Abe H, Kikkawa Y, Aoki H, Akehata T, Iwata T, Doi Y
Polymer Chemistry Laboratory, The Institute of Physical and Chemical Research (RIKEN), Saitama, Japan.
Int J Biol Macromol. 1999 Jun-Jul;25(1-3):177-83. doi: 10.1016/s0141-8130(99)00032-x.
Melt-crystallized films of poly[(R)-3-hydroxybutyric acid-co-10mol% 6-hydroxyhexanoic acid] (P[(R)-3HB-co-6HH]) were prepared by isothermal crystallization at various temperatures for 3 days, and subsequently stored at room temperature after the films formed well-developed and volume-filled spherulites. The lamellar morphologies and properties of melt-crystallized films were characterized by means of wide-angle X-ray diffraction, small-angle X-ray scattering, differential scanning calorimetry, transmission electron microscopy, and atomic force microscopy. The melting endotherm of P[(R)-3HB-co-6HH] films was composed of a broad peak starting around room temperature and of a sharper peak starting above the isothermal crystallization temperature. The stacking of flat-on lamellae with lamellar periodicity of 8-10 nm was detected on the surface of P[(R)-3HB-co6HH] films after the primary crystallization at 110 degrees C. On storage at room temperature above the Tg (-5 degrees C) of copolyester, thin crystals of 1-4 nm thickness appeared on the surface of P[(R)-3HB-co-6HH] films crystallized at 110 degrees C. These results suggest that long sequences of (R)-3HB units in a random copolyester form relatively thick P[(R)-3HB] crystalline lamellae during the primary crystallization process at a given crystallization temperature, while shorter sequences of (R)-3HB units, which are incapable of crystallizing at a given crystallization temperature, form relatively thin crystalline lamellae during the subsequent crystallization process at room temperature.
聚[(R)-3-羟基丁酸-co-10mol% 6-羟基己酸]（P[(R)-3HB-co-6HH]）的熔融结晶薄膜通过在不同温度下等温结晶3天制备，然后在薄膜形成发育良好且充满体积的球晶后于室温下储存。通过广角X射线衍射、小角X射线散射、差示扫描量热法、透射电子显微镜和原子力显微镜对熔融结晶薄膜的片层形态和性能进行了表征。P[(R)-3HB-co-6HH]薄膜的熔融吸热由一个从室温左右开始的宽峰和一个从等温结晶温度以上开始的尖锐峰组成。在110℃初次结晶后，在P[(R)-3HB-co6HH]薄膜表面检测到具有8-10nm片层周期的平躺片层堆积。在高于共聚酯的玻璃化转变温度（-5℃）的室温下储存时，在110℃结晶的P[(R)-3HB-co-6HH]薄膜表面出现了厚度为1-4nm的薄晶体。这些结果表明，在给定结晶温度下的初次结晶过程中，无规共聚酯中长序列的(R)-3HB单元形成相对较厚的P[(R)-3HB]结晶片层，而较短序列的(R)-3HB单元在给定结晶温度下无法结晶，在随后的室温结晶过程中形成相对较薄的结晶片层。
