Abstract
Novel $i(bis)(3-propenyl-4-cyanatidophenyl) and $i(bis)(3,5-dipropenyl-4-cyanatidophenyl) compounds of respective general formula (I), in which A is H- or CH¿3?-CH=CH-, X is -CH¿2?-, -CR¿2?-, -C(=O)-O-, -Y-, or -Z-(-Y-Z-)¿n?, where R has 1-4 carbon atoms and is alkyl or perfluoroalkyl, Y is a direct bond, O, CO, S, or SO¿2?, Z is arylene (preferably $i(para)- or $i(meta)-phenylene), each Y and Z may be the same or different where occurring more than once, and n is 0 or an integer in the range 1 to about 30 such that the compound has a molecular weight of not more than 10,000 are prepared using as starting material a diallyl or tetra-allyl$i(bis)-phenol containing the desired group X, which is isomerized to the dipropenyl or tetrapropenyl$i(bis)-phenol by heating under reflux with potassium hydroxide in methanol. The phenolic groups are esterified to cyanate ester groups using cyanogen bromide and triethylamine, and the compound having both cyanate and propenyl functions is obtained as predominantly the $i(trans) geometrical isomer. It may be polymerized alone or preferably by co-reaction with $i(bis)-maleimides, $i(bis)-citraconimides, aspartimides, compounds containing epoxide groups or other cyanate esters. The polymeric products may serve as matrix resins for structural composites and laminating resins for microelectronic applications, e.g., in the manufacture of printed circuit boards. Carbon-fibre reinforced laminates incorporating compounds of the invention with commercial $i(bis)-maleimides and cyanate ester monomers were found to display markedly improved mechanical properties, with particular regard to fracture toughness, and processability compared with the homopolymers.