High‐Modulus Cross‐Linked PVDF Films Prepared With Synergistic Hydrogen Bonding and Electron Beam Irradiation

In this study, hydroxyl‐terminated polybutadiene (HTPB) containing carboxyl (denoted as HC) was synthesized by thiol‐ene click reaction. HC with different degrees of carboxyl functionalization confirmed by 1 H NMR spectroscopy was then physically blended with poly(vinylidene fluoride) (PVDF) to prepare cross‐linked PVDF films by an electron beam irradiation. Differential scanning calorimetry (DSC) analysis showed that the successful introduction of carboxyl group significantly increased the glass transition temperature of HTPB resulting from the effect of hydrogen bonding. The hydrophilicity of PVDF films could be tuned with water contact angle (WCA) between 73.4° and 100.86° by adjusting the degree of functionalization and the addition amount of HC. Dynamic mechanical analysis (DMA) revealed that the introduction of HC to PVDF film led to a remarkable increase in the storage modulus ( E ′). Specifically, the PVDF film modified with 1 wt% of HC (17.6% functionalization) exhibited an enhancement in E ′ of nearly 600 MPa compared with pure PVDF. For 100 and 200 kGy irradiated films, the E ′ values of 1 wt% HC‐modified PVDF films increased with the carboxyl functionalization degree increased and were higher than pure PVDF. This work demonstrates that carboxyl‐functionalized HTPB enables to tune hydrophilicity of PVDF films, and apparently improve the dynamic mechanical properties which also was applicable for the irradiated PVDF films, offering a novel strategy for the functional modification of PVDF.