POSS-tethered fluorinated diblock copolymers with linear- and star-shaped topologies: synthesis, self-assembled films and hydrophobic applications

Abstract

Polyhedral oligomeric silsesquioxane (POSS) tethered fluorinated diblock copolymers including linear-shaped ap-POSS–PMMA-b-PDFHM and star-shaped s-POSS–(PMMA-b-PDFHM)₁₆ are synthesized by octakis(dibromoethyl)POSS (POSS-(Br)₁₆) and aminopropylisobutyl POSS (ap-POSS) initiating methylmethacrylate (MMA) and dodecafluoroheptylmethacrylate (DFHM). In THF solution, both diblock copolymers could self-assemble into 200 nm core/shell micelles with a POSS/PDFHM core and 70–80 nm PMMA shell. These micelles are able to produce typical films with a fluorine-rich top-surface and POSS-gathered sub-surface. Although PDFHM segments and POSS cages are competitively migrating onto the film surface, the migration of the PDFHM segments is actually improved by the POSS cages. Comparatively, the surface of the ap-POSS–PMMA-b-PDFHM film is much more rough and fluorine-rich than the s-POSS–(PMMA-b-PDFHM)₁₆ film, therefore, the ap-POSS–PMMA-b-PDFHM film has higher viscoelasticity and higher oleophobicity, but a little lower hydrophobicity than the s-POSS–(PMMA-b-PDFHM)₁₆ film. The hydrophobic application of both linear- and star-shaped topologies to glass, cotton fabric and stone substrates reveals that the treated samples exhibit superhydrophobicity for the cotton fabric (>150°) and obvious hydrophobicity for the stone and glass (>135°) in terms of resistance to water and other liquids like coffee, milk, coke and green tea. It is believed that the properties of self-assembled films and the hydrophobic applications are related closely to the topologies of block copolymers.