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

聚（[R]-3-羟基丁酸酯）（P（3 HB））作为细胞内碳源和能源材料，被广泛研究，是一种生物可降解、生物相容性好的热塑性塑料。然而，二次结晶的P（3 HB）均聚物膜的力学性能显着恶化。最近，我们成功地获得了强大的P（3 HB）薄膜和纤维的冷拉伸和两步拉伸程序。P（3 HB）纤维的拉伸强度超过1.3GPa。力学性能的提高不仅是由于分子链的取向，而且还由于纤维和层状晶体形成的锯齿形构象和网络结构的产生。机械性能在6个月内保持不变。这些强膜和纤维在天然河流淡水中4周内完全降解。P（3 HB）薄膜的腐蚀速率受材料结晶度的控制。用等温结晶法从稀溶液中制备了P（3 HB）单晶。单晶的酶促降解从晶体的边缘或沿着其长轴进行，同时产生小片段。

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.