Copolymerization of CO2 and propylene oxide using ZnGA/DMC composite catalyst for high molecular weight poly(propylene carbonate)

Enhanced Double Metal Cyanide Catalysts for Modulating the Rheological Properties of Poly(propylene carbonate) Polyols by Modifying Carbonate Contents

Poly(propylene carbonate) (PPC) polyol is an environmentally sustainable material derived from abundant and renewable greenhouse gas, CO2. Optimizing their synthesis and properties is crucial to their application in the production of polyurethane products. In this study, we synthesized PPC polyols with varying carbonate contents using heterogeneous Zn/Co double metal cyanide (DMC) catalysts, which were prepared with poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123) as an effective complexing agent. Analysis of the influence of calcination temperature revealed that the DMC-P123 catalyst calcined at 100 °C exhibited superior catalytic performance owing to reduced crystallinity and enhanced formation of the monoclinic phase. Additionally, by precisely controlling the CO2 pressure, high propylene carbonate contents of up to 32.8 wt % in the polyol structure were achieved. The increased carbonate content enhanced the intermolecular attraction between polyol chains, thereby promoting hydrogen bonding and significantly modulating the rheological properties of the polyol. The novel findings of this study establish a solid foundation for the synthesis of CO2-based polyols with desirable properties, serving as alternatives to conventional petroleum-based polyols.

Fabrication and characterization of the ternary composite catalyst system of ZnGA/RET/DMC for the terpolymerization of CO2, propylene oxide and trimellitic anhydride

To achieve the poly(propylene carbonate trimellitic anhydride) (PPCTMA) with excellent performance, high molecular weight, enhanced yield and good thermal stability, the ternary composite catalyst system of zinc glutarate/rare earth ternary complex/double metal cyanide (ZnGA/RET/DMC) was proposed to perform the terpolymerization of CO₂, propylene oxide and trimellitic anhydride. Since the crystallinity and surface activity point of Zn–Co DMC could significantly influence the catalytic ability, mechanical ball milling was applied to increase the surface area of the Zn–Co DMC catalyst with better surface activity point. Moreover, the ZnGA/RET/DMC composite catalytic system and polycarbonate products were comparatively evaluated by XRD, SEM, FT-IR, TGA, NMR, XPS and TEM. Experimental results showed that the ZnGA/RET/DMC composite catalyst system displayed outstanding synergistic effect on the terpolymerization of CO₂, PO and TMA with better selectivity, activity, and higher molecular weight (M_w) tercopolymer than those of the individual catalyst. According to optimum reaction conditions, the M_w of PPCTMA could be up to 8.29 × 10⁴ g mol⁻¹, and the yield could be up to 66 g_polym/g_cat. The alternating tercopolymer, PPCTMA, showed wonderful thermal stability and high decomposition temperature (TGA_10% = 313 °C). A possible synergistic catalytic mechanism of the ZnGA/RET/DMC ternary composite catalyst system was also conjectured.

For poly(propylene carbonate trimellitic anhydride) with good yield, thermal stability and high molecular weight, a catalyst of zinc glutarate/rare earth ternary complex/double metal cyanide was used for terpolymerization of CO₂, propylene oxide and trimellitic anhydride.

DMC-Mediated Copolymerization of CO2 and PO—Mechanistic Aspects Derived from Feed and Polymer Composition

The influence of composition of liquid phase on composition of poly(propylene ether carbonates) in the copolymerization of CO2 with propylene oxide (PO), mediated by a zinc chloride cobalt double metal cyanide, was monitored by FT-IR/CO2 uptake/size exclusion chromatography in batch and semi-batch mode. The ratio of mol fractions of carbonate to ether linkages F (~0.15) was found virtually independent on the feed between 60 and 120 °C. The presence of CO2 lowers the catalytic activity but yields more narrowly distributed poly(propylene ether carbonates). Hints on diffusion and chemistry-related restrictions were found underlying, broadening the distribution. The incorporation of CO2 seems to proceed in a metal-based insertion chain process, ether linkages are generated stepwise after external nucleophilic attack. The presence of amines resulted in lower activities and no change in F. An exchange of chloride for nitrate in the catalyst led to a higher F of max. 0.45. The observations are interpreted in a mechanistic scheme, comprising surface-base-assisted nucleophilic attack of external weak nucleophiles and of mobile surface-bound carboxylato entities on activated PO in competition to protonation of surface-bound alkoxide intermediates by poly(propylene ether carbonate) glycols or by surface-bound protons. Basic entities on the catalyst may promote CO2 incorporation.

Synthesis of CO2-based polycarbonate-g-polystyrene copolymers via NMRP

The synthesis of CO₂-based APC-graft-polystyrene copolymers via NMRP.

Synthesis of vegetable-oil based polymer by terpolymerization of epoxidized soybean oil, propylene oxide and carbon dioxide

Although carbon dioxide (CO₂) is well known as one of the major green-house gases, it is also an economical C1 resource. Thus, CO₂ has been regarded as an appealing starting material for the synthesis of polymers, like polycarbonates by the reaction with epoxides. Herein the reaction between natural epoxidized soybean oil (ESO), propylene oxide (PO) and CO₂ under high pressure (4.0MPa) with the presence of Co-Zn double metal cyanide (Co-Zn DMC) catalyst was studied. Temperature and reaction time were varied accordingly and the products obtained were characterized by FTIR, GPC and ¹H NMR. The results obtained indicate the formation of polycarbonates in the samples collected with yields vary from 60 to 85%. The number average molecular weight (M_n) of the resultant polymer prepared at reaction temperature of 80°C and reaction time of 6h can reach up to 6498g/mol.