title: Identifying the phase behavior of biodegradable poly(hexamethylene succinate-co-hexamethylene adipate) copolymers with FTIR.
abstract: Whether a phase separation or a cocrystallization occurs in poly(hexamethylene succinate-co-hexamethylene adipate) (P(HS-co-HA)) copolymers was studied with a combination of wide-angle X-ray diffraction (WAXD) and Fourier transform infrared (FTIR) spectroscopy. With HA as the majority, the presence of HS comonomers leads to weakening and broadening of (10l) peaks in the X-ray fiber diffraction patterns, while a crystal structure similar to PHS is formed in the copolymer with HS as the majority. The X-ray diffraction patterns imply possible cocrystallization between HS and HA comonomers, but cannot lead to an unambiguous conclusion, which was clarified with the compensative tool of FTIR. Following the characteristic absorption bands of crystals, cocrystallization of HS and HA comonomers was observed in copolymers with HA comonomer as the majority during which HA initiated the nucleation at high temperatures. With HA as minority, cocrystallization of HS and HA can still be achieved with a fast quenching to below 0 degrees C, while a phase separation occurs and only HS comonomer crystallizes at high temperatures. This demonstrates that P(HS-co-HA) has an asymmetric phase diagram. Because of the sensitivity to local conformations, FTIR spectroscopic method is demonstrated to be a powerful tool on study phase behaviors of polymers with similar crystal structure.
authors.affiliation: National Synchrotron Radiation Laboratory and Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, China.
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Li
authors.forename: Zhenfei
authors.initials: Z
authors.lastname: Hong
authors.forename: Jie
authors.initials: J
authors.lastname: Sun
authors.forename: Yong
authors.initials: Y
authors.lastname: Geng
authors.forename: Youju
authors.initials: Y
authors.lastname: Huang
authors.forename: Haining
authors.initials: H
authors.lastname: An
authors.forename: Zhe
authors.initials: Z
authors.lastname: Ma
authors.forename: Baijin
authors.initials: B
authors.lastname: Zhao
authors.forename: Chunguang
authors.initials: C
authors.lastname: Shao
authors.forename: Yapeng
authors.initials: Y
authors.lastname: Fang
authors.forename: Chuanlu
authors.initials: C
authors.lastname: Yang
authors.forename: Liangbin
authors.initials: L
authors.lastname: Li
mesh_terms: D000272:Adipates / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray / Q000379:methods; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011091:Polyesters / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013055:Spectrophotometry, Infrared / Q000379:methods; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors; D014961:X-Ray Diffraction
chemical_list: D000272:Adipates; D001672:Biocompatible Materials; D011091:Polyesters; D011108:Polymers; C543482:poly(hexamethylene succinate-co-hexamethylene adipate); C029900:adipic acid