POLAR INTERACTION IN A CYANATED POLY(ETHER SULFONE)-MODIFIED POLYCYANURATE

Low molecular weight cyanated poly(ether sulfone) (CPES, Mn = 3200) wa s prepared, and cured with bisphenol A dicyanate (BPADCy). The resulti ng polycyanurates of different compositions show an S-shaped T-g-compo sition curve. This unexpected S-shaped curve is interpreted in term of the polar interaction between poly(ether sulfone) and s-triazine ring s formed by polycyclotrimerization of aromatic dicyanates. Separate st udy on u.v. spectra of mixture model compounds suggests that this pola r interaction belongs to an n-pi interaction between the lone pair el ectrons of the N-atoms in the s-triazine ring and the pi-orbital of t he phenylene rings neighbouring to the sulfone linkage. I.r. study on the cured polycyanurates indicates that this polar interaction causes the shift of the -C = N stretching from 1564 to 1580 cm(-1). (C) 1998 Elsevier Science Ltd. All rights reserved.