Stereochemical heterogeneity of biodegradable poly(L-lactide) homopolymer as revealed by temperature rising elution fractionation and successive self-nucleation/annealing thermal fractionation

• Published in: Journal of polymer science. Part B, Polymer physics Vol. 50; no. 18; pp. 1277 - 1285
• Main Authors: Luo, Jun, Huo, Fei, Lin, Hui, Lin, Zhouli, Chen, Zhengjian, Yuan, Fang, Jiang, Hongliang, Wang, Hongjun, Tu, Kehua, Liu, Dingrong, Tan, Songwei, Wang, Li-Qun
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 15.09.2012; Wiley
• Subjects: Applied sciences; crystallization and melting behavior; differential scanning calorimetry (DSC); Exact sciences and technology; heterogeneous polymers; isotactic; Organic polymers; Physicochemistry of polymers; poly(L-lactide); polylactide; Properties and characterization; separation of polymers; SSA; structural characterization; Structure, morphology and analysis; structure-property relations; TREF; SSA; Differential scanning calorimetry; Tacticity; Fractionation; Annealing; differential scanning calorimetry (DSC); Thermal method; Optically active polymer; structural characterization; Coupled method; Experimental study; separation of polymers; structure-property relations; Lactic acid polymer; poly(L-lactide); crystallization and melting behavior; heterogeneous polymers; Optical activity; Physical separation; TREF; Optical purity; isotactic; Commercial form; polylactide
• ISSN: 0887-6266; 1099-0488
• DOI: 10.1002/polb.23127

Commercial poly(L‐lactide) is typically heterogeneous in chain structure due to the existence of a small amount of D‐lactyl units that are produced by the racemization reactions during the synthesis. In this article, the stereochemical heterogeneity of two commercial poly(L‐lactide) was investigated with temperature rising elution fractionation (TREF) and successive self‐nucleation/annealing (SSA) thermal fractionation. For both samples, three fractions were collected and characterized with rotatory power analysis and DSC. The fractions show distinct optical purity and DSC results, which reflect the structure differences among them directly. After SSA treatment, the observation of multiple endotherms for each physically separated fraction confirms the fractionated sample contains a heterogeneous intermolecular and intramolecular distribution of defects. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 Biodegradable poly(L‐lactide) is successfully separated with temperature rising elution fractionation (TREF) in a quantitative manner for the first time. The stereochemical heterogeneity of PLLA fractions is investigated with successive self‐nucleation/annealing thermal fractionation. This work provides a good example for extending the application of TREF. It is expected that TREF will be applied to more and more other biodegradable polyester with similar chain structure.