Sulfone-containing bismaleimide modulated gamma PVDF films: Irradiation crosslinking strategy for ultra-high dimensional stability at high temperatures

Irradiation crosslinking has emerged as an efficient and eco-friendly strategy for polymer modification, aligning with green chemistry and sustainable development principles. This study incorporated sulfone-containing bismaleimide (s-BMI) into PVDF films via solution casting method, systematically investigating the effects of s-BMI incorporation and electron beam irradiation (0–228 kGy) on PVDF. FTIR results show that both s-BMI incorporation and the irradiation did not alter the predominant γ-phase formation in PVDF film. After the incorporation of s-BMI into PVDF, the shift of infrared characteristic absorption peaks, the singular melting/crystallization peaks in the DSC curves and the decrease in melting point and crystallization temperature of PVDF were observed, confirming the existence of molecular interaction between s-BMI and PVDF chain. PVDF film even containing 10 wt% s-BMI is homogeneous without defects and has good light transmittance of 54.8 % at 500 nm. SEM results confirm the uniform dispersion of s-BMI in the PVDF film, which indicates the good compatibility of s-BMI and PVDF. The incorporation of only 5 wt% s-BMI and the irradiation at 228 kGy increased the gel content (G c ) of PVDF film from 46.6 % to 66.6 % and thus significantly improved the dimensional stability at high temperatures with the strains at 230 °C of only 5.9 %. This study shows that sulfone-containing bismaleimide is an effective additive with good compatibility with PVDF and can significantly improve the efficiency of PVDF irradiation crosslinking. The irradiation-induced highly cross-linked PVDF films with polar crystalline phases developed in this study exhibits significant potential for application in functional devices operating under high-temperature conditions in the future.