Thermoresponsive polymers, such as poly(N-isopropylacrylamide), exhibit a lower critical solution temperature and a responsive nature when grafted onto a surface. Covalently bound layer-by-layer assemblies containing a stimulus responsive poly(N-isopropylacrylamide)-c-poly(N-acryloxysuccinimide) polymer and aminated silica nanoparticles were grafted onto a silicon wafer. These polymer composite grafts, ~1 µm thick in the dry state, are known to change wettability and topography in response to external stimuli. Here we have investigated the changes in the Young’s elastic modulus of the polymer composite surface induced by external stimuli. The influence of temperature and the addition of counter ions to the surrounding aqueous environment from the Hofmeister series of salts were examined to investigate their effects on the structure and mechanics of the polymer composite grafts. For the nanomechanical studies, colloidal probe atomic force microscopy was used to measure the elastic modulus of the polymer film. The elastic modulus was found to vary from ~ 3 MPa to 190 MPa; dependent on the exposure of the polymer composite to varied temperatures, counter ions and film preparation procedures.

Studies of stimuli responsive polymer composites grafts by colloidal probe microscopy

249th National Meeting (2015)

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