Robust and superomniphobic core-shell SiO₂@poly(1H,1H,2H,2H-heptadecafluorodecyl methacrylate-co-methyl methacrylate) coating materials synthesized by thiol lactam initiated radical polymerization

Superomniphobic SiO₂@poly(1H,1H,2H,2H-heptadecafluorodecyl methacrylate-co-methyl methacrylate) (SiO₂@poly(FMA-co-MMA)) core-shell spheres were synthesized via a thiol lactam initiated radical polymerization (TLIRP). SiO₂ and poly(FMA-co-MMA)s were used as they imparted both surface roughness and low surface energy for superhydrophobic surfaces. SiO₂ particles were synthesized using the Stöber method, and their surface was subsequently modified with (3-mercaptopropyl) trimethoxysilane and used as seeds for polymerization in the presence of γ-butyrolactam. The CH₂ peaks (4.26 and 2.56 ppm) from poly(FMA) and the CH₃ peak (3.53 ppm) from poly(MMA) were observed in the ¹H-NMR spectra, indicating successful preparation of SiO₂@poly(FMA-co-MMA) by TLIRP. The maximum water and hexadecane contact angles of an aluminum plate coated with particles were 164.0° and 130.1°, respectively. The cross-cut tape test of the coated aluminum plate showed that adhesion between the coating material and the substrate was classified as 5B, without damage. Furthermore, the substrate maintained superhydrophobicity after 40 cycles of tape peeling, although the water contact angle slightly decreased (163.1°) and the sliding angle slightly increased (2° to 3°). The mechanical strength of the coated aluminum plate was enhanced by heat treatment above the T_g of SiO₂@poly(FMA-co-MMA)s. The SiO₂ content of SiO₂@poly(FMA-co-MMA)s affected the wettability of the coating surface due to roughness generated by the core SiO₂ particles.