Cross-linkable carbosilane polymers with imbedded disilacyclobutane rings derived by acyclic diene metathesis polymerization

Cyclolinear carbosilane polymers with disilacyclobutane (DSCB) rings in the main-chain structure were prepared by means of acyclic diene metathesis (ADMET) polymerization of the corresponding 1,3-dibutenyl-1,3-disilacyclobutanes. The copolymerization of a monomer of this type with a noncyclic organosilane diene allowed for the incorporation of a varying number of DSCB rings into the polymer backbone. Subsequent hydrogenation of the double bonds with p-toluenesulfonhydrazide resulted in a saturated hydrocarbon structure in the main chain without affecting the DSCB ring. All of the resultant polymers are well-defined materials with DSCB rings incorporated into the backbone structure, as evidenced by NMR spectroscopy and GPC analyses. The thermal behavior of these polymers was characterized by DSC and TGA. DSC indicated low T(g)s, and TGA evidenced high thermal stability in an inert atmosphere. In addition, large exothermic peaks were observed in the DSC, which indicated, along with the IR and solid-state Si-29 NMR spectra, that cross-linking occurs during heating to ca. 250 degreesC via opening of the imbedded DSCB rings. The swelling properties of the resultant, thermally stable, carbosilane network materials on exposure to various solvents were also examined.