Synthesis and structural study of copolymers of l-lactic acid and bis(2-hydroxyethyl terephthalate)

详细信息	查看全文 | 推荐本文 |

• 作者：Ewa Olewnik ; Wojciech Czerwiń ; ski ; Jacek Nowaczyk ; Marie-Odile Sepulchre ; Martine Tessier ; Slim Salhi ; Alain Fradet
• 关键词：Biodegradable polymers ; Copolymerization ; l-Lactic acid ; Polycondensation ; Poly(ethylene terephthalate)
• 刊名：European Polymer Journal
• 出版年：2007
• 期刊代码：35_00143057
• 类别：ms
• 出版时间：March 2007
• 卷：43
• 期：3
• 页码：1009-1019
• 文件大小：725 K

摘要

Poly(ethylene terephthalate)–poly(lactic acid) (PET–PLLA) copolyesters were synthesized by the melt reaction of bis(2-hydroxyethyl terephthalate) (BHET) with l-lactic acid oligomers (OLLA) in the presence of SnCl₂, H₂O–p-toluene sulfonic acid, H₂O catalytic system. The ¹H and ¹³C NMR studies confirm the incorporation of lactate units in PET chains after reaction. Copolyesters containing nearly equimolar terephthalate/lactate ratio are not completely random and present some block-copolymer character, while the microstructure of PET-rich copolyesters is a random one. Due to a longer PET sequence length, the latter exhibit a melting point close to 210 °C while the other ones are amorphous. SEC/MALDI-TOF MS off-line coupling was used to obtain the absolute average molar masses of the copolyesters. The results indicate that the conventional polystyrene calibration method leads to a strong overestimation of PET–PLLA molar masses, while the determined by NMR is much closer to the SEC/MALDI value.