Thin surface-attached multilayer hydrogels of stimuli-responsive polymers have great potential for applications in sensing, actuation, and advanced delivery of functional molecules. Spin-assisted layer-by-layer (LbL) assembly of polymers at surfaces allows for fabrication of ultrathin multilayer films with highly stratified internal architectures. Previously, pH-triggered swelling of poly(methacrylic acid) (PMAA) multilayer hydrogel films has been shown to be modulated by the mode of the LbL construction where spin-assisted PMAA multilayer hydrogels retained internal organization upon crosslinking and exhibited increased swelling thickness when compared to less organized hydrogels obtained via conventional dipped LbL assembly. The molecular weight of poly(N-vinylpyrrolidone) (PVPON) sacrificial layers in PMAA/PVPON hydrogen-bonded precursor films significantly affected thickness, morphology, and architecture of hydrogen-bonded (PMAA/PVPON) precursors and the corresponding PMAA hydrogels as studied by ellipsometry and neutron reflectometry. In this study, nanomechanical properties of PMAA multilayer hydrogels and hydrogen-bonded PMAA/PVPON precursor films were probed using atomic force microscopy (AFM) in quantitative nanomechanical mapping (QNM) mode. Nanomechanical behavior of the surface-attached multilayers was studied in both dry and hydrated states to elucidate the effects of PVPON molecular weight on pH-dependent rigidity of the hydrogels.

Nanomechanics of thin poly(methacrylic acid) multilayer hydrogels probed by AFM

255th National Meeting (2018)

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