Materiais Nanoestruturados e Revestimentos Funcionais para aplicações em Conforto e Segurança, Workshop Fibrenanmics 2012

1. Workshop Fibrenamics na Proteção Pessoal
Universidade do Minho, Campus de Azurém, 24 outubro, 2012
Materiais Nanoestruturados e Revestimentos
Funcionais para aplicações em Conforto e Segurança
Vasco Teixeira , Joaquim Carneiro, Sofia Azevedo, Jorge Neves*
GRF-Functional Coatings Group & * Textile Eng. Dept
Universidade do Minho
Guimarães - Portugal email: vasco@fisica.uminho.pt
Sumário
Nanotecnologia, aplicações e impacto sócio-económico
Materiais Nanoestruturados e Revestimentos Funcionais
Algumas aplicações no conforto e proteção pessoal
“Smart” nanocoatings (Revestimentos inteligentes)
Anti-sujidade, auto-limpantes (self-cleaning)
Termo- e Electrocromáticos
Potenciais aplicações: desafios futuros
Conclusões
Vasco Teixeira

2. GRF- Functional Coatings Group
Innovative nanoscale coating architectures for functional decorative and
smart surfaces
50
10ºC
40
Transmittance (%)
a b 30
) ) 20
10 70ºC
0
500 1000 1500 2000 2500
Wavelength (nm)
Vasco Teixeira

3. Thin film deposition systems
Magnetron Sputtering – DC and pulsed DC mode
Single Magnetron Sputtering Ion Beam Assisted
Multi Magnetron Sputtering Sputtering Deposition
DC and Pulsed DC
RF- insulator materials
DC-Conductive materials Pulsed DC- All
type of materials
Vasco Teixeira

4. Nanotecnologia
A nanotecnologia é uma área de investigação e desenvolvimento
muito ampla e multidisciplinar que se baseia nos mais
diversificados tipos de materiais (polímeros, cerâmicos,
metais, semicondutores compósitos e biomateriais),
estruturados à escala nanométrica (nanoestruturados) de modo
a formar blocos de construção (building blocks) como clusters,
nanopartículas, nanotubos, nanofibras e nanofilmes, que por
sua vez são formados a partir de átomos ou moléculas.
Vasco Teixeira

5. Nanotecnologia e impacto
sócio-económico
A nanotecnologia está a emergir como o campo
mais promissor e de maior expansão de I&D
As expetativas para que a nanotecnologia melhore a
segurança e a qualidade de vida dos cidadãos são
bastante elevadas e por outro lado apresenta um potencial
enorme para novas soluções para problemas industriais
através de técnicas de nanofabricação emergentes.
A Nanotecnologia já começou a ter um considerável impacto
sócio-económico na Europa, EUA e Japão. Segundo alguns
estudos de mercado poderá vir a ser responsável por mais
de 100 milhões de postos de trabalho diretos ou
indiretamente à escala mundial nos próximos 15 anos.
Vasco Teixeira

6. Classes de Materiais Nanoestruturados
Uma grande classe de materiais, com microestruturas moduladas desde
zero a 3 dimensões na escala de comprimento menor que 100 nm
R.W. Siegel, Nanophase Materials, Encyclopedia of Applied Physics, VCH Publishers 1994
Vasco Teixeira

7. % de átomos nas fronteiras de grão em materiais
nanocristalinos
HRTEM image of a region of nanocrystalline palladium
-As variações mais importantes são provocadas não pela ordem de grandeza
da redução no tamanho, mas pelos novos fenómenos observados, que são
intrínsecos ou tornam-se dominantes à nanoescala.
-Estes fenómenos incluem confinamento devido ao tamanho, predominância
de fenómenos de interface (à nanoescala, a relação superfície/volume é
particularmente dominante) e fenómenos quânticos.
Vasco Teixeira

8. Aplicações da Nanotecnologia
• Materiais
– materiais nanoporosos
– materiais nanoestruturados
– nanocompósitos
– catálise
– multifuncionais, moduláveis, materiais inteligentes (smart materials)
• Biotecnologia
– nanosensores, nanoprovas de actividade/função biológica
– máquinas biomoleculares, libertação controlada de farmacos
– bioeletrónica, nanomedicina (nanorobots), tecidos/orgâos artificiais
– materiais auto-organizados (self-assembling)
• Electrónica, ótica e fotónica
– confinamento quântico (pontos quânticos-quantum dots)
– Lasers (comunicações de fibra óptica)
– eletrónica à escala molecular
– eletrónica transparente e flexível
– filmes finos para eletrónica e fotónica
Vasco Teixeira

9. Nanotechnology Applications on textiles
Nanofibres production (ex. electrofiation)
Putting nanoparticles on the fibres
Surface treatment/modification with plasma treatments
Production of nanocoatings on the textile surfaces (ex. by PVD)
The nanocoatings on textiles should have enough elasticity,
resistance to wash and to be functional.
The techniques used to produce this treatments should operate to
compatible temperatures with textiles resistance
Some nanocoatings applications / functionality on textiles:
• TiO2 – UV Protection, photocatalysis effect, self-clean effect, anti-static
• Ag – Antimicrobial activity
• SiO2 – ceramic wear resistant nanocoatings
Nano titanium dioxide and nano-silica are used to improve the wrinkle resistance
of cotton and silk. Vasco Teixeira

10. Nanotechnology Applications on textiles
Incorporation of nanoparticles, such as silver nanoparticles and
carbon nanotubes, can be used to create fibers that are
antimicrobial or have increased strength of electrical conductivity
Other news functions have
been addressed, such as
speciality textiles for medical
therapy. Silver-containing
fabrics have been successfully
investigated for treating
neurodermatitis.
http://www.biomedcentral.com/1472-6750/9/34/figure/F8?highres=y
Silver containing socks have
been reported for preventing
Comparison between
foot odour.
an untreated synthetic The well known UV protective
filament (top) with a property of titanium dioxide has
treated filament
(bottom). The filament also been added to textile
is approximately 10µm fibres.
in width.
Vasco Teixeira

11. IMPACT RESISTANCE
“Liquid Armor” (shear
thickening fluid) – its
nanoparticle based
coating material allows
fabric to remain flexible,
,
but upon impact becomes
hard.
Applications for body
armor vests, helmets,
and gloves.
Vasco Teixeira

12. Anti-sujidade
Superfície super-hidrofóbica
Vasco Teixeira

13. Commercial Applications
• Nano-Care™ Plain-Front Chinos are amazing
trousers that do not wrinkle and, when a glass of
red wine is spilt onto the cream coloured fabric, it
just rolls off! Bonded to the fabric is a durable
stain- and wrinkle-resistant Nano-Care by Nano-
Tex treatment that ensures creases stay in, but
stains and wrinkles stay out.
A well known hydrophobic material is
Polytetrafluorethylen (PTFE) or Teflon. This
material has been used to produce waterproof
clothing such as Gore-Tex, which consists of
several laminated layers surrounding a thin Teflon
membrane.
More recent approaches are based on the use of
nanoparticles and dendrimers.
Nanoparticles such as SiO2 increase the washing
permanence of the textile finish.
Vasco Teixeira

14. Smart nanocoatings – Self-cleaning and anti-dirt surfaces
Water droplets at surfaces: contact angle
θ << 90° hydrophilic surface
θ= 120° hydrophobic surface (e.g. Teflon)
sliding drops, no roll off
θ 180° super-hydrophobic surface
roll off angle 0°
Super-hydrophobic surfaces: “Self-cleaning effect”
-Rolling water drops
act as “mini-wipers“
(flat) hydrophobic surface hydrophobic surface combined -no adhering water drops =>
90°<= intrinsic contact angle θi <=120° with specific surface nano-roughness evaporation residues,
no
contact angle θ 180° “spots”
-self-cleaning
Vasco Teixeira

15. Photocatalytic Activity of TiO2 Sputtered Coatings for
Self-Cleaning Applications
TiO2 - MICROSTRUCTURE AND MORPHOLOGY (SEM) and (AFM)
(a) (b) SEM micrographs showing
the surface morphology of
TiO2 films deposited under
two different sputtering
pressures:
800 nm 800 nm a) pressure of 0.4 Pa;
b) pressure of 0.5 Pa.
AFM 3D images of TiO2 films
deposited under the same
total pressure of 0.5 Pa and
with different iron
concentration:
(a)
(b) a) low iron concentration
Ra. = 1.985 nm Ra = 4.518 nm
Rms = 2.585 nm Rms = 5.697 nm
b) high iron concentration
“Study of the deposition parameters and Fe-dopant effect in the photocatalytic activity of TiO2
films prepared by dc reactive magnetron sputtering”, J.O. Carneiro, V. Teixeira, A. Portinha,
L. Dupák, A. Magalhães and P. Coutinho, Vacuum, Vol 78, 2005, p.37-46
Vasco Teixeira

16. TiO2 -EVALUATION OF PHOTOCATALYTIC
ACTIVITY
90
Transmittance spectra: %T
85
TiO2 coated substrate Rhodamine-B
aqueous solution 80
Mercury 75
tube lamp rhodamine B
15 min
70
30 min
45 min
%T≅65.8
65 60 min
75 min
%T≅63.4 90 min
60
450 470 490 510 530 550 570 590 610 630 650
UV-Vis
irradiating light
λ≅554 nm
c ln (%T 100 )   C 
= ln %  = 4.6 − kt C0 is the initial aqueous RhB
c 0 ln (%T0 100 ) 

  Co 
 concentration, and C is the aqueous
RhB concentration after 15 up to 90
Kinetic first-order reaction: k is the min irradiation time.
apparent photodegradation rate constant
Vasco Teixeira

17. Active nanocoatings
Smart multilayered nanocoatings – smart windows and smart labels
Electrochromic materials change their optical properties
persistently and reversibly under the action of voltage pulses. By
sandwiching the electrochromic material and an ion rich transparent
Carl M. Lampert, Materials Today, March 2004 p.28-35
solid between a layer of a transparent conductor, a very small
potential can induce an electric field that causes ions to cross to the
electrochromic layer and change its colour state.
colour
→
xM + + xe − + WO 3 M x O3
←
bleach DaimlerChrysler Courtesy: C. Granqvist, ChromoGenics
Ferrari
Vasco Teixeira

18. Nanocoatings Ativos
Revestimentos Termocromáticos
Materiais Termocromáticos como
o óxido de vanádio entre outros,
são usados em dispositivos onde a
mudança de propriedades
óticas/cor (reversível) é ativada por
mudanças de temperatura.
50
10ºC
40
Transmittance (%)
30
20
10 70ºC
0
500 1000 1500 2000 2500
Wavelength (nm)
Vasco Teixeira

19. THERMOCHROMIC COATINGS
VO2(M)
T Low T High
Vanadium oxides are a class
of materials with outstanding
physical and chemical
T ~ 68ºC
properties
Reversible
They undergo an abrupt Semiconductor Metallic
transition from a non- Monoclinic phase Tetragonal phase
metallic to a metallic state
with increasing temperature Low ---- IR reflectance --- High
High --- Electrical resistance --- Low
They find technological applications such as:
- optical and electrical switching devices
- light detectors
- temperature sensors
- microbatteries
Vasco Teixeira

20. THERMOCHROMIC COATINGS
Solar control coatings are a technology with growing interest due to the
necessity of improving the energy efficiency of buildings avoiding excessive energy
consumption with cooling systems on summer.
VO2(M) is being considered as
a potential candidate for
application in smart windows
with active solar control for
energy savings
However, I.P. Parkin and T.D. Manning, Journal of Chemical Education 83 (2006) 393-400
- improved transmittances (VIS) and higher thermochromic switch (IR) are required
- doping is necessary in order to decrease the intrinsic phase transition temperature
(~68ºC) to acceptable values (25-30ºC)
- color (yellow-brown) neutralization is also an issue to be addressed
Vasco Teixeira

21. Thermochromic coatings: Pure VO2
λ=2.5 µm
50 50
45 Heating
10ºC
Cooling
40 40
Transmittance (%)
35
Transmittance (%)
30 30
25
20
Ts=63ºC 20
15
10 70ºC
10
5
0
0 10 20 30 40 50 60 70 80 90 100 110 0
500 1000 1500 2000 2500
Temperature (ºC)
Wavelength (nm)
Ts heating/cooling determined by
differentiating the respective curves
Ts = (Ts heating+Ts cooling)/2
Vasco Teixeira

22. Thermochromic coatings: V0.97W0.03O2
λ=2.5 µm
50 50
45 Heating
Cooling 10ºC
40
40
35
Transmittance (%)
Transmittance (%)
30
30
25
20
20
15
Ts = 40ºC 70ºC
10
10
5
0
0 10 20 30 40 50 60 70 80 0
500 1000 1500 2000 2500
Temperature ºC
Wavelength (nm)
W doped films with different switching temperatures (e.g. 20 to 60ºC)
and max. transmittance over 40%, in the visible, can be easily
obtained by reactive magnetron sputtering.
Vasco Teixeira

23. Biomimetic Textiles using Nanocomposites
Chameleon Effect Thermocromic Pigments can be used to change
the colour state of textile materials.
Changes from colour to colourless states as
Heating
temperature rises.
Cooling With decreasing temperature, the colour returns.
The pigment is encapsulated in aqueous conditions
and the resultant pigment is in slurry form.
SHELL
(Polymer material) Vasco Teixeira

24. Self-Cleaning textiles using biodegradable fibers: Poly(lactic acid)
- PLA
Poly(lactic acid) (PLA) is a biodegradable
polymer which consists of linear aliphatic
thermoplastic polyester derived from 100% of
renewable sources such as corn.
PLA is used broadly in textile applications due to
the fact that PLA is biodegradable and its life
SEM micrographs of TiO2 coated surface of PLA textile fibres:
cycle potentially reduces the Earth’s carbon
(a)—without washing treatments; (b)—with washing treatments.
dioxide level.
Ra = 6.76nm
Rms = 9.16nm AFM image of TiO2
Photocatalytic Ability nanocoating
produced via
Pulsed Magnetron
Sputtering (PMS).
Development of
Super-hydrophobic
Textile Surfaces
Vasco Teixeira

25. Scanning Electronic Microscopy (SEM)
and Atomic Force Microscopy (AFM
PLA fiber without plasma treatment
PLA fiber with plasma treatment
V. Teixeira, Invited talk at NATO Advanced Research Workshop on “Textile Composites”,
May 18-21, Kiev, Ukraine
Vasco Teixeira

26. Hidrophobicity of PLA fabrics
Contact angle for the Contact angle for the PLA
non treated PLA fabric fabric treated with PVD
plasma
Vasco Teixeira

27. Scanning Electronic Microscopy (SEM/EDX)
and Atomic Force Microscopy (AFM)
TiO2 Nanocoating on PLA fibers
without plasma treatment TiO2 Nanocoating on PLA fibers
V. Teixeira, Invited talk at NATO advanced research workshop on
with plasma treatment
“Textile Composites”, May 18-21, Kiev, Ukraine
Vasco Teixeira

28. PLA Fabrics - Antibacterial Properties
PLA fabric without nanocoating PLA fabric with TiO2 nanocoating
did not show bactericide activity shows 100% bactericide activity
Vasco Teixeira

29. Wearable Electronic Textiles
Transport and
automotive industries is
one of the largest that
benefits from interactive
electronic and technical
The ”life jacket” is a medical devise worn
Textiles (heating, anti- by the patient that consequently reads their
odour). They have uses blood pressure or monitors the heart rate;
in space shuttles, the information is transferred to a computer
aircraft and racing cars. Medical and read by medical staff.
Automotive &
Transport Entertainment
Interactive
Textiles Club wear that reacts to
movement, heat and light.
Clothing
Sportswear
/Leisure
Gloves that contain
heaters, or built in Military
LED’s emitting light
so that a cyclist can Some sports clothing
be seen in the dark. such as car and motorbike
Voice active wearable racing also astronauts
computers that enable the user suits contain integrated
to work hands free whilst electronic components.
operating machinery etc... Vasco Teixeira

30. Potential Applications: Future Challenges
A nanocoating that could possibly have the ability to self
heal (self-repairing function)
Textile surfaces which can remove surface scratches
and scuff marks; repel insects; and decolorize red wine
stains are under development
Nanotechnology is being used to develop “sensorized”
garments with the ability to monitor body temperature
and vital signs
Bioreactive polymeric coatings are being developed to
protect the wearer against biological and chemical
attacks
Military uniforms are being developed that will change
colors on command to camouflage the user Vasco Teixeira

31. CONCLUSÕES
Filmes finos eletro- / termo- cromáticos capazes de modular a
cor das superfícies têxteis, e controlar o fluxo de calor.
Revestimentos nanoestruturados e filmes finos para superfícies
inteligentes (implantes biomédicos, auto-limpante, anti-
microbianas, auto-regeneração, dispositivos sensoriais e de
nanodiagnóstico médico).
Superfícies nanograduadas e nanocompósitos com
incorporação de nanopartículas (p.ex. filmes de dióxido de
titânio com pigmentos orgânicos, fibras têxteis com nanopartículas
– libertação controlada de aromas e/ou fármacos).
Sistemas para eletrónica flexível: sistemas ultra-eficientes de
energia, células solares de última geração nano, integração de
sistemas fotovoltaicos e OLED’s em superfícies flexíveis,
nanofilmes e tratamentos plasma para polímeros e têxteis.
Vasco Teixeira