As a means for the chemical fixation of carbon dioxide and the synthesis of biodegradable polycarbonates, copolymerizations of carbon dioxide with various epoxides such as cyclohexene oxide (CHO), cyclopetene oxide, 4-vinyl-1-cyclohexene-1,2epoxide, phenyl glycidyl ether, allyl glycidyl ether, propylene oxide, butene oxide, hexene oxide, octene oxide, and 1-chloro-2,3-epoxypropane were investigated in the presence of a double metal cyanide catalyst (DMC). The DMC catalyst was prepared by reacting K3Co(CN)6 with ZnCl2, together with tertiary butyl alcohol and poly(tetramethylene ether glycol) as complexing reagents and was characterized by various spectroscopic methods. The DMC catalyst showed high activity (526.2 g-polymer/g-Zn atom) for CHO/CO2 (PCO2 = 140 psi) copolymerization at 80 °C, to yield biodegradable aliphatic polycarbonates of narrow polydispersity (Mw/Mn = 1.67) and moderate molecular weight (Mn = 8900). The DMC catalyst also showed high activities with different CO2 reactivities for other epoxides to yield various aliphatic polycarbonates with narrow polydispersity. 相似文献
The construction of amphiphilic polycarbonates through epoxides/CO2 coupling is a challenging aim to provide more diverse CO2‐based functional materials. In this report, we demonstrate the facile preparation of diverse and functional nanoparticles derived from a CO2‐based triblock polycarbonate system. By the judicious use of water as chain‐transfer reagent in the propylene oxide/CO2 polymerization, poly(propylene carbonate (PPC) diols are successfully produced and serve as macroinitiators in the subsequent allyl glycidyl ether/CO2 coupling reaction. The resulting ABA triblock polycarbonate can be further functionalized with various thiols by radical mediated thiol–ene click chemistry, followed by self‐assembly in deionized water to construct a versatile and functional nanostructure system. This class of amphiphilic polycarbonates could embody a powerful platform for biomedical applications. 相似文献
Allyl glycidyl ether (AGE), allyl 1,1,2,3,3,3-hexafluoropropyl ether (AFE), allyl 2-naphthyl ether (ANE), 2-vinyl-1,3-dioxolane (2VD) and allyl alcohol (AA) have been examined as transfer agents in the radical polymerization of methyl methacrylate (MMA) at 60°C; the transfer constants are 1.1 × 10?3, 0.1 × 10?3, 0.2 × 10?3, 1.1 × 10?3 and 0.6 × 10?3, respectively. AFE and AA barely affect the rate of polymerization: AGE, ANE, and 2VD act as weak retarders. There is no direct correlation between effectiveness as a transfer agent and the extent of retardation for these additives. For copolymerization with MMA (monomer-1), the monomer reactivity ratios r1 are 42 ± 5 and 32 ± 5 for AGE and ANE, respectively; for both cases, r2 is very close to zero; 2VD engages in copolymerization with MMA to a negligible extent. Experiments involving styrene or acrylonitrile gave results consistent with those obtained using MMA. 相似文献
Functional aliphatic polycarbonate was synthesized by copolymerization of carbon dioxide and allyl glycidyl ether in the presence of a catalyst system based on ZnEt2 and pyrogallol at a molar ratio of 2 : 1. The polycarbonate obtained was oxidized with m‐chloroperbenzoic acid to give poly(epoxycarbonate). These polymers were degraded in an aqueous buffer of pH 7.4 at 37°C. Hydrolytic degradation was monitored by determination of the weight loss. 相似文献
3-Allyloxy-2-hydroxypropylcelluloses (AHP-celluloses), reactive unsaturated cellulose derivatives, were homogeneously synthesized
by the reaction of cellulose with allyl glycidyl ether (AGE) in NaOH/urea aqueous solution. Water-soluble AHP-celluloses with
DSNMR = 0.32–0.67 were prepared from microcrystalline cellulose. The degree of substitution (DS) of AHP-celluloses could be controlled
by varying the molar ratio of AGE and NaOH to AGU and the reaction conditions. The structure of AHP-cellulose samples were
characterized by means of FT-IR, NMR spectroscopy and size exclusion chromatography. The cellulose ether shows thermoreversible
flocculation. Bromination reactions were carried out as subsequent functionalization both to illustrate the reactivity of
the allyl function and to determine the DS values. 相似文献
A series of linear poly glycidol copolymers, tethering with both alkene and hydroxyl groups, were prepared by a combination of anionic ring-opening polymerization (ROP) using specific reactions of ethoxy ethyl glycidyl ether (EEGE) and allyl glycidyl ether (AGE) firstly, and subsequently removal of the protection group of glycidol in EEGE to achieve the linear copolymer pendant with both hydroxyl groups and double bonds. The EEGE/AGE monomer reactivity ratio is measured to be 3.30/1.13. The chemical compositions of the as-synthesized polymers were characterized by tH NMR and GPC, and the glass transition temperatures (Tg) of as-synthesized polymers were determined by DSC. The final copolymers have abundant double bonds and hydroxyl as side groups. Furthermore, the ratio of the double bonds to hydroxyl groups can be controlled by the ratio of the starting materials in a wide range. 相似文献
The bimetallic catalysts of Osgan and Teyssie, (RO)2Al-O-Zn-O-Al(OR)2, are effective, unusual catalysts for polymerizing epoxides. The polymer obtained from propylene oxide when R = n-Bu is preponderantly isotactic and highly crystalline and thus, largely head-to-tail. Crystallizable, sulfur vulcanizable propylene oxide rubber was made by copolymerizing propylene oxide (PO) with allyl glycidyl ether (AGE) with this catalyst. This product after S vulcanization exhibited gum tensile and other properties which were superior to the commercially available, amorphous PO–AGE copolymer of similar composition. However, the Osgan–Teyssie catalyst is very sensitive to reactive, polar impurities. Hindered alkyl aluminums and especially alkoxides such as Et2AlOtert–Bu can be added to help alleviate this problem. The reported favorable (but slow) copolymerization of epichlorohydrin with propylene oxide in nonpolar media with the Osgan–Teyssie catalyst has been confirmed and an alternate explanation for this unusual result suggested. 相似文献
A series of functional polycarbonates, poly((isopropylidene glyceryl glycidyl ether)‐co‐(glycidyl methyl ether) carbonate) (P((IGG‐co‐GME) C)) random copolymers with different fractions of 1,2‐isopropylidene glyceryl glycidyl ether (IGG) units, is synthesized. After acidic hydrolysis of the acetal protecting groups, a new type of functional polycarbonate prepared directly from CO2 and glycerol is obtained, namely poly((glyceryl glycerol)‐co‐(glycidyl methyl ether) carbonate) (P((GG‐co‐GME) C)). All hydroxyl functional samples exhibit monomodal molecular weight distributions with PDIs between 2.5 and 3.3 and Mn between 12 000 and 25 000 g mol−1. Thermal properties reflect the amorphous structure of the polymers. The materials are stable in bulk and solution. 相似文献
The alternating copolymerization of biorenewable limonene dioxide with carbon dioxide (CO2) catalyzed by a zinc β‐diiminate complex is reported. The chemoselective reaction results in linear amorphous polycarbonates that carry pendent methyloxiranes and exhibit glass transition temperatures (Tg) up to 135 °C. These polycarbonates can be efficiently modified by thiols or carboxylic acids in combination with lithium hydroxide or tetrabutylphosphonium bromide as catalysts, respectively, without destruction of the main chain. Moreover, polycarbonates bearing pendent cyclic carbonates can be quantitatively prepared by CO2 insertion catalyzed by lithium bromide. 相似文献
Transparent films were prepared by cross‐linking polyunsaturated poly(ether carbonate)s obtained by the multicomponent polymerization of CO2, propylene oxide, maleic anhydride, and allyl glycidyl ether. Poly(ether carbonate)s with ABXBA multiblock structures were obtained by sequential addition of mixtures of propylene oxide/maleic anhydride and propylene oxide/allyl glycidyl ether during the polymerization. The simultaneous addition of both monomer mixtures provided poly(ether carbonate)s with AXA triblock structures. Both types of polyunsaturated poly(ether carbonate)s are characterized by diverse functional groups, that is, terminal hydroxy groups, maleate moieties along the polymer backbone, and pendant allyl groups that allow for versatile polymer chemistry. The combination of double bonds substituted with electron‐acceptor and electron‐donor groups enables particularly facile UV‐ or redox‐initiated free‐radical curing. The resulting materials are transparent and highly interesting for coating applications. 相似文献
Chemical assembling of the silica surface modified by dimethylchlorosilane was performed by the catalytic hydrosilylation
of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, α-methyl styrene, acetophenone, allyl butyl and allyl glycidyl ethers with dimethylchlorosilane.
The effect of the nature of complexes of platinum, palladium, rhodium and ruthenium on the parameters of hydrosilylation was
studied. It was shown that the maximum rate of hydrosilylation was observed in the reaction with allyl glycidyl ether, and
minimum, with α-methylstyrene; the most effective catalyst of hydrosilylation was [Rh(CO)2(acac)]. 相似文献
Copolymerization of epichlorohydrin with allyl glycidyl ether under the action of boron trifluoride tetrahydrofuranate in diethyl ether and dimethoxyethane was studied under the conditions of synthesis of alkyl ether and diols where water was used to produce terminal hydroxy groups. 1H NMR spectroscopy showed the formation of a copolymer. The integrated intensity ratio for the signals related to allyl and other groups showed that the rate of allyl glycidyl ether introduction into the copolymer is higher than that of epichlorohydrin. Alkyl- and hydroxy-containing oligoethers with enhanced content of functional groups of different nature were obtained by polymer analogous reaction. 相似文献
A novel water insoluble, multifunctional poly(ethylene glycol), poly(hydrazide ethylene glycol‐co‐benzyl glycidyl ether) (P(HZ‐co‐BnGE)), is synthesized via thiol‐ene click reaction of poly(allyl glycidyl ether‐co‐benzyl glycidyl ether) (P(AGE‐co‐BnGE)). The base polymer P(AGE‐co‐BnGE) is previously prepared by anionic ring‐opening copolymerization of the corresponding monomers. To demonstrate utility, bicompartmental microspheres and microcylinders containing P(HZ‐co‐BnGE) in one of the compartments are prepared via electrohydrodynamic (EHD) co‐jetting. Next, spatially controlled surface reactivity toward sugars is demonstrated by selective binding of 2α‐mannobiose to the P(HZ‐co‐BnGE) compartment only, as confirmed by a carbohydrate‐lectin‐binding assay. These sugar‐reactive hydrazide‐presenting microparticles have potential applications for glyco‐targeted drug delivery.