1. Laboratori de Termodinàmica, ETSEIB, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain;2. Departament de Química Analítica i Química Orgànica, Universitat Rovira i Virgili, Marcel?·?lí Domingo s/n, 43007 Tarragona, Spain
Abstract:
Mixtures of DGEBA with 4‐phenyl‐γ‐butyrolactone (PhBL) were cationically copolymerized in the presence of ytterbium triflate or triarylsulfonium hexafluoroantimoniate as thermal or photo initiator respectively. Changes during curing and final properties of the cured materials were studied by means of DSC, FT‐IR/ATR, TMA, DMTA, TGA and densitometric measurements. The formation of a network containing polyether and poly(ether‐ester) moieties was demonstrated to take place through the ring‐opening polymerization of a spiroorthoester intermediate (SOE) formed during the copolymerization. An increase in the proportion of lactone resulted in an increase in the curing rate, a decrease in the shrinkage after gelation and in the thermal stability and glass transition temperature (Tg). A strong influence of the initiator on the curing mechanism was observed. As a consequence, the photocured materials exhibited superior thermal stability and Tg than those obtained thermally.
