Fabrication of Polydimethylsiloxane-Based Nanowire-Shaped Micelles as a Highly Hydrophobic and Adhesive Coating for Protecting Sandstone Cultural Relics

Although high-performance protective coatings have been realized, the impact of self-assembled arrays or superstructures obtained from copolymers on surface and interfacial properties remains poorly understood. Thus, a detailed investigation of assembled micelle-surface/interface properties is needed. Herein, we report a copolymer-based micelle-induced self-assembled film-forming mechanism for fabricating high-performance protective coatings. Diblock copolymers of polydimethylsiloxane-block-poly(glycidyl methacrylate) (PDMS-b-PGMA) were synthesized using the atom transfer radical polymerization method. The macromonomer (bromine-functionalized PDMS) initiated GMA polymerization. The copolymer formed PGMA-core-PDMS-shell nanowires (up to a micrometer in length) through a typical time-dependent shape evolution from spherical micelles in chloroform (CHCl₃). Uniform spherical micelles with a PDMS core and PGMA shell were detected in acetone, while irregular micelles with a PGMA-core and PDMS-shell were detected in dioxane and N,N-dimethylformamide, indicating the critical dictating role of the solvent in the self-assembled pattern. The assembled nanowires of PDMS-b-PGMA in CHCl₃ were stable, regardless of the PGMA block length and concentration. The CHCl₃-derived nanowire-based coating exhibited better hydrophobic properties and adhesive strength than the acetone-derived spherical micelle-based coating. Thus, we propose a micelle-induced self-assembled film-forming mechanism by regulating the migration and arrangement of PDMS and the solvent evaporation rate. Nanowires comprising PDMS shells exhibited greater curvature, which is highly conducive to the PDMS group migrating to the surface during the film-forming process. The PDMS-b-PGMA micelle-induced coating effectively improved hydrophobicity for protecting sandstones. This study provides a solution by regulating micelle-induced self-assembled film formation for fabricating high-performance protective coatings with wide application prospects.