基于剪切增稠液的聚乙烯醇凝胶薄膜的微观形貌及力学性能研究OA

To overcome the inherent limitations of shear-thickening fluids(STFs),notably their fluidity and susceptibility to leakage under ambient conditions,we developed a novel solid-like shear-thickening gel film by encapsulating an STF composed of SiO2 nanoparticles and poly(ethylene glycol)(PEG)within a poly(vinyl alcohol)(PVA)matrix via solu-tion blending.This strategy leverages the formation of a three-dimensional physically cross-linked network,effectively immobilizing the STF while simultaneously enhancing the mechanical performance of the composite.Microstructural analysis revealed that in the wet gel state,the composite containing 50 wt%SiO2 exhibited a hierarchical dispersion mor-phology,featuring monodispersed nanoparticles(～360 nm)coexisting with micron-scale agglomerates(0.8～10 μm).Upon dehydration,the SiO2 nanoparticles self-assembled into a heterogeneous concentration gradient along the pore walls of the PVA porous skeleton,thereby preserving the interconnected porous architecture.Notably,increasing the SiO2 loading to 67.5 wt%promoted stronger van der Waals interactions and interfacial hydrogen bonding,leading to the formation of larger agglomerates(20～110 μm)and a～36%reduction in average pore diameter compared to the 50 wt%system.Mechanical testing demonstrated exceptional performance for the 50 wt%SiO2 composite:it exhibited a 1.43-fold increase in tensile strength,an 8.4-fold enhancement in elongation at break,and a remarkable 9.2-fold im-provement in toughness relative to pristine PVA.These improvements are attributed to four synergistic reinforcement mechanisms:(i)the formation of an extensive hydrogen-bonding network at the PVA-SiO2,PEG-PVA,and PEG-SiO2 interfaces;(ii)stress field superposition induced by rigid SiO2 nanoparticles;(iii)the plasticizing effect of PEG,which facilitates polymer chain mobility and rearrangement;and(iv)reversible energy dissipation enabled by the dynamic shear-thickening behavior of the embedded STF.