New force-field parameters for use in molecular simulations of s-triazine and cyanurate-containing systems. 1 - derivation and molecular structure synopsis

Cyanate ester resins are an emerging family of high performance polymers th at are being studied for a variety of technological applications. The struc ture of the aromatic sym-triazine ring formed during cure of these polymers is investigated here by analysis of X-ray crystallographic data from a num ber of model compounds. The data show a preferred conformation of the ring structure with alternating internal bond angles of ca. 112 degrees nitrogen (C-N-C) and 128 degrees at carbon (N-C-N). The C-N bond lengths are also s horter than those found in pyridine or pyrimidine, leading to a non-planar ring conformation. Force constants for the bond stretch, bend and torsional motions of the sym-triazine ring have also been calculated, using MOPAC, t he semi-empirical quantum mechanics package. (C) 2001 Elsevier Science Ltd. All rights reserved.