Linseed Oil-Based Thermosets by Aza-Michael Polymerization

Aza-Michael addition on acrylated linseed oil (AELO) is performed to synthetize biobased bulk thermosets without any catalyst. First, acrylation of epoxidized linseed oil (ELO) allows to obtain acrylate functions with vicinal hydroxyl groups which enhance the reactivity of acrylates. The autocatalytic effect of hydroxyl groups on acrylate monomers is highlighted by kinetic studies monitored by NMR and FTIR analyses on model molecules. Then, Priamine 1071, amine terminated poly(propyleneoxide) (PPO) and meta-xylylenediamine (MXDA) are used as cross-linkers with AELO. Curing kinetics are studied by DSC analyses to compare the reactivity of these structures. Priamine 1071 shows the highest reactivity; curing at room temperature is performed and high conversion is reached. Two enthalpies are observed with MXDA and only one at high temperature for PPO-based materials. Thermosets with a large range of mechanical properties are finally obtained from soft materials with PPO-diamine to hard materials with MXDA. Practical Applications: Thermosets are obtained by curing AELO with various diamines via aza-Michael reaction. Model reaction allows to demonstrate catalytic effect of hydroxyl groups on Aza-Michael reaction of acrylated oil with amines. Hence, linseed oil is a promising resource in terms of sustainable development in polymer science.