We are living in a materials world made of synthetic polymers, which have become indispensable for modern life and the global economy. However, one major issue many synthetic polymers encountered at present is that they are predominantly petroleum-based and disposed after a single use, causing severe negative environmental impacts, such as Green House Gases emission and post-consumer polymer wastes. As the environmental crisis grows, both academia and industry aim to develop sustainable polymers, defined most recently as ‘materials designed from renewable feedstocks and having sensible end of life options’. To compete with existing petroleum-derived polymers from both performance and cost perspectives, it is highly desirable to develop new sustainable polymers which not only fulfill the sustainability criteria but also possess useful material properties synthesized via industrially relevant processes. Unfortunately, the creation of such sustainable polymers is a formidable challenge facing the field of polymer science. Very recently, a team of Chinese scientists led by Prof. HONG Miao at the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, has now developed new sustainable polymers. As they report in the journal Nature Chemistry (https://www.nature.com/articles/s41557-021-00817-9), non-strained five-membered lactones, commonly occurring in nature or produced in large quantities from biomass, are used as starting materials for the synthesis of sustainable polymers. Despite of renewable resources, this family of lactones are commonly referred as “non-polymerizability” in previous literatures and textbooks on account of their non-strained rings that cannot provide the sufficient ring strain to drive ring-opening polymerizations (ROPs). Here, HONG and co-workers established a new strategy, so-called irreversible ring-opening polymerization (IROP), by introducing a sulfur atom into above lactones to construct innovative γ-thionobutyrolactone monomer and its methyl derivatives. Substantially different from the conventionally ROP, this IROP is thermodynamically driven by the S/O isomerization instead of ring strain, thus rendering the non-strained five-membered rings readily polymerizable for the first time at industrially relevant temperature of 80-100 °C. The resultant poly(γ-thiobutyrolactone), obtained by IROP of γ-thionobutyrolactone, is determined to be a tough semicrystalline thermoplastic with a high melting temperature (100 °C) and external stimuli-triggered degradability, thereby establishing a new sustainable polymer which not only meets the sustainability criteria but also possesses useful material properties competitive to those of commercial petroleum-based low-density polyethylene. The authors anticipate: the robustness of IROP strategy will open up unique opportunities for efficiently converting a family of five-membered lactones and even the other non-strained monomers, commonly inaccessible by the other polymerization methods, into new sustainable polymers with a wide range of notable properties and potential applications.
HONG Miao Ph.D.Professor Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences Ling Ling Road 345 Shanghai 200032 China Tel: 0086-21- 54925610 Email: miaohong@sioc.ac.cn |
