Recycling a Borate Complex for Synthesis of Polycarbonate Polyols: Towards an Environmentally Friendly and Cost‐Effective Process

• Published in: ChemSusChem Vol. 13; no. 18; pp. 5080 - 5087
• Main Authors: Patil, Naganath, Bhoopathi, Senthil, Chidara, Vamshi, Hadjichristidis, Nikos, Gnanou, Yves, Feng, Xiaoshuang
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 18.09.2020
• Subjects: Carbon dioxide; Copolymerization; Diols; initiator recycling; Initiators; Liquid chromatography; NMR spectroscopy; polycarbonate polyol; Polycarbonate resins; polymeric; Polyols; Propylene; Recycling; Substrates; tetrabutylammonium; triethylborane; polycarbonate polyol; triethylborane; initiator recycling; tetrabutylammonium; polymeric
• ISSN: 1864-5631; 1864-564X; 1864-564X
• DOI: 10.1002/cssc.202001395

In this investigation, a metal‐free process was developed that enables the synthesis of poly(propylene carbonate) (PPC) diols/polyols by copolymerization of CO2 with propylene epoxide (PO) under environmentally friendly and cost‐effective conditions. This process implies the recycling of triethylborane and of ammonium salts that both enter in the composition of the initiators used to copolymerize CO2 and PO. In complement to the above approach, a polymeric support, poly(diallyl dimethylammonium chloride), was synthesized and modified to carry ammonium carboxylate salts along its chain. The prepared polymeric initiator was utilized to copolymerize CO2 with PO under heterogeneous conditions. Not only were the polymerization results similar to the samples obtained under homogeneous conditions, but the polymer substrate could easily be recovered by simple filtration. The integrity of the polycarbonate diols/polyols and the recycling process were followed by 1H and 11B NMR spectroscopy, gel permeation chromatography, and matrix assisted laser desorption ionization time of flight (MALDI‐TOF) MS. Ready for Industrialization: A cost‐effective and environmentally friendly process is developed for the recycling of triethyl borane and the tetrabutylammonium cation that both enter in the composition of the initiators for preparation of poly(propylene carbonate) diols/polys. In addition, a polymeric support that carries ammonium carboxylate salts along its chain can obtain similar polymerization results as soluble salts but is easily recovered by simple filtration.