Synthesis and characterization of novel dihydrobenzoxazine resins

Three dihydrobenzoxazines are synthesized from bisphenol A (BPA), 4,4′‐biphenol (BIP), and dicyclopentadiene phenol adduct (DCPD). Polydihydrobenzoxazine containing 4,4′‐biphenol (BIPDB) had the most rigid structure of the three and was found to possess the best mechanical and thermal properties. The glass transition temperature of BIPDB was 206°C, and that of BPA‐type polydihydrobenzoxazine (BPADB) and dicyclopentadiene type polydihydrobenzoxazine (DCPDDB) were 184 and 183°C, respectively. DCPDDB, with a rigid hydrophobic cycloaliphatic structure, was found to possess excellent properties such as low moisture absorption, low dielectric constant, low polarization. The resulted polymer from DCPDDB had a dielectric constant of 2.94U, which was better than that of polymers derived from BPA (3.31U), BIP (3.45U), and traditional phenolic resin (3.9–4.0U). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 342–347, 2006