Water structure and hydration of polymer network in PMEO2MA hydrogels
Krzysztof Piechocki, Marcin Kozanecki, Jakub Saramak
Abstract
The hydration of amphiphilic polymers with some different hydrophilic centers, such as poly(2-(2-methoxyethoxy)ethyl methacrylate) (PMEO2MA), is important to understand well their thermo-responsivity. The PMEO2MA hydrogels with varying swelling degree, synthetized by radiation-induced cross-linking polymerization, has been investigated by ATR-FTIR supported by DFT calculations. This study broadens the knowledge about mechanism of hydration of PMEO2MA and explores the relationships between the water content in hydrogels, polymer-water, and water-water interactions. A complete picture of hydration processes of all hydrophilic centers (carbonyl and ether groups) was shown and correlated with water structure for the first time. It was found that firstly, small water clusters, and water bridges between the polymer segments are formed. Next, the bridges break and polymer chains start to separate. Finally, water tend to structure characteristic for bulk water. The obtained results may be an excellent basis for the analysis of local changes in PMEO2MA hydration during volume phase transition.