Design of degradable core-shell starch nanoparticles by radical ring-opening polymerization of 2-methylene-1,3-dioxepane and their toughening of poly (lactic acid)

A degradable core-shell starch nanoparticle (dCSS), in which the rigid core was starch and soft shell was the copolymer of 2-methylene-1,3-dioxepane (MDO) and methyl acrylate (MA), was successfully synthesized. Then the dCSS was melt-blended with poly (lactic acid) to achieve degradable PLA/dCSS nanocomposites with strikingly improved mechanical property. Interestingly, the obtained dCSS can be successfully degraded under accelerated hydrolytic conditions by hydrolytic degradation test, which indicated the excellent degradability of dCSS. Mechanical property test indicated that the elongation at break of PLA/dCSS-15 was increased significantly to 310%, which was much higher than that of neat PLA. Moreover, the resulting PLA/dCSS blends still maintained a relatively high tensile strength of about 40.0 MPa. These results established a novel and efficient strategy for the preparation of degradable polymer blends with excellent stiffness-toughness.

Automated summary

A degradable core-shell starch nanoparticle was successfully synthesized and melt-blended with poly(lactic acid) to prepare nanocomposites with significantly improved mechanical properties. The starch nanoparticle showed excellent degradability under accelerated hydrolytic conditions, while the resulting blends exhibited significantly increased elongation at break and maintained relatively high tensile strength. This study established a novel and efficient strategy for preparing degradable polymer blends with excellent stiffness-toughness properties.