Flexible polyurethane composites prepared by incorporation of polyethylenimine-modified slightly reduced graphene oxide

Contributed by the highly reactive, antibacterial, and readily reducible polyethylenimine (PEI), polyurethane (PU) composites incorporated with slightly reduced graphene oxide (SRGO) modified with PEI (SRGO-PEI) were prepared by in situ polymerization. X-ray photoelectron spectroscopy confirmed that SRGO-PEI was only slightly reduced under mild reducing conditions, because the carbon-to-oxygen atomic ratios increased slightly, from 2.56 to 4.00. The Fourier transform infrared spectra and the results of X-ray diffraction indicated that the PEI on SRGO-PEI were not only covalently grafted but also intercalated into SRGO interlayers. The mechanical properties and thermal stability of PU/SRGO-PEI were highly enhanced because of the chemical bonds formed between SRGO-PEI and PU matrices. With the incorporation of 1.0-wt% SRGO-PEI, the elongation at break, tensile strength, and Young's modulus of PU/SRGO-PEI increased by 32.7%, 251.1%, and 172.7%, respectively. Moreover, the adhesion of bacteria on functionalized GO/PU composites was reported for the first time. The PU/SRGO-PEI composites exhibited enhanced bacterial antiadhesive property when compared with that of pure PU and PU/GO. This desirable antibacterial property of SRGO-PEI is proposed to be mainly contributed by the presence of high-density amine groups in the PEI chains.