Toughening Cellulose: Compatibilizing Polybutadiene and Cellulose Triacetate Blends.

We report the synthesis of an ABA triblock copolymer of the structure CTA--PB--CTA (CTA = cellulose triacetate and PB = polybutadiene) and its ability to compatibilize immiscible CTA/PB polymer blends. CTA--PB--CTA was synthesized via ring-opening metathesis polymerization of cyclooctadiene (COD) in the presence of CTA containing a single olefin on the reducing end. The ABA triblock copolymer was incorporated into CTA/PB blends, resulting in films that were clear, tough, and creaseable, and increases in modulus, elongation at break, and toughness were observed with addition of as little as 1 wt % compatibilizer. Scanning electron microscopy revealed well-defined PB phases in the CTA matrix that decreased in domain size as more compatibilizer was added. This work may enhance the application scope of CTA and other cellulose-derived renewable polymers.