Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

This mini-review summarizes the applications of olefin metathesis in synthesis and functionalization of polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials. Three types of processes, i.e., cross metathesis (CM) of vinyl-substituted POSS with terminal olefins, acyclic diene metathesis (ADMET) copolymerization of divinyl-substituted POSS with α,ω-dienes and ring-opening metathesis polymerization (ROMP) of POSS-substituted norbornene (or other ROMP susceptible cycloolefins) are discussed. Emphasis was put on the synthetic and catalytic aspects rather than on the properties and applications of synthesized materials.

Molecular and kinetic design for the expanded control of molecular weights in the ring-opening metathesis polymerization of norbornene-substituted polyhedral oligomeric silsesquioxanes

Rod-like POSS-containing polynorbornenes with high molecular weights were synthesized using ROMP with molecular and kinetic control.

Thermal and mechanical properties of POSS-Cyanate ester/epoxy nanocomposites

A new cyanate ester functionalized polyhedral oligomeric silsesquioxane (POSS-Cy) monomer was prepared by reacting hydroxyl functionalized POSS-OH with cyanogen bromide (CNBr) in the presence of triethylamine (Et3N). The precursor POSS-OH and the corresponding cyanate ester POSS-Cy were characterized by Fourier transform infrared (FTIR), 1H and 13C nuclear magnetic resonance (13C-NMR) spectral techniques. Nanocomposites were prepared by reacting diglycidylether of bisphenol-A, POSS-Cy and 4,4’-diaminodiphenylmethane (DDM). The structure of the cross-linked networks was confirmed by FT-IR. The POSS particles formed clusters in some regions leading to phase separation as revealed by scanning electron microscopy (SEM) analysis. Dynamic mechanical analysis (DMA) shows that the glass transition temperature decreases from 161oC to 155oC when the POSS-Cy content was increased from 0% to 15%. But, the T10% of the epoxy resin (369oC) increased significantly (404°C) on incorporating 15% of POSS-Cy. The LOI values indicate that these blends have good flame-retardant properties.