Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA.
Nat Chem. 2016 Jan;8(1):42-9. doi: 10.1038/nchem.2391. Epub 2015 Nov 23.
Ring-opening polymerization (ROP) is a powerful synthetic methodology for the chemical synthesis of technologically important biodegradable aliphatic polyesters from cyclic esters or lactones. However, the bioderived five-membered γ-butyrolactone (γ-BL) is commonly referred as 'non-polymerizable' because of its low strain energy. The chemical synthesis of poly(γ-butyrolactone) (PγBL) through the ROP process has been realized only under ultrahigh pressure (20,000 atm, 160 °C) and only produces oligomers. Here we report that the ROP of γ-BL can, with a suitable catalyst, proceed smoothly to high conversions (90%) under ambient pressure to produce PγBL materials with a number-average molecular weight up to 30 kg mol(-1) and with controlled linear and/or cyclic topologies. Remarkably, both linear and cyclic PγBLs can be recycled back into the monomer in quantitative yield by simply heating the bulk materials at 220 °C (linear polymer) or 300 °C (cyclic polymer) for one hour, which thereby demonstrates the complete recyclability of PγBL.
开环聚合（ROP）是一种强大的合成方法，可用于从环酯或内酯化学合成技术上重要的可生物降解脂肪族聚酯。然而，由于应变能低，生物衍生的五元γ-丁内酯（γ-BL）通常被称为“不可聚合”。通过 ROP 工艺合成聚（γ-丁内酯）（PγBL）仅在超高压（20,000 大气压，160°C）下实现，并且仅产生低聚物。在这里，我们报告说，在合适的催化剂存在下，γ-BL 的 ROP 可以在环境压力下顺利进行，转化率高达 90%，从而得到数均分子量高达 30kg/mol 的 PγBL 材料，并具有可控的线性和/或环状拓扑结构。值得注意的是，通过简单地将块状材料在 220°C（线性聚合物）或 300°C（环状聚合物）下加热一个小时，线性和环状 PγBL 都可以定量回收回单体，从而证明了 PγBL 的完全可回收性。
