超高吸水性聚丙烯酸钠的制备

以聚-γ-巯丙基硅氧烷作为引发剂,将丙烯酸和少量交联剂对二乙烯基苯,在四氯化碳和氢氧化钠水溶液中进行共聚,可得到吸水量400倍以上的超高吸水性聚丙烯酸钠。如果同时加入二氧六环,没有交联剂对二乙烯基苯,也可以得到吸水量将近400倍的超高吸水性聚丙烯酸钠。     

Long-lived polymer radicals. IV. Reactions of poly(N-methylacrylamide) and poly(N-methylmethacrylamide) radicals with binary mixtures of vinyl monomers

N-methylacrylamide (NMAAm) and N-methylmethacrylamide (NMMAm) were polymerized to give polymer microspheres containing living propagating radicals. The microsphere polymer radicals were allowed to react with some binary mixtures of vinyl monomers including alternating copolymerization combinations. The reaction processes were investigated by ESR spectroscopy. In the poly(NMMAm) radical/methyl methacrylate (MMA)/styrene (St) system, the propagating radical from MMA was mainly observed at the higher MMA concentration, while polySt radical prevailed at the lower MMA concentration. In the poly(NMMAm) radical/α-methylstyrene (α-MeSt)/diethyl fumarate system, the α-MeSt radical was exclusively observed, while the maleic anhydride (MAn) radical was predominantly observed in the α-MeSt/MAn system. In the MAn/diphenylethylene system, the propagating radicals from both monomers were observed at comparable concentrations. The poly(NMAAm) microsphere radical behaved differently in the reaction with the MMA/St mixture. The poly(NMAAm) microsphere was found to incorporate preferentially St, leading to formation of the St radical. The St preference was enhanced in the St/cyclohexyl methacrylate (CHMA) system. These results were in agreement with those of block copolymerization via the reaction of poly(NMAAm) radical with the MMA/St or CHMA/St mixture, where the compositions of the resulting polymers were analyzed by pyrolysis gas chromatography.     

Graft copolymerization of butyl acrylate onto casein initiated by potassium diperiodatonickelate(IV) in alkaline medium

The novel redox system, potassium diperiodatonickelate (Ni(IV))-casein, was used to initiate graft copolymerization of butyl acrylate onto casein under heterogeneous conditions in aqueous 5% potassium hydroxide solution, which showed high grafting efficiency and percent grafting. FT i.r. spectroscopy, thermal analysis and scanning electron microscopy characterized the structures and properties of the grafted copolymer. The effects of synthesis variables in the graft copolymerization have been discussed in the light of grafting efficiency, percent grafting and the rate of polymerization. A possible initiation mechanism is proposed.     

Synthesis of poly(ethylene glycol) block copolymers by a redox process and their spectral characterization

Novel block copolymers of poly(ethylene glycol) (PEG) with acrylamide (AAm) and methacrylic acid (MAA) were synthesized using a redox system consisting of ceric ions and PEG in aqueous acidic medium. The molecular weight of PEG in the redox system was varied to obtain a series of block copolymers with differing molecular weights of PEG segment. The polymerization proceeded via macroradical generation, which was substantiated by ESR spectroscopy. This macroradical acted as a redox macroinitiator for the block copolymerization of the vinyl monomers. The formation of the block copolymers was confirmed by fractional precipitation technique.     

Stabilizer‐free dispersion copolymerization of maleic anhydride and vinyl acetate. I. Effects of principal factors on microspheres

A novel dispersion copolymerization of maleic anhydride (MAn) and vinyl acetate (VAc) without adding stabilizer is developed, which gives uniform copolymer microspheres with tunable sizes. Some principal factors affecting the microspheres, such as reaction time, monomer concentration and feed ratio, reaction media, and cosolvent, were investigated. It was found that the stabilizer‐free dispersion copolymerization of MAn and VAc is a rapid process, and the particle size grows in accordance with the evolution of polymerization. The chemical composition of the copolymer microspheres was characterized by FT‐IR and ¹³C NMR spectroscopies. Over a wide range of monomer concentrations, the microspheres can always be formed and stably dispersed, with uniform sizes ranging from 180 nm to 740 nm. The yield of copolymer microspheres reaches a maximum at 1:1 feed ratio of MAn to VAc, owing to the alternating copolymerization between the binary monomers by a known charge‐transfer‐complex mechanism. However, the diameter of microspheres drastically increases when MAn content is enhanced. Only some specific alkyl ester solvents, such as n‐butyl acetate, isobutyl acetate, n‐amyl acetate, are desirably fit for this unique stabilizer‐free dispersion polymerization. Furthermore, we found that when some acetone is added as a cosolvent, the copolymer microspheres can still be formed, with much larger diameters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3760–3770, 2005     

The Copolymerization of Alkenes with Maleic Anhydride

The investigations presented deal with the experimental results of the copolymerization of maleic anhydride (MAn) with alkenes. The course of the reaction is explained by the overall rate of the copolymerization (v _Br), which correlates with the solution viscosity of the copolymer, and the dependence of the v _Br maximum on the mole ratio of the monomers at constant total monomer concentration. The use of solvents with increasing donor power leads to increased complexing of the free MAn molecules and of the MAn radical chain ends. The results demonstrate that, for low 1-alkenes, the addition of the MAn chain radical is the rate-determining step of the copolymerization. As the substituents on the olefinic double bond become larger or the double bond shifts to the 1,2-position, the addition of MAn to the hydrocarbon radical becomes more and more the rate-determining step. On the other hand, an increase of the CT complexation of the MAn polymer radical by use of donor solvents decreases the alkene addition rate.     

Contribution to the mechanism of copolymerization of phenylvinyl alkyl ethers and thioethers with maleic anhydride

The equilibrium constants of the charge-transfer complex monomers of phenylvinyl alkyl ethers (I) and thioethers (II) with maleic anhydride (MAn) were determined by the transformed Benessi—Hildebrand NMR method, and it was found that the bulkiness of alkyl groups had no significant influence on the equilibrium constant. The rate of copolymerization, however, was largely dependent on the bulkiness of the alkyl groups in the phenylvinyl alkyl ether series. The rate of copolymerization of I (R = Et; sec-Bu) and II (R = Et; sec-Bu) with MAn was proportional to the square root of AIBN concentration, and intrinsic viscosity of poly-I (R = Et)-co-MAn was proportional to the reciprocal square root of AIBN concentration. Spontaneous copolymerization did not occur, but I (R = Et) copolymerizes with MAn in the presence of oxygen; II did not copolymerize with MAn in the presence of oxygen; nor in the presence of peroxide initiators. In the copolymerization of I (R = Et) and MAn, it was found that molecular weight increases with conversion. By applying the generalized model described by Shirota and co-workers, the reactivity ratios k_1c/k₁₂ and k_2c/₂₁ for copolymerization of I (R = Et) and II (R = Et) with MAn were calculated from the change of copolymerization rate with monomer feed at constant total monomer concentration.     

丙烯酰胺与二甲基二烯丙基氯化铵共聚动力学

采用膨胀计法研究了以过硫酸铵 亚硫酸氢钠为引发剂,丙烯酰胺（AM）和二甲基二烯丙基氯化铵（DMDAAC）在水溶液中的共聚反应动力学,测定了相应的聚合表观活化能、聚合速率方程和单体竞聚率。 结果表明,当AM与DMDAAC摩尔比分别为5∶5、6∶4和7∶3时,表观活化能分别为Ea1=90.61 kJ/mol、Ea2=88.88 kJ/mol和Ea3=85.15 kJ/mol;聚合反应温度为45 ℃下,聚合速率方程分别为Rp1=kc(M)2.84c(IO)0.51·c(IR)0.61,Rp2=kc(M)2.77c(IO)0.51c(IR)0.59和Rp3=kc(M)2.73c(IO)0.50c(IR)0.56;2种单体的竞聚率分别为rAM=6.11,rDMDAAC=0.14。 上述实验结果可从动力学角度为不同阳离子度共聚物Poly(DMDAAC-co-AM)（PDA）聚合反应速率差别及产物特征黏度值差异进行解释。     

Atom transfer radical polymerization of styrene in toluene/water mixtures

The atom transfer radical polymerization (ATRP) of styrene in water/toluene mixtures was studied. A linear dependence of the molecular weight on conversion was observed, but the initiation efficiency decreased when the catalyst concentration increased. The variation of the amount of water in the system affected the control of the ATRP, indicating that the presence of the aqueous phase influenced the concentration of copper halides in the organic phase. The partitioning of copper halides resulted in almost complete migration of Cu^II into the aqueous phase, which assisted with catalyst removal after polymerization. For example, the amount of residual copper in the organic phase determined by inductively coupled plasma was less than 1 ppm when the polymerization mixture was exposed to air for 30 min. The ATRP of styrene in water/toluene mixtures occurred with the preservation of Br at the polymer chain end, as confirmed by successful block copolymerization. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3153–3160, 2002     

Photocopolymerization of methacryloyl-L-valine methyl ester with maleic anhydride

Methacryloyl-L -valine methyl ester (MAVM) and maleic anhydride (MAn) were photopolymerized without initiator in dioxane at 35°C. Copolymer having a 1:1 molar ratio of the monomers was obtained regardless of both molar ratio of monomers in the feed and polymerization time. The circular dichroism (CD) spectrum of the copolymer before and after hydrolysis showed the induction of asymmetric centers into the polymer main chain. Spectroscopic and kinetic studies suggested the alternating and stereoregular copolymerization of MAVM and MAn, in which a charge transfer complex with a 1:1 molar ratio of monomers participated.     

Synthesis of 3,6-dioxa-Δ-4-trifluoromethyl perfluorooctyl trifluoromethyl sulfonimide: bis[(perfluoroalkyl)sulfonyl] superacid monomer and polymer

A new type of ion exchange polymer, bis[(perfluoroalkyl)sulfonyl]imide ionomers (PFSI), were developed by the copolymerization of sodium 3,6-dioxa-Δ⁷-4-trifluoromethyl perfluorooctyl trifluoromethyl sulfonimide with tetrafluoroethylene (TFE) using an aqueous redox initiation system in an emulsion type polymerization. These polymers have been prepared in various equivalent weights and processed into functional membranes. The new ionomers exhibit excellent chemical and thermal stability. The materials have high potential for electrochemical applications especially as solid polymer electrolytes (SPE) in proton exchange membrane (PEM) fuel cells.     

在胶束溶液中铈盐引发制备双亲嵌段共聚物PSt-b-PVP及其表征

采用过氧化氢-硫酸亚铁的氧化还原引发体系,首先使苯乙烯(St)在乳液聚合体系中进行均聚合,制得了端羟基聚苯乙烯(PSt-OH),然后将PSt-OH增溶于十二烷基硫酸钠的胶束溶液中,在硫酸铈铵的引发作用下,使水溶液中的N-乙烯基吡咯烷酮(NVP)在PSt-OH端羟基部位发生嵌段共聚合,制得了双亲嵌段共聚物PSt-b-PVP。采用红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)、凝胶渗透色谱(GPC)、差示扫描量热(DSC)等手段对嵌段共聚物的组成与结构进行了表征。结果表明:在Ce(Ⅳ)盐的氧化作用下,增溶于胶束中的端羟基聚苯乙烯端会在端基产生自由基,顺利地实现NVP的嵌段共聚合反应。随着共聚合时间的延长,共聚物PSt-b-PVP大分子链中亲水嵌段PVP的比例不断增大。     

FREE-RADICAL-INITIATED COPOLYMERIZATION OF 2-CHLOROSTYRENE, 4-CHLOROSTYRENE,AND 2,6-DICHLOROSTYRENE WITH MALEIC ANHYDRIDE

The title copolymers have been prepared by the free-radical-initiated copolymerization of 2-chlorostyrene (2-ClSt), 4-chlorostyrene (4-ClSt) and 2,6-dichlorostyrene (2,6-DClSt) with maleic anhydride (MAn) in toluene at 65°C. Copolymers of chlorinated styrenes with MAn prepared under different monomer-to-monomer ratios in the feed have alternating composition. In all cases, the mixture of comonomers forms charge-transfer complex monomers (CTC). The initial rate of copolymerization increases with the increase of electron donors in the comonomer feed, and the highest rates were at the equimolar ratios of comonomers in the feed. The thermal stability of the polymers was measured by thermogravimetric analysis in nitrogen. Homopolymers decompose by a one-step mechanism, while copolymers are more thermostable and decompose by a two-step mechanism. Glass transition temperatures (T_gs) of homopolymers are lower than T_gs of copolymers. The number and weight average molecular weights of chlorinated copolymers are higher than those of the corresponding homopolymers.     

Copolymerization of N-vinylpyrrolidone with N,N-dimethyl-N,N-diallylammonium chloride

The possibility of synthesizing copolymers of N,N-dimethyl-N,N-diallylammonium chloride (DMDAAC) and N- vinylpyrrolidone (VP) was demonstrated and the features of radical copolymerization of these monomers in aqueous and alcohol media were investigated. The optimum conditions of conducting the reaction were determined and the kinetic features of the copolymerization reaction in the region of low degrees of conversion, for which the usual order mechanisms for radical polymerization are preserved, were investigated. The dependence of the initial rate of co polymerization on the composition of the starting mixture of comonomers is nonlinear, and the rate of copolymerization decreases significantly as the concentration of DMDAAC in the starting mixture increases. The composition of copolymers formed was studied and the copolymerization constants r₁ ^ef=r₂ ^ef=1 were calculated, i.e., the system is azeotropic, which is also detected for significant degrees of conversion.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1969–1973, September, 1990.     

丙烯酰胺在聚乙二醇水溶液中的聚合动力学

用改进溴法对丙烯酰胺 (AM)在聚乙二醇 (PEG)水溶液中聚合动力学进行研究 .在单一和氧化还原引发体系中分别考察了引发剂、单体和PEG用量、不同HLB值乳化剂以及聚合温度等因素对动力学的影响 .得到AM聚合速率与过硫酸铵 (APS)浓度的 0 91次方成正比 ;单一APS和APS 三乙醇胺 (TEA)氧化还原引发体系中的AM聚合表观活化能分别为 96 1和 4 2 3kJ mol.     

Radiation-induced solid-state copolymerization of maleic anhydride and acenaphthylene

Radiation-induced solid-state copolymerization of the maleic anhydride–acenaphthylene system was carried out for the purpose of studying the solid-state polymerization of vinyl compounds in a binary system. Melting point measurement confirmed that this binary monomer system forms a eutectic mixture in the solid state. The solid-state polymerization of these monomers proceeds at maximum rate at the eutectic composition, and the polymerization products consist of a mixture of polyacenaphthylene and 1:1 maleic anhydride–acenaphthylene alternating copolymer. Since the 1:1 copolymer was obtained in solution polymerization also and maleic anhydride did not homopolymerize in solid state, it is considered that the solid-state copolymerization of maleic anhydride and acenaphthylene occurs in a liquidlike state at the boundary of the two monomer crystals.     

马来酸酐与乙酸乙烯酯交替共聚合反应的研究

本文研究了马来酸酐（MAn）在过氧化苯甲酰（BP）引发作用下与醋酸乙烯酯（VAc）的交替共聚反应。红外光谱证明了交替共聚物的结构，分析结果表明共聚物是由反应单体技1：1摩尔比例组成。当c（BPO）＝6．8×10~（－3）moi／L，c（VAc）＝3．4×10~（－3）mol／L，p（MAn）＝32．7g／L，63～65℃反应18小时，转化率可达92％以上。     

Radical polymerization of metal-coordinated monomers with ligands of pyrrole-containing schiff bases

The copper complexes and the cobalt complex with the ligand of 3-(2-pyrrolylmethyl-enimino)propene-1 (PIP) or p-(2-pyrrolylmethylenimino)styrene (PIS) were synthesized and homopolymerizations and the copolymerization with styrene, acrylonitrile, methyl methacrylate and acrylic acid studied. In the polymerization of chelate monomers, inhibition of radical polymerization by the central metal ion was observed, but the chelate polymer could be obtained only if the initiator was present in higher concentrations in the feed. It is considered that the strength of inhibition depends on the electronic configuration of d-orbitals of the central metal ion. The initiation mechanism of the cupric chelate monomer may be reduction of the metal ion by the redox reaction with a primary radical via the intramolecular electron transfer through the π-conjugated system of the ligand prior to the propagation step. This mechanism was verified by studying the redox reaction of various copper complexes with DPPH. In the system of the copper complex containing PIS and acylic acid the alternating copolymer could be obtained at any mole fraction of monomer mixture in feed.     

以PAAS为模板AM与DMC的模板共聚合反应

在水溶液中以聚丙烯酸钠(PAAS)为模板,进行了丙烯酰胺(AM)与2-甲基丙烯酰氧乙基三甲基氯化铵(DMC)的共聚合反应。研究了其聚合动力学,并对模板共聚物的序列结构进行了表征,最后对其进行了絮凝性能评价。结果表明:聚合反应符合模板聚合Ⅰ型机理,聚合反应速率分别与单体浓度和引发剂浓度的1.63和1.64次方成正比,此种共聚物与无模板参与聚合的普通共聚物相比具有更长的DMC序列长度,对高岭土悬浮液的絮凝沉降速率优于普通共聚物。     

The structuring and properties of hydrogels prepared with a biologically active macromonomer

The copolymerization of a macromonomeric inhibitor of proteolytic enzymes with acrylamide and N,N′-methylenebis(acrylamide) in an aqueous solution in the presence of a redox catalyst has been studied. It has been shown that the addition of mercaptoacetic acid as a chain-transfer agent to the polymerization system results in a change in the structure of the forming hydrogel, i.e., a decrease in the number of large pores. Simultaneously, a substantial increase in the degree of the macromonomer incorporation into the hydrogel is attained and favorable conditions for the development of the biological activity of the macromonomer are created.