Mixed Isodimorphic/Isomorphic Crystallization in Aliphatic Random Copolycarbonates

作者：Yilong Liao, Ricardo A. Pérez‐Camargo, Tianyi Ma, Jon Maiz, Antxon Martı́nez de Ilarduya, Haritz Sardón, Guoming Liu, Dujin Wang, Alejandro J. Müller · 发表于：Macromolecules · 年份：2024 · DOI：10.1021/acs.macromol.4c01716 · 被引用次数：13 · 研究领域：biodegradable polymer synthesis and properties、Crystallization and Solubility Studies、Polymer crystallization and properties

In this work, we investigate the crystallization behavior of two series of novel aliphatic random copolycarbonates: poly(heptamethylene- ran -octamethylene carbonate) (PC7/PC8) and poly(octamethylene- ran -dodecamethylene carbonate) (PC12/PC8). Both copolymers display apparent isodimorphic behavior as they crystallize over the entire composition range, exhibiting pseudoeutectic points at 45 and 76 mol % of PC8 content for PC7/PC8 and PC12/PC8, respectively. However, the evolution in melting enthalpies (Δ H m ) and crystallinities ( X c ) deviate from the expected pseudoeutectic behavior, indicating mixed isodimorphic/isomorphic crystallization, a behavior reported for the first time recently by us in poly(hexamethylene- ran -octamethyelene carbonate) (PC6/PC8). Further understanding of this behavior was obtained through structural and conformational characterization employing in situ synchrotron radiation wide- and small-angle X-ray scattering (WAXS/SAXS) and Fourier-transform infrared spectroscopy (FT-IR). For PC7/PC8 copolymers, a new third crystalline phase, from now on named the γ phase, different from PC7- and PC8-type crystalline phases (or any of their polymorphs: δ, α, and β), emerged for intermediate compositions, i.e., 34–45 mol % PC8, in line with the atypical variations of Δ H m and X c . For PC12/PC8 copolymers, a coexistence of the γ/PC8 type phase was found at PC8-rich contents. According to FT-IR results, the γ phase adopted a polyethylene-like conformation in...