Co-Nonsolvency Transition of Poly(N-isopropylacrylamide) Brushes in a Series of Binary Mixtures

• DOI: 10.1021/acs.macromol.9b01286
• Publication Date: 2019-08-14T12:26:56Z
• Authors: Huaisong Yong; Eva Bittrich; Petra Uhlmann; Andreas Fery; Jens-Uwe Sommer
• Keywords: Miscibility

Co-nonsolvency occurs if a mixture of two good solvents causes the collapse or demixing polymers into polymer-rich phase in certain range compositions these solvents. In this work, we systematically study co-nonsolvency behavior poly(N-isopropylacrylamide) brushes different grafting densities series alcohol–water binary mixtures with increasing hydrophobic parts ranging from methanol to 1-butanol by using ellipsometry. We report strong transition alcohol concentration water-rich phase, which is enhanced for longer-chain alcohols. The analysis thermodynamic properties displays that an tendency between and water correlated enhancement brush. increase density weakens but does not shift solvent composition point maximum brush collapse, agreement predictions recently proposed mean-field model based on preferential adsorption concept. Among fully miscible solvents, most sensitive switching found 1-propanol while already miscibility gap at higher volume fractions.