Alternating copolymerization of benzofuran and acrylic monomers in the presence of organoaluminum compounds

The copolymerization of benzofuran and acrylic monomers, such as acrylonitrile, methacrylonitrile, methyl acrylate, and methyl methacrylate, was investigated in the presence of aluminum compounds as complexing agents for acrylic monomers. Among the various kinds of aluminum compound, ethylaluminum sesquichloride is the most suitable for alternating copolymerization, whereas ethoxyaluminum compounds of low acidity allow the incorporation of excess acrylic monomer and dichloride of strong acidity is likely to induce cationic homopolymerization of benzofuran as a side reaction. The equimolar amount of sesquichloride with respect to acrylic monomer is necessary for alternating copolymerization. Azobisisobutylonitrile (AIBN) is an effective initiator but benzoyl peroxide is not. Nuclear magnetic resonance (NMR) of the copolymer indicates that the copolymer is essentially alternating, although some block sequences of acrylic monomer sometimes exist. As a mechanism the copolymerization via a ternary complex of acrylic monomer, aluminum compound, and benzofuran is considered. Free acrylic monomer participates in copolymerization when the amount or acidity of the complexing agent is insufficient. A quantitative relation between monomer and copolymer composition is derived from a scheme based on the copolymerization of the donor monomer-acceptor monomer complex with free acrylic monomer.     

氯乙烯/N-取代马来酰亚胺共聚竞聚率及共聚物组成

研究了氯乙烯(VC)与多种N-取代马来酰亚胺的溶液共聚合,求得各对单体的竞聚率.结果表明,各种马来酰亚胺的竞聚率都远高于VC的竞聚率,即N-取代马来酰亚胺单体的活性均比VC单体活性高.计算得到N-取代马来酰亚胺Q和e值.由于苯环的共轭效应,N-苯基及N-取代苯基马来酰亚胺具有较大的Q值.各对单体的e值差别较大,表明有形成交替共聚物的倾向.此外,还考察了聚合过程中共聚物组成的变化,用递推法预测了这类体系共聚物瞬时和累积组成随转化率的变化.     

三价锰离子引发烯类单体在聚乙烯醇上接枝聚合的研究

<正> 无论是淀粉;纤维素,还是聚乙烯醇(PVA)的接枝反应,Ce(Ⅳ)被认为是一个十分有效的引发剂,已有较详尽的研究。与Ce(Ⅳ)相类似,Mn(Ⅲ)也可以和一些高聚物组成氧化还原引发体系,由此产生自由基,引发烯类单体在高分子主干上进行接枝聚合。Ranby等人,以焦磷酸络合的三价锰离子引发烯类单体在纤维素和淀粉的接枝反应中,获得了高效的接枝产物。有用这种引发体系在淀粉上接枝丙烯腈获得吸水276     

Copolymerization of Chloroprene with Methyl Methacrylate by the EtnAICI3.n (n=1, 1.5, 2)-Vanadium Compound System

Abstract

The copolymerization of chloroprene with methyl methacrylate was studied in the presence of Et_n A1C1_3-n (n=1, 1.5, 2)-vanadium compounds. Monomer reactivity ratios in various catalyst concentrations were compared with that of a usual radical initiator. The apparent monomer reactivity ratio changed with the concentration of alkylaluminum halide. In this polymerization, alternating copolymer could not be prepared by the ordinary catalyst concentration by which the alternating copolymerization of chloroprene with acrylonitrile was carried out. The addition of more than 10 mole % of the alkylaluminum halide based on two monomers was required to prepare the copolymer which had equimolar composition irrespective of the feed monomer ratio.

The configuration in the repeating unit of the copolymer was discussed by comparison with the NMR and IR spectra of the radical copolymer and the cyclic Diels-Alder adduct of chloroprene-methyl methacrylate. The high alternating tendency was clarified by ozonolysis of the copolymer which was prepared under the conditions which produced equimolar copolymer in various feed monomer ratios. The chloroprene unit of the copolymer was present in the 1, 4-trans structure in the copolymer prepared by the Et_n A1C1_3-n -vanadium compound system.     

Charge transfer complex formation in in-situ maleic anhydride and N-vinyl caprolactam copolymer and copolymer/organo-montmorillonite nanoarchitectures

The binary copolymerization of maleic anhydride (MA) and N-vinyl caprolactam (VCL) or considered as acceptor (A)?donor (D) monomer systems were used (MA:VCL) 50:50 in BPO (0.5%) as an initiator at 70°C under nitrogen atmosphere. The functional copolymers, having a combination of rigid/flexible linkages and an ability of complex-formation with interlayered surface of organo-silicate, and their nanocomposites have been synthesized. Interlamellar in situ complex-radical copolymerization of intercalated monomer complexes of MA and VCL undergoes with stearyl amine surface modified montmorillonite (O-MMT) and monomer mixtures. Charge transfer complex formation was followed and identified by UV-Vis-NIR spectroscopy. Equilibrium constant (K_AD) molar absorption coefficient (?^AD)) of the complex were determined by the Benesi-Hildebrand, Scott and Ketaalar equations respectively. The results show that copolymerization of MA:VCL system was preceded via alternating copolymerization mechanism. Obtained functional alternating copolymer and copolymer/O-MMT nanostructures were characterized by XRD and TEM.     

Radiation-induced copolymerization of hexafluoroacetone with 2-methyl-1-pentene

Copolymerization of hexafluoroacetone (HFA) with 2-methyl-1-pentene (2MP) in trichlorotrifluoroethane (R-113) was carried out by γ-ray irradiation in a low-temperature region of ?100 to 0°C. Though HFA does not homopolymerize and 2MP scarcely does, the copolymerization took place at various monomer compositions. The copolymerization rate and the molecular weight in the low-temperature region were much higher than those at 0°C. Above room temperature the copolymerization did not take place and only the adduct of monomers was formed. The copolymerization was inhibited to some extent by cation scavengers, but not by radical or electron scavengers. Elemental analysis and nuclear magnetic resonance (NMR) spectra show that the copolymer consists of almost equimolar monomer units and has two types of structure, head to tail and head to head or tail to tail. It has been concluded that copolymerization probably proceeds via a cationic mechanism to form an alternating copolymer.     

An alternating copolymer of maleimide and atropic acid with narrow molecular weight distribution prepared by radical mechanism

Three basic conditions for preparation of alternating copolymer with narrow molecular weight distribution were derived from the element kinetic equations of binary radical copolymerization. Using maleimide (MI) and atropie acid (ATA) as model monomer pairs and dioxane as the solvent the alternating copolymer with molecular weight distribution in the range of 1.09--1.20 was prepared successfully by charger transfer complex (CTC) mechanism in the presence of benzoyl peroxide at 85℃. The monomer reactivity ratioes r_1(MI)=0.05±0.01 and r_2(ATA)=0.03±0.02 were measured. The alternating eopolymerization was carried out through formation of a contact-type CTG and then alternating addition of MI and ATA monomers. The molecular weight of the copolymers is nearly independent of the feed ratio in a large range and the polymerization rate dropped with an increase in ATA in feed ratio.     

Copolymerization of methyl acrylate and vinyl acetate catalyzed by ethylaluminium chlorides

The copolymerization of vinyl acetate with methyl acrylate in the presence of Et₂AlCl, Et_1.5AlCl_1.5, and Et₂AlCl-benzoyl peroxide systems has been investigated. The influence of monomer ratios and organoaluminium compound concentration on the copolymer yield and composition have been determined and discussed. The monomer sequences distribution has been studied by means of ¹³C-NMR. It was found that organoaluminium compounds in the studied systems catalyze not only the alternating copolymerization, but also the homopropagation of both monomers. An alternating copolymer was obtained in reactions carried out at ?78°C, when a large excess of vinyl acetate was used in the monomer feed.     

Optimization of polymerization conditions of furan with aniline for variable conducting polymers

A high-throughput multiparameter optimization of chemical oxidative polymerization conditions has been developed for a facile synthesis of furan homopolymers and furan/aniline copolymers using a combinatorial method. The polymerization yield, molecular structure, and properties of the polymers would be optimized against typical polymerization parameters, including oxidant species, medium species, temperature, oxidant/monomer ratio, monomer concentration, dopant concentration, and furan/aniline comonomer ratio. The electrical conductivity, lead ion adsorptivity, chemical resistance, and thermal behavior of the polymers were also elaborated. It is found that only a combination of FeCl(3) and nitromethane as oxidant and medium, respectively, is appropriate for the furan homopolymerization. The homopolymerization yield increases consistently with an increase in the monomer concentration from 0.05 to 0.2 M and the FeCl(3)/furan molar ratio from 0.25 to 1.25. Although the as-prepared polyfuran exhibits very low conductivity, down to 10(-11) S cm(-1), the HCl- and HClO(4)-doped polyfurans possess much higher conductivities of 9.2 x 10(-8) and 2.38 x 10(-5) S cm(-1), respectively. In addition, the conductivity of the furan/aniline copolymer rises steadily with increasing aniline content, although the copolymerization yield shows a minimum at the furan/aniline molar ratio of 60/40, which is evidence of the occurrence of a real copolymerization between the furan and aniline monomers. The difficulty of synthesizing conducting polyfuran could be overcome to some extent by the polymerization in an appropriate condition optimized in this study. Particularly, the difficulty of synthesizing poly(furan-co-aniline) having much higher conductivity than the polyfuran would be largely conquered by chemical oxidative copolymerization of furan with aniline.     

Alternating copolymer of butadiene and ethylene. I. Copolymerization by TiCl4–R3Al catalyst systems

Alternating copolymerization of butadiene and ethylene was investigated by the TiCl₄?R₃Al system as catalyst with the use of toluene solutions of monomers of various compositions or by introducing a 1:1 gaseous mixture of both monomers into the reaction system. It was found that the copolymer composition is much influenced by the monomer composition or by the flow rate of monomer. Copolymers containing sequences of alternating monomer arrangement are formed by the polymerization of a monomer mixture having a butadiene: ethylene ratio of 4:1. A suitable catalyst for the alternating copolymerization was found to consist of R₃Al?TiCl₄ at a ratio of 2. The addition of amine was found to modify the catalyst to favor the alternating copolymerization but was accompanied by a decrease in catalyst activity.     

Anionic alternating copolymerization behavior of bifunctional six‐membered lactone and glycidyl phenyl ether

A copolymerization of 10‐methyl‐2H,8H‐benzo‐[1,2‐b:5,4‐b′]bipyran‐2,8‐dione ( 1 ) and glycidyl phenyl ether (GPE) was studied. 1 was a bislactone designed as a bifunctional analogue of 3,4‐dihydrocoumarin (DHCM), of which anionic 1:1 alternating copolymerization with GPE has been reported by us, previously. This alternating nature was inherited by the present copolymerization of 1 and GPE, leading to an intriguing copolymerization behavior in contrast to the ordinary statistical copolymerizations of monofunctional monomers and bifunctional monomers usually controlled by the proportional dependence of the crosslinking density on the monomer feed ratio: (1) When the feed ratio [GPE]₀/[ 1 ]₀ was 1, the two monomers underwent the 1:1 alternating copolymerization. In this case, 1 behaved as a monofunctional monomer, that is, only one of the two lactones in 1 participated in the copolymerization allowing the other lactone moiety to be introduced into the side chain almost quantitatively. (2) Increasing the feed ratio [GPE]₀/[1]₀ to larger than 4 allowed almost all of the lactone moieties to participate in the copolymerization system to give the corresponding networked polymers efficiently. The compositions of the copolymers [GPE unit]/[ 1 ‐derived acyclic ester unit] were always biased to smaller values than the feed ratios [GPE]₀/[lactone moiety in 1 ]₀ by the intrinsic 1:1 alternating nature of the copolymerization. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3662–3668, 2009     

Anionic copolymerization of p-anisaldehyde with dimethylketene

Anionic copolymerization of p-anisaldehyde (ANA) with dimethylketene (DMK) was made with use of benzophenone–dilithium complex as an initiator at ?78°C in a high vacuum. In spite of a copolymerization in such a good polar solvent as tetrahydrofuran, the composition of the copolymer was nearly exactly 1 : 1 over a quite wide range of the monomer feed. From the analytical data of the product after the hydrogenolysis of the copolymer with lithium aluminum hydride, the copolymer was found to have a structure resulting from the alternating addition of the C?O double bond of ANA to the C?C double bond of DMK. No copolymerizations of ANA with phenyl isocyanate and methyl isocyanate take place under the same conditions.     

Kinetic Study of Radical Polymerization VI. Copolymer Composition and Kinetic Parameters for Coplymerization of Styrene‐Itaconic Acid by On‐Line 1H‐NMR

Free radical solution copolymerization of styrene (St) and itaconic acid (IA) in dimethylsulfoxide‐d₆ (DMSO‐d₆) as the solvent and the use of 2,2′‐azobisisobutyronitrile (AIBN) as the initiator at 78°C was investigated by an on‐line ¹H‐NMR spectroscopy technique. Individual monomer conversion vs. reaction time, which was calculated from the ¹H‐NMR spectra data, was used to study the drift in monomer mixture composition vs. conversion. It was found that in general, both monomers were incorporated almost equally into the copolymer. However, when the mole fraction of IA was low, the tendency of IA toward incorporation into the copolymer chain was somewhat higher than St and by increasing the mole fraction of IA in the reaction mixture, the inverse tendency was observed. Overall monomer conversion as a function of time was calculated from individual monomer conversion data and used for the estimation of k_p /k_t ^0.5 for various monomer mixture compositions. This ratio was decreased with increasing the amount of IA in the initial feed, indicating a decrease in the rate of copolymerization. Changes in the copolymer composition vs. overall monomer conversion were investigated experimentally from the NMR spectra. This was in good agreement with the changes in monomer mixture composition vs. reaction progress. Plotting the copolymer composition vs. initial monomer feed showed tendency of the system toward alternating copolymerization.     

Alternating copolymerization of polar vinyl monomers in the presence of zinc chloride. I. Propagation and initiation of the copolymerization of acrylonitrile with styrene copolymer

Copolymerization of acrylonitrile with styrene spontaneously occurred on addition of zinc chloride without addition of any other radical initiator. The composition of the copolymer approached that of strictly alternating copolymer as zinc chloride added to the copolymerization system increased. The significance of the apparent monomer reactivity ratios of this copolymerization system was studied from a kinetic point of view, and it was shown that the monomer sequence distribution is indicated by the apparent monomer reactivity ratios. Further, equations which represent the relation between the apparent monomer reactivity ratios and Q,e values at a given salt concentration were derived. These equations reasonably accounted for the decrease of the apparent monomer reactivity ratios of the copolymerization of acrylonitrile with styrene in the presence of zinc chloride and the behavior of the other acrylonitrile copolymerization systems in the presence of zinc chloride. The initiation step of the spontaneous radical copolymerization of acrylonitrile with styrene in the presence of zinc chloride was explained by a cross-initiation mechanism.     

Activity of diallylamido-bis(diethylamido)guanidinium chloride in radical polymerization reactions

The activity of diallylamido-bis(diethylamido)guanidinium chloride in radical polymerization and copolymerization with vinyl monomers giving rise to random copolymers has been studied. A lower activity of diallylamido-bis(diethylamido)guanidinium chloride than that of vinyl monomers has been demonstrated. It has been shown that this monomer readily copolymerizes with sulfur dioxide and alternating copolymers of equimolar composition are formed regardless of the comonomer ratio in the initial mixture and the reaction conditions (the nature of solvent and initiator, temperature, and conversion). The structure of polymers has been studied by ¹³C NMR spectroscopy.     

DL－丙交酯与2－氢－2－氧－1，3，2－二氧磷杂环己烷的开环共聚合研究

在三异丁基铝催化下ＤＬ－丙交酯与２－氢－２－氧－１，３，２－二氧磷杂环己烷开环共聚，制备了一类新型水溶性共聚物Ｐ（ＬＡ－ｃｏ－ＴＭＰ）。用１ＨＮＭＲ、ＩＲ谱对其结构进行了表征，并研究了催化剂用量及不同单体配比对总转化率、共聚物组成及特性粘度的影响。     

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.     

N-丁基马来酰亚胺/苯乙烯微乳液共聚合研究

研究了氘代氯仿中Ｎ－丁基马来酰亚胺（ＮＢＭＩ）和苯乙烯（Ｓｔ）的络合性能。以十二烷基硫酸钠（ＳＤＳ）和正戊醇（ＰＴＬ）为复合乳化剂,配制了含有ＮＢＭＩ（Ｍ１）和Ｓｔ（Ｍ２）的Ｏ／Ｗ微乳液。用过硫酸钾引发该体系进行微乳液共聚合。固定乳化剂的浓度为〔ＳＤＳ〕＝０．２１ｍｏｌ／Ｌ,〔ＰＴＬ〕＝０．２８ｍｏｌ／Ｌ,详细研究了聚合温度、单体配比和引发剂用量对共聚合动力学的影响。用元素分析法确定共聚物的组成,     

一种新颖丙烯腈基含糖共聚物的合成和表征

利用无保护的糖内酯与甲基丙烯酸-2-氨乙基酯盐酸盐反应高效简便合成了一种新颖的直链糖,并用水相沉淀聚合的方法将其与丙烯腈进行了共聚合。考察了单体配比、聚合时间、引发剂浓度和总单体浓度对聚合行为的影响,红外、核磁用来表征聚合物,证明水相沉淀聚合是一种有效的聚合方式。     

One-shot block copolymerization

This paper describes a new method of the preparation of block copolymer, in which a mixture of two monomers is subjected to polymerization (simultaneous feeding) by the aid of an initiator. The new method is performed with the polymerization of a family of 2-oxazolines, which proceeds via electrophilic propagating species, cation or covalent bond having electrophilic reactivity. The key to the block copolymer formation with one-shot feeding of monomers is the difference of reactivity of polymerization (nucleophilicity) between the two monomers. First the monomer of higher reactivity is polymerized to completion, and then the monomer of decreased reactivity is polymerized starting from the propagating species of the first polymerization. For the high selectivity of the production of block copolymer, each of two propagations should be of “living mechanism”. Two combinations of monomers, i.e., 2-methyl-2-oxazoline/2-(heptafluoro-n-propyl)-2-oxazoline and 2-phenyl-2-oxazoline/2-(pentafluoroethyl)-2-oxazoline, together with an initiator of methyl tosylate were found to follow the pattern of the new process. Block copolymer of the former monomers' combination was water-soluble, and its aqueous solution showed an excellent value of surface tension.