Synthesis and in situ foaming of biodegradable malonic acid ESO polymers

In this study, biodegradable rigid cellular materials were synthesized from the reaction of malonic acid with epoxidized soybean oil. Malonic ester reacts with two epoxy reaction, initially formed malonic acid monoester (MAME) can decarboxylate and produce CO2, which acts as the blowing agent leading to in situ foaming of the polymer. Epoxide addition and decarboxylation reactions of MAME occur competitively and simultaneously and by controlling their relatives rates, foams of controlled density were produced. H-1 NMR spectrum of the synthesized foams showed that increasing the temperature increases the rate of decarboxylation reaction of MAME and decreases crosslink dencity leading to softer and lower density foams. Addition of 1,4-diazabicyclo[2.2.2]octane (DABCO) as a catalyst also increases the rate of decarboxylation. Load deflection curves of the cellular materials showed that decreasing the temperature and addition of DABCO increase compressive modulus of samples. Cell morphology was studied by microscopic images of foam samples that showed that foam samples have a closed cell structure and a wide distribution of cell volume. Soil burial test was done todetermine rate of biodegradation of foam samples. A half-life of 815 days showed that foam samples are highly biodegradable. (c) 2008 Wiley Periodicals, Inc.