Polycarbonates from carbon

Sakashita, T. Shimoda, T. Catalytic Process for Preparing Polycarbonates from Carbonic Acid Diester US Patent 5,026,817, June 25, 1991. 

All of the eommereial alkyl eyanoaerylate monomers are low-viseosity liquids, and for some applications this can be an advantage. However, there are instances where a viseous liquid or a gel adhesive would be preferred, sueh as for application to a vertical surface or on porous substrates. A variety of viscosity control agents, depending upon the desired properties, have been added to increase the viscosity of instant adhesives [21]. The materials, which have been utilized, include polymethyl methacrylate, hydrophobic silica, hydrophobic alumina, treated quartz, polyethyl cyanoacrylate, cellulose esters, polycarbonates, and carbon black. For example, the addition of 5-10% of amorphous, non-crystalline, fumed silica to ethyl cyanoacrylate changes the monomer viscosity from a 2-cps liquid to a gelled material [22]. Because of the sensitivity of cyanoacrylate esters to basic materials, some additives require treatment with an acid to prevent premature gelation of the product. 

In our previous work [8], we rqjorted the synthesis of (2-oxo-l,3-dioxolan-4-yl)methacrylate (DOMA) finrn carbon dioxide and glycidyl methacrylate (GMA) using quaternary salt catalysts. In the present work, we studied the catalytic pra rmance of alkyhnethyl imidazolium salt ionic liquid in the synthesis of polycarbonate from the copolyraerization of CO2 with GMA. The influences of copolymerization variable like catalyst structure and reaction tenperature on the conversion of GMA and the yield of the polycarbonate have been discussed. 

Synthesis of polycarbonates from glycidyl methacrylate and carbon dioxide with different... 

Aluminum porphyrins with alkoxide, carboxylate, or enolate can also activate CO2, some catalytically. For example, Al(TPP)OMe (prepared from Al(TPP)Et with methanol) can bring about the catalytic formation of cyclic carbonate or polycarbonate from CO2 and epoxide [Eq. (6)], ° - and Al(TPP)OAc catalyzes the formation of carbamic esters from CO2, dialkylamines, and epoxide. Neither of the reactions requires activation by visible light, in contrast to the reactions involving the alkylaluminum precursors. Another key difference is that the ethyl group in Al(TPP)Et remains in the propionate product after CO2 insertion, whereas the methoxide or acetate precursors in the other reactions do not, indicating that quite different mechanisms are possibly operating in these processes. Most of this chemistry has been followed via spectroscopic (IR and H NMR) observation of the aluminum porphyrin species, and by organic product analysis, and relatively little is known about the details of the CO2 activation steps. 

Salen Metal Complexes as Catalysts for the Synthesis of Polycarbonates from Cyclic Ethers and Carbon Dioxide... 

Abstract This chapter focuses on well-defined metal complexes that serve as homogeneous catalysts for the production of polycarbonates from epoxides or oxetanes and carbon dioxide. Emphasis is placed on the use of salen metal complexes, mainly derived from the transition metals chromium and cobalt, in the presence of onium salts as catalysts for the coupling of carbon dioxide with these cyclic ethers. Special considerations are given to the mechanistic pathways involved in these processes for the production of these important polymeric materials. 

The scope of this chapter will be to focus on well-defined metal complexes that serve as homogeneous catalysts for the production of polycarbonates from epoxides and carbon dioxide. Although there are numerous such well-characterized metal complexes that catalyze this transformation, we will focus this chapter on recent contributions involving metal salicylaldimine (salen) and derivatives thereof [6, 7]. Some of the alternative catalysts systems are very active and selective for copolymer production. Most notably among these are the zinc p-diiminates reported by Coates and coworkers [8, 9]. These systems have been reviewed in detail elsewhere [10]. 

Darensbourg DJ (2007) Making plastics from carbon dioxide salen metal complexes as catalysts for the production of polycarbonates from epoxides and CO2. Chem Rev 107 ... 

Li XH, Meng YZ, Chen GQ, Li RKY (2004) Thermal properties and rheological behavior of biodegradable aliphatic polycarbonate derived from carbon dioxide and propylene oxide. J Appl Polym Sci 94 711-716... 

Preparation of a Polycarbonate from 4,4-lsopropylidenediphenol (Bisphenol A) and Diphenyl Carbonate by Transesterification in the Melt... 

But not only palladium(O) complexes can activate CO or O2, also palla-dium(II) complexes have been reported to be active in the presence of carbon monoxide or dioxygen as it was shown in the direct synthesis of polycarbonate from CO and phenol or bisphenol A [79,80]. The authors could confirm the positive influence of the NHC ligand comparing the activity and reactivity of the palladium-carbene complex with the corresponding PdBr2 catalyst. The molecular weights and yields of the polycarbonates improved with increasing steric hindrance of the substituents in the l,T-position of the car-bene complex. 

Polymers from Carbon Dioxide Polycarbonates, Polythiocarbonates, and Polyurethanes... 

A kinetic study of the ring-opening polymerization (ROP) of trimethylene carbonate similarly afforded AG at 383 K of 101.9 kj mol-1, a value which was very close in energy to that found for the production of poly(TMC) from oxetane and C02. Hence, based on these experimental findings, the formation of polycarbonate from the oxetane and C02 coupling reaction was shown to occur via two different or concurrent pathways-that is, the intermediacy of TMC formation, and the subsequent polymerization and/or direct enchainment of oxetane and C02 (Figure 8.16). The presence of small amounts of ether linkages in the copolymer also supported this conclusion. 

Scheme 1. Solvent-free synthesis of polycarbonate from bisphenol A and diphenyl carbonate [10].

Polycarbonates (formed from carbonates and alcohols or phenols). 

Haba, O. Ueda, M. Kuze, S. Synthesis of polycarbonate from dimethyl carbonate and bisphenol-A through a non-phosgene process. J. Polym. Sci. A, Polym. Chem. 1999,37,2087-2093. 

Chen, X. McCarthy, S.P. Gross, R.A. Synthesis, characterization, and epoxidation of an aliphatic polycarbonate from 2,2-(2-pentene-l, 5-diyl)trimethylene carbonate (cHTC) ringopening polymerization. Macromolecules 1997, 30 (12), 3470-3476. 

SCHEME 6.12 Polycarbonates from diphenyl carbonate and bisphenol A. 

A series of copolymers containing both imide and carbonate units have been reported by Sato et al. [84,85]. The structures are depicted in Table 26. Two copolymers have been synthesised and coreacted together in differing ratios above a 1 1 ratio thermotropic behaviour was observed. The first copolymer was constructed from pyromellitic dianhydride separated from carbonate groups by aliphatic spacers. This polymer was isotropic on its own. The second polymer was a thermotropic polycarbonate containing a biphenyl unit and spacers. The MI score=9.1 at the onset of mesogenic properties. This value is surprisingly low and is about half a unit lower than observed with PEIs. 

Tsuge et al. [263] showed that Py-GC can be used to determine the molecular weight of polycarbonates from the terminal groups. Py-GC has also been shown to be applicable to the determination of the degree of cross-linking of carbon exchange resins in the hydrogen and sodium fonns on the basis of these copolymers [264]. The application... 

Polycarbonates and cyclic carbonates are obtained by the well-known and well-studied reactions of CO2 and oxiranes (Scheme 7). These reactions have also been successfully performed in supercritical mixtures. [28] It turned out, however, that the industrial production of ethylene carbonate (similar to propylene carbonate) in a liquid (product) phase (190-200 °C, total pressure 80 bar) is more economical for capacities of 4000 t per year and installation when it is run nearly stoichio-metrically. [44] In the cases of substituted or polycyclic oxiranes, solvents are usually added and 1 to 40 bar of CO2 are introduced, depending on the catalyst employed. [28] However, the development of a CO2-soluble Zn catalyst formed the polycarbonate from... 

Polycarbonates are a special class of polyesters derived from carbonic acid (HO-di-OH) and have the following general structure ... 

Linear and cyclic structures of polycarbonates from bisphenol-A, from bisphenol-Z, and from 4,4 -dihydroxydiphenyl-3,3-pentane, were determined by PSD MALDI-TOF experiments. It was foimd that the fragmentation behavior of these polycarbonates depends on the substituents boimd to the central carbon atom of the bisphenol unit. The cleavage of the polymer backbone is suppressed, and the spectra are dominated by the loss of side groups. PSD MALDl spectra of these polycarbonates could be acquired only from Li adduct ions, because the sodium or potassium cationized adduct ions yield only dissociation of the cation from the polymer. ... 

A synthetic route to polycarbonates was reported that uses crown ethers. Crown ethers generally form stable complexes with metal cations and, by increasing the dissociation of ion pairs, provide highly reactive, unsolvated anions. This led to direct preparations of new polycarbonates from a,ft>-dibromo compounds, carbon dioxide and potassium carbonate, or salts of the diols ... 

In the 1950s, two chromium-based eatalysts, Ziegler-Natta and Phillips, were introdueed for use in polymerisation reaetions. The Phillips eatalyst is part of the industrial development of polyethylene and is still in use today. Using these eatalysts as a template, researehers are developing chromium-based catalysts for the polymerisation of monomers other than ethene, including the formation of polycarbonates from epoxides and carbon dioxide. 

The graph in Fig. 3.25 shows a plot of the visible transmittance of cast thin films of Aedotron -C that were dip-coated on polycarbonate from a propylene carbonate dispersion and dried at 80°C. The sheet resistance of each film is also shown in the graph. 

Flame-retardant additives that degrade to give a non-combustible gas blanket (as distinct from other mechanisms) are rare. Flame-resistant polycarbonates evolve carbon dioxide, among other gases, by breakdown of the carbonate structure. 

Shen Y., Chen X., Gross R.A., Polycarbonates from sugars Ring opening polymerization of 1,2-0-isopropylidene-D-xylofuranose-3,5-cyclic carbonate (IPXTC), Macromolecules, 32, 1999, 2799-2802. 

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