Uncovering interactions and gelation behaviour between thermoreversible polymers and polyphenols

Soluplus, a thermoresponsive PVCL-PVAc-PEG graft copolymer, forms reversible gels near physiological temperatures, making it attractive for topical drug delivery. However, its weak gel strength limits bioadhesion and retention. This proposal aims to investigate the supramolecular interactions between Soluplus and polyphenolic compounds—tannic acid, rosmarinic acid, and fisetin—using Small-Angle Neutron Scattering (SANS) on SANS2D. Polyphenols, known for their adhesive properties and interactions with PEG, are hypothesised to form secondary cross-linking domains within Soluplus gels, enhancing mechanical integrity and topical performance. Preliminary data show a tenfold increase in elasticity and improved tissue retention when polyphenols are added to Soluplus. SANS will be used to probe micellar structure and network organisation in both dilute (1, 5 wt.%) and concentrated (10, 20 wt.%) regimes at 25, 37, and 45 °C under two contrast conditions (100% D₂O and 70.5% D₂O). A total of 72 measurements are proposed to capture temperature- and concentration-dependent structural transitions. This study will provide the first structural insights into Soluplus–polyphenol interactions and guide the rational design of bioadhesive thermogels.