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Conductive Cellulose Materials Coated with Silver ParticlesKaren RichardsGroup Meeting 05/08/2014

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Introduction Indium tin oxide (ITO)TranslucentConductive

Uses for ITOConductive layer on LCD screens

2Reasons for finding a replacementITO is becoming scarce due to over usage Price is steadily increasing

Proposed ITO replacement Percolating network of silver in cellulose dispersionImmerse polymer in dispersion with silverPress into filmSolar cells

Solar cells

Introduction: cost projections 3

ITO (indium-tin oxide)Coating Cellulose with SilverRoughly $0.25-$0.69 to cover the LDC screen on an iPhone 5Roughly $0.02 to coverthe LDC screen on an iPhone 5

(Kalowkamo J., Baker E., 2009)

Models for mechanical properties4

Percolation modelpercolation on

Takayanagi et al. J. Polym. Sci. 1964, C5, 113. Ouali et al. J. Plast. Rubber Comp. Process. Appl. 1991, 16, 55. Halpin, Kardos J. Appl. Phys. 1972, 43, 2235. Hajji et al. Polym. Comp. 1996, 17, 612. Polymer Eng. Sci. 1997, 37, 1732. Halpin-Kardos / Halpin-Tsai: Mean field approachfibers are smeared into the matrix to form a homo-geneous continuum

0o 45o 90o-45omean field / percolation off

The first method should leads to an electrically conductive material.complete interconnected network of fillers within the matrix

Discuss with Johan on how to change this??4

Introduction: approach 5Coating sulfonated tunicate cellulose aerogel with silverCoating cellulose dispersion with silverSulfonated cellulose dispersion Carboxylated cellulose dispersion Two approachesAll of these methods were tested. The sulfonated cellulose dispersion gave the best results.

Coating tunicate aerogel with silver6

Tunicate cellulose aerogelReducing agent + surfactantNaHBH4 (Reducing agent) CTAB (Surfactant)

AgNO3Reducing agent + surfactant + tunicate cellulose aerogel Silver covered tunicate cellulose aerogelSilver covered tunicate cellulose film+

This three step reaction produces a translucent, conductive film from a tunicate cellulose aerogel.

Coating c-CNC dispersion with silver7c-CNC dispersion c-CNC dispersion coated in Silver particle AgNO3

Water, CTAB (surfactant), NaBH4

This two step reaction produces a c-CNC dispersion coated in silver.Sulfonated c-CNC dispersion

Ask if Johan still wants the video of solution changing color here or on slide 127

Function of reducing agent 8Reducing agent: NaBH4

Sodium borohydride reduces silver nitrate to create a silver particle in situ.

Function of surfactant 9

Surfactant (CTAB) changes the characteristics of the surface of the silver particle. This forms an attraction between the particle and the alcohol groups of the cellulose fiber.

Silver coated c-CNCs and t-CNCs10Sulfonated c-CNCs and t-CNCsCarboxylated c-CNCs

Coating tunicate cellulose aerogel with silver11

LyophilizeCharacterizationt-CNC aerogelImpregnateSEM images suggest the above procedure creates a coating of silver on the aerogel.

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Coating sulfonated c-CNC dispersion with silver12SampleAgNO3 conc. (M)Cellulose conc. (mg/ml)pH before AgNO3additionpH afterAgNO3addition1A1.05.07.987.571B0.55.07.989.091C0.15.07.989.561D105.07.983.282A1.01.09.587.102B0.51.09.588.912C0.11.09.589.42D101.09.585.96

Results indicate a correlation between the amount of AgNO3 added to the dispersion with both the color and pH of that dispersion.

pH change with addition of AgNO313

SampleAgNO3 conc. (M)Cellulose conc. (mg/ml)pH before AgNO3additionpH afterAgNO3addition1A1.05.07.987.571B0.55.07.989.091C0.15.07.989.561D105.07.983.282A1.01.09.587.102B0.51.09.588.912C0.11.09.589.42D101.09.585.96

The chart shows an inverse relationship between the concentration of AgNO3 and the pH of the dispersion.

As the concentration of AgNO3 decreases, the pH increases.

pH change with addition of AgNO314

The chart shows an inverse relationship between the concentration of AgNO3 and the pH of the dispersion.

As the concentration of AgNO3 decreases, the pH increases.

SampleAgNO3 conc. (M)Cellulose conc. (mg/ml)pH before AgNO3additionpH afterAgNO3addition1A1.05.07.987.571B0.55.07.989.091C0.15.07.989.561D105.07.983.282A1.01.09.587.102B0.51.09.588.912C0.11.09.589.42D101.09.585.96

Transmission Electron Microscope (TEM)15

2 m

TEM images of sample 2A with 1.0 M AgNO3 and 1.0 mg/ml sulfonated c-CNCs.

Coating sulfonated c-CNC dispersion with silver16

SampleConc. of cellulose (mg/ml)Conc. Of AgNO3 (M) Filter (0.22 mM)pH before AgNO3additionpH after AgNO3addition4A10.5 No8.48.34B10.5 No8.48.34C0.10.5 Yes8.48.24D0.10.5 Yes8.48.2

Results from previous samples show aggregated cellulose. Lower concentrations of cellulose and AgNO3 were tested. The pores in the 0.22mM filter were too small to let any cellulose through.

Coating sulfonated c-CNC dispersion with silver17

SampleAgNO3 conc. (M)Cellulose conc. (mg/ml)Filter(0.45 mM)pH before AgNO3 additionpH after AgNO3 addition6A1.01.0No9.49.06B1.01.0Yes9.48.76C0.51.0No9.49.16D0.51.0Yes9.49.16E0.50.1No9.669.86F0.50.1Yes9.667.8

Results indicate a correlation between the amount of AgNO3 added to the dispersion with both the color and pH of that dispersion.

Video is 1.5x its original speed.

Should video of color change go here???17

Transmission Electron Microscope (TEM)18

The top two images display different concentrations of silver and cellulose from samples 6B and 6F. Silver particles are formed in different concentrations. The bottom image displays the anisotropic silver particles from sample 2A.

Coating carboxylated c-CNCs with silverSampleConc. of cellulose (mg/ml)Conc. Of AgNO3 (M) Filter (0.22 mM)pH before AgNO3additionpH after AgNO3addition5A10.5 No8.48.85B10.5 Yes8.48.95C0.10.5 No8.49.05D0.10.5 Yes8.47.95E0.010.5No8.48.35F0.010.5Yes8.48.9

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Sulfonated c-CNCs seem to be a better template for this project. TEM images were inconclusive. It was too difficult to differentiate the silver particles. The pore size of the filter was too small.

Conclusion20

Sulfonated c-CNC dispersion

The best method to create a percolating network of silver on CNCs TEM images

Carboxylated c-CNC dispersion

TEM images were inconclusive

Tunicate cellulose aerogel

The aeorgel did not have an even coating of silver

Cause:

light-weight porous aerogel floats in solution and is not fully immersedThe pores caused solution to be trapped and did not circulate throughout the aerogel

Future plan21

Find a polymer that is both conductive and translucent when condensed into film with dispersion

Possible polymers: LiClO4-doped ethylene oxide-epichlorohydrin (EO-EPI) (Schroers M., et. al, 2004)

Coat polymer with silver sulfonated c-CNC dispersion

Condense material into thin film

Characterize material

A special thanks to22

Prof. Chris WederProf. E. Johan FosterDr. Mehdi JorfiSandra C. EspinosaJens Natterodt

Silvana MullerCarola EndesJanak SapkotaApiradee NicharatSara TurnerAnd everyone at AMI

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Thank you for your attention!