Xerogel
textile
- solvent Temp.
How to improve the UPF of Textiles(ultraviolet protection factor)
+ fabric design+ tighter weaving or knitting
+ higher weight
+ textile finishing+ organic dyes absorbing UV light
+ optical brighteners (in detergents)
+ dark coloration
+ fiber modification
+ TiO2, ZnO nano pigments for dulling of chemical fibers+ coating is essential to prevent photocatalytic reactions
+ terephthalic acid absorbs in the spectral UV range
+ protection is increased by additional dulling (µ/n-TiO2)+ best protection possible
Polyester (PET, PPT, PBT)
Fiber Raw Materials and UV Protection
Polyamide (PA 6, PA 6,6) - nylon
natural fibers (cotton, wool, linen)) & regen. cellulose fibers (CV, CLY)
+ only „full dull“ types provide good protection
+ little to no protection at all (especially when wet)
+ full dull viscose (TiO2) was available a few years ago
Application of nano TiO2 on Fibers
PA uncoated PA 2 % nano-TiO2 coating
UP
F
UPF after nano TiO2 Coating
UPF Rating according to AS/NZS 4399:1996
60
5050
4035
3030
25
20
1010
5
0
CO (100 %) 142 g/m2 PES/CO (50/50) 125 g/m2 PA (100 %) 97 g/m2
UPF (uncoated)
UPF (2 % Nano-TiO2)
Photocatalytic Degradation of Matter
with TiO2 (Anatase Crystal-Modification)
+ photocatalytic TiO2 nanoparticles in anatase crystalmodification in presence with UV-radiation, water and
oxygen generate free radicals
+ radicals destroy organic substances
+ catalytic process, therefore large and free accessible
surface area (e.g. nano) is required
Photocatalysis
When a semiconductor material is illuminated with
ultra band gap light it becomes a powerful redox
catalyst capable of killing bacteria, cleaning water,
and even splitting water to give hydrogen and
oxygen.
When photocatalyst titanium dioxide (TiO2) absorbs Ultraviolet (UV)* radiation from sunlight or illuminated light source (fluorescent lamps), it will produce pairs of electrons and holes. The electron of the valence band of titanium dioxide becomes excited when illuminated by light. The excess energy of this excited electron promoted the electron to the conduction band of titanium dioxide therefore creating the negative-electron (e-) and positive-hole (h+) pair. This stage is referred as the semiconductor's 'photo-excitation' state. The energy difference between the valence band and the conduction band is known as the 'Band Gap'. Wavelength of the light necessary for photo-excitation is: 1240 (Planck's constant, h) / 3.2 ev (band gap energy) = 388 nm
The positive-hole of titanium dioxide breaks apart the water molecule to form hydrogen gas and hydroxyl radical. The negative-electron reacts with oxygen molecule to form super oxide anion. This cycle continues when light is available.
Fiber Degradation (SEM Image of Polyamide)
Nature as the Role Model:Shark Skin with minimized Flow Resistance
source:
Bionics: Swimmsuits with Shark-Skin-Effect
+ different frictioncoefficients on the fabric(knitted or printed)
+ creation of micro vortices
Soil Repellence (Lotus Effect®)
+ nature as the role model (“bionics”)
+ combination of micro- and nanostructures with lowsurface energy generated by wax crystals
+ such high performance is not achieved by commonfluorocarbon finish
+ water, oil and dirt simply roll off
+ but: structures are sensitive to mechanical stress(scratching, abrasion, washing)
+ effect is lost if structures are damaged
+ nature can re-grow these structures - but textiles not (yet)
Self-Cleaning Process in Nature (1)
hydrophobic surfacehydrophilic surface
nanostructure
for small particles
microstructure
for larger particles
Self-Cleaning Process in Nature (2)
Self-Cleaning on Plants (Spiraea)
species 2species 1
Self-Cleaning on Insects (Rose Beetle)
Self-Cleaning on Insects (Housefly)
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self-cleaning textile coatingwith nanostructured surface
SEM image (top) andAFM surface topography of a lotus leaf
Self-Cleaning on Plants (Lotus Leaf)
source: Schoeller Textiles
Other Advancements
Other Applications
Woven opticalfibers ( screen )
Woven orprinted Bus
Woven or PrintedElectrodes
Silk Organza( Silk + Gold )
EmbroidedNRIKeypad
Circuit onOrganza
SMART TEXTILES
References
Beringer, Dr. Jan (2005). Nanotechnology in Textile Finishing. State of the Art and future Prospects. Hohenstein Insitutes.
McLaughlin, James (2004). Nanotechnology & Its Applications in Textiles. University of Ulster.
Sawhney, P.,Singh, K., Codon, B., Sachinvala, N., and David Hui. Nanotochnology in Modern Textiles
http://www.mchnanosolutions.com/mechanism.html