Electrospinning a Thermoelectric Polymer - Materials Science and ...

ENMA490 

Spring 2012 

By: Natan Aronhime 

Jason Thomen 

Sepi Parvinian 

Chris Wolfram 

Eric Epstein 

Kevin Mecadon 

Komal Syed 

Matt Widstrom 

Electrospinning 

a 

Thermoelectric 

Polymer 

1

2 

Motivation 

People using too 

much energy 

Need renewable 

sources 

http://www.heatingoil.com/category/blog/opec-blog/ 

A tremendous 

amount of energy 

is wasted as heat 

http://www.savewaveenergy.com/store/alternative_energy

3 

Thermoelectrics 

Bismuth Telluride most common 

thermoelectric 

Expensive 

Polymers 

Good electrical conductivity 

Naturally poor thermal conductivity

4 

Design Goals 

Design a thermoelectric device using electrospun 

conductive polymer fibers 

Predict thermoelectric properties of our device 

Target: Power factor on order of PEDOT:PSS thin film 

Power Factor = 4.8 x 10 -6 W/mK 2 

Efficiency = .006% 

Predict size of electrospun fibers based on easily 

measurable processing parameters to within 9% 

error

5 

Intellectual Merit 

Extend dimensional analysis (Helgeson et. 

al. 2008) to electrospinning with carrier 

polymer and asses accuracy/applicability 

Compare conductivity and 

thermoelectric parameters of fibers to 

bulk

6 

Broader Impacts and Ethics 

Wasted heat is almost everywhere 

Efficient conversion of thermal gradient to electricity 

ΔTà ΔV 

Optimization of Thermoelectric properties/minimizing 

cost 

Increase in fiber alignment by stretching during 

electrospinning 

Many thermoelectric devices are either not cost 

effective or use complicated processing techniques 

Some of our solvents can be harmful if released in 

large quantities 

Electrospinning uses very high voltages

7 

Basic Design 

High V 

Power 

Source 

Syringe with electrospinning 

solution 

Glass slide with two 

grounded Cu electrodes

8 

PEDOT:PSS 

http://clevios.com/media/webmedia_local/media/datenblaetter/81076210_Clevios_PH_1000_20101222.pdf 

General Properties: 

Conductive polymer 

Soluble in water 

Thermoelectric Properties: 

Electrical Conductivity (thin film) = 850 S/cm 

Bi 2 Te 3 =1100 S/cm (M. Takelishi et al., Japan Symposium on Thermophysical 

properties, 2006.) 

Seebeck coefficient (thin film) = ~10 μV/K 

Bi 2 Te 3 =287 μV/K (Proceedings of SPIE. 5836, 711)

9 

Material Selection 

Electrospin PEDOT:PSS 

Good electrical properties 

Research reveals pure PEDOT:PSS very difficult to 

electrospin 

Carrier polymer required for electrospinning: 

Polyacrylonitrile (PAN) 

Dopant: Sorbitol 

Copper electrodes 

Lower workfunction than PEDOT-ohmic contact

10 

Materials Science Aspects 

Material Properties 

Processing 

Electrospinning voltage 

Electrospinning flow rate 

Shear thinning 

Electrical conductivity 

Thermal conductivity 

Seebeck coefficient 

Viscosity 

Surface tension 

Dielectric constant 

Polymer entanglement 

Solid State Physics 

Density of states 

Fermi level shift 

Characterization 

SEM 

Tensiometer 

Viscometer 

LCR meter 

Nanovoltmeter 

Materials 

Chemistry 

Weight percent calculations 

Solution miscibility 

Solubility 

Carrier polymers

11 

Technical Approach: VRH 

We will test Variable Range Hopping 

Electrical conductivity: 

σ=σ↓0 exp[−(T↓0 /T )↑γ ] 

PEDOT:PSS and PAN can be arranged 

either in parallel or in series within the fiber 

σ↓Parallel =σ↓PAN φ↓PAN +σ↓PEDOT 

φ↓PEDOT 

σ↓Series =1/φ↓PAN /σ↓PAN +φ↓PEDOT / 

σ↓PEDOT 

Lichtenecker equation is an in-between case 

log(σ↓T )=φ↓PEDOT log(σ↓PEDOT )+φ↓PAN 

log(σ↓PAN )

12 


Seebeck coefficient 

S=k↓B↑2 /2e (T↓0 T)↑1/2 (dlnN(E)/ 

σa>>σb 

dE )↓E=Ef 

ST = Sa 

ST = Sa * σa + Sb * σb 

σa + σb 

Annika Lenz, Hans Kariis, Anna Pohl, Petter Persson, Lars Ojamae. (2011). The 

Electronic Structure and Reflectivity of PEDOT:PSS from Density Functional 

Theory. Chemical Physics, 384, 1-3 

Park, Sungeun, Sung Ju Tark, and Donghwan Kim. "Effect of Sorbitol Doping in 

PEDOT:PSS on the Electrical Performance of Organic Photovoltaic Devices." 

Current Applied Physics 11.6 (2011): 1299-301

13 


Using image J DOS information was extracted around the Fermi 

energy. Optimal Seebeck Coefficient: 6.20E-04 V/K corresponds 

to a Fermi energy shift of 0.075 eV and 1.8% sorbitol.

Electrospinning: Solutions 

Prepared 

Design (Ideal) 

Solution 

-PEDOT:PSS and 

sorbitol in 

EG:NMP 

-PAN in DMF 

-Individual 

solutions mixed 

Diluted 

Solution 

Clevios 

- Successfully 

electrospun 

- Ratio PEDOT:PSS - 7.1 wt% Clevios 

to PAN reduced (water + PEDOT) 

from 5% to 3.34% - 

- Attempted to 

0.08% wt% 

PEDOT 

electrospin: - 8 wt% PAN 

Failed 

- DMF solvent

15 

Background: Electrospinning 

Underlying theory based on 

“electrohydrodynamics” (Taylor & Melcher, 1966) 

In 2001, Hohman et al. predict 3 modes that 

apply to electrospinning/electrospraying: 

Rayleigh mode 

Dominated by surface tension effects 

Applies when low/no electric field 

Axisymmetrical conducting mode 

Whipping conducting mode 

Dominate due to 

surface charge effects 

at high field strengths

16 

Whipping vs. Axisymmetrical Modes 

Decreasing Applied Electric Field 

POLYMER ENGINEERING AND SCIENCE, 2005, 705 

Take-home message: Balance of electromechanical 

stresses with intrinsic stresses within fluid (viscosity/capillary 

stresses) lead to formation of stable jet

Electrospin Modeling: Dimensional 

Analysis (Helgeson et. al. 2008) 

Π= (ε−ε↓0 )E↑2 R↓j↑3 /π 

η↓e Q 

Oh=η↓0 /(ργR↓j )↑0.5 

captures the jet 

dynamics during the 

streching regime 

captures free resistance to jet 

breaking up into droplets and 

surface flow disturbances which 

lead to capillary breakup 

Simplified expression 

(Helgeson et. al. 2007)

Electrospin Modeling: Experimental 

Observations 

Oh=HΠ1↑−m 

Rj ∝ solution parameters 

18 

PEO-water 

PEO-water-ethanol 

poly(ethylene terephthalateco-ethylene 

isophthalate)-chloroform- 

Dimethylformamide 

poly(methyl 

methacrylate)-dimethylformamide 

(Figure from Helgeson et. al. 2007)

Electrospin Modeling: Experimental 

Observations 

Oh=HΠ↑−m 

Rj ∝ solution parameters 

19 

(Figure from 

Helgeson et. 

al. 2008)

Electrospin Modeling: Determination of R j and 

R f relation 

Usually, this approximation made: 

R↓f =R↓j 

w↓p↑0.5 

Derivation from volume conservation: 

20 

w↓p =πR↓f↑2 l↓f /πR↓j↑2 l↓j →w↓p =R↓f↑2 l↓f /R↓j↑2 l↓j 

Wang et. al. 2007 determined experimentally: 

R↓f =R↓j w↓p↑0.9653 =R↓j w↓p↑0.5 

w↓p↑0.4653 ; √⁠l↓j /l↓f =w↓p↑0.4653 

Extra term inverse extension ratio, dominated by solvent 

evaporation


R f relation 

21 

(Data from El-Aufy 2004) 

Limited data, 

differing 

solvent 

evaporation 

ratesà No 

smooth fit 

possible


R f relation 

22 

Estimate solvent 

evaporationà 

qualitatively correct 

fit at low w p (region 

of interest for 

design)à use fit in 

calculationsà 

assume 

R↓f =R↓j w↓p↑0.9653 

(Wang et. al. 2007) 

b/c PAN in DMF is 

dominating the fit 

curve

Electrospin Modeling: Dimensional Analysis 

Helgeson 2007 Plot 

23

Electrospin Modeling: Dimensional Analysis 

Helgeson 2008 Plot 

24

Effect of viscosity: 

Too low viscosity à jet breaks up to polymer droplets 

à electrospraying 

Low viscosity causes formation of beaded fiber 

Very high viscosity à unable to pump the solution 

There is a viscosity range which electrospining is 

effective 

As viscosity increases so does the average fiber 

diameter 

25

Viscosity of Diluted Solution: 

Viscosity was measured by cone 

and plate viscometer 

Data was inaccurate due to 

excessive noise 

Qualitative analysis: 

Electrospinning failed due to 

very low viscosity 

Diluted “solution” turned out to 

be suspension of polymer, not 

solution 

Fluid broke up into droplets rather 

than forming stable Taylor cone

Viscosity Tests on Clevios Solution: 

Viscosity was measured by cone and plane viscometer 

σ= kɵᵒn 

n=0.43 (power law index) 

Shear-Thinning Fluid : 

27 

Still within the window of electrospinning

28 

Electrospinning Result: Fibers 

from Clevios Solution 

Fiber diameter range: 100-250nm

29 

TE Modeling Results: 

σ ll (S/ 

cm) 

σ Li (S/ 

cm) 

PF ll (W/ 

mK 2 ) 

PF Li (W/ 

mK 2 ) 

η ll (%) η Li (%) 

Ideal 

Solution 

Diluted 

Solution 

.125 1.48 E-11 4.79 E-6 5.67 E-16 .006 7.33 E-13 

.103 1.21 E-11 3.98 E-6 4.67 E-16 .005 6.03 E-13 

Clevios .024 5.81 E-12 9.21 E -7 2.23 E-16 .001 2.88 E-13 

Goal: 

PF = 4.8 x 10 -6 W/mK 2 

η = .006 %

TE Measurements on Prototype 

Seebeck Coefficient: S=−∆V/∆T 

Measure using voltmeter and thermocouple 

while heating 

Measured a value of 6.36 μV/K 

Attempted to measure electrical conductivity 

using four point probe: R= l/σA 

Unable to obtain measurements using 4 pt. 

probe

31 

Conclusions: Thermoelectric 

Goals and Insight from Results 

Goal: to fabricate nanofiber TE device 

that rivaled that of PEDOT:PSS thin films in 

terms of Power Factor and efficiency 

Insight from Results: If percolation is 

reached, can obtain similar efficiency to 

a doped PEDOT:PSS thin film 

(Less conductive polymer required)

32 

Conclusion: Electrospinning 

Goals and Results 

Goal: Predict diameter of electrospun fibers based on 

easily measurable processing parameters 

Results: Helgeson model does not fully agree to 

experimental observations of complex systems 

Insight from Results: Dimensional analysis still useful as 

engineering design tool 

Future work: Design electrospinning solution using PEO 

as carrier polymer 

Cleaner environmental impact: use water as solvent 

Obtain accurate trends of dielectric constants, viscosities, 

and surface tension in polymer solutions to make more 

robust model

Facilities 

Dr. Hu – electrospinning device & SEM 

Dr. Rabin – electrical conductivity and Seebeck 

coefficient 

Physics Machine Shop (Setup prepared) and LCR 

meter in Undergraduate Teaching Lab(KIM)- 

Dielectric Constant Measurements 

 

Dr. Calabrese and Dr. Raghvan for rheology 

measurements 

Dr. Phaneuf’s lab for solution preparation

35 

Acknowledgements 

First and foremost, we would like to thank Dr. 

Phaneuf for helping and guiding us throughout the 

semester with this project. In addition, we would 

like to thank all the faculty members who have 

met with us, helped us, and let us borrow their labs 

and grad students. Without these resources, we 

would not have been able to accomplish what 

we did. Lastly, we would like to extend our 

sincerest appreciation to the entire faculty of the 

Materials Science department. It is the education 

and guidance that you provided over the years 

that enabled us to come this far.

References 

[1] Nidhi Dubey and Mario Leclerc. (2011). Conducting Polymers: Efficient Thermoelectric Materials. Journal of Polymer 

Science Part B: Polymer Physics, 49 (7). http://onlinelibrary.wiley.com/doi/10.1002/polb.22206/pdf 

[2] Kaiser, A. B. "Thermoelectric Power and Conductivity of Heterogeneous Conducting Polymers." Physical Review B 40.5 

(1989): 2806-813. 

[3] David K. Taggart, et al. Enhanced Thermoelectric Metrics in Ultra-long Electrodeposited PEDOT Nanowires. Nanoletters, 

2010. 

[4] Farshad Faghani. Thermal Conductivity Measurement of PEDOT:PSS by 3-Omega Technique. Thesis, Linkoping University, 

2010. 

[5] Afaf Khamis El-Aufy. (2004). Nanofibers and Nanocomposites Poly(3,4-ethylene dioxythiophene)/Poly(styrenesulfonate) 

by Electrospinning. (Doctoral dissertation). 

[6] Dale S. Pearson et al. Effect of molecular Weight and Orientation on the Conductivity of Conjugated Polymers. 

Macromolecules Vol. 26, 2003. 

[7] Environmental Fate and Effects of Ethylene Glycol used at Airports. American Chemistry Council. February 2000. 

http://www.huntsman.com/performance_products/media/fate_and_effects.pdf 

[8] G. Long, M. E. Meek, and M. Lewis. N,N-dimethylformamide. World Health Organization, United Nations Environment 

Programme, and the International Labor Organization. 2001. http://www.who.int/ipcs/publications/cicad/en/cicad31.pdf 

[9] Environmental Profile N-Methylpyrrolidone. EPA, 1998. http://nepis.epa.gov 

[10] D. A. Saville. ELECTROHYDRODYNAMICS: The Taylor-Melcher Leaky Dielectric Model. Annu. Rev. Fluid Mech. 1997. 29:27– 

64. 

[11] Moses M. Hohman, Michael Shin, Gregory Rutledge, and Michael P. Brenner. Electrospinning and electrically forced jets. 

II. Applications. Phys. Fluids, Vol. 13, No. 8, August 2001. 

[12] Sergey V. Fridrikh, Jian H. Yu, Michael P. Brenner, and Gregory C. Rutledge. Controlling the Fiber Diameter during 

Electrospinning. Phys. Rev. Lett., 2003, 90, 14, 144502-1-144502-4. 

[13] Matthew E. Helgeson & Norman J. Wagner. (2007). A Correlation for the Diameter of Electrospun Polymer 

Nanofibers. AIChE Journal, 53(1), 51-55. DOI 10.1002/aic. 

[14] Matthew E. Helgeson, Kristie N. Grammatikos, Joseph M. Deitzel, Norman J. Wagner. (2008). Theory and kinematic 

measurements of the mechanics of stable electrospun polymer jets. Polymer, 49, 2924–2936. 

[15] Weiwei Zuo, Meifang Zhu, Wen Yang, Hao Yu, Yanmo Chen, Yu Zhang. Experimental Study on Relationship Between Jet 

Instability and Formation of Beaded Fibers During Electrospinning. POLYMER ENGINEERING AND SCIENCE, 2005, 704-709. 

[16] Nishuang Liu, Guojia Fang, Jiawei Wan, Hai Zhou, Hao Long and Xingzhong Zhao. (2011). Electrospun PEDOT:PSS–PVA 

nanofiber based ultrahigh-strain sensors with controllable electrical conductivity. J. Mater. Chem., 21, 18962. 

[17] Jaewon Choi, Jeongwoo Lee, Jinsub Choi, Dongsoo Jung, Sang Eun Shim. (2010). Electrospun PEDOT:PSS/PVP nanofibers 

as the chemiresistor in chemical vapour sensing. Synthetic Metals, 160, 1415–1421. 

[18] Ali Shakouri and Suquan Li. (1999). Thermoelectric Power Factor for Electrically Conducive Polymers. Proceeding of 

International Conference on Thermoelectrics. http://www.dtic.mil/cgi-bin/GetTRDocAD=ADA459010 

36

37 

References 

 

 

[19] Alexandre Mantovani Nardes, Rene A. J. Janssen, and Martijn Kemerink. (2008.) A Morphological Model for the Solvent-Enhanced 

Coonductivity of PEDOT:PSS Thin Films. Advanced Finctional Materials, 18, 6. 

http://onlinelibrary.wiley.com/doi/10.1002/adfm.200700796/pdf 

[20] N. F. Uvarov. Estimation of Composites Conductivity Using a General Mixing Rule. Solid State Ionics. 2000. 

http://144.206.159.178/ft/959/29907/13356419.pdf 

 

[21] Park, Sungeun, Sung Ju Tark, and Donghwan Kim. "Effect of Sorbitol Doping in PEDOT:PSS on the Electrical Performance of Organic 

Photovoltaic Devices." Current Applied Physics 11.6 (2011): 1299-301. 

[22] Annika Lenz, Hans Kariis, Anna Pohl, Petter Persson, Lars Ojamae. (2011). The Electronic Structure and Reflectivity of PEDOT:PSS from 

Density Functional Theory. Chemical Physics, 384, 1-3. http://www.sciencedirect.com/science/article/pii/S0301010411001571 

[23] Snyder, G. Jeffrey and Tristan S. Ursell. "Thermoelectric Efficiency and Compatibility". Physical Review Letters: Volume 91, Number 14 

2003 

 

 

 

 

 

 

 

 

 

 

 

[24] Abolghasem Jouyban , Shahla Soltanpour, Hak-Kim Chan. (2004). A simple relationship between dielectric constant of mixed 

solvents with solvent composition and temperature. International Journal of Pharmaceutics, 269, 353–360. 

[25] Abolghasem JOUYBAN, Anahita FATHI-AZARBAYJANI, and William Eugene ACREE, Jr. (2004). Surface Tension Calculation of Mixed 

Solvents with Respect to Solvent Composition and Temperature by Using Jouyban–Acree Model. Chem. Pharm. Bull., 52(10) 1219—1222. 

[26] Chi Wang, Huan-Sheng Chien, Chia-Hung Hsu, Yin-Chi Wang, Cheng-Ting Wang, and Hsin-An Lu. (2007). Electrospinning of 

Polyacrylonitrile Solutions at Elevated Temperatures. Macromolecules , 40, 7973-7983. 

[27] Seeram Ramakrishna, Kazutoshi Fujihara, Wee-Eong Teo, Teik-Cheng Lim, & Zuwei Ma. (2005). An Introduction to Electrospinning And 

Nanofibers. World Scientific. 

[28] Ethylene Glycol: Product Guide. (2008). The MEGlobal Group of Companies. Retrieved from: http://www.meglobal.biz/media/ 

product_guides/MEGlobal_MEG.pdf 

[29] J.T. Baker. (2006). MATERIAL SAFETY DATA SHEET. Mallinckrodt Baker, Inc. Retrieved from: http://talasonline.com/photos/msds/ 

MSDS_NMP.pdf 

[30] DIMETHYLFORMAMIDE. (1999). Retrieved from: http://cameochemicals.noaa.gov/chris/DMF.pdf 

[31] Di Zhang, Amar B. Karki, Dan Rutman, David P. Young, Andrew Wang, David Cocke, Thomas H. Ho, Zhanhu Guo. (2009). Electrospun 

polyacrylonitrile nanocomposite fibers reinforced with Fe 3 O 4 nanoparticles: Fabrication and property analysis. Polymer, 50, 4189–4198. 

[32] Ji-Huan He, Yu-Qin Wan, and Jian-Yong Yu. (2008). Effect of Concentration on Electrospun Polyacrylonitrile (PAN) Nanofibers. Fibers 

and Polymers, 9(2), 140-142. 

[33] R. Jalili et al. “Fundamental Parameters Affecting Electrospinning of PAN Nanofibers as Uniaxially Aligned Fibers.” Journal of Applied 

Polymer Science. 101:6, 2006. 

[34] A. M. Summan. Electrical Conductivity of Heat Treated Polyacrylonitrile and its Copper Halide Complexes. Journal of Polymer 

Science Part A: Polymer Chemistry. Vol. 37, Issue 16. Dec. 1998. 

http://onlinelibrary.wiley.com/doi/10.1002/%28SICI%2910990518%2819990815%2937:16%3C3057::AID-POLA2%3E3.0.CO;2-J/pdf

Electrospinning a Thermoelectric Polymer - Materials Science and ...

Create successful ePaper yourself

Delete template?

Save as template?