POSS end-capped diblock copolymers: Synthesis, micelle self-assembly and properties

• Diblock copolymers ap-POSS–PMMA-b-P(MA-POSS) are synthesized.
• The micelles of ap-POSS/MA-POSS core and PMMA shell are formed.
• The films with low viscoelasticity and high hydrophobicity are produced.
• POSS end-capped diblock copolymers could provide high thermostability.

Polyhedral oligomeric silsesquioxane (POSS) end-capped diblock copolymers are synthesized using aminopropylisobutyl POSS (ap-POSS-Br) to initiate atom transfer radical polymerization (ATRP) of methylmethacrylate (MMA) and methacrylisobutyl POSS (MA-POSS). Their chemical structures are confirmed as ap-POSS–PMMA152.0-b-P(MA-POSS)4.3, 4.8, 10.0 with 19,840–24,770 g mol−1 by 1H NMR and SEC. In tetrahydrofuran (THF) solution, the obtained diblock copolymers could self-assemble into 150–300 nm core–shell micelles as ap-POSS/MA-POSS core and PMMA shell, or 164 nm core–shell–crown micelles as P(MA-POSS) core, PMMA shell and ap-POSS crown when P(MA-POSS) content is increased. These micelles can produce typical films with lower surface roughness (0.816–1.690 nm), lower water absorption and lower viscoelasticity, but higher hydrophobicity (112–126° water contact angle) and higher thermostability in glass transition temperature Tg > 110 °C and decompose temperature Td > 380 °C than pure POSS–PMMA film. In this study, the results strongly support the potential application of the POSS end-capped diblock copolymers as the coatings.

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