Journal of Polymer Science Part A: Polymer Chemistry, Vol.44, No.15, 4559-4565, 2006
Oligomeric cyanate ester resins: Application of a modified Ullmann synthesis in the preparation of thermosetting polymers
New multiple aromatic ether containing oligomeric cyanate ester resins have been synthesized using a modified Ullmann reaction. The oligomeric monomers were prepared by reacting resorcinol and 1,3- or 1,4-dibromobenzene in the presence of potassium carbonate and a catalytic amount of a copper(I) complex in a N,N-dimethylformamide/toluene mixture. The hydroxyl terminated intermediates were endcapped with the cyanate moiety by reaction with cyanogen bromide in the presence of triethylamine in dry acetone. The oligomeric cyanate ester monomers are liquid at room temperature, which enhance their processability to polymeric networks. The thermo-oxidative properties were determined for the new cyanate ester polymers as well as their storage modulus. The length of the aromatic ether spacer between the terminal cyanate ester groups was varied to investigate the effect of changing the spacer length on the properties of the material. (c) 2006 Wiley Periodicals, Inc.