Branched polymers with directional polymer chains require scaffolds with multiple functional groups oriented in a single direction. Inorganic clusters are suitable for attaining unique three-dimensional structures. The incompletely condensed polyhedral oligomeric silsesquioxanes (IC-POSS) contain three silanol groups at the open corners of the cubic siloxane core. The three-directional silanol groups were readily converted into hydrosilanes, which could be modified by hydrosilylation with allyl-terminated poly(methyl methacrylate). The thermal and mechanical properties of the directionally branched polymers were compared with those of an IC-POSS-terminated linear polymer. The hardness of the polymer film is enhanced by its directionally branched structure.
