Structure and mechanical properties of poly(lactic acid) filled with (starch nanocrystal)-graft-poly(ε-caprolactone)

Poly(E-caprolactone) (PCL) was grafted to the surface of starch nanocrystals (StN) via microwave-assisted ROP. The resultant nanoparticles were then incorporated into a poly(lactic acid) matrix to produce fully-biodegradable nanocomposites with good mechanical properties. A loading level of 5 wt.-% StN-g-PCL resulted in simultaneous enhancements of strength and elongation. The StN-g-PCL self-aggregated as rubbery microparticles to enhance the elongation by ca. 10-fold over that of neat PLA. Meanwhile, the grafted PCL chains were miscible with PLA and formed a stress-transferring interface to the StN, providing a reinforcing function.