Poly(propylene carbonate). 1. More about Poly(propylene carbonate) Formed from the Copolymerization of Propylene Oxide and Carbon Dioxide Employing a Zinc Glutarate Catalyst

Chamberlain B.M., Cheng M., Moore D.R., Ovitt T.M., Lobkovsky E.B., Coates G.W.

A series of zinc(II) and magnesium(II) alkoxides based upon a beta-diiminate ligand framework has been prepared. [(BDI-1)ZnO(i)Pr](2) [(BDI-1) = 2-((2,6-diisopropylphenyl)amido)-4-((2,6-diisopropylphenyl)imino)-2-pentene] exhibited the highest activity and stereoselectivity of the zinc complexes studied for the polymerization of rac- and meso-lactide to poly(lactic acid) (PLA). [(BDI-1)ZnO(i)()Pr](2) polymerized (S,S)-lactide to isotactic PLA without epimerization of the monomer, rac-lactide to heterotactic PLA (P(r) = 0.94 at 0 degrees C), and meso-lactide to syndiotactic PLA (P(r) = 0.76 at 0 degrees C). The polymerizations are living, as evidenced by the narrow polydispersities of the isolated polymers in addition to the linear nature of number average molecular weight versus conversion plots and monomer-to-catalyst ratios. The substituents on the beta-diiminate ligand exert a significant influence upon the course of the polymerizations, affecting both the degree of stereoselectivity and the rate of polymerization. Kinetic studies with [(BDI-1)ZnO(i)Pr](2) indicate that the polymerizations are first order with respect to monomer (rac-lactide) and 1.56 order in catalyst. Polymerization experiments with [(BDI-1)MgO(i)Pr](2) revealed that this complex is extremely fast for the polymerization of rac-lactide, polymerizing 500 equiv in 96% yield in less than 5 min at 20 degrees C.

Darensbourg D.

Oxiranes and carbon dioxide are known to cycloadd and/or copolymerize in the presence of a variety of catalysts. Indeed, cyclic carbonates are prepared on a technical scale by coupling epoxides and carbon dioxide. The fact that cyclic carbonate formation represents one of the few examples of successful carbon dioxide utilization, coupled with the high reactivity of epoxides, has resulted in many papers which reveal a remarkable variety of active catalysts for the CO2/epoxide coupling processes. Catalysts include simple alkali metal salts, ammonium salts, phosphines, main-group metal complexes, and both non-oxidative and oxidative transition-metal complexes. The purpose of this review is to compile the different catalysts into their general groups of similarity, with the hopes of shedding light on some of the important differences in reaction pathways. There generally appears to be a lack of detailed mechanistic studies; therefore, it is hoped that this review will emphasize where mechanistic clarification is most importantly needed. Furthermore, we anticipate that this review will provide insight into cyclic carbonate vs. polycarbonate production from the CO2/epoxide coupling process.

Shimasaki K., Aida T., Inoue S.

Aida T., Ishikawa M., Inoue S.

Premier exemple d'obtention d'un polycarbonate aliphatique de distribution etroite controlee par copolymerisation vivante et alternee

Aida T., Inoue S.

Kuran W., Górecki P.

Poly(propylene carbonate) (PPC) was treated with diethylzinc in 1,4-dioxane solution at 30°C, Zn(C2H5)2 being used in excess or defficiency with regard to carbonate units. PPC was found to undergo degradation and depolymerization reactions, which were followed via the polymer intrinsic viscosity and the propylene carbonate yield. A model reaction between diethyl carbonate and diethylzinc was carried out too. From the results, a mechanistic view for both pathways, degradation and depolymerization, is proposed.

Aida T., Inoue S.

Inoue S., Koinuma H., Tsuruta T.

Trofimchuk E.S., Chernov I.V., Toms R.V., Rzhevskiy S.A., Asachenko A.F., Plutalova A.V., Shandryuk G.A., Chernikova E.V., Beletskaya I.P.

The simple approach of increasing the elastic properties of atactic poly(propylene carbonate) (PPC) with Mn = 71.4 kDa, ĐM = Mw/Mn = 1.86, and predominantly carbonate units (>99%) is suggested by selecting the appropriate hot pressing temperature for PPC between 110 and 140 °C. Atactic PPC is synthesized through ring-opening copolymerization of (rac)-propylene oxide and CO2 mediated by racemic salen complex of Co(III). Hot pressing PPC results in the release of a small amount of propylene carbonate (PC), sufficient to lower the glass transition temperature from 39.4 to 26.1 °C. Consequently, increasing the pressing temperature from 110 to 140 °C generates materials with a reduced modulus of elasticity (from 1.94 to 0.09 GPa), yield strength (from 38 to 2 MPa) and increased tensile elongation (from 140 to 940%). Thermomechanical analysis has shown a significant expansion in sample volume by hundreds of percent within the 80–130 °C range. PPC also displays large, reversible deformations, which can be utilized by creating shape memory materials.

Yang G., Xie R., Zhang Y., Xu C., Wu G.

Chen Z., Zhou Y., Luo C., Zhou Q., Wang X., Wu Y., Yang Z.

Hahladakis J.N., Iacovidou E., Gerassimidou S.

Wu Y., Nie Y., Sun L., Xi Z., Liu Z.

Chernikova Elena V., Beletskaya Irina P.

Carbon dioxide (CO2) plays a vital role in organic and polymer chemistry as a source of cheap and available raw material for the synthesis of many valuable products, including polymer materials with a specified set of properties, and as a solvent for chemical reactions. This review is devoted to the synthesis, properties and applications of polycarbonates obtained by copolymerization of CO2 with epoxides, a hot topic that has aroused great interest among the scientific community and industry representatives. The existing data on the catalytic systems used for the synthesis of polycarbonates are analyzed and summarized, depolymerization of polycarbonates, which is a key aspect in the polymer recycling, is discussed, information on the properties and applications of polycarbonates is systematized, and prospects for the development of this area of chemistry are considered.Bibliography — 438 references.

Yang Y., Sung K., Lee J.D., Ha J., Kim H., Baek J., Seo J.H., Kim S., Lee B.Y., Son S.U., Kim B., Kim Y., Park J., Jang H.

Gupta V., Justyniak I., Chwojnowska E., Szejko V., Lewiński J.

Ji G., Zhang X., Wang W., He J., Huang J., Li T., Wang S., Dong W.

It's significant but challenging to prepare PPC with supramechanical performance and multi-functions. In this work, a mechanically robust, fluorescent, transparent and UV-shielding PPC composite is successfully prepared for the first time by incorporating a hydroxyalkylated tannin acid (mTA). Compared to TA, mTA shows an excellent compatibility to PPC due to the grafted plentiful flexible isopropanol oligomers with terminal hydroxyl group. The effects of content and grafting degree of mTA on the mechanical properties of PPC/mTA composites are investigated and the mechanism for the high strength and high toughness is revealed. By introducing 3 phr mTA with medium grafting degree (m-mTA), PPC/m-mTA3 shows a tensile strength of 23.38 ± 0.96 MPa and an elongation at break of 852 ± 37%, which is comparable to LDPE and LLDPE and implies the great potential of PPC to replace non-biodegradable PE materials. The supramechanical performance is the result of the combined multiple hydrogen bonding and plastic deformation zone originating from the excellent compatibility. Besides, Tg of mTA will affect the yield strength of PPC/mTA composites. More importantly, PPC/m-mTA film shows the fluorescent effect with dual-mode responsiveness, good UV-shielding effect and transparency, which will expand the application of PPC into advanced packaging materials. We envision that this work opens a novel yet facile way to prepare PPC with supramechanical performance and multi-functions, and will promote the practical application of PPC materials.

Alroaithi M., Xu W.

Padmanaban S., Yoon S.

Recently, catalytic conversion of the greenhouse gas carbon dioxide to chemical commodities has received much interest. Among various possibilities, the copolymerization of CO2 with cyclic ethers to produce aliphatic polycarbonates is a promising approach. Among various homogeneous and heterogeneous catalysts, the Zn-dicarboxylates and double metal cyanide complexes are mainly used in the large-scale production of aliphatic polycarbonates. In this chapter, the developments in the heterogeneously catalyzed copolymerization of CO2 with cyclic ethers are briefly reported.

Yang Y., Lee J.D., Seo Y.H., Chae J., Bang S., Cheong Y., Lee B.Y., Lee I., Son S.U., Jang H.

Zinc-glutarate (ZnGA) is a promising catalyst that can form polymers from CO2 and epoxides, thereby contributing to the development of CO2 utilization technologies and future sustainability. One of the obstacles to commercializing ZnGA in polymer industries is its low catalytic activity. In this study, we introduced activated two-dimensional (2D) ZnGA to improve its catalytic activity in polymerization. The morphology-controlled 2D ZnGA was treated with H3Co(CN)6, and a porous granular-type Co-modified ZnGA (Co-ZnGA) was prepared. The morphology of 2D ZnGA is a prerequisite for the activation by H3Co(CN)6. The catalytic properties of Co-ZnGA were evaluated by copolymerization of various epoxides and CO2, and exhibited catalytic activity of 855, 1540, 1190, and 148 g g-cat-1 with propylene oxide, 1,2-epoxyhexane, 1,2-epoxybutane, and styrene oxide, respectively. This study provided a new strategy using 2D ZnGA instead of conventional ZnGA for increasing the catalytic activity in CO2 polymerization.

Milocco F., Chiarioni G., Pescarmona P.P.

In this chapter, a didactic and critical overview of the main classes of heterogeneous catalysts for the conversion of CO2 into cyclic carbonates or polycarbonates is provided. The type of active sites, the catalytic mechanism and the state-of-the-art strategies to design active, selective and stable heterogeneous catalysts for these reactions are presented and discussed.

Rosato A., Romano A., Totaro G., Celli A., Fava F., Zanaroli G., Sisti L.

Commercial hydrolytic enzymes belonging to different subclasses (several lipases, proteinase k, cutinase) were investigated for their ability to degrade different aliphatic polyesters, i.e., poly(butylene succinate) (PBS), poly(butylene succinate-co-adipate) (PBSA), two poly(caprolactone), having two different molecular weights, poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC). The enzyme screening was first carried out by investigating the capacity of fully degrading the target polymers in 24 h, then weight loss measurements of selected polyesters and target enzymes were performed. Solid residues after enzyme degradation were characterized by proton nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetry (TGA). Liquid fractions were studied via GPC, 1H NMR and high-performance liquid chromatography (HPLC). PCL and PBSA were found to be the most biodegradable polyesters, under the conditions used in this study. PBS was fully degraded only by cutinase, whereas none of the tested enzymes were able to completely degrade PLA and PPC, in the conditions assessed here. Cutinase exhibited the highest hydrolytic activity on PBSA, while lipase from Candida sp. (CALB) on low molecular weight PCL. Chemical analyses on residual solids showed that the enzymatic degradation occurred homogeneously from the surface through an erosion mechanism and did not significantly affect the macromolecular structure and thermal stability. Cleaving action mode for each enzyme (endo- and/or exo-type) on the different polyesters were also proposed based on the evaluation of the degradation products in the liquid fraction.

Wang W., Ye S., Liang J., Fan C., Zhu Y., Wang S., Xiao M., Meng Y.

Poly(propylene carbonate phthalate) (PPC-P) is a chemically modified poly(propylene carbonate) (PPC) biodegradable thermoplastic by introducing phthalic anhydride (PA) as the third monomer into the copolymerization of propylene oxide (PO) and CO2. To enhance the thermal and mechanical properties of PPC-P, a branching agent pyromellitic anhydride (PMDA) was introduced into the terpolymerization of PO, PA and CO2. The resulting copolymers with branched structure, named branched PPC-P, can be obtained using metal-free Lewis pair consisting of triethyl borane (TEB) and bis(triphenylphosphine)iminium chloride (PPNCl) as catalyst. The products obtained were analyzed by NMR spectroscopy and their thermal, mechanical properties and melt processability were evaluated by DSC, TGA, tensile test and melt flow index (MFI) measurement. The obtained branched PPC-P has a high molecular weight up to 156.0 kg·mol−1. It shows an increased glass transition temperature (Tg) higher than 50 °C and an enhanced tensile strength as high as 38.9 MPa. Noteworthily, the MFI value decreases obviously, indicative of an improved melt strength arising from the branched structure and high molecular weight. What is more, the branched PPC-P exhibits reasonable biodegradability, which demonstrates the great potential as a new green thermoplastic for the family of biodegradable plastics.