Synthesis of New Polymers for Capacitor Application

1. MURI Annual Review October 28, 2011 Synthesis of New Polymers for Capacitor Application Gregory A. Sotzing Professor of Organic and Polymer Chemistry University of Connecticut Currently on Sabbatical at AFRL/RYDP Wright Patterson Air Force Base

2. Role of the Sotzing Effort Be guided by the theoreticians of the group to prepare new polymers Theoretician will propose a structure based upon their calculations Extensive literature research is carried out to see if the polymer has ever been made If the structure has never been made, we propose pathways by which it could be made If there is no literature that helps us in the proposed pathway or alternate pathways we find a structure that is a close fit that is realistic to mak Prepare New Polymer Preparation of monomers and their purification/characterization Preparation of polymers and their purification/characterization Prepare films of the polymers for impedance measurements

3. Polysilanes Feed from Theorist: Predicted to have high dielectric constants based upon polarizability The smaller the groups attached to the Si backbone, the better Hydrogen is preferred, Fluoride was understood to be better Practical Considerations: Si-H bonds are hydrolytically unstable (Polysilane - John et al. JCS Chem. Commun, 1983, p. 1496) Polymer with solely F has not been prepared According to one report, Si-F bonds are hydrolytically unstable (within this study a Si version of polyvinylidene fluoride was prepared, Interrante, et al. J. Am. Chem. Soc., 1997, 119 (49),12020–12021) Polysilanes with alkyl groups can be made via Wurtz coupling. Those polysilanes that have been made have not been tested for capacitor application

4. Poly(dimethylsilane)*: R=Me, R’=Me Polysilanes Prepared Poly(di-n-octylsilane)#: R=Oct, R’=Oct Poly(di-n-butylsilane)#: R=Bu, R’=Bu Poly(phenylmethylsilane)#: R=Ph, R’=Me Poly(diphenylsilane)*: R=Ph, R’=Ph *Insoluble Polymers # Limited Solubility

5. Polysilanes Prepared Still have limited solubility

6. Poly(Phenylmethylsilane) Shims Diameter = 2” Thickness= 0.01” Uniform Stainless Steel Edges were left blank for test 12 Layers deposited at 600rpm Resistance: 1 kW role of ions on low resistance, purification, and measurement made in dry environment

7. Polysilanes Conclusion Polysilanes in it of themselves are too conjugated to be good dielectrics Must introduce breaks in conjugation

8. Parallel Effort – Poly(silylarylenes) Have isolated segments of conjugation, pi and sigma, through the backbone of a polymer.

9. Poly(silylarylenes)

10. a b Poly(EDOTdimethylsiloxane) – 1H NMR c a b Hexanes CHCl3 MeOH c Polymer was precipitated in methanol and hexanes.

11. Poly(EDOTdimethylsiloxane) - FTIR 3000-2800 cm-1 (C-H Stretch), 1463-1356 cm-1 (thiophene ring), 1256 cm-1 (Si-CH3), 1172 cm-1 (ethylenedioxy ring), 1056 cm-1 (Si-O) IR spectra was taken using polymer casted KBr pallet.

12. Energy Gaps Ar =

13. Electrochemistry Oxidizing onset; V vs Fc/Fc+ redox. Fc/Fc+ redox vs vacuum; -5.1 eV.

14. Molecular Weight and Thermal

15. Even with the siloxane units to break conjugation, even one ring system and two silane units are too much conjugation for a dielectric Conclusions – Poly(Arylenesilylene)s

16. Continue to shorten conjugation length of Si units From RampiRamprasad Present/Future Work

17. Present/Future Work

18. Present/Future Work

19. Present/Future Work