Copolymers Based on PBS and Polydimethylsiloxane with Improved Properties and Novel Functions: Effect of Molecular Weight of Polydimethylsiloxane

The serious environmental pollution caused by nonbiodegradable plastics has led to an increased demand for biodegradable plastics. Poly-(butylene succinate) (PBS) is a very essential biodegradable polymer because of its good combined properties. But its drawbacks of low impact strength and lack of functionality restrain its application. In this work, polydimethylsiloxane (PDMS) is used to synthesize the diatom-like structure poly-(butylene succinate)-b-polydimethylsiloxane (PBSP), and the effect of molecular weight on the structure and properties is investigated systematically for the first time. The unique layered structure limited by the covalently connected blocks endowed PBSP with an excellent combined performance. The resulting PBSP possesses good thermal and mechanical properties. The mechanical properties improved substantially; especially, the impact strength increased evidently from 34.6 J/m of PBS to 162.5 J/m of PBSP. Furthermore, PDMS blocks endow the copolymers with good hydrophobicity and antismudge and self-healing properties, which greatly broadens the application range of the PBS materials. The surface analysis and Flory-Huggins solution theory testified that the PDMS blocks with higher molecular weight preferentially enriched the surface and sublayer of the material, due to the huge difference in solubility parameters between PBS and PDMS. PBSP with regulatable mechanical properties and functions could be obtained by changing the molecular weight of the PDMS blocks.