Controlled synthesis of aliphatic polycarbonate diols using dimethyl carbonate and various diols

Abstract

Polycarbonate diols (PCDLs) are mainly used as soft segments for the synthesis of high‐performance polyurethanes. In this work, dimethyl carbonate (DMC) and aliphatic diols are selected as reactants and CH3COONa is used as a catalyst to synthesize a series of PCDLs with different structures and different molecular weights by ester exchange polymerization reaction. The chemical structures of the PCDLs are characterized by FT‐IR, 1H NMR, and 13C NMR, and the components of the distillates in the ester exchange stage are analyzed by gas chromatography. Due to the azeotropic problem of DMC and by‐product methanol during the ester exchange process, It is difficult to design and control the reactions of PCDLs to obtain the target molecular weight products. Based on the reaction process of PCDLs, we proposed a method to design and synthesize the target molecular weight of PCDLs by using the reaction molar ratio of DMC and aliphatic diols involved in the transesterification reaction, which is not affected by the conditions of transesterification reaction and is applicable to the reactions of DMC with various diols.

Metal-Free Synthesis of Biodegradable CO2-Based Oligo(carbonate-ester) Diols as Building Blocks for Thermoplastic Polyurethanes

“…Generally, strategies for synthesizing polycarbonate diols (PCDLs) mainly include the phosgene method, 8 ester exchange polymerization, 9 ring-opening polymerization of cyclic carbonates, 10 and alcoholysis of high-molar-mass poly(propylene carbonate) (PPC), 11 while polyester diols can be obtained through ring opening of lactones (e.g., polycaprolactone diols, PCLDL) or condensation of diacids and diols. 12,13 Yet, these approaches either involve highly toxic materials or harsh conditions and complicated routes, and besides, confront the limitations of available monomers and uncontrollable reaction in the preparation, thus making them unfavorable for the structural diversity design and large-scale production of oligo(carbonate ester) diols.…”

“…Generally, strategies for synthesizing polycarbonate diols (PCDLs) mainly include the phosgene method, ester exchange polymerization, ring-opening polymerization of cyclic carbonates, and alcoholysis of high-molar-mass poly­(propylene carbonate) (PPC), while polyester diols can be obtained through ring opening of lactones (e.g., polycaprolactone diols, PCLDL) or condensation of diacids and diols. , Yet, these approaches either involve highly toxic materials or harsh conditions and complicated routes, and besides, confront the limitations of available monomers and uncontrollable reaction in the preparation, thus making them unfavorable for the structural diversity design and large-scale production of oligo­(carbonate ester) diols. , Previous studies reported by Inoue in 1985 have proved that the production of PCDLs via immortal epoxides/CO 2 copolymerization could be implemented, which is a type of living polymerization that contains chain exchange reaction with protic chain transfer agents . Due to the rapid and reversible chain transfer reaction between living chains and protic compounds, relatively homogeneous polymer chains with hydroxyl end groups and narrow dispersity (PDI) can be harvested, which shows the following metrics over the traditional strategies: (1) the direct utilization of nontoxic and renewable CO 2 can reduce dependence on petroleum resources; (2) the M n of macrodiols can be precisely regulated by varying the feeding ratio of monomer and protic compounds; (3) the macrodiols structure can be delicately designed with the required properties by changing the monomer.…”