Polymer Brushes and Gels in Competing Solvents: The Role of Different Interactions and Quantitative Predictions for Poly(N-isopropylacrylamide) in Alcohol–Water Mixtures

• DOI: 10.1021/acs.macromol.0c00033
• Publication Date: 2020-04-03T19:52:36Z
• Authors: Huaisong Yong; Holger Merlitz; Andreas Fery; Jens-Uwe Sommer
• Keywords: Poly(N-isopropylacrylamide); Aqueous two-phase system

Cononsolvency occurs if a mixture of two good solvents causes the collapse or demixing polymers into polymer-rich phase in certain range compositions these solvents. The better solvent is usually called cosolvent, and other common solvent. An unsolved problem understanding cononsolvency transition role various polymer–solvent cosolvent–solvent interactions. In this work, using mean-field model, we offer comprehensive quantitative theoretical study effect neutral immobilized polymers, particular, poly(N-isopropylacrylamide) (PNiPAAm) brushes macrogels. Our model quantitatively describes predicts phase-transition behaviors PNiPAAm gels aqueous alcohol solutions. We demonstrated that addition to dominant polymer–cosolvent preferential adsorption monomer–cosolvent–monomer triple contact (cosolvent-assisted temporary cross-linking effect), nonideal mixing between polymer shifts lower-concentration region while an increase tendency cosolvent reduces width transition. Moreover, weakening cosolvent-poor solutions at high hydrostatic pressure can be explained by suppression tendencies water, water case PNiPAAm.