DEVELOPMENT OF NOVEL FUNCTIONALIZED ARYL CYANATE ESTER OLIGOMERS .1. SYNTHESIS AND THERMAL CHARACTERIZATION OF THE MONOMERS

A range of allyl-functionalized cyanate ester oligomers (and their precursors) containing four and six phenylene groups in the backbone were prepared in high yield and characterized using H-1 and (1)3C nuclear magnetic resonance (NMR) spectroscopy and microanalysis. The thermally-initiated polymerization of the monomers was studied using differential scanning calorimetry (DSC) and the kinetic parameters of the reaction obtained: the polycyclotrimerization was extremely well-fitted to a first-order model over the apparent conversion range 5-50% (yielding Arrhenius parameters as apparent activation energies of 211.7 kJ mol(-1) and In A = 39.8 for 6 and 148.1 kJ mol(-1) and in A = 27.0 for 12). The effect of increasing allyl-functionalized cyanate ester content upon a commercial cyanate ester/bis(maleimide) blend was examined using DSC, giving further evidence of a coreaction. The thermal-oxidative stability of the polymeric blends and terpolymers was investigated using thermogravimetric analysis (TGA) and revealed that incorporation of functionalized oligomeric cyanate esters (ranging between 12.5 and 50%) into bis(maleimide) networks can be achieved without dramatic stability penalties.