Tertiary-amine-free, non-planar, sulfone-containing, tetrafunctional epoxy and its application as a high temperature matrix

Non-amine-derived tetrafunctional epoxies have several advantages over the amine-derived N,N,N ',N '-tetraglycidyl-4,4 '-diaminodiphenyl methane (TGDDM) in high temperature applications. Although two non-amine-derived tetrafunctional epoxies were developed in our laboratory, further improvements in toughness using less loading amount is still desirable. Thus, a tertiary-amine-free, non-planar and triphenylmethane-containing tetrafunctional epoxy (STFE) with a sulfone spacer was synthesized. When it was mixed with diglycidyl ether of bisphenol A (DGEBA) and cured with 4,4 '-diaminodiphenylsulfone (DDS), both thermal and mechanical performances outperformed TGDDM. Moreover, STFE modified system shows the highest toughness (35.7 kJ m(-2)) among three amine-free and triphenylmethane-containing epoxies at merely 5 wt% loading. Molecular simulation and thermomechanical analysis results suggest that the improved mechanical properties could be related to the geometry of the molecule and larger free volume. Despite a marginal drop in T-g, the thermal degradation temperature is better than that of TGDDM/DDS. In addition, the moisture resistance of STFE/DGEBA/DDS is much better than that of TGDDM/DDS. Thus, STFE modified DGEBA could be a potential replacement for TGDDM in some high temperature applications. (c) 2020 Society of Chemical Industry