Synthesis and properties of aliphatic polycarbonates derived from carbon dioxide,propylene oxide and maleic anhydride

Terpolymerization of carbon dioxide (CO₂) with propylene oxide (PO) and maleic anhydride (MA) was successfully carried out using supported zinc glutarate catalyst. Consequently giving high molecular weight poly(propylene carbonate maleate) (PPCMA) in a very high yield (72.5 g polymer/g catalyst). The resulting terpolymers were fully characterized by FTIR, ¹H NMR, ¹³C NMR, and wide‐angle X‐ray diffraction (WAXD) techniques. NMR measurements showed that PPCMA had an almost alternating structure for the components of carbon dioxide and PO. The influence of molecular weight and MA content on the properties of PPCMA was also investigated. Differential scanning calorimetry (DSC) measurements revealed that the glass transition temperature (T_g) of PPCMA increased with increasing molecular weight. Thermogravimetric analysis (TGA) indicated that PPCMA51 exhibited a very high decomposition temperature (263°C) due to the introduction of the double bond of MA into the backbone of terpolymer. The terpolymers with double bonds can be readily subjected to crosslinking reaction in high temperature to give a slightly crosslinked PPCMA, which exhibit superior thermal stability. Tensile tests also showed that the mechanical properties of PPCMA increased with increasing molecular weight. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis, characterization and hydrolysis of an aliphatic polycarbonate by terpolymerization of carbon dioxide, propylene oxide and maleic anhydride

Terpolymerization of propylene oxide (PO), carbon dioxide (CO₂) and maleic anhydride (MA) was carried out by using a polymer-supported bimetallic complex (PBM) as a catalyst. A degradable aliphatic poly(propylene carbonate maleate) (PPCM) was synthesized, and determined by FT-IR, ¹H NMR, ¹³C NMR, DSC, TGA and WAXD measurements. The influences of various reaction conditions such as molar ratio of the monomers, reaction time and reaction temperature on the terpolymerization progress were investigated. The results showed that MA was inserted into the backbone of CO₂–PO successfully. The viscosity, glass transition temperature and decomposition temperature of the terpolymers were much higher than those of poly(propylene carbonate) (PPC). Because of the existence of the MA ester unit, PPCM had stronger degradability than PPC in a pH 7.4 phosphate-buffered solution. MA offered an ester structural unit that gave the terpolymers remarkable degradability. And the degradation rate of the backbone increased with the insertion of MA into the terpolymers.     

Vapor-phase selective hydrogenation of maleic anhydride to succinic anhydride over Ni/TiO2 catalysts

A series of supported Ni/TiO₂ catalysts were prepared by incipient wetness impregnation method under different calcination temperatures, and the as-prepared catalysts were characterized by X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H₂-TPR) and X-ray photoelectron spectroscopy (XPS). The catalytic properties of these Ni/TiO₂ catalysts were investigated in the vapor phase hydrogenation of maleic anhydride (MA) to succinic anhydride (SA). The results showed that the catalytic activity and the selectivity of the Ni/TiO₂ catalysts were strongly affected by the calcination temperature. The catalyst calcined at 1023 K showed a relatively higher SA selectivity of 96% at high MA conversion (96%) under the tested conditions (493 K and 0.2 MPa). The improvement of SA selectivity could be mainly assigned to the presence of suitable metal–support interaction, which can play a role in catalytic property of active nickel species as electron promoter. Besides, the change of surface properties of TiO₂ support with the increasing calcination temperatures, e.g., the decrease of Lewis acid sites, might also have some positive role in reducing the side-products like γ-butyrolacetone (GBL).     

Alternating copolymerization of carbon dioxide and propylene oxide by single-component cobalt salen complexes with various axial group

A series of single-component cobalt salen complexes, N,N′-bis(salicylidene)-1,2phenylenediamino cobaltIII X (X = Cl (1a), Br (1b), NO3 (1c), CF3COO (1d), BF4 (1e), and N3 (1f)) (SalphCoX), were prepared for alternating copolymerization of carbon dioxide and propylene oxide(PO) under mild condition. The axial anion X group of the SalenphCoX played important role in tailoring the catalytic activity, polymeric/cyclic carbonate selectivity, as well as stereochemistry of carbonate unit sequence in the polymer chain. SalenphCoX with an electron-withdrawing axial X group (complex 1c) was an ideal catalyst for the copolymerization of CO2 and PO to selectively produce polycarbonate with ∼99% carbonate linkage and over 81% head-to-tail structure.     

Carbon dioxide/propylene oxide coupling reaction catalyzed by chromium salen complexes

A series of chromium/Schiff base complexes N,N′-bis(salicylidene)-1,2-phenylenediamino chromium^III X were prepared and employed for the alternating copolymerization of carbon dioxide with racemic propylene oxide in the presence of (4-dimethylamino)pyridine. The effect of the complex structure and reaction conditions on the catalytic activity, the poly(propylene carbonate)/cyclic carbonate (PPC/PC) selectivity, and the polymer head-to-tail linkages was examined. The experiments indicated that N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-phenylenediamino chromium^III (NO₃) exhibited the highest PPC/PC selectivity as well as polymer head-to-tail linkages and N,N′-bis(3,5-dichlorosalicylidene)-1,2-phenylenediimino chromium^III (NO₃) possessed the highest catalytic activity among these chromium/Schiff base complexes. The structure of the produced copolymer was characterized by the IR, ¹H NMR, and ¹³C NMR measurements. Almost 100% carbonate content of the resulting polycarbonate were obtained with the help of these effective catalyst systems under facile conditions.     

Preparation of potentially electroactive thallium polymers derived from the acidic copolymers of maleic anhydride

Maleic anhydride copolymers with vinyl ethyl ether and N-vinyl-2-pyrrolidone were prepared in tetrahydrofuran at 60°C, using AIBN as initiator. Copoly (MA-VEE) was hydrolysed to various degrees of hydrolysis and the extent of hydrolysis monitored by i.r. Various acidic derivatives of copoly (MA-VEE), copoly(MA-N-vinyl-2-pyrrolidone) and copoly(MA-ethylene) were prepared and characterized by elemental analysis and spectroscopy. The inter- and intramolecular crosslinking of carboxylic groups in copoly(succinic acid-VEE) were studied by g.p.c. Also thallium (III) derivatives of several acidic polymers were prepared and characterized.     

苯乙烯/马来酸酐接枝聚乙烯蜡的研究

用溶液法制备了马来酸酐和马来酸酐/苯乙烯双单体接枝的聚乙烯蜡,考察了反应时间、温度、引发荆、单体用量对产物接枝率的影响.结果表明二叔丁基过氧化物是一种优良的接枝反应引发剂,在ω(引发剂)=0.4%、ω(马来酸酐)=6.0%、ω(苯乙烯)=4.0%、反应温度143℃、反应时间2.5 h的条件下,聚乙烯蜡接枝率为3.4%.并对产品进行了红外光谱分析、热分析表征.     

Properties and morphology of nanocomposites based on styrenic polymers, Part II: Effects of maleic anhydride units

Based on enhancement in exfoliation for polyolefin-g-maleic anhydride composites with the addition of as little as 1 wt% maleic anhydride (MA), the effect of MA in styrene–maleic anhydride copolymer (SMA)-based nanocomposites was studied. SMA nanocomposites were mixed using a DSM melt compounder followed by injection molding in a pneumatic bench top molder. These materials produced the same modulus enhancement and TEM-based areal particle densities on a weight percent basis as SAN-based nanocomposites from a previous study, but the areal TEM-based particle densities remained lower overall than literature values for polyolefin-g-MA mixtures. This behavior is explained by repulsive interactions between styrene and the alkyl tail of the surfactant, suggesting that polar surfactant tails could lead to improved exfoliation in styrene copolymer-based/montmorillonite nanocomposites. The role of increased melt viscosity and shearing on particle dispersion as MA is added to the copolymer is discussed.     

Electrochemical synthesis of dimethyl carbonate from methanol,CO2 and propylene oxide in an ionic liquid

BACKGROUND: Dimethyl carbonate (DMC) can be used effectively as an environmentally benign substitute for highly toxic phosgene and dimethyl sulfate in carbonylation and methylation, as well as a promising octane booster owing to its high oxygen content. Two‐step transesterification from epoxide, methanol, and CO₂ is widely used in the bulk production of DMC. However, major disadvantages of this process are high energy consumption, and high investment and production costs. A one pot synthesis of DMC from carbon dioxide, methanol, and epoxide was, therefore, developed. But the yields of DMC are below 70% due to the thermodynamic limitation. RESULTS: Electrochemical synthesis of DMC was conducted with platinum electrodes from methanol, CO₂ and propylene oxide in an ionic liquid was conducted. The bmimBr (1‐butyl‐3‐methylimidazolium bromide)‐methanol‐propylene oxide system with CO₂ bubbling allows DMC to be effectively synthesized and a high yield (75.5%) was achieved. CONCLUSION: In this electrolysis, redox reactions of substrates, CO₂, methanol, and propylene oxide, on Pt electrodes were carried out, producing the activated particles, CH₃O^?, CH₃OH⁺, CO₂^? and PO^?, resulting in the effective synthesis of DMC with a 75.5% yield in an ionic liquid (bmimBr). Finally, a mechanism for this synthesis reaction was proposed, which is very different from those reported in the literature. Copyright © 2011 Society of Chemical Industry     

Radical copolymerization of maleic anhydride and substituted styrenes by reversible addition-fragmentation chain transfer (RAFT) polymerization

Reversible addition fragmentation transfer (RAFT) copolymerization with benzyl dithiobenzoate (BDTB) as chain transfer agent was used to copolymerize maleic anhydride (MA) with styrene (St) and with the substituted styrenes p-chlorostyrene (pClSt), p-methoxystyrene (pMeOSt) and p-methylstyrene (pMeSt). Kinetic studies indicated that radical copolymerizations proceeded with apparent ‘living’ character, deduced from experiments demonstrating an increase in molar mass with monomer conversion, narrow molar mass distribution and chain extension to form block copolymer. All copolymers were alternating in chain structure as confirmed by determinations of monomer reactivity ratios. The degree of control in the RAFT mechanism and the establishment of the fragmentation equilibrium incorporating MA are discussed for styrene and for p-substituted styrenes, in relation to experimental copolymerizations producing molar masses somewhat higher than expected. For copolymerizations of MA with α-methylstyrene (αMeSt), conventional rather than controlled behaviour was observed, suggesting that the fragmentation equilibrium could be shifted towards the αMeSt propagating radical.     

Catalytic oxidation of butane to maleic anhydride enhanced yields in the presence of CO2 in the reactor feed

The addition of CO₂ to the reaction mixture for the oxidation of butane over a VPO catalyst gives rise to significantly improved yields of maleic anhydride.     

Phase equilibria of the propylene glycol/CO2 and propylene glycol/ethanol/CO2 systems

The high-pressure vapour–liquid phase equilibria (P–T–x–y) of the binary mixture propylene glycol/CO₂ have been experimentally investigated at temperatures of (398.2, 423.2 and 453.2) K over the pressure range from (2.5 to 55.0) MPa using a static-analytic method. Furthermore, the high-pressure vapour–liquid phase equilibria (P–T–x–y) of the ternary mixture propylene glycol/CO₂/ethanol at constant temperatures of (398.2, 423.2 and 453.2) K and at constant pressure of 15.0 MPa have been determined using a static-analytic method. Initial concentrations of components in propylene glycol (PG)/ethanol (EtOH) mixture vary from 10 up to 90 wt.%. In general, for binary system it was observed that the solubility of CO₂ in the heavy propylene glycol reach phase increases with increasing pressure at constant temperature. On the contrary, the composition of gaseous phase is not influenced by the pressure or the temperature. On average the solubility of PG in light phase of CO₂ amounts to 30 wt.%. The system behaviour at temperature of 398.2 K was investigated up to 70.0 MPa and a single-phase region was not observed. Above the pressure 60.0 MPa a single-phase region of the system was observed for the temperature of 423.2 K. For the temperature of 453.2 K the single-phase was observed above the pressure of 48.0 MPa. For ternary system it was observed that the composition of heavy phase is slightly influenced by the temperature when the mass fraction of EtOH in initial mixture is higher than 50 wt.%. If the mass fraction of PG in initial mixture is higher than 50 wt.%, the composition of heavy phase is not influenced by the temperature anymore. The composition of the PG, EtOH and CO₂ in light phase remains more or less unchanged and it is not influenced by the conditions.     

Effects of polypropylene-g-(maleic anhydride/styrene) compatibilizer on mechanical and rheological properties of polypropylene/clay nanocomposites

To enhance the dispersibility of clay in polypropylene (PP) matrix, PP-g-(maleic anhydride/styrene) (MA/ST) was prepared as a compatibilizer by graft copolymerization of maleic anhydride (MA) and styrene (ST) with PP. The addition of ST was known to be effective in improving the graft degree. PP/clay nanocomposites with the compatibilizer were prepared by melt intercalation. The X-ray diffraction (XRD) peaks of (0 0 1) plane of the organo-modified montmorillonite (O-MMT) were shifted to lower angles by an addition of PP-g-(MA/ST), indicating the intercalation capability of PP-g-(MA/ST) in the silicate layers. Transmission electron microscopy (TEM) photographs showed that the O-MMT in the presence of PP-g-(MA/ST) was intercalated and partly exfoliated during melt mixing. The addition of O-MMT and PP-g-(MA/ST) improved the thermal stability, tensile and rheological properties of the nanocomposites.     

Copolymerization of styrene and maleic anhydride in supercritical carbon dioxide

The copolymerization of styrene (St) and maleic anhydride (MA) was carried out in supercritical carbon dioxide (SC CO₂). It was found that St and MA are easy to copolymerize in SC CO₂ and the conversion can reach 97%, and that very fine and dry powders are obtained. The products were characterized using Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). GPC data showed that the molecular weight of the copolymer reach 3.62 × 10⁴ g mol^?1. Scanning electron microphotographs showed the minimum particle size of the product is about 200 nm. DSC measurements indicated that the glass transition temperature (T_g) of the copolymer increases with increasing the MA content in the copolymer. TGA curve showed that the copolymers were decomposed at about 350°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

One-pot terpolymerization of CO2, cyclohexene oxide and maleic anhydride using a highly active heterogeneous double metal cyanide complex catalyst

This paper describes a convenient one-pot terpolymerization of CO₂, cyclohexene oxide (CHO) and maleic anhydride (MAH) to afford a poly (ester-carbonate) with a low content of ether units (2.9-4.3 mol%) using a highly active Zn-Co(III) double metal cyanide complex (DMCC) catalyst. Terpolymerization was carried out in tetrahydrofuran (THF) at 75-90 °C and 1.0-4.0 MPa and no cyclic carbonate was observed in NMR spectra. The number-average molecular weight (M_n) of the terpolymer was up to 14.1 kg/mol with a narrow molecular weight distribution of 1.4-1.7. The apparent efficiency of the catalyst was up to 12.7 kg polymer/g Zn, representing the highest catalytic activity for terpolymerization of CO₂, epoxides and cyclic anhydrides to date. THF dramatically inhibited polyether formation in this terpolymerization owing to its nucleophilicity towards the Zn²⁺ center of Zn-Co (III) DMCC. This presents the first example of solvent-assisted selectivity for inhibiting ether units in CO₂ polymerization catalyzed by a heterogeneous system. Kinetic analyses of MAH/CHO/CO₂ terpolymerization (MAH/CHO 0.2) suggested that polyester production was slightly faster than polycarbonate production in the early stage. A mechanism for this terpolymerization catalyzed by Zn-Co (III) DMCC catalyst was proposed. Moreover, addition of small amounts of MAH (MAH/CHO molar ratio ≤0.2) during CO₂/CHO copolymerization can improve the thermal properties of the resultant terpolymers.     

聚碳酸亚丙酯马来酸酐共聚物的合成工艺研究

研究了二氧化碳、环氧丙烷(PO)和马来酸酐(MA)在负载双金属PBM型催化剂下合成聚碳酸亚丙酯马来酸酐(PPCMA)的反应,考察了反应物的配比、反应压力、反应时间和反应温度对反应产物的影响。实验结果表明,较合适的反应条件为MA与PO摩尔比3∶5,反应温度60℃,二氧化碳压力4MPa、反应时间48 h。在上述条件下,产物的收率为39.2%。利用红外光谱和核磁共振等方法分析产物的结构,得到了产物的结构表达式。     

环氧丙烷与二氧化碳合成碳酸丙烯酯

介绍了PC的性质、应用情况和生产工艺。通过对影响合成PC的主要因素和机理的讨论,指出催化剂和溶剂是影响PC收率的重要因素,较高的压力对提高产品的选择性有利。     

Physical properties of aliphatic polycarbonates made from CO2 and epoxides

A homologous series of aliphatic polycarbonates with different side‐chain lengths was synthesized by ring‐opening polymerization of terminal epoxides with CO₂ using zinc adipionate as catalyst [patented process of Empower Materials (formerly PAC Polymers Inc.)]. Additionally, a polycarbonate was made having a cyclohexane unit in its backbone, together with a terpolymer having both cyclohexane and propylene units. After characterization of thermal properties the aliphatic polycarbonates were found to be completely amorphous. Polycarbonates derived from long‐chain epoxides showed a glass‐transition temperature (T_g) below room temperature, whereas polycarbonates derived from cyclohexene oxide showed a T_g of 105°C, the highest yet reported for this class of polymers. The initial decomposition temperature of the polymers in air and nitrogen atmospheres was found to be less than 300°C. The mechanical properties and the dynamic mechanical relaxation behavior of the polymers were also reported. The effect of the chemical structure on the physical properties of aliphatic polycarbonates was discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1163–1176, 2003     

Modified Zinc Oxide for the Direct Synthesis of Propylene Carbonate from Propylene Glycol and Carbon dioxide

A series of modified zinc oxide catalysts were prepared and their catalytic activities were evaluated by the direct synthesis of propylene carbonate from propylene glycol and carbon dioxide in the presence of acetonitrile, which acted as not only the solvent but also the dehydrating reagent in the reaction. The reusability test indicated that the modified catalysts had the high stability. Ammonium carbonate was added into the reaction to significantly elevate the selectivity of propylene carbonate.     

Simultaneous kinetic resolution of chiral propylene oxide and propylene glycol in a continuous reactive distillation column

Traditionally kinetic resolutions are conducted by batch processing to recover one of the desired enantiomers of the racemate, while the product formed by the resolution is discarded due to its low purity. However, chiral materials are economically valuable and simultaneously conducting the reaction and separation, using reactive distillation, allows for both a reactant enantiomer and a product enantiomer to be recovered in high enantiomeric excess and yield. A feasible design of a continuous reactive distillation column is presented which performs a simultaneous kinetic resolution of racemic propylene oxide to produce both enantiomerically-pure propylene oxide and propylene glycol.