Publikation

L. P. Kreuzer, T. Widmann, N. Hohn, K. Wang, L. Bießmann, L. Peis, J. F. Moulin, V. Hildebrand, A. Laschewsky, C. M. Papadakis, P. Müller-Buschbaum
Swelling and Exchange Behavior of Poly(sulfobetaine)-based Block Copolymer Thin Films
Macromolecules 2019, 52, 3486
DOI: 10.1021/acs.macromol.9b00443
The water exchange in thin diblock copolymer films is investigated by time-of-flight neutron reflectometry (TOF-NR).. The block copolymer is composed of a nonionic block, namely poly(N-isopropylacrylamide) PNIPAM, and a zwitterionic block, namely [poly(N,N-dimethyl-N-(3-(methacrylamido)propyl) ammoniopropanesulfonate)] PSPP. Swelling in H2O atmosphere is monitored in situ, followed by water exchange with D2O. It is compared to the reverse experiment , i.e., swelling in D2O atmosphere and subsequent water exchange with H2O. Static and kinetic TOF-NR measurements indicate clear differences in the interactions between the PSPP80-b-PNIPAM130 thin film and H2O or D2O. These are attributed to the different H- and D-bonds between water and the polymer. FTIR spectroscopy probes the changes in the chain conformation and hydrogen bonding during the swelling and exchange processes, revealing the key role of the anionic -SO3- group in the PSPP block and the polar amide groups of both blocks during water uptake and exchange.
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