Exploring the Solubility Characteristics of a Biocompatible Polymer: The Case of PAmOx in Water

This study investigates the behavior of a biocompatible polyoxazoline (PO) polymer in water. POs are of interest for biological applications due to their biocompatibility and thermoresponsive behavior, making them ideal polymers for developing smart materials. This study focuses on PAmOx, a macromolecule that has recently been used to develop nanoscale tools for water remediation. However, despite the significant interest in the applications of PAmOx, its behavior in water and its thermal response remain to be thoroughly characterized. To address such a gap, we present a combined computational and experimental study of PAmOx's properties in aqueous solution. UV–Vis experimental results reveal a distinct transition temperature of 40°C, which is consistent with the thermoresponsive nature of numerous POs. Above this temperature, significant macromolecular aggregation occurs. Computational results demonstrate that, while temperature has no impact on hydration at the single-chain level in water, an increase in temperature promotes aggregation by enhancing hydrophobic effects. Crucially, during aggregation, interchain hydrogen bonds replace polymer-water interactions, thereby stabilizing the aggregate by maintaining an almost constant number of hydrogen bonds per monomer.