Polylactide (PLA), a commercially available thermoplastic derived from plant sugars, finds applications in consumer products, disposable packaging, and textiles, among others. The widespread application of this material is limited by its brittleness, as evidenced by low tensile elongation at break, impact strength, and fracture toughness. Herein, a multifunctional vegetable oil, acrylated epoxidized soybean oil (AESO), was investigated as a biodegradable, renewable additive to improve the toughness of PLA. AESO was found to be a highly reactive oil, providing a dispersed phase with tunable properties in which the acrylate groups underwent cross-linking at the elevated temperatures required for processing the blends. Additionally, the presence of hydroxyl groups on AESO provided two routes for compatibilization of PLA/AESO blends:(1) reactive compatibilization through the transesterification of AESO and PLA and (2) synthesis of a PLA star polymer with an AESO core. The morphological, thermal, and mechanical behaviors of PLA/oil blends were investigated, in which the dispersed oil phase consisted of AESO, soybean oil (SYBO), or a 50/50 mixture of AESO/SYBO. The oil additives were found to toughen the PLA matrix, with significant enhancements in the elongation at break and tensile toughness values, while maintaining the glass transition temperature of neat PLA. In particular, the blend containing PLA, AESO, SYBO, and the PLA star polymer was found to exhibit a uniform oil droplet size distribution with small average droplet size and interparticle distance, resulting in the greatest enhancements of PLA tensile properties with no observable plasticization.

Utilization of biomass for commodity polymers has gained tremendous interest. We report a method to prepare high molecular weight renewable homopolymers and block copolymers derived from natural rosin. Monomers with high renewable content (70 wt %) were prepared via a simple esterification reaction between dehydroabietic alcohol and 5exo-norbornenecarboxylic acid. Living and controlled polymerization of these monomers were achieved by ring-opening metathesis polymerization to obtain polymers with molecular weight up to ∼500 kg/mol. These homopolymers exhibit structure-dependent glass transition temperatures, excellent thermal stabilities, and thermoplastic properties. Chain entanglement molecular weight was determined via rheological assessments for such polymers with bulky side moieties. Using the living ROMP, dehydroabietic-based homopolymer was chainextended with a soybean oil-derived norbornene monomer to yield triblock copolymers, which showed behaviors of thermoplastic elastomers.

Phenylhydrazine is an effective modifier for conventional ATRP syntheses, providing systematic control over the dispersity of polymers with unimodal molecular weight distributions.

A rosin-derived polymethacrylate, poly­(dehydroabietic ethyl methacrylate) (PDAEMA), was evaluated as a sustainable end block in triblock copolymer-based thermoplastic elastomers. Triblock copolymers containing glassy PDAEMA end blocks and a rubbery poly­(n-butyl acrylate) (PnBA) midblock were synthesized through atom transfer radical polymerization. The volume fraction of PDAEMA in the triblock copolymer was varied at constant midblock molecular weight. At lower PDAEMA content, the triblock copolymers exhibited microphase separated morphologies lacking long-range order, which transitioned to a well-defined cylindrical morphology as the PDAEMA content was increased. Observed thermal properties were consistent with the presence of distinct PDAEMA and PnBA domains. The order–disorder transition temperature increased with increasing PDAEMA content in the block copolymer, and the Flory–Huggins interaction parameter of PDAEMA/PnBA was strongly temperature-dependent yet small in value. The triblock copolymers exhibited elastomeric behavior at room temperature and accessible order–disorder transitions, appropriate for thermoplastic elastomer applications.