Poly(ethylene glycol) octafunctionalized polyhedral oligomeric silsesquioxane: WAXD and rheological studies

A homologous series of PEG (various chain length)-substituted octasilsesquioxanes prepared by the hydrosilylation of unsaturated PEGs (poly(ethylene glycol)s) with octa(dimethylsiloxy)silsesquioxane (Q(8)M(8)(H)) were studied by wide-angle X-ray diffraction WAXD and rheology. The WAXD results indicate that neat POSS is highly crystalline material, while its PEG hybrids show evidence of small, disordered POSS crystals. Rheological characterization shows largely Newtonian behavior of POSS-PEG materials, with an interesting interplay between attached PEG chain length and weight fraction of POSS, with regards to melt viscosity and activation energy of flow.