Application of MALDI-TOF, 1H NMR and 13C NMR to follow the progress of the synthesis of high molecular weight epoxies from hydroxylated soybean oil and bisphenol A based epoxy resin

In the last couple of years growing attention is paid to environmental concerns with a special attention to bio-and renewable resources as feedstock for the chemical industry. In this article we synthesized bio-based high molecular weight epoxy resins with hydroxylated soybean oil (SMEG) and a low-molecular-weight epoxy resin (EPR 0162), using the epoxy fusion process. The course of the synthesis was studied by means of Matrix-Assisted Laser Desorption/Ionization time of flight (MALDI-TOF) mass spectrometry and NMR spectroscopy. A two-stage change in the value of the epoxy and the hydroxyl value, as well as the weight average molecular weight were observed during the SMEG_EPR polyaddition reaction. As a result of the reaction between functional groups, the product of the reaction of one molecule of SMEG and one molecule of EPR (1SMEG + 1EPR) is formed. Then it reacts with subsequent molecules of EPR or SMEG with the creation of products: 1SMEG + 1EPR, 1SMEG+ 2EPR, 2SMEG +1EPR. It is also shown that the obtained adducts are not the main products of the analyzed reaction, but are the intermediate reagents throughout the formation of products with higher molecular weights. Based on the progress of the SMEG_EPR epoxy fusion process in the registered m/z range, it has been found that products with linear, rather than branched, structure are more likely to be formed. At the same time this discovery states about less likelihood of crosslinking of the system based on modified soybean oil.