Comparison between Ultrathin Films and the Bulk of Microbial Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) with Regard to Their Melt-Isothermal Crystallization Kinetics
Comparison between Ultrathin Films and the Bulk of Microbial Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) with Regard to Their Melt-Isothermal Crystallization Kinetics
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DOI：
10.1021/acs.macromol.2c00389
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发表时间：
2022-07
期刊：
影响因子：
5.5
通讯作者：
T. V. Nguyen;Toshiteru Nagata;Kosei Noso;Kenshiro Kaji;H. Masunaga;T. Hoshino;S. Sakurai;S. Sasaki
中科院分区：
文献类型：
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作者：
T. V. Nguyen;Toshiteru Nagata;Kosei Noso;Kenshiro Kaji;H. Masunaga;T. Hoshino;S. Sakurai;S. Sasaki
成功研究了微生物聚（3-羟基丁酸酯）（P3 HB）和聚（3-羟基丁酸酯-co-3-羟基己酸酯）（PHBH）熔体的等温结晶动力学。50 nm厚的薄膜上的分子到层状尺度的时间分辨掠入射广角X射线衍射（GIWAXD）和小角X射线散射（GISAXS）测量使用同步辐射。在60、70和80 °C的结晶温度Tcs下，在SiO2膜中的成核和结晶速率远低于本体中的成核和结晶速率。此外，有人建议，第一次形成的亚稳晶体结构更无序的薄膜中比在体。结晶的分子扩散速率在薄膜中比在本体中低。晶体生长速率也可能在薄膜中比在块体中低。只有在较高的Tc下，P3 HB薄膜才发生从边缘富集到平坦富集的层状取向的转变。具有较高的3 HH含量的PHBHs的层状堆叠方式在PHBHs膜更无序。
Isothermal crystallization kinetics from the melt of microbial poly(3-hydroxybutyrate) (P3HB) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) were successfully investigated for ca. 50 nm thick ultrathin films on a molecular-to-lamellar scale by time-resolved grazing-incidence wide-angle X-ray diffraction (GIWAXD) and small-angle X-ray scattering (GISAXS) measurements using synchrotron radiation. The nucleation and crystallization rates were much lower in the ultrathin films than in the bulk at crystallization temperatures,Tcs, of 60, 70, and 80 °C. Moreover, it was suggested that the first-formed metastable crystal structures were more disordered in the ultrathin films than in the bulk. The molecular diffusion rate for crystallization was lower in the ultrathin film than in the bulk. The crystal growth rate might also be lower in the ultrathin film than in the bulk. The transformation from an edge-on-rich to a flat-on-rich lamellar orientation occurred only in the P3HB ultrathin films at higherTcs. The lamellar stacking manner in the ultrathin films was more disordered for PHBHs having a higher 3HH content.