SUCROSE-BASED EPOXY MONOMERS AND THEIR REACTIONS WITH DIETHYLENETRIAMINE

Two sets of sucrose-based epoxy monomers, namely, epoxy allyl sucroses (EAS), and epoxy crotyl sucroses (ECS), were prepared by epoxidation of octa-O-allyl and octa-O-crotyl sucroses (OAS and OCS, respectively) . Synthetic and structural characterization studies showed that the ne w epoxy monomers were mixtures of structural isomers and diastereoisom ers that contained varying numbers of epoxy groups per sucrase. EAS an d ECS can be tailored to contain an average of one to eight epoxy grou ps per sucrose. Quantitative C-13-NMR spectrometry and titrimetry were used independently to confirm the average number of epoxy groups per sucrose. Sucrose-based epoxy monomers were cured with diethylenetriami ne (DETA) in a differential scanning calorimeter (DSC), and their curi ng characteristics were compared with those of diglycidyl ether of bis phenol A (DGEBA) and diepoxycrotyl ether of bisphenol A (DECEBA). EAS and DGEBA cured at 100 to 125 degrees C and exhibited a heat of cure o f about 108.8 kJ per mol epoxy. ECS and DECEBA cured at 150 and 171 de grees C, respectively, and exhibited a heat of cure of about 83.7 kJ p er mol epoxy. Depending upon the degree of epoxidation (average number of epoxy groups per sucrose) and the concentration of DETA, glass tra nsition temperatures (T(g)s) of cured EAS varied from -17 to 72 degree s C. DETA-cured ECS containing. an average of 7.3 epoxy groups per suc rose (ECS-7.3) showed no DSC glass transition between -140 and 220 deg rees C when the ratio of amine (NH) to epoxy group was 1:1 and 1.5:1. Maximum T(g)s obtained for DETA-cured DGEBA and DECEBA polymers were 1 34 and 106 degrees C, respectively. DETA-cured bisphenol A-based epoxy polymers degraded at about 340 degrees C, as observed by thermogravim etric analysis (TGA). DETA-cured sucrose-based epoxy polymers degraded at about 320 degrees C. Sucrose-based epoxies cured with DETA were fo und to bind aluminum, glass, and steel. Comparative lap shear tests (A STM D1002-94) showed that DETA-cured epoxy allyl sucroses with an aver age of 3.2 epoxy groups per sucrose (EAS-3.2) generated a flexible adh esive comparable in bond strength to DGEBA. However, DETA-cured ECS-7. 3 outperformed the bonding characteristics of both DGEBA and EAS-3.2. All sucrose-based epoxy polymers were crosslinked and insoluble in wat er, N,N-dimethylformamide, tetrahydrofuran, acetone, and dichlorometha ne. (C) 1998 John Wiley & Sons, Inc.