Polymethacrylates with Polyhedral Oligomeric Silsesquioxane (POSS) Moieties: Influence of Spacer Length on Packing, Thermodynamics, and Dynamics

Polymethacrylates with polyhedral oligomeric silsesquioxane (POSS) moieties (poly­(POSS-MA)­s) with flexible spacers between the POSS cages and the methacrylate group have distinctly different properties from their linear counterpart, i.e., PMMA. POSS cages modify interchain correlations and result in multiple dynamic processes that reflect the cooperative relaxations of both the pendant POSS units and ester dipoles and the polymer backbone. As a result, the freezing of the backbone dynamics is shifted to lower temperatures, and the nanocomposites appear softer than linear PMMA chains of similar degrees of polymerization. POSS cages can be employed as nanometer size blocks that, depending on the polymer backbone and the spacer, can impart mobility and control over the mechanical properties of nanocomposites