Synthesis and structural study of copolymers of l-lactic acid and bis(2-hydroxyethyl terephthalate)
| Autor: | Marie‐Odile Sepulchre, Alain Fradet, Wojciech Czerwiński, Ewa Olewnik, Slim Salhi, Martine Tessier, Jacek Nowaczyk |
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| Rok vydání: | 2007 |
| Předmět: |
chemistry.chemical_classification
Ethylene Materials science Condensation polymer Molar mass Polymers and Plastics Organic Chemistry General Physics and Astronomy Sulfonic acid Lactic acid chemistry.chemical_compound chemistry Polymer chemistry Materials Chemistry Melting point Copolymer Polystyrene |
| Zdroj: | European Polymer Journal. 43:1009-1019 |
| ISSN: | 0014-3057 |
| DOI: | 10.1016/j.eurpolymj.2006.11.025 |
| Popis: | 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 M n ¯ determined by NMR is much closer to the SEC/MALDI value. |
| Databáze: | OpenAIRE |
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