Issue 43, 2019

Polymer-supported metal catalysts for the heterogeneous polymerisation of lactones

Abstract

A series of metal complexes were immobilised onto an inert poly(styrene) (PS) support and utilised in the solvent free ring-opening polymerisation (ROP) of various lactones. PS-LHZnOAc, PS-LHSnOct and PS-LClSnOct were identified as the most successful heterogeneous catalysts for the ROP of L-lactide. Investigations by in situ ATR-FT-IR revealed conversions reaching ca. 90% in 6, 2.3 hours and 55 minutes, respectively, with excellent molecular weight control and dispersities (ĐM 1.15–1.17). Catalyst loadings as low as 15 ppm metal and TOF values of up to 810 h−1 could also be achieved. Higher molecular weights could be targeted (ca. 35 kDa) whilst maintaining low dispersities in comparison to the industrial standard. Catalyst reuse was also possible, with up to 7 reuse cycles, albeit accompanied by a progressive reduction in conversion. Energy-Dispersive X-ray (EDX) spectroscopy and Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) showed low metal content in the unpurified polymer (as low as 335 ppm, similar to what is found in polymer purified by classical methods), suggesting these systems as promising reusable catalysts for the industrial production of metal-free renewable polymers.

Graphical abstract: Polymer-supported metal catalysts for the heterogeneous polymerisation of lactones

Supplementary files

Article information

Article type
Paper
Submitted
23 iyl 2019
Accepted
15 okt 2019
First published
22 okt 2019
This article is Open Access
Creative Commons BY license

Polym. Chem., 2019,10, 5894-5904

Polymer-supported metal catalysts for the heterogeneous polymerisation of lactones

I. C. Howard, C. Hammond and A. Buchard, Polym. Chem., 2019, 10, 5894 DOI: 10.1039/C9PY01472A

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