Abstract
Complex coacervation offers a versatile platform for designing stimuli-responsive materials. Among others, surfactant micelle-polymer complex coacervates provide the added advantage of encapsulating and delivering hydrophobic substances via micellar structures. In this study, we investigate the phase behaviour and interfacial properties of a model system composed of mixed surfactant micelles and a cationic polymer. We demonstrate that micelle composition, particularly the fraction of ionic surfactant, governs surface charge and conformation of micelles, which in turn drive phase transitions from soluble complexes to coacervates and ultimately to precipitates. Under iso-ionic dilution, we observe dilution-induced complex coacervation (DICC), with the coacervation window tunable by micelle charge and polymer-to-surfactant stoichiometry. Contact angle measurements reveal that the resulting coacervates spread efficiently on both hydrophilic and hydrophobic surfaces. Notably, they exhibit superior spreading on hydrophobic substrates with multiscale nano-micro structures compared to micelle solutions alone. This enhanced wetting behaviour is likely driven by the network structure formed by micelle-polymer complexes within the coacervates, which facilitates cooperative surfactant adsorption and promotes the transition from the Cassie-Baxter to the Wenzel wetting regime. These findings underscore the potential of micelle-polymer complex coacervates as tunable, stimuli-responsive materials for advanced surface coating applications.
| Original language | English |
|---|---|
| Pages (from-to) | 7610-7621 |
| Number of pages | 12 |
| Journal | Soft Matter |
| Volume | 21 |
| Issue number | 39 |
| DOIs | |
| State | Published - Oct 8 2025 |
Funding
This work is supported by Grant No. 2022-67022-38145 from the USDA National Institute of Food and Agriculture. We acknowledge Dr Keith Gutowski for providing the LA65N we used in this study. SANS measurements were performed at the Bio-SANS instrument of the Centre for Structural Molecular Biology (FWP ERKP291) under IPTS-27249, a Structural Biology Resource of the U.S. DOE Office of Biological and Environment Research. This research used resources at the High Flux Isotope Reactor, a U.S. DOE Basic Energy Sciences User Facility operated by the Oak Ridge National Laboratory (ORNL). This manuscript has been coauthored by UT-Battelle, LLC, under contract no. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript or allow others to do so, for United States Government purposes.