Surface Properties of Stimuli-responsive Multilayer Hydrogel Networks with Controlled Internal Architectures

摘要

Stimuli-responsive ultrathin surface-attached multilayer hydrogels have shown great promise in areas of advanced drug delivery, sensing, and actuation applications. Layer-by-layer (LbL) assembly of polymers at surfaces allows for fabrication of multilayer films with highly stratified internal architectures, where it was previously demonstrated that the method of LbL construction of poly(methacrylic acid) (PMAA) multilayer hydrogel films influenced pH-triggered swelling. Spin-assisted PMAA multilayer hydrogels retained internal organization upon crosslinking and exhibited increased swelling thickness when compared to less organized hydrogels that were constructed via conventional dipped LbL assembly. The molecular weight of poly(N-vinylpyrrolidone) (PVPON) sacrificial layers in PMAA/PVPON hydrogen-bonded precursor films significantly affected the film thickness, morphology, and architecture of both the precursor films and the crosslinked PMAA hydrogels as studied by ellipsometry and neutron reflectometry. In this study, the topological and nanomechanical properties of PMAA multilayer hydrogels, as well as the hydrogen-bonded PMAA/PVPON precursor films, were probed using atomic force microscopy in quantitative nanomechanical mapping mode (AFM-QNM). The multilayer hydrogels were characterized under both ambient and hydrated conditions to understand the effects of LbL construction method and PVPON molecular weight on the pH-dependent multilayer network properties.