FT-IR study of state of molecular hydrogen in bisphenol A polycarbonate dissolved by high-pressure hydrogen gas exposure

•We dissolved hydrogen into polycarbonate (PC) by high-pressure gas exposure.•FT-IR measurement was conducted for the PC after the exposure.•We found a “foreign” peak at 4125 cm−1 in the spectra.•The foreign peak is assignable to H-H vibration of the molecular hydrogen.•We presumed that the hydrogen in PC is isolated by molecular chain.