Stimuli responsive thin films combine the advantages of polymers in bulk, i.e. their increased stability, and of polymer solutions, i.e. their fast response. Therefore, they are attractive for a wide range of applications. To extend it even further, we investigate the not yet well-understood phenomenon of co-nonsolvency. We prepared thin films of the thermoresponsive diblock copolymer PMMA-b-PNIPMAM, which exhibits a co-nonsolvency induced collapse transition when organic cosolvents, like acetone or methanol, are introduced in a certain ratio into the surrounding vapor atmosphere. The macroscopic changes during the swelling in aqueous vapor and the collapse transition in cosolvent vapor mixtures were investigated by spectral reflectance (SR) and verified through time-of-flight neutron reflectometry (ToF-NR) measurements. On the molecular level we further elucidate the underlying mechanism by in situ Fourier-transform infrared spectroscopy (FTIR) measurements to gain further insight into the origin of the co-nonsolvency effect.

Co-nonsolvency induced collapse transition in thin PMMA-b-PNIPMAM films

ACS Spring Meeting 2021

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