title: Cocrystallization model for synthetic biodegradable poly(butylene adipate-co-butylene terephthalate).
abstract: Synthetic biodegradable poly(butylene adipate-co-butylene terephthalate), P(BA-co-BT), with 56 mol % butylene adipate, BA, was characterized by solid-state NMR spectroscopy, thermal analysis, X-ray diffraction, computer modeling, and polarization microscopy. The NMR study showed the presence of BA and butylene terephthalate, BT. T(1C) NMR measurements proved that some BA and BT units were in crystalline regions. Thermal analysis showed one glass-transition temperature and a single diffuse melting endotherm corresponding to a large melting-point depression of about 100 degrees C compared with poly(butylene terephthalate), PBT. These results suggest that there is only one crystalline phase. An X-ray fiber diagram of a stretched film could be indexed with the same unit cell as that for PBT. Computer modeling showed that the adipate unit fits into the crystal structure of PBT by adopting a TTGTG dihedral angle sequence in the crystalline conformation proposed for the cocrystallization model. The predicted fiber diagram from the proposed model qualitatively agrees with the experimental one. Polarization microscopy revealed that the spherulite growth rate of P(BA-co-BT) was similar to that for poly(butylene adipate), PBA.
authors.affiliation: Department of Chemistry, McGill University, 3420 University Street, Montreal, Quebec H3A 2A7, Canada.
authors.forename: Emily
authors.initials: E
authors.lastname: Cranston
authors.forename: Jumpei
authors.initials: J
authors.lastname: Kawada
authors.forename: Stephane
authors.initials: S
authors.lastname: Raymond
authors.forename: Frederick G
authors.initials: FG
authors.lastname: Morin
authors.forename: Robert H
authors.initials: RH
authors.lastname: Marchessault
mesh_terms: D020341:Absorbable Implants; D002152:Calorimetry, Differential Scanning; D003198:Computer Simulation; D003460:Crystallization; D007700:Kinetics; D015394:Molecular Structure; D011091:Polyesters / Q000138:chemical synthesis* / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry*; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D011091:Polyesters; D011108:Polymers; C488797:poly(butylene adipate-co-butylene terephthalate)