POSS Moieties with PEG Vertex Groups as Diluent in Polyurethane Elastomers: Morphology and Phase Separation

Polyhedral oligomeric silsesquioxane moieties with poly(ethylene glycol) groups attached on the cage (PEG-POSS) were blended with an elastomeric polyurethane matrix, in contents up to 10 wt %. Several experimental techniques in agreement with each other show that the PEG-POSS moieties disperse well on the molecular level and act as diluents plasticizing the molecular dynamics. Although the degree of microphase separation is only weakly affected in all the compositions, changes in the macromorphology related to the POSS moieties have an impact on the matrix properties, decreasing the storage modulus. The PEG-POSS themselves display segmental dynamics, glass transition, and crystallinity; however, none of these properties are observed in the blends, providing additional support for excellent miscibility with the matrix. The results are compared to those of previous works where different synthesis approaches resulting in different POSS topologies were used.