Mechanism of Alternating Copolymerization of Vinyl Acetate and Maleic Anhydride

Vinyl acetate and maleic anhydride are known to give 1:1 alternating copolymerization regardless of the monomer feed composition. The existence of a charge transfer complex between the comonomers has been shown and its equilibrium constant determined.

The mechanism has been discussed, starting from a study of the copolymerization rate when varying the solvent, the temperature, and the concentration of comonomers.     

Quasi “Tacticity” of Rigidly Alternating Copolymers of Isobutyl Vinyl Ether and Maleic Anhydride

Since the copolymers of maleic anhydride, a cyclic monomer, and vinyl ethers, such as isobutyl vinyl ether, are made of rigidly alternating monomer unit sequences, quasi "isotactic" and quasi "syndiotactic" configurations for the monomer unit diads and triads are proposed considering the relative orientation of the cyclic anhydride group and the ether side chain with respect to the copolymer backbone.     

A Novel,Facile Method for the Preparation of Uniform,Reactive Maleic Anhydride/Vinyl Acetate Copolymer Micro‐ and Nanospheres

Summary: A novel, stabilizer‐free dispersion polymerization with alkyl esters as reaction media gives uniform alternating microspheres of maleic anhydride (MAn)/vinyl acetate (VAc) copolymer. The diameter of the copolymer microspheres could be precisely controlled from 80 to 750 nm by changing the monomer concentration or feed ratio. Moreover, this new type of copolymer microspheres with reactive anhydride groups on the surface has good solubility in common nontoxic solvents such as water and ethanol.

SEM image of the powder surface of copolymer microspheres formed at [MAn] = [VAc] = 1.5 M .     

马来酸酐—醋酸乙烯酯梳状聚合物单阳离子导体的制备及表征

马来酸酐－醋酸乙烯酯交替共聚物以聚乙二醇单醚醇解，得到带有不同长度的聚醚氧侧链的羧酸型梳状聚合物，其碱金属盐在加入适当增塑剂成膜后，可作为聚合物单阳离子导体，其结构以非晶态为主，具有较低的玻璃化转变温度及较好的热稳定性，增塑后的室温电导率最高可达１０－５Ｓ／ｃｍ．研究发现，适当增加侧链的长度有利于提高聚合物膜的离子电导率．此外，还详细探讨了增塑剂、阳离子半径、温度及外加频率等因素对电导率的影响．     

乙烯醇-醋酸乙烯嵌段共聚物的制备

采用混合溶剂醇解法制备嵌段聚乙烯醇，考察了混合溶剂甲醇／苯质量百分比，醇解催化剂碱的用量、醇解温度、时间等工艺条件对嵌段特性的影响。在优化条件下制备了嵌段特征为0.4-0.6，表面性能优良的两亲性嵌段聚乙烯醇。     

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.     

Modification of Maleic Anhydride Copolymers with Aliphatic Alkylamines and Sulfanilamide

Russian Journal of Applied Chemistry - Macromolecular amides were synthesized from copolymers of maleic anhydride with styrene or vinyl acetate and amines: ethylamine, propylamine, and...     

Donor-Acceptor Complexes in Copolymerization. LIX. Alternating Diene-Dienophile Copolymers. 13. Copolymerization of Dicyclopentadiene and Maleic Anhydride

The solution and bulk copolymerization of dicyclopentadiene (DCP) and maleic anhydride (MAH) occurs over the temperature range 80–240°C, upon the addition of a free-radical catalyst which has a short half-life at the reaction temperature. An unsaturated 1/1 MAH/DCP copolymer, derived from the copolymerization of MAH with the norbornene double bond, followed by a Wagner-Meerwein rearrangement, is obtained in the presence of a large excess of DCP at 80° C, while a saturated 2/1 MAH/ DCP copolymer, derived from the cyclocopolymerization of the residual cyclopentene unsaturation, is obtained at higher temperatures or in the presence of excess MAH. The copolymers prepared under other conditions with intermediate MAH/DCP mole ratios contain both 1/1 and 2/1 repeating units. The copolymer obtained from bulk copolymerization above 170° C contains units derived from cyclopentadiene-MAH cyclocopolymerization as well as DCP-MAH copolymerization.     

苯乙烯-马来酸酐共聚物的核磁共振分析

利用^1H NMR、^13C NMR及DEPT(无畸变极化转移增强)核磁共振技术研究了苯乙烯-马来酸酐共聚物(SMA)的序列结构和组成，并比较了几种核磁共振实验技术对分析SMA结果的准确性；实验表明^1H NMR是分析组成的简单、快速而有效的方法，DEPT谱进行序列结构计算准确度较高。     

Vinyl Acetate Copolymers in Die Pressing of Alumina

The studies on the application of the emulsions of poly(vinyl acetate-co-allyl ether)s containing nonionic hydrophilic poly(oxyethylene) fragments as binders in the die pressing of alumina is presented. It was found that introduction of hydrophilic fragments into molecules of a typical water dispersible polymer led to better polymer affinity to the ceramic powders. It was also shown that low molecular mass of such copolymers should be relatively low ca 1500 g mol^–1 to increase the density and thickening uniformity of the samples before and after sintering. The resultant sinters indicated exceptionally high mechanical strength (bending strength ca 500 MPa). This revised version was published online in August 2006 with corrections to the Cover Date.     

Copolymerization of 2,3-Dihydropyran and Ethyl Vinyl Ether with Maleic Anhydride

2,3-Dihydropyran (DHP) and ethyl vinyl ether (EVE) were co-polymerized with maleic anhydride (MA) with benzoyl peroxide at 60°C, and 1:1 alternating copolymers were obtained. The rates were maximum at 1:1 monomer composition. Spontaneous copolymerization and solvent effect on the rate were observed in the copolymerization of DHP with MA, in which initial rates were slower in more polar solvents. Participation of charge transfer complex was considered. EVE copolymerized rapidly with MA, reaching the theoretical limiting conversion of 1:1 alternating copolymerization. Although DHP-MA comonomer pair and EVE-MA comonomer pair formed similar 1:1 charge transfer complexes, DHP copolymerized slowly with MA to produce a low molecular weight copolymer, and the limiting conversion was much lower than the theoretical one. To explain these, degradative chain transfer to DHP monomer is proposed as the initial rate of DHP-MA copolymerization is proportional to the initiator concentration to the power 1.1. Q and e values of DHP were calculated to be 0.013 and -0.93, respectively, from the monomer reactivity ratios of copolymerization of DHP with acrylonitrile [r₁ (DHP)=0.003 ± 0.006 and r₂ (AN)=3.6 ± 0.3].     

Kinetic Investigations of Reactions with Maleic Anhydride Copolymers and Model Compounds

Alternating copolymers that contain maleic anhydride (MAn) as a component occur in two different stereochemical configurations which are differentiated by their reactivity. Model compounds, 2, 3-dialkylsuccinic acids and their anhydrides, were investigated and it was demonstrated that there is a distinct difference between threo and erythro configurations in their chemical and physical behavior. Both configurations also occur in the alternating copolymers. Beside the model compounds, the alternating copolymers ethylene-MAn, propylene-MAn, and styrene-MAn were investigated in their reactions with amines, alcohols, and water (hydrolysis). The cis configurations showed the higher reaction rates. Reactions of the anhydride moieties with equimolar amounts of aniline, ethanol, and water demonstrated that reactions follow second-order rate laws. With excess reactant, the reaction follows a pseudo-first-order rate law. The rate constants depend on the degree of polymerization and on the comonomer. Increasing steric hindrance and molecular weight lead to a decrease of the reaction rate. Catalysis of the hydrolysis reaction by tertiary amines results in similar rate constants for the configurations of the substituted succinic acid anhydrides. The reasons are discussed.     

Self-assembly of Amphiphilic Alternating Copolymers

Polymer self-assembly has been a hot research topic for several decades. Different types of polymers with various architectures, like block copolymers, brush polymers, hyperbranched polymers and dendrimers, etc., are currently being investigated. Alternating copolymers (ACPs) are regular copolymers with an alternating monomeric unit structure in the polymer backbones. However, despite the great progress in the synthesis of ACPs, their self-assembly is still in an infant stage. Very recently, our group reported a new type of amphiphilic ACPs through click copolymerization and obtained spheres, vesicles, nanotubes, and even hierarchical sea urchin-like aggregates through the self-assembly process. In addition, we have found some intriguing features in the self-assembly of amphiphilic ACPs when compared with other copolymers, including their facile syntheses, readily functionalization, novel self-assembly structures, new folding-chain mechanisms, and uniform but ultrathin feature length. In this Concept article, we present the self-assembly of amphiphilic ACPs together with their unique features by reviewing our latest results and related studies. Moreover, the future perspective on the self-assembly of amphiphilic ACPs is also proposed. Our aim is to capture the attention and interest of chemists in this new area of polymerization.     

Kinetic Features and Mechanism of Alternating Copolymerization of lndene with Maleic Anhydride

The radical copolymerization of indene (IN) with maleic anhydride (MA) was investigated. The charge-transfer complexes (CT complexes) between comonomers were studied by means of spectrophotometric measurements. It was found that the maximum copolymerization rate occurred at a comonomer feed ratio that did not correspond to the composition of the CT complex and the composition of copolymer. It was shown that rate maximum was displaced towards an excess of IN in the solvents with strong donicity. The Acceptor Number of solvent influences neither the initial rate nor the position of the rate maximum. Some kinetic calculations were made to assess values of the cross-propagation rate constants and to elucidate the mechanism of propagation of macromolecular chains.     

Acid-Catalyzed Methanolysis of Vinyl Acetate Polymers and Copolymers. I. Polyvinyl Acetate

Acid (HCL) catalyzed methanolysis of polyvinyl acetate and of model compounds was carried out in solvent mixtures with various amounts of methanol and tetrahydrofuran. The initial rate was first order vs methanol concentration. The acceleration was mainly dependent on the extension of the chain and was enhanced by a tighter coiling of the macromolecule; it is suggested that coiling favors the trapping of the catalyst ions.     

Organometallic‐Mediated Alternating Radical Copolymerization of tert‐Butyl‐2‐Trifluoromethacrylate with Vinyl Acetate and Synthesis of Block Copolymers Thereof

Organometallic‐mediated radical polymerization (OMRP) has given access to well‐defined poly(vinyl acetate‐alt‐tert‐butyl‐2‐trifluoromethacrylate)‐b‐poly(vinyl acetate) and poly(VAc‐alt‐MAF‐TBE) copolymers composed of two electronically distinct monomers: vinyl acetate (VAc, donor, D) and tert‐butyl‐2‐trifluoromethacrylate (MAF‐TBE, acceptor, A), with low dispersity (≤1.24) and molar masses up to 57 000 g mol⁻¹. These copolymers have a precise 1:1 alternating structure over a wide range of comonomer feed compositions. The reactivity ratios are determined as r _VAc = 0.01 ± 0.01 and r _MAF‐TBE = 0 at 40 °C. Remarkably, from a feed containing >50% molar VAc content, poly(VAc‐alt‐MAF‐TBE)‐b‐PVAc block copolymers are produced via a one‐pot synthesis. Such diblock copolymers exhibit two glass transition temperatures attributed to the alternating and homopolymer sequences. The OMRP of this fluorine‐containing alternating monomer system may provide access to a wide range of new polymer materials.

     

马来酸酐均聚反应机理的理论研究Ⅰ: 马来酸酐的基态和激发态电子结构

用AM1方法计算了马来酸酐的基态和激发态电子结构、电荷分布和键级。马来酸酐基态分子的HOMO和LUMO分别是双键C=C的成键π-MO和反键π*-MO。从微观电子结构层次探讨了马来酸酐在不同条件下的均聚反应机理。计算结果能很好地阐明实验事实。     

Donor-Acceptor Complexes in Copolymerization. XXXVI. Alternating Diene-Dienophile Copolymers. 4. Copolymerization of Furan and 2-Methylfuran with Maleic Anhydride

Abstract

The copolymerization of furan and 2-methylfuran with maleic anhydride in the presence of a radical catalyst yields equimolar, alternating copolymers in which the furan units have a 2,5-linkage (NMR and IR). The copolymerization appears to have a floor temperature of about 40°C. The furan-maleic anhydride Diels-Alder adduct polymerizes in solution in the presence of a radical catalyst at temperatures above 60°C to yield the identical copolymer as is obtained from the monomers. The adduct undergoes a retrograde reaction above 60°C to regenerate the monomers which then copolymerize through excitation of the ground state comonomer charge transfer complex.     

Covalent Immobilization of Subtilisin A onto Thin Films of Maleic Anhydride Copolymers

Enzymes cleaving the biopolymer adhesives of fouling organisms are attracting attention for the prevention of biofouling. We report a versatile and robust method to confine the serine protease Subtilisin A (or Subtilisin Carlsberg) to surfaces to be protected against biofouling. The approach consists of the covalent immobilization of the protease onto maleic anhydride copolymer thin film coatings. High‐swelling poly(ethylene‐alt‐maleic anhydride) (PEMA) copolymer layers permitted significantly higher enzyme loadings and activities than compact poly(octadecene‐alt‐maleic anhydride) (POMA) films. Substantial fractions of the immobilized, active enzyme layers were found to be conserved upon storage in deionized water for several hours. Ongoing studies explore the potentialities of the developed bioactive coatings to reduce the adhesion of various fouling organisms.

     

稀土催化异戊二烯—马来酸酐交替共聚

首次用 Nd( naph) 3 -Al Et3 催化体系合成异戊二烯 -马来酸酐交替共聚物 .实验结果表明 ,共聚反应适宜条件为 :[M]总 =2 .6mol/L( [Ip]/[MAn]=1 ) ,n( Al) /n( Nd) =1 0 ,[Nd]=5× 1 0 -3 mol/L,甲苯 /二氧六环混合溶剂 (体积比为 2 /5) ,于 5℃聚合 2 h.共聚物收率达到 70 % .用元素分析、 IR和 13 C NMR对共聚物进行表征 ,所得共聚物为交替结构