Construction of Dual-Functional Emulsion Micelle Interface With Ionic and Reactive Groups

Internal emulsification emulsions are environmentally friendly and do not emit volatile organic compounds (VOCs). However, their micelle interface, dominated by ionic hydrophilic groups, hinders cross-linking reactions and affects performance. We proposed a dual-functional micellar interface (DFMI) that distributes both ionic and reactive hydrophilic groups, enhancing cross-linking performance without significantly compromising emulsification properties. In this study, a series of sugar-based hyperbranched waterborne polyurethane emulsions were synthesized with 2,2-dimethylolpropionic acid (DMPA) as the ionic hydrophilic moiety. Dopamine (DA) was introduced at varying levels as the reactive hydrophilic moiety for terminal modification. The results showed that monomolecular micelles and vesicular micelles could be formed by symmetric and asymmetric modification of terminal DA. Symmetric modification tended to form unimolecular micelles, while asymmetric modification tended to form vesicular structures. Adhesion tests conducted after cross-linking with gelatin showed that the asymmetrically modified adhesives with seven-layer structured DA exhibited better cross-linking degrees. Adhesion performance and swelling tests confirmed that the asymmetric structure exposed more terminal reactive groups, enhancing the utilization of the modified groups, as indicated by dynamic light scattering (DLS) for emulsion particle size and surface zeta potential. This study successfully prepared hyperbranched polyurethane emulsions with tunable micelle morphology, balancing emulsification ability, and cross-linking degree, supporting the controlled emulsification of hyperbranched polymers and the development of bio-based adhesives.