Piezo-resistive materials

1. A pressure sensor composition comprising a crosslinked polymer comprising a poly(hexamethylene dicarbamoyl) cross linker and a poly(bisphenol A-co-epichlorohydrin); a conductive carbon material; and an elastomeric rubber.

2. The pressure sensor composition of claim 1 , wherein the conductive carbon material is carbon black, carbon nanotubes, graphene, graphite, or a combination thereof.

3. The pressure sensor composition of claim 1 , wherein the elastomeric rubber comprises polybutadiene, polyisoprene, polyacrylonitrile, and copolymers thereof.

4. The pressure sensor composition of claim 1 , wherein the number average molecular weight of the poly(bisphenol A-co-epichlorohydrin) is about 20,000 amu about 70,000 amu.

5. The pressure sensor composition of claim 1 , wherein the number average molecular weight of poly(hexamethylene dicarbamoyl) is about 500 amu-about 2,500 amu.

6. The pressure sensor composition of claim 1 , wherein the pressure sensor composition comprises 90-95% by weight crosslinked polymer, 4-6% by weight conductive carbon material, and 0.5%-2% by weight elastomeric rubber.

7. The pressure sensor composition of claim 6 , wherein the crosslinked polymer comprises poly(bisphenol A-co-epichlorohydrin) and poly(hexamethylene dicarbamoyl) cross linker in a mass ratio of 1:2 to 1:3.

8. The pressure sensor composition of claim 6 , wherein the number average molecular weight of poly(hexamethylene dicarbamoyl) is about 2,000 amu-about 2,500 amu and the number average molecular weight of the poly(bisphenol A-co-epichlorohydrin) is about 45,000 55,000 amu.

9. The pressure sensor composition of claim 8 , wherein the elastomeric rubber is a hydroxyl-terminated butadiene-acrylonitrile copolymer.

10. A method of preparing the pressure sensor composition of claim 1 , comprising:

contacting a blocked poly(hexamethylene diisocyanate); poly(bisphenol A-co-epichlorohydrin); conductive carbon material; and elastomeric rubber thereby forming the pressure sensor of claim 1 .

11. The method of claim 10 , wherein the blocked poly(hexamethylene diisocyanate) is blocked with an optionally substituted phenol; an optionally substituted imidazole; or an optionally substituted pyrazole.

12. The method of claim 11 further comprising the step of contacting a poly(hexamethylene diisocyanate) with an optionally substituted phenol; an optionally substituted imidazole; or an optionally substituted pyrazole thereby forming the blocked poly(hexamethylene diisocyanate).

13. The method of claim 10 , wherein the number average molecular weight of the poly(bisphenol A-co-epichlorohydrin) is 20,000 amu 70,000 amu.

14. The method of claim 10 , wherein the number average molecular weight of the blocked poly(hexamethylene diisocyanate)is 500-2,500 amu.

15. The method of claim 10 , wherein the mass ratio of the poly(bisphenol A-co-epichlorohydrin); the blocked poly(hexamethylene diisocyanate); the conductive carbon material; and the elastomeric rubber is 1:0.4:0.06:0.005 to 1:0.5:0.09:0.015.

16. The method of claim 10 further comprising the step of curing the pressure sensor composition at a temperature of 110-180° C.

17. The method of claim 10 , wherein the blocked poly(hexamethylene diisocyanate) is blocked with 3,5-dimethylpyrrazole and the step of contacting the 3,5-dimethylpyrrazole blocked poly(hexamethylene diisocyanate); the poly(bisphenol A-co-epichlorohydrin); the conductive carbon material; and the elastomeric rubber is conducted in the presence of a metal catalyst.

18. A pressure sensor comprising the pressure sensor composition of claim 1 and an electrode.

19. The pressure sensor of claim 18 , wherein the electrode is a flexible silver electrode.

20. The pressure sensor of claim 19 , wherein the flexible silver electrode comprises a poly(hexamethylene dicarbamoyl) cross linker and poly(bisphenol A-co-epichlorohydrin); and silver particles.