Four-leaf clover-shaped cage silsesquioxane-based giant molecular clusters: synthesis, properties, and hybridization behavior in poly(methyl methacrylate)

Abstract C3- and C6-linked isobutyl- and phenyl-substituted four-leaf clover-shaped cage silsesquioxane derivatives were prepared by hydrosilylating the corresponding monoallyl- and monohexenyl-polyhedral oligomeric silsesquioxane (POSS) and double-decker silsesquioxane, respectively. Poly(methyl methacrylate) (PMMA) films containing 2 wt% POSS derivatives were prepared by casting chloroform solutions onto glass substrates at room temperature. The PMMA composite films containing isobutyl-substituted POSS derivatives showed good transparency in the visible region. The composite films containing the phenyl-substituted POSS derivatives were translucent, particularly the phenyl-substituted C6-linked derivatives. The static water contact angles for the casted films containing the isobutyl-substituted C3- and C6-linked POSSs were 100.8 ± 0.4° and 101.4 ± 0.4°, respectively. For the cast film containing the phenyl-substituted POSSs, the static water contact angles were unchanged from those of the bare PMMA film, indicating no segregation. The addition of the phenyl-substituted derivatives increased the glass transition temperature of PMMA. The present study demonstrates that the simple technique of adding a small amount of POSS to resins can be used to choose between surface segregation or to improve the bulk properties by designing POSS-based giant molecular clusters.