The new highlights (4 bullet points) are: (Can also refer to the attached document). SPI films were crosslinked by DCMC- a cellulose-based crosslinking agent. Mechanical properties, water resistance and thermal stability of SPI films were improved by DCMC crosslinking. Tensile strength of SPI films increased by 218% after crosslinking with DCMC. Good compatibility and effective crosslinking were believed to be key causes of property enhancements.