High-functionability of ultra-high-molecular-weight biodegradable polyesters produced by recombinant Escherichia coli

聚（[R]-3-羟基丁酸酯）（P(3HB)）是由多种微生物作为细胞内碳和能量材料积累的，作为可生物降解和生物相容性的热塑性塑料被广泛研究。然而，P（3HB）均聚物薄膜的力学性能因二次结晶而明显恶化。最近，我们成功地通过冷拔和两步拉伸工艺获得了强P（3HB）薄膜和纤维。P（3HB）纤维的抗拉强度在1.3 GPa以上。力学性能的改善不仅是由于分子链的取向，而且还由于纤维和片层晶体形成的之字形构象和网络结构的产生。力学性能在6个月内保持不变。这些坚硬的薄膜和纤维在4周内被天然河流淡水完全降解。P（3HB）膜的侵蚀速率受材料结晶度的控制。用等温结晶法制备了P（3HB）单晶。单晶的酶降解从晶体的边缘开始，或者沿着晶体的长轴进行，同时产生小的碎片。

Poly([R]-3-hydroxybutyrate) (P(3HB)) is accumulated by a wide variety of microorganisms as intracellular carbon and energy material, and is extensively stud led as a biodegradable and biocompatible thermoplastic. However, the mechanical properties of P(3HB) homopolymer films markedly deteriorate by secondary crystallization. Recently, we succeeded in obtaining strong P(3HB) films and fibers by cold-drawing and two-step drawing procedures. The tensile strength of P(3HB) fiber is over 1.3 GPa. The improvement of mechanical properties is due not only to the orientation of molecular chains but also to the generation of a zigzag conformation and network structure formed by fibril and lamellar crystals. The mechanical properties remained unchanged for 6 months. These strong films and fibers were completely degraded in natural river freshwater within 4 weeks. The rate of erosion of P(3HB) films was controlled by the crystallinity of materials. P(3HB) single crystals were prepared from a dilute solution by isothermal crystallization. Enzymatic degradation of single crystals progressed from the edge of the crystals, or along their long axis while making small fragments.