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

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-PMMA_152.0-b-P(MA-POSS)_{4.3, 4.8, 10.0} with 19,840-24,770gmol^-1 by ¹H NMR and SEC. In tetrahydrofuran (THF) solution, the obtained diblock copolymers could self-assemble into 150-300nm core-shell micelles as ap-POSS/MA-POSS core and PMMA shell, or 164nm 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 (0.816-1.690nm), lower water absorption and lower viscoelasticity, but higher hydrophobicity (112-126° water contact angle) and higher thermostability in glass transition temperature T_g>110°C and decompose temperature T_d>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.