摘要 : The water swelling and subsequent solvent exchangeincluding co-nonsolvency behavior of thinfilms of a doublythermo-responsive diblock copolymer (DBC) are studied viaspectral reflectance, time-of-flight neutron reflectometry, andFo... 展开 The water swelling and subsequent solvent exchangeincluding co-nonsolvency behavior of thinfilms of a doublythermo-responsive diblock copolymer (DBC) are studied viaspectral reflectance, time-of-flight neutron reflectometry, andFourier transform infrared spectroscopy. The DBC consists of athermo-responsive zwitterionic (poly(4-((3-methacrylamidoprop-yl) dimethylammonio) butane-1-sulfonate)) (PSBP) block, featur-ing an upper critical solution temperature transition in aqueousmedia but being insoluble in acetone, and a nonionic poly(N-isopropylmethacrylamide) (PNIPMAM) block, featuring a lowercritical solution temperature transition in water, while being solublein acetone. Homogeneous DBCfilms of 50-100 nm thickness arefirst swollen in saturated water vapor (H2OorD2O), before theyare subjected to a contraction process by exposure to mixed saturated water/acetone vapor (H2OorD2O/acetone-d6 = 9:1 v/v).The affinity of the DBCfilm toward H2O is stronger than for D2O, as inferred from the higherfilm thickness in the swollen state andthe higher absorbed water content, thus revealing a pronounced isotope sensitivity. During the co-solvent-induced switching bymixed water/acetone vapor, a two-stepfilm contraction is observed, which is attributed to the delayed expulsion of water moleculesand uptake of acetone molecules. The swelling kinetics are compared for both mixed vapors (H2O/acetone-d6 and D2O/acetone-d6) and with those of the related homopolymerfilms. Moreover, the concomitant variations of the local environment around thehydrophilic groups located in the PSBP and PNIPMAM blocks are followed. Thefirst contraction step turns out to be dominated bythe behavior of the PSBP block, whereas the second one is dominated by the PNIPMAM block. The unusual swelling andcontraction behavior of the latter block is attributed to its co-nonsolvency behavior. Furthermore, we observe cooperative hydrationeffects in the DBCfilms, that is, both polymer blocks influence each other's solvation behavior. 收起