Flexible, biocompatible, and electroconductive Polyurethane foam composites coated with graphene oxide for ammonia detection

Abstract Polyurethane foam (PUF) composites are of great interest in various polymer applications due to their tunable mechanical and stretchable properties, and easy fabrication. In this study, flexible, biocompatible, and electroconductive PUF composites (PUF-graphene oxide (GO), PUF-polypyrrole (PPy)-GO, and PUF-poly(3,4-ethylenedioxythiophene) (PEDOT)-GO) were synthesized using a sequential procedure of vapor phase polymerization (VPP) and GO impregnation. First, hydroxyl groups in polytetramethylene ether glycol (PTMEG) and diisocyanate functional groups in polymeric methylene diphenyl diisocyanate (PMDI) underwent a reaction to generate urethane bonds. Then, by adding water, CO2 gas was used during the reaction of isocyanate to generate bubbles creating a porous interconnected foam. Conductive polymers (CPs) such as PPy and PEDOT were vapor-phased polymerized on the synthesized PUF matrix. Then, these composites were integrated with GO by impregnation on the surface of PUF-conductive polymers (CP). The flexible, and electroconductive PUF composites were analyzed and compared with respect to pore size distribution, mechanical, thermal, and electrical properties. Indirect biocompatibility and cell proliferation with PUF composites were also evaluated for 7 days. Among the PUF composites, the PUF-PPy-GO was further investigated as an NH3 gas sensing material and showed high values in sensitivity coefficients as well as the selectivity coefficients, demonstrating the sensor's utility in determining NH3 gas incidence.