100% Atom-Economy Efficiency of Recycling Polycarbonate into Versatile Intermediates

Abstract

This study demonstrates a simple and convenient two-step one-pot, highly efficient process of recycling poly-(bisphenol A carbonate), i.e., PC, into versatile intermediates for polymers such as polyurethanes (PUs). Via a highly efficient and selective amine carbonylation reaction, PC is depolymerized by aliphatic diamines forming hydroxyl-N,N′-diphenylene-isopropylidenyl biscarbamates (hydroxyl DP-biscarbamates) as major interim prepolymers. Both short-and long-chained prepolymers are prepared with their respective diamines, and the prepolymers are chain-extended with commercially available regents such as diisocyanates to produce a variety of PU polymers. Hence, PC is cleaved into pieces of soluble hydroxyl DP-biscarbamates first and then reassembled into new linear polymers without resorting to a separation process. Different from PC-recycling processes reported in the literature, each carbonate group of PC in this new process is fully utilized for making one carbamate group and one hydroxyl terminated intermediate in the absence of catalyst under mild conditions. Most significantly, this process attains 100% atom-economy efficiency and demonstrates the feasibility of converting one functional polymer into another.

Evaluation of Carbon Dioxide-Based Urethane Acrylate Composites for Sealers of Root Canal Obturation

“…For the spectrum of the initial mixture of IPDI and PCPO 500, two distinct peaks at 2260 and 1742 cm −1 were present for isocyanate, and carbonyl group of carbonate ester, respectively. After 2 h into the reaction, a newly emerged shoulder at 1718 cm −1 was observed, indicating the formation of urethane carbonyl group [36,37]. Moreover, the urethane prepolymer end-capped with isocyanates was further reacted with HEMA to provide the product of UAC50 as evident by the near disappearance of isocyanate group and the formation of a new adsorption peak at 1638 cm −1 of vinyl group.…”

Back-to-monomer recycling of polycondensation polymers: opportunities for chemicals and enzymes

“…A one-pot process that converts the depolymerization products into new molecules will reduce the costs and material losses. Wu and co-workers 150 report on an aminolysis process at mild conditions of which the resulting products could subsequently converted into polyurethanes in a one-pot reaction. The authors treated BPA-PC with aliphatic diamines to obtain hydroxyl terminated biscarbamates in the absence of any catalyst and at mild temperatures (<80 °C) ( Scheme 12 ).…”

Degradation of polycarbonate to produce bisphenol A catalyzed by imidazolium-based DESs under metal-and solvent-free conditions

“…From the perspective of resource conservation and sustainable development, chemical recycling of this discarded PC is still an important issue and has attracted widespread attention. 2,3 Several chemical methods, including thermal pyrolysis, 4-6 glycolysis, 7,8 hydrolysis 9-11 and aminolysis 12,13 have been studied by many researchers. Some good results with high conversion and high yield have been obtained, but there are still many disadvantages, such as low purity of BPA, slow reaction rate, unrecyclable catalyst and harsh reaction conditions, resulting in high cost and high energy consumption.…”

“…Under a nitrogen atmosphere, the reaction was heated and stirred at 80 C for 2.0 h, until a colorless, transparent and homogeneous liquid was completed, the reaction was over and the product [EmimOH]Cl-2Urea (13.8 g) was collected with the yield of 97.5%. [EmimOH]Cl-2Urea13 C NMR (126 MHz, d 6 -DMSO), d ¼ 159.7 (s), 136.8 (s), 123.3 (s) 122.6 (s), 59.3 (s), 51.5 (s), 35.6 (s) (see Fig. S2 †).…”