Crystalline dicarboxylated poly(L-lactic acid)s (dcPLLAs) with number-average molecular weights (M(n)'s) of 10(3) to 10(4) g/mol were synthesized via the melt polycondensation of L-lactic acid (LLA) in the presence of succinic anhydride (SAD), with tin(II) chloride and toluene-4-sulfonic acid as binary catalysts. They were characterized by end-group titration, (1)H-NMR, differential scanning calorimetry, and wide-angle X-ray diffraction. The terminal COOH percentage reached over 98%, and the molecular weight could be controlled by the molar ratio of LLA to SAD. The thermal behaviors depended on the molecular weight. The poly(L-lactic acid) s (PLLAs) crystallized slowly for M(n) <= 2000 but quickly for M(n) >= 4000. The crystallinity increased from 27 to 40% when M(n) grew from 4000 to 10,000. With comparison to ordinary PLLA, the dcPLLA had the same crystallization structure but a slightly lower crystallizability. The glass-transition temperature was clearly higher than that of amorphous dcPLLAs. With a controllable molecular weight, high COOH percentage, and crystallinity, the dcPLLA with M(n) >= 4000 appeared to be a suitable prepolymer for the preparation of high-molecular-weight crystalline PLLA via chain extension. (C) 2011Wiley Periodicals, Inc. J Appl Polym Sci 121: 3246-3251, 2011