electroactive polymers slm f

8/3/2019 Electroactive Polymers SLM F

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ELECTROACTIVE POLYMERS:

Insight, Applications and Challenges

MIICS 2008

V. Sencadas, J.Gomes, S. Lanceros-Mendez

Physics Department University of Minho


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Summary

ElectroactivePolymers Overview

PVDF Polymer Other SmartMaterials

ProcessingTechniques

CharacterizationTechniques

Applications Partners


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Multifunctional materials: the same material haveseveral functionalities e.g. sensor/actuator

Smart materials: respond to an excitation force with asignificant (and reproductive) variation of a given physical property

Smart structures: structures with increased functionality(e.g. failure detection and warning (even repairing); health monitoring;MEMS)

Introduction


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Electroactive Polymers:

Overview Materials that respond, in reproducible and stable form, with a significant

external variation in certain property when subjected to an external stimulus.

Stimulus Answer

Stimuli: Mechanical Electric

Thermal

Answer: Mechanical Electric


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WhyPolymers

Are lightweight,flexible and tough

Can be obtained in the formof ultrathin films, fibers andeven liquid crystals

Can be easily

transformed intoto the desiredconfiguration

Their physical properties can be

controlled over a wide range byappropriate chemical modifications

Some of them arebiocampatible.

Some have piezo-, pyro- andferroelectric properties


Overview


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Piezoelectric and Pyroelectric Polymers

3,2,1,,

=

=

jiTEj

iij

Pd

T

Pp

=

Dynamic response

electric field)3 (direction of the applied

1 (direction of the mechanical force)2 (perpendicular to the mechanical force direction)


Overview


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NASA Space Centre, ICASE PIEZOElectric Materials, 2001


Overview


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Material

(g.cm-3)

r

(1kHz)

d31

(pC.N-1)

p(mC.m-2K-

1)

k(%)

PVDF 1,76 8-13 20 40 6P(VDF-TrFE) 1,9 15 20 15 30 30 - 40 20

Nylon 11 1,1 4 3 3 _ _ _

PZT-5 7,75 700 171 60-500 34

BaTiO3 5,7 1700 78 200 21

Quartzo 2,86 4,5 2 _ _ _ 9


Overview


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Crystalline

Region

AmorphousRegion

Spherulite Nucleus

MaterialsPVDF Poly(vinylidene Fluoride)

Phase -

PVDFPhase - Phase - Phase -


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Monomer

-PVDF -PVDF

PVDF Poly(vinylidene Fluoride)


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Processing conditions enable the control of the materials properties:

MorphologyFerroelectricBehaviourMechanical

Properties

CrystallinePhase

Thermalproperties

6.0 6.5 7.0 7.5 8.0


-10

0

10

20

140C

142.5C145C

147.5C

Q/mW

time / min

.


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140C 150C

Crystallization kinetics: Phase and microstructure formation

0 20 40 60 80 100 120 140 160 1800

10

20

30

40

50

60

70

80

Radius/m

time / min

-PVDF 150C-PVDF 155C-PVDF 160C-PVDF 165C-PVDF 160C-PVDF 165C

160C 165C

150 155 160 165

-3

-2

-1

-5.6

-5.2

-4.8

-4.4

Ln(G)/m.min-1

Ln(G)/m.min-1

T / C

-PVDF

-PVDF


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0 100 200 300 400 500 600 700

0

3

6

9

12

15

R = 5R = 4R = 3R = 2

/

MPa

/ %

R = 1

R = 1

R = 3 R = 4

R = 5

0 5 10 15 20 25

0

2

4

6

8

10

12

-1.00E-009

0.00E+000

1.00E-009

2.00E-009

3.00E-009

Tenso

/MPa

/ %

V/V

Transio de fase?

V

AAKK

A

F += )/()(

1 2 3 4 5

0

20

40

60

80

140C

100C

80C

F()/%

R

90C

Some Results: to phase transformation


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400 500 600 700 800 900 1000

0

20

40

60

80

(442)

(510)

(600)

Transmitncia/%

Nmero de onda / cm-1

(840)

PCT/IB 2006052474

Some Results: 100% phase material

R l


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-60 -30 0 30 60 90 120 150

0

1000

2000

3000

4000

5000

6000

7000

E'/MP

a

Temperature / C

-PVDF80C R=5 80C R=5 140C R=5 140C R=5

Results

-50 0 50 100 150

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

Tan

Temperature / C

-PVDF80C R=5 80C R=5 140C R=5 140C R=5

Dynamical Mechanical Behavior

All samples have similar mechanical behaviour

E is higher for the unoriented samples (-PVDF) A relaxation process is detected at T -35 C. This process, has been labelled ora.It is assigned to the cooperative segmental motions within the main chains of theamorphous regions

Above 50C (for the stretched samples), a new relaxation process appears associated

to -relaxation. Absent in amorphous PVDF.

R l


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Results

-100 -50 0 50 100 1500

5

10

15

20

25

30

0.00

0.25

0.50

0.75

1.00

'

T / C

-PVDFT80R5

T140R5

Tan

0.0030 0.0033 0.0036 0.0039 0.0042 0.0045-5

0

5

10

15

20

ln()/Hz

1/T / K-1

80C

90C

100C

140C

R = 5

0.0030 0.0033 0.0036 0.0039 0.0042 0.0045-5

0

5

10

15

20

ln()

1/T / K-1

R1

R4

R5

T = 80C

Dielectric Behavior

Increase of the dielectric constant with increasing

-phase content.

Effect of stretching temperature in the relaxationbehavior is much lower than the effect of thestretching ratio.

Phase content and orientation (mainly) play a veryimportant role on the relaxation parameters.

R lt


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80C 0 Ea TVF Tg mR s-1 eV K K

1 1.84E-10 0.061 200.40 226.42 102.10

4 9.2E-11 0.073 208.90 239.57 94.03

5 2.77E-11 0.087 193.92 228.67 82.65

R5 0 Ea TVF Tg mT (C) s-1 eV K K

80 2.77E-11 0.087 193.92 228.67 82.65

90 2.2E-11 0.085 195.92 229.84 85.75

100 6.54E-11 0.071 201.64 230.99 95.92

140 9.31E-11 0.070 199.47 229.11 99.29

Results

= )(exp0 VFBaTTk

E

2

0 )/1)(10(ln

/

g

gVTF

TT

kTE

m =

VFT

Fragility parameter

VFT Fitting Results

R lt


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Results

-100 -50 0 50 100 150

0.00

0.15

0.30

0.45

0.03

0.06

0.09

0.12

0.15

T

an

Tan

T / C

-PVDFT80R5

T140R5

0.0030 0.0033 0.0036 0.0039 0.0042 0.0045

-15

-10

-5

0

5

10

15

20

ln()

1/T / K-1

R1

R4

R5

T = 80C

Dielectrical vsDynamical Mechanical

-100 -50 0 50 100 1500

5

10

15

20

25

30

0

1000

2000

3000

4000

5000

6000

7000

'

T / C

-PVDFT80R5

T140R5

E/MPa

The -relaxation is identified by an increase of E

anda corresponding decrease of , i.e. anincrease in the mechanical stiffness and adecrease in the dipole mobility

The -relaxation is mainly observed in themechanical experiments, especially in themeasurements performed parallel to the drawdirection.

R lt


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0.0030 0.0032 0.0034 0.0036 0.0038 0.0040 0.0042 0.0044-15

-10

-5

0

5

10

15

20

ln()

1/T / K-1

Dielectric

Mechanical - Paralel

Mechanical - Perpendicular

0.0034 0.0036 0.0038 0.0040 0.0042 0.0044

-8

-4

0

4

8

12

16

ln()

1/T / K-1

Dielectric



0.0032 0.0034 0.0036 0.0038 0.0040 0.0042 0.0044-12

-8

-4

0

4

8

12

16

ln()

1/T / K-1

Dielectric

Mechanical - ParalelMechanical - Perpendicular

0.0032 0.0034 0.0036 0.0038 0.0040 0.0042 0.0044-8

-4

0

4

8

12

16

20

ln()

1/T /K-1

Dielectric



90C

140C

Dielectrical vs Dynamical MechanicalResults

80C

100C


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-1,2x108-6,0x10

7 0,0 6,0x107

1,2x108

-8,0x10-2

-6,0x10-2

-4,0x10-2

-2,0x10-2

0,02,0x10

-2

4,0x10-2

6,0x10-2

8,0x10-2

E=100MV/m; =10HzE=130MV/m; =10Hz

E (V/m)

P (C/m2)

Field

(kV/mm)

(Hz) 33 d33(m/V)

1 67 12 23e

-12

-1,2x108-6,0x10

7 0,0 6,0x107

1,2x108-1,8x10

-2

-1,5x10-2

-1,2x10-2

-9,0x10-3

-6,0x10-3

-3,0x10-3

0,0E=100MV/m; =10HzE=130MV/m; =10Hz

E (V/m)

S

-8,0x10-2

-4,0x10-2 0,0 4,0x10

-28,0x10

-2-1,8x10-2

-1,5x10-2

-1,2x10-2

-9,0x10-3

-6,0x10-3

-3,0x10-3

0,0

E=100MV/m; =10HzE=130MV/m; =10Hz

s

P(C/m2)

Optimization and origin of the electroactive

properties

O


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Non-poled

Optimization and origin of the electroactiveproperties

300nm

300nm

-5.00E-05

-4.50E-05

-4.00E-05

-3.50E-05

-3.00E-05

-2.50E-05

-2.00E-05

-1.50E-05

-1.00E-05

-5.00E-06

0.00E+00

-80 -60 -40 -20 0 20 40 60 80


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Smart Materials

Other Smart Materials being developed:

Conductive Polymers (PANI, Ppy, PEDOT:PSS)

Polymer-matrix (PVDF) composites

PVDF Ag nanoparticle composites

PVDF-PZT composites

PVDF- Carbon nanotubes/ Carbon nanofibre composites

Polymer-matrix (PVDF) Magnetoelectric composites

Piezoresistive Materials


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Processing Techniques

Sheet Extrusion(Thin Film)

TricomponentExtrusion

Electrospinning /Meltspinning

Spin Coating Inkjet Printing PVD


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Characterization Techniques

Microscopy

SPM -AFM SEM OpticalMicroscopy


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Characterization Techniques

Electrical Analysis

Mechanical and Thermal Analysis

FerroelectricProperties

Conductivity EFM, MFM,PFM

DielectricSpectroscopy

DSC-TGADMA Stress - Strain


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Applications

Key features of Piezoelectric Polymers:

Low density

Multi-Shape possibilities

High flexibility

Ideal for wearable sensor actuator applications

Low cost (processing and materials) Tunability


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Applications

Vibration Monitoring

Airplane Wings Buildings and Structures

Bio Sensors

Electroactive Scaffolds

Implant healt monitoring systems

Physiological condition monitoring (heart rate, temperature)

Wearables

Flexible and Transparent Touchpads in clothing

Flexible microphones Flexible sensor-actuators in footwear


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Applications

Energy - Electronics

Photovoltaic Solar Cells (EU funded project) Energy generating devices

Upgraded Electronic devices

Multimedia Flexible and Transparent Touchpads and Touchscreens

Electrochromic effects

Interactive Structures

Others

Applications involving an electric/mechanical stimuli

resulting in an electric, mechanical, optic or thermalresponse

Fl


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Flux sensor

Sensor based on the Doppler Effect.

One ultrasound transducer emits ultrasounds, at a frequency of hundreds of

kHz, through the flow. The particles suspended in the liquid reflect the

ultrasounds to a second transducer that will receive them.

Pipe

Flow direction

UltrasoundsUltrasoundtransducer

Ultrasound

transducer

Suspendedparticles

Pipe

Flow direction

UltrasoundsUltrasoundtransducer

Ultrasound

transducer

Suspendedparticles


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Challenges

Optimization of the electroactive response

Optimization of physical properties copolymers and blends;doping

Multifunctional materials:

Adding metallic nano-particles (Optical properties)Adding carbon nano-fibers and nanotubes (thermal andelectrical properties)

Processing in the form of film or long/short fibers

Processing porous or nonporous material

Processing of ultrathin films (10 100 nm)

1.4m

Application Challenges


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Application Challenges

Generation and accumulation of energy (ex. shoe/textile)

Multifunctional actuation (heating, force, )

Flexible sensors (breath, heart, etc), implementation in cloths, etc

Electro-active fibers

Flexible tactile, temperature, form and shape sensors.

Interactive, flexible displays

Electro-chromic

Stimulation or cell growth~ 0.22 0.036 pC/N

800nm


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Partners

National:

-Universidade do Minho

-Universidade de Aveiro

-Universidade do Porto

- CeNTI, Centre for Nanotechnologyand Smart Materials

International:

-University of Halle (Germany)

-University of Postdam (Germany)

-Montana State University (USA)

-Pennsilvania state Unversity (USA)-Universidade Politcnica de Valencia (Spain)

-Universidad del pas Vasco (Spain)

-Universidade Federal de So Carlos (Brazil)Industry:- Amtrol-Alfa;

- Galp (projects); Shoes; Foams (projects);

-MSI;

-Solvay (material)


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Acknowledgments

Bilateral cooperation programs CRUP (Brasil, Spain, Germany)

Portuguese Foundation for Science and Technology (FCT), several project fundings

and PhD grants

COST-12 Structuring Polymers

SIUPI program for up-scaling of processes

Plastinet alpha program from EU

Internet webpage

http://www.arauto.uminho.pt/pessoas/lanceros/ProjectoPiezo/index.html

Special thanks to the Organizers

electroactive polymers slm f

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