1. Liquid Crystal Elastomer Dielectric Constant Measurements Ferroelectric Workshop – Kent State UniversitySaturday, June 23, 2007 Liquid Crystal Institute Kent State University Kent, Ohio Liquid Crystal Institute Kent State University Kent, Ohio

2. Liquid Crystal Elastomers liquid crystal + rubber LC nematic monodmain synthesize here - need to characterize LC mesogen polymer backbone cross-linker

3. Experiment 1 Variac Ne Trans. ITO Glass Elastomer Elastomer is suspended on a string between two parallel pieces of ITO coated glass. Elastomer aligns along sufficiently strong applied field.

4. Video of Experiment

5. Experimental Data Field On Field Off

6. Overview Want to solve

7. Theory Energy of elastomer:

8. Theory In general: where

9. TheoryTheory Make substitutions: then cont’d

10. Theory Choose A & B such that then

11. Theory Recall Thus Want to solve

12. Theory Need the following: Also So where

13. Depolarizing Factors Assume depolarizing factors for an ellipse can be used:

14. Elastomer Properties l w d

15. Electric Field Measurement V in V out R1R1 R2R2 Voltage divider: Thus

16. Experiment 2 Elastomer is sandwiched between aluminum plates and capacitance is measured with bridge Capacitance Bridge Elastomer Al plates spacers V out CBCB CUCU

17. Theory & Results Without elastomer: Find Using With elastomer: Find

18. Results LHS RHS Using:

19. Possible Future Work Remove shape effects: OR Remove anisotropy effects: Repeat experiments in magnetic field

20. Conclusions Electric field response used to determine elastomer dielectric constant values Would like to do similar magnetic field measurements Still a work in progress