Table of Contents
Journal of Polymers
Volume 2014 (2014), Article ID 830137, 7 pages
http://dx.doi.org/10.1155/2014/830137
Research Article

Cyclic Oligolactic Acid in Direct Polycondensation PLLA and Its Extraction with Organic Solvent

1Department of Biobased Materials Science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
2Rajamangala University of Technology Thanyaburi, Rangsit-Nakhon Nayok, Pathum Thani 12110, Thailand

Received 22 August 2014; Revised 17 October 2014; Accepted 18 October 2014; Published 25 November 2014

Academic Editor: Iliya Rashkov

Copyright © 2014 Keiichiro Nomura et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The contents of poly(L-lactic acid) (PLLA) prepared by direct condensation polymerization without using a catalyst were studied. 1H NMR and mass spectrometry analyses suggested that PLLA contained cyclic oligo(L-lactic acid) (c-OLLA) with 3–20 repeat units. Notably, only c-OLLA was extracted and isolated using hexane or cyclohexane at 4°C; thus the hydrophobicity, topology, and temperature dependence of the solubility of the obtained PLLA enabled the selective extraction of c-OLLA. The effect of cyclic compounds on direct polycondensation and the potential for c-OLLA to form molecular inclusion complexes were also discussed.