Structure and Mechanical Properties of Poly(lactic acid) Filled with (Starch nanocrystal)-graft-poly(e-caprolactone) Jiahui Yu, Fujin Ai, Alain Dufresne, Shanjun Gao, Jin Huang, * Peter R. Chang * Introduction Nowadays, the claim of environmental protection and the lack of petroleum resources provide a new opportunity for developing materials derived from biomass resources. [1,2] Since the basic substance, lactic acid (2-hydroxypropionic acid), is derived from renewable agricultural source (such as corn), [3,4] poly(lactic acid) (PLA) is defined as a biomass material. Currently, PLA-based materials have been widely studied for packaging application by virtue of their good mechanical performances, biodegradability, non-toxicity and biocompatibility. [5] In addition, numerous other areas of advantage have been demonstrated: i) consumption of CO 2 in the process of its production, [6] ii) significant savings of energy, [7] iii) recycling and composting char- acteristics, [8] iv) improvement for farm economies, and v) manipulation of physical and mechanical properties associated with polymer architecture. [9–12] Full Paper J. Yu, J. Huang College of New Drug Innovation Research & Development, East China Normal University, Shanghai 200062, China E-mail: huangjin@iccas.ac.cn F. Ai, S. Gao, J. Huang Joint Laboratory of Polymer Modification and Functional Materials, College of Chemical Engineering and College of Materials Science & Engineering, Wuhan University of Technol- ogy, Wuhan 430070, China A. Dufresne Ecole Francaise de Papeterie et des Industries Graphiques, Institut National Polytechnique de Grenoble (EFPG-INPG) BP65, 38402 Saint-Martin d’He ´res Ce ´dex, France P. R. Chang Bioproducts and Bioprocesses National Science Program, Agri- culture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, S7N 0X2, Canada E-mail: changp@agr.gc.ca Poly(e-caprolactone) (PCL) was grafted to the surface of starch nanocrystals (StN) via micro- wave-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 rub- bery 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. Macromol. Mater. Eng. 2008, 293, 763–770 ß 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/mame.200800134 763