Double metal cyanide catalyst prepared using H<sub>3</sub>Co(CN)<sub>6</sub>for high carbonate fraction and molecular weight control in carbon dioxide/propylene oxide copolymerization

Lee

J of Applied Polymer Sci

et al. 2016

Self Cite

The condensation of a mixture of dimethyl carbonate and phthalate derivatives with 1,4‐butanediol (BD), catalyzed by sodium alkoxide, generated high‐molecular weight poly(1,4‐butylene carbonate‐co‐aromatic ester)s with molecular weights (Mn) of 50–120 kDa. The subsequent addition of polyols [BD, glycerol propoxylate, 1,1,1‐tris(hydroxymethyl)ethane, or pentaerythritol] chopped these high‐molecular weight polymers to afford macrodiols or macropolyols with facile control of their molecular weights (Mn, 2000–3000 Da) and unique chain topological compositions. Macropolyols prepared by chopping poly(1,4‐butylene carbonate‐co‐terephthalate) were waxy in nature, whereas those containing isophthalate and phthalate units were oily. The macropolyols synthesized by this chopping method may have potential applications in the polyurethane industry. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43754.

Section: Introductionmentioning

confidence: 99%

Chopping high‐molecular weight poly(1,4‐butylene carbonate‐co‐aromatic ester)s for macropolyol synthesis

Lee

J of Applied Polymer Sci

et al. 2016

Self Cite

Topics in Organometallic Chemistry

“…Both heterogeneous and homogeneous catalysts are known, with the latter generally showing significantly faster rates and much finer control compared to the solid-state materials. This review only briefly describes heterogeneous or surface catalysis; for more insights into this topic, the reader is referred to previous reports and reviews [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. It is also important to draw the reader's attention to various comprehensive reviews in the area of homogeneous catalysis [6,[33][34][35][36][37][38][39][40][41][42][43][44][45][46].…”

Section: Polycarbonates From Comentioning

confidence: 99%

Dinuclear Metal Complex-Mediated Formation of CO2-Based Polycarbonates

Romain

Thevenon

Saini

et al. 2015

This review describes selected metal catalysts for the copolymerisation of epoxides and carbon dioxide to produce polycarbonates. It highlights kinetic and mechanistic studies which have implicated di-or (multi-) metallic pathways for this catalysis and the subsequent development of highly active and selective di-/(multi-) nuclear catalysts. The emphasis is on homogeneous di-/bimetallic catalysts.

“…That implies that DMC catalyst structure in particular the basic equivalents is an important issue, as it determines an internal rate of protonation. It seems that the importance of the protonation is not adequately considered in the mechanistic description [116][117][118][119][120][121][122], and with that the susceptibility of a catalyst to incorporate CO 2 in the backbone. This is, so far as we can understand, the catalytic action today, a crucial extension to mechanisms proposed in the open literature [70,[123][124][125][126].…”

Section: Scheme 6 Ppec Formation By Dmc With Anionic Sites (Alternatmentioning

confidence: 99%

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

Stahl

Luinstra

2020

Catalysts

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.