Renewable Thermosets and Thermoplastics from Itaconic Acid

Renewable materials are a research necessity, with the creation of a sustainable chemical industry representing a grand challenge for the field of chemistry and materials science. On this basis, biorenewable resources are being transformed into degradable or recyclable high value polymers with a diverse array of applications. Itaconic acid (IA) is a notable biorenewable resource due to its low cost and large annual production. We report the synthesis of renewable thermosets and thermoplastics that are almost completely derived from IA. Using catalytic, solvent-free, and high yielding transformations from an itaconate source, we efficiently synthesized a saturated diol, a saturated diester, and an unsaturated diester. Subsequent binary step-growth polycondensation polymerizations between the diol and either diester generated polyesters with relatively high molar masses (>10 kg/mol). Ternary polymerizations of all three monomers in varying feed ratios produced polyesters with tunable amounts of unsaturated units along the backbone. Atom economies and low process mass intensities for these reactions reflect green processes. Thermoset materials were generated from these unsaturated terpolymers through thiol-ene click reactions with a potentially renewable cross-linker. We then established the tensile properties and molar mass between cross-links of these thermosets through mechanical testing and demonstrated hydrolytic stability under acidic and neutral conditions, but hydrolytic degradation under basic conditions. An α,ω-hydroxy terminated saturated polyester was prepared, functionalized with an atom transfer radical polymerization initiator, and then chain-extended with the α-methylene-butyrolactone, which can be derived from IA, to give triblock polymers.