塑料的降解与可降解塑料——聚羟基脂肪酸酯的合成

The degradation of plastics and the production of polyhydroxyalkanoates (PHA)

摘要:

近年来，塑料污染的问题始终困扰着人类社会。为了解决不可回收的塑料带来的环境问题，“降塑再造”的理念被提出。“降塑再造”主要包括塑料的降解和塑料的再生。而再生成为可降解的聚羟基脂肪酸酯(polyhydroxyalkanoates, PHA)则是实现塑料内循环的一种方式。PHA是一种可由多种微生物合成的生物聚酯，以其特有的生物相容性和可降解性以及热加工性能而被大家所关注。同时利用PHA的多样化的单体组成、加工技术和改性方法，可以进一步改善PHA的性能，产生类型多样、性能各异的PHA材料，也可以创造平衡耐久性和生物降解性的新产品，这些特性使PHA有望成为传统塑料的替代品之一。利用极端微生物进行生产的“下一代工业技术(next-generation industrial biotechnology, NGIB)”可以增加PHA的市场竞争力，为国家碳中和目标顺利实施提供参考。本文综述了各类塑料降解并生产PHA的可能性、PHA材料的基础材料属性、加工和改性方法及获得的新材料、新技术和独特的材料性质。

Abstract:

In recent years, the petroleum-based plastic pollution problem has been causing global attention. The idea of “degradation and up-cycling of plastics” was proposed for solving the environmental pollution caused by non-degradable plastics. Following this idea, plastics would be firstly degraded and then reconstructed. Polyhydroxyalkanoates (PHA) can be produced from the degraded plastic monomers as a choice to recycle among various plastics. PHA, a family of biopolyesters synthesized by many microbes, have attracted great interest in industrial, agricultural and medical sectors due to its biodegradability, biocompatibility, thermoplasticity and carbon neutrality. Moreover, the regulations on PHA monomer compositions, processing technology, and modification methods may further improve the material properties, making PHA a promising alternative to traditional plastics. Furthermore, the application of the “next-generation industrial biotechnology (NGIB)” utilizing extremophiles for PHA production is expected to enhance the PHA market competitiveness, promoting this environmentally friendly bio-based material to partially replace petroleum-based products, and achieve sustainable development with carbon-neutrality. This review summarizes the basic material properties, plastic upcycling via PHA biosynthesis, processing and modification methods of PHA, and biosynthesis of novel PHA.