Phase separation of nonionic polymers that can stick and slide

The molecules with a propensity to undergo liquid-liquid phase separation (LLPS) form two distinct liquid-like phases known as dense and dilute phases. The dense phase formed from LLPS has unique characteristics such as a density higher than water, low viscosity, and low underwater interfacial tension. These distinct features facilitate the use of dense phases as scaffolds for drug delivery, tissue adhesive, and protein encapsulant. Most synthetic systems that undergo LLPS are created by complexing oppositely charged polymers. The formation of a dense phase from complexation requires careful tuning of the molar ratios of oppositely charged polymers, maintaining the correct pH and ionic strength. The instability of charged polymers to external factors and their potential cytotoxicity can hinder the use of such multicomponent complexed dense phases in dynamic wet environments with fluctuations in pH and ionic strength. Here we discuss, a tropoelastin-inspired design of synthetic nonionic polymers (HyPPos) that undergo single-component LLPS above their lower critical solution temperature. The phase separation behavior of these polymers is insensitive to the changes in pH. Using HyPPos, we studied the minimal physicochemical parameters required for the synthesis of the polymers that undergo single-component LLPS. We show that the designed polymers can be engineered to hydrolytically degrade, stick underwater, and displace selective biofilms submerged underwater.