Catalytic Chain Transfer Copolymerization of Propylene Oxide and CO₂ using Zinc Glutarate Catalyst

Abstract

Oligo and poly(propylene ether carbonate)‐polyols with molecular weights from 0.8 to over 50 kg/mol and with 60–92 mol % carbonate linkages were synthesized by chain transfer copolymerization of carbon dioxide (CO 2 ) and propylene oxide (PO) mediated by zinc glutarate. Online ‐monitoring of the polymerization revealed that the CTA controlled copolymerization has an induction time which is resulting from reversible catalyst deactivation by the CTA. Latter is neutralized after the first monomer additions. The outcome of the chain transfer reaction is a function of the carbonate content, i. e . CO 2 pressure, most likely on account of differences in mobility (diffusion) of the various polymers. Melt viscosities of poly(ether carbonate)diols with a carbonate content between 60 and 92 mol % are reported as function of the molecular weight, showing that the mobility is higher when the ether content is higher. The procedure of PO/CO 2 catalytic chain copolymerization allows tailoring the glass temperature and viscosity.

Construction and arm evolution of trifunctional phenolic initiator-mediated polycarbonate polyols produced by using a double metal cyanide catalyst

“…No apparent change is seen of the molecular weight distri-bution (Đ) (Table 2), most probably because the chain exchange reaction occurs rapidly relative to the propagation reaction. 21 Moreover, under the studied copolymerization conditions, the CU linkage in the resultant polyols was in the range of 36.9-44.0%, and W cPC was less than 3.0% (Table 2). It was also found that the reaction time was shortened by more than 3 times from 8.0 h to 2. a Copolymerization conditions: T = 95 °C, P CO2 = 4 MPa, catalyst = 15 mg, and PO = 50 mL (0.72 mol).…”

“…6,7,[9][10][11][12][13][14][15][16][17] Most of the reported works have been focused on linear oligo(carbonate-ether) diol polymers. [18][19][20][21][22][23][24] However, the bifunctional linear structure usually makes it difficult to construct rigid and soft crosslinked PU foams.…”

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

“…Care is taken to keep the heat content of the reaction mixture below the reactors' safety limits; it always needs to be assured that the catalyst has been activated and PO is consumed before additional feeding of PO, e.g., to get to higher molecular weights. The products of this study all are liquids-the thermal properties [68] follow the Flory-Fox equation-and are dependent on the molecular weight and the composition. The timeline of a typical copolymerization experiment ( Figure 1c) thus comprises (i) a drying procedure at 120 • C, (ii) the initiation by catalyst activation (in the presence of PO and argon respectively CO 2 ), (iii) for copolymerization, adjustment of CO 2 pressure and temperature to the desired value and addition of PO in batch or semi-batch mode.…”

“…DDA does not show any effect on the induction time or conversion of batch PO. This may be related to either the low coordination strength or the fact that DDA can react with PO to generate a further CTA of low coordination strength [68]. The copolymer composition seems to be largely unaffected by the presence of TEA or DDA at N = 0.115 and at 120 • C. The carbonate content is still in the range of 14 mol% (Table 8, Entry 35-39 and 45-48).…”

“…Two mechanistic proposals for the action of these DMC catalysts have been put forward: one involving insertion of PO into an intermediate metal alkoxide and one with more evidence comprising an external attack of an alcohol on a coordinated (activated) PO molecule (Scheme 2). The latter reaction step may also be a part of the action of zinc carboxylates in the PO/CO 2 copolymerization [68]. Thus, an interesting mechanistic issue remains on how the action of the heterogeneous catalyst with both ether and carbonate linkage formation is to be understood, and how to relate this to the strictly alternating copolymerization of the homogenous catalysts.…”