A homologous series of PEG (various chain length)-substituted octasilsesquioxanes were prepared by the hydrosilylation of unsaturated PEGs (poly(ethylene glycol)s) with both octa(dimethylsiloxy)silsesquioxane (Q 8 M 8 H ) and octahydridosilsesquioxane (T 8 H ). The silsesquioxane-PEGs materials were produced by the initial synthesis of a series of allyl-modified poly(ethylene glycol)s and subsequent attachment to both (Q 8 M 8 H ) and (T 8 H ). The products were chemically characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance ( 1 H, 13 C, and 29 Si NMR) spectroscopy, and the properties of the allyl PEGs and their POSS hybrids were thermally characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The attachment of the PEGs onto the POSS macromonomers (Q 8 M 8 H and T 8 H ) clearly demonstrated a chainlength-dependent increase in T g and a concomitant suppression of crystallization.

A series of POSS (PEG)n)2-6 macromonomers were further functionalized by reaction with methacryloyl chloride and then polymerized with methyl methacrylate to produce a series of hybrid materials where the amounts of POSS (PEG)n)2-6 used as cross-linkers varied from 0.1 to 0.5 mol %. Thermal investigations using TGA and DSC techniques revealed that both POSS concentrations and PEG chain length play important roles in defining structure-property relationships. Incorporation of POSS always increased thermal stability. Although the POSS is a bulky and multifunctional cross-linker, glass transitions did not always increase. In some instances bulkiness of the group created free volume and chain separation, which led to a reduction in the glass transition temperature.

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 (Q8M8 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.