Electrically conductive elastomer films based on copoly(urethane-imide) composites with carbon particles of various types

New composite materials were obtained on the basis of segmental copoly(urethane-imides) and carbon particles of various types: amorphous carbon (carbon black), carbon nanofibers, and graphene. The matrix copoly(urethane-imides) were prepared by known procedures starting from toluylene 2,4-diisocyanate-terminated poly(propylene glycol), pyromellitic dianhydride, and 4,4′-diaminodiphenyl ether (the first matrix) and 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride and m-phenylenediamine (the second matrix). The thermal stability and mechanical and electrical properties were determined; the structural features of film composite surface were characterized. It was shown that the composites behave as high-strength elastomers. The elongation at rupture is 100–1000%, and the specific bulk conductivity reaches 1.1 S m⁻¹. Regarding the mechanical and electrical properties, the composite based on propylene glycol, pyromellitic dianhydride, and 4,4′-diaminodiphenyl ether containing 20 wt. % carbon black was found to be optimal among the investigated film samples as an elastomer planar electrode. Using methyl thiazolyl tetrazolium (MTT) assay, the material was found to be nontoxic to human dermal fibroblasts, which is significant for the intended use of the composite in wearable medical and cosmetic devices.