Formation of icephobic film from POSS-containing fluorosilicone multi-block methacrylate copolymers

Polyhedral oligomeric silsesquioxane (POSS)-containing fluorosilicone multi-block methacrylate copolymers (PDMS-b-(PMAPOSS-b-PFMA)2) were synthesized via RAFT polymerization of methacryloisobutyl POSS (MAPOSS) with hexafluorobutyl methacrylate (HFBMA) or dodecafluoroheptyl methacrylate (DFHMA) as different fluorinated side groups. A macro-RAFT chain transfer agent of polydimethylsiloxane with dithiobenzoate groups at both ends was initially used. Characterizations of surface chemical composition and morphology of the copolymer films suggested that the PDFHMA chains with longer fluorinated side groups, as compared with PHFBMA chains, were easy to migrate onto the surface and the surface roughness was enhanced by introducing PMAPOSS segments. The film of multi-block copolymer PDMS-b-(PMAPOSS-b-PDFHMA)2 produced a fluorine-rich surface due to the enrichment of fluorinated blocks and exhibited the highest receding contact angle (103.8 ± 0.5°) and lowest water contact angle hysteresis (8.7 ± 1.4°) among all the samples, attributed to the introduction of PMAPOSS segments and the synergistic effect of silicon and fluorine. Measurements of icephobic properties demonstrated that the supercooled water droplet could easily slip away from the tilted PDMS-b-(PMAPOSS-b-PDFHMA)2 surface (45°) at −20 °C and the ice shear strength tended to decrease from 361 kPa to 264 kPa with incorporation of PMAPOSS blocks in comparison with PDMS-b-(PFMA)2. However, it was found that decreasing wettability of the block copolymer film did not have significant effect on reducing the ice shear strength. The prepared POSS-containing fluorosilicone multi-block methacrylate copolymers with good icephobicity can be used as icephobic coating materials potentially.