Understanding polymer-surfactant interactions is essential for regulating phase transition and polymer aggregation, enabling the design of functional materials with tailored morphologies and mechanical properties. Here, we developed a new class of programmable dextran-based thermoresponsive polysaccharide condensates by chemically converting the hydrophilic homopolysaccharide dextran into hydrophobic derivatives. These materials exhibited reversible phase transitions and tunable lower critical solution temperatures. Photo-initiated radical polymerization permits hydrogel crosslinking, harnessing phase separation to generate hydrogels with distinct microstructures. We systematically evaluated the impact of anionic sodium dodecyl sulfate (SDS), cationic hexadecyltrimethylammonium bromide (CTAB), nonionic Pluronic F-127, and zwitterionic 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS) surfactants on phase transition dynamics. Surfactant charge density, hydrophilic—lipophilic balance (HLB), and critical micelle concentrations (CMC) jointly control temperature-triggered phase separation. Ionic surfactants such as SDS and CTAB effectively regulate Dex-MA phase separation within their CMC range, whereas non-charged and zwitterionic surfactants require higher concentrations beyond CMC for similar effects. The resulting phase-separated gels demonstrated surfactant-specific and concentration-dependent surface wettability, forming distinct hydrogel microstructures, including core-shell structures, interconnected elongated micelles, and dual emulsions. Micromechanical characterization of surfactant-polysaccharide gels exhibited structurally coordinated mechanical properties and adhesive strength, for example, the non-ionic surfactant Pluronic exhibiting core-shell structure significantly reduced adhesion, while the cationic surfactant CTAB with more elongated structures effectively lowered the modulus. Together, these findings provide a framework for selecting suitable surfactants to regulate polymer/polymer and polymer/solvent interactions, enhancing insights into microstructure-property-performance relationships and enabling the design of biocomposite materials with tailored properties.
