Sustainable Thermoplastic Elastomers Derived from Lignin Bio-Oils via an ABA Triblock Copolymer Strategy

A lignin-derived polyacrylate, namely, poly(guaiacyl acrylate) (PGA), is evaluated as an end block in linear ABA triblock copolymer-based sustainable thermoplastic elastomers. Triblock copolymers containing a rubbery poly(methyl acrylate) (PMA) midblock and glassy PGA end blocks are prepared via Cu(0)-mediated living radical polymerization or single electron transfer living radical polymerization. A suite of triblock copolymers with different block ratios and a constant end block molecular weight is prepared. Even a low-end block content (<5% mole ratio) can significantly increase the material's mechanical strength (3-7 folds) and long elongation at break. The enhanced mechanical properties are attributed to microphase separation morphologies evidenced by calorimetric and scattering analyses. These elastomers also exhibit enhanced thermal stability compared with that of their parent homopolymers.