Polymerization and copolymerization in associated monomer aggregates

The polymerization of acrylic acid in bulk is controlled by linear plurimolecular H-bonded aggregates of the monomer which lead to the formation of a syndiotactic polymer. Polar solvents do not dissociate these aggregates unless high dilutions are reached. In contrast, “normal” kinetics are observed in the presence of 10–20 per cent toluene, n-hexane or chloroform. The polymerization of methacrylic acid is not affected to the same extent by molecular aggregates. In the copolymerization of acrylic acid with methyl acrylate or acrylonitrile, the reactivity ratios are altered by solvents. The acrylic acid content is higher in copolymers formed in bulk than in toluene solution. But similar effects are observed in the presence of DMF which does not dissociate the aggregates of acrylic acid; moreover, copolymerization data obtained with methacrylic acid indicate that other factors may be involved in determining reactivity ratios.Acrylamide also forms H-bonded aggregates and its copolymerization behaviour is strongly affected by solvents. No simple correlation holds, however, between reactivity ratios and extent of association.A very strict control of chain propagation occurs when 4-vinylpyridine is polymerized in the presence of polycarboxylic acids. A considerable rate increase was observed when vinylpyridine was grafted into polytetrafluoroethylene films which contained poly(acrylic acid) branches. This effect is explained by assuming that the pyridine groups form strong associations with the carboxylic sites, thereby providing a very favourable orientation of the vinyl groups for chain propagation.     

两种双亲性聚合物自组装胶束复合水溶液的乳化性能

以苯乙烯(St)、含香豆素光敏单体(VM)、丙烯酸(AA)为单体,偶氮二异丁腈(AIBN)为引发剂引发自由基共聚,合成了双亲性光敏无规共聚物P(St-co-VM-co-AA)(简称PSVA);又以St及甲基丙烯酸二甲胺乙酯(DMAEMA)为单体,AIBN为引发剂引发自由基共聚,制得二元双亲性无规共聚物P(St-co-D...     

Copolymerization of vinyl acetate and unsaturated acids in the presence of germanium tetrachloride in methanol

The influence of catalytic amounts of germanium tetrachloride on the copolymerization of vinyl acetate with acrylic acid and methacrylic acid in methanol is examined. It is shown that germanium tetrachloride exerts different effects on the formation rate, molecular-mass characteristics, and composition of copolymers formed in these systems. For example, at a germanium tetrachloride-to-acrylic acid ratio of 0.02 (mol/mol), an alternating copolymer is formed, whereas in the case of methacrylic acid, a copolymer considerably enriched with methacrylic acid units is produced at the same ratio. The results are explained by different copolymerization mechanisms for both systems.     

Composition equation for matrix copolymerization

A mechanism of matrix copolymerization in which a monomer (or macroradical) is complexed by matrix was considered. For this case a composition equation was formulated. It was shown that in general case reactivity ratios are dependent on the matrix concentration. The influence of the critical length of a complexed radical on the process of copolymerization is also discussed. A series of copolymerizations of methacrylic acid and styrene were carried out using various compositions of initial monomer mixtures. The process was performed in benzene in the presence of poly(ethylene glycol) as a matrix. The copolymerization were carried out at various ratios of the monomer being complexed (methacrylic acid) to the matrix. Compositions of the complexes prepared were determined by the NMR method. Reactivity coefficients for both monomers were found and the results are discussed on the basis of the derived equation.     

Novel temperature‐responsive water‐soluble copolymers based on 2‐hydroxyethylacrylate and vinyl butyl ether and their interactions with poly(carboxylic acids)

Novel water‐soluble amphiphilic copolymers have been synthesized by free radical copolymerization of 2‐hydroxyethylacrylate with vinyl butyl ether. In water these copolymers exhibit lower critical solution temperature, which depends on the content of hydrophobic vinyl butyl ether units. The interaction between these copolymers and poly(acrylic acid) or poly(methacrylic acid) in aqueous solutions results in formation of interpolymer complexes stabilized by hydrogen bonds and hydrophobic interactions. An increase in hydrophobicity of the copolymers leads to the enhancement of their complex formation ability with respect to poly(acrylic acid) and poly(methacrylic acid). Poly(methacrylic acid) forms stronger complexes with the copolymers when compared with poly(acrylic acid). The complexes exhibit dual sensitivity to pH‐ and temperature and this property may be easily adjusted regulating the strength of interaction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 195–204, 2006     

Effect of introducing acrylic and methacrylic acid groups on molecular relaxation of poly(ethyl methacrylate)

Dielectric and infrared data have been obtained over a wide temperature range on copolymers of ethyl methacrylate with methacrylic and acrylic acid synthesized by radical copolymerization. The dissociation energy ΔH⁰ for the acid dimer in the copolymer is estimated from the temperature dependence of the relaxation strength Δε_α of the α relaxation, which is associated with the glass transition. The value of δH⁰ obtained by this method is in fair agreement with that determined by infrared (IR) spectroscopy. The strength of the α relaxation and its activation energy are both increased by the incorporation of methacrylic acid units but are decreased by acrylic acid units. This behavior is attributed to the restriction of main-chain motions by hydrogen-bonded acid dimers in the copolymers with methacrylic acid and to the incorporation of more flexible links in the copolymers with acrylic acid. The β relaxation observed below the glass transition temperatures is almost unaffected by the incorporation of methacrylic acid.     

三唑酮分子印迹预组装体系的分子模拟与吸附性能

以三唑酮为模板分子, 以丙烯酰胺(AM)、 丙烯酸(AA)、 甲基丙烯酸(MAA)和三氟甲基丙烯酸(TFMAA)为功能单体预组装了分子印迹聚合物体系, 采用半经验法和从头算法, 利用Hyperchem软件模拟了三唑酮与4种功能单体所组成的分子印迹预组装体系的构型、 能量、 反应配比及复合反应的结合能, 选择复合物结合能最高的功能单体用于分子印迹聚合物的合成. 采用密度泛函方法计算了模板与单体在不同致孔剂中的溶剂化能. 结果表明, 三唑酮与三氟甲基丙烯酸所形成复合物的作用力最强, 在非极性溶剂中溶剂化能最弱. 由预组装体系的差示紫外光谱法研究发现, 一分子三唑酮可与两分子三氟甲基丙烯酸在氯仿中形成氢键复合物, 与分子模拟的结果一致. 在最佳模拟条件下, 合成了三唑酮的印迹聚合物, 利用吸附等温线Langmuir和Freundlich模型研究了印迹聚合物的吸附行为及识别机理. 上述方法对于分子印迹体系的筛选及分子印迹聚合物性能的预测有重要的意义.     

Radiation-initiated emulsion copolymerization of styrene and carboxylic acid monomers

The emulsion Copolymerization of styrene and carboxylic acid monomers such as acrylic, methacrylic, and itaconic acids (AAc, MAAc, IAc) was studied by using ⁶⁰Co γ-rays as initiator and sodium do-decylsulfate as emulsifier. The polymerization behavior of these acid monomers was followed by simultaneous conductometric and potentiometric titrations for a latex sample taken in polymerization. The polymerization rate of these acid monomers increases in the following order of hydrophobicity: IAc < AAc < MAAc; this suggests that their polymerization sites are mainly the surface and/or subsurface regions of latex particles. The copolymerization rate of styrene and acid monomer increases with an increase in the acid monomer content for AAc and MAAc, whereas for IAc the rate decreases. The particle sizes determined by the stopped-flow method reveal that this variation of copolymerization rate cannot be explained by the number of growing particles and should be attributed to another factor; for instance, the transfer rate of styrene molecules from oil droplets to growing particles.     

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.     

Surface modification of polyamide-6: graft copolymerization of vinyl monomers onto polyamide-6 and thermal analysis of the graft copolymers

Graft copolymerization of vinyl monomers onto polyamide-6 using radical initiation has been investigated. Two monomers were used: methacrylic acid and acrylic acid. The initiators selected included hydrogen peroxide, benzoyl peroxide and azobisisobutyronitrile. The extent of graft copolymerization depends on the concentrations and identity of the initiator and monomer and the time and temperature of the reaction. The graft copolymers were not soluble in solvents that will dissolve the starting material; definitive proof for the formation of the graft copolymers was obtained from infrared spectroscopy. Thermogravimetric analysis was performed on the graft copolymers and it was found that the presence of the acid invariably accelerated the degradation of the polyamide. © 1998 John Wiley & Sons, Ltd.     

Alkali salts of (ω-sulphoxyalkyl)-acrylates and -methacrylates: Radical polymerization and copolymerization

A new preparation of alkali salts of (ω-sulphoxyalkyl)-acrylates and -methacrylates, by reaction of alkali salts of acrylic and methacrylic acids with cyclic sulphates, is described; spectral characterization of the products is described. The kinetics of the radical polymerization of sodium (2-sulphoxyethyl)methacrylate (SSEM) were studied; monomer reactivity ratios for copolymerization with methacrylic acid were: r₁ = 1.1 ± 0.15 and r₂ = 0.73 ± 0.05. Dark electrical surface conductivity of some homopolymers and copolymers with methacrylic acid was found to be 10⁴–10¹¹$\text{Ω}{}^{\mathrm{?1}}$, depending on relative humidity.     

Frontal Polymerization of Deep Eutectic Solvents Composed of Acrylic and Methacrylic Acids

Frontal polymerization of deep eutectic solvents (DESs) made with acrylic or methacrylic acid as the monomer and hydrogen bond donor was studied. Fronts with acrylic acid and choline chloride propagated more uniformly than with pure acrylic acid, so an exploration into how the DES affected frontal polymerization was performed. The hydrogen bond acceptor of the DES was replaced by several analogs to determine the effect on the DES front behavior. The analogs used were talc, DMSO, lauric acid, and stearic acid, which acted as a heat sink, inert diluent, hydrogen bonding diluent, and inert phase change material, respectively. None of the methacrylic acid‐analog systems were able to sustain a front. While the acrylic acid‐analog systems did sustain a front (with the exception of stearic acid), none of the fronts replicated the acrylic acid DES behavior. The acrylic acid–talc sample behaved more violently—like pure acrylic acid polymerization—than the acrylic acid DES, and the DMSO and lauric acid samples produced slower fronts than that of the acrylic acid DES. We propose that the reactivity of the acrylic acid and methacrylic acid is enhanced in the DES. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 4046–4050     

Functional polymers. II. Preparation and polymerization of methyl 5-vinylsalicylate,methyl 5-vinylacetylsalicylate, 5-vinylsalicylic acid,and 5-vinylacetylsalicylic acid

Four new derivatives of 5-vinylsalicylic acid were prepared and their homopolymerization and copolymerization with acrylic acid and methacrylic acid investigated. Methyl 5-vinylsalicylate was prepared in a six-step synthesis from methyl salicylate in an overall yield of 35%. Acetylation in the last step yielded methyl 5-vinylacetylsalicylate. Hydrolysis of methyl 5-vinylsalicylate gave 5-vinylsalicylic acid which was acetylated to 5-vinylacetylsalicylic acid (5-vinyl aspirin). The 5-vinyl-substituted salicylic acid derivatives could be readily homopolymerized and copolymerized with acrylic acid and methacrylic acid to give various compositions of copolymers. It is worth noting that even the monomers with free phenol groups could be readily polymerized with azobisisobutyronitrile as radical initiator to high molecular weight polymers without interference of the phenolic OH group.     

Influence des associations moleculaires sur la copolymerisation de l'acide acrylique avec l'acide methacrylique et avec l'acrylate de methyle

The copolymerization of acrylic acid with methacrylic acid in bulk is investigated at 40 and 60°. It is confirmed that a “matrix effect” occurs only for high contents of acrylic acid. The critical concentration beyond which the matrix effect disappears is shifted towards lower acrylic acid contents for higher temperatures. The copolymer composition is independent of temperature. The copolymerization of acrylic acid with methyl acrylate is investigated in a mixture which determines an “exaltation of the matrix effect” in the homopolymerization of acrylic acid (molar fractions: m_Monomers = 0.34; m_n-Hexane = 0.52; m_Methanol = 0.14). The resulting copolymers are found to contain a much larger fraction of acrylic acid residues than the copolymers formed in bulk or in toluene or DMF solutions.     

二乙基二烯丙基氯化铵与丙烯酰胺、丙烯酸共聚竞聚率

二乙基二烯丙基氯化铵;丙烯酰胺;丙烯酸;共聚合;竞聚率     

Membranes permselectives obtenues par greffage radiochimique des acides acrylique et methacrylique sur des films de poly(chlorure de vinyle)

Membranes were prepared by subjecting to gamma-rays PVC films swollen in a mixture of acrylic acid and methylene chloride. The kinetics of the reaction were investigated as a function of monomer concentration, temperature and dose-rate. The swelling properties of the resulting membranes were studied as well as those of PVC films grafted with methacrylic acid. It was found that PVC films grafted with methacrylic acid only swell slightly in water even for high grafting ratios and the swelling is very slow. At elevated temperatures the films swell more quickly and reach a higher limiting swelling, but the effect is small. PVC films grafted with acrylic acid swell much more quickly and reach much higher swelling ratios. The extent of swelling markedly increases with temperature but this effect is not reversible: once the membranes have reached a high swelling ratio at elevated temperatures, they keep the same ratio when dipped in water at 20°. The Arrhenius plot of the swelling ratio exhibits a break at 50–60° apparently corresponding to a glass transition temperature. In methanol the swelling is significantly higher for PVC films grafted with methacrylic than with acrylic acid. Swelling of the membranes was also investigated in mixtures of water with methanol and methanol with methylene chloride. The results are interpreted by assuming a strong dipole-dipole interaction between the grafted branches and the trunk polymer resulting in a quasimolecular dispersion of the carboxylic chains in the PVC matrix. The latter acts as a barrier against the penetration of water. Heat treatment favours a segregation of the two polymeric species into microphases and this non-reversible transformation is assumed to be responsible for the unexpected behaviour of PVC films grafted with acrylic acid. The significant differences between the properties of PVC films grafted with either acrylic or methacrylic acid are attributed to the much higher hydrophobic character of the methacrylic chains.     

Formation of Nonspherical Particles with Uneven Surface in Emulsion Copolymerization of Styrene and Methacrylic Acid with Nonionic Emulsifier

Summary: Emulsion copolymerization of styrene and methacrylic acid with nonionic emulsifier and potassium persulfate as initiator gave nonspherical copolymer particles having uneven surface. The formation was based on the coagulation of byproduct nano-sized (ca. 35 nm) particles, which were formed throughout the copolymerization until monomer phase disappeared, onto main submicron-sized (234 ∼ 445 nm) particles.     

Study on soap‐free P(MMA‐EA‐AA or MAA) latex particles with narrow size distribution

Soap‐free poly(methyl methacrylate‐ethyl acrylate‐acrylic acid or methacrylic acid) [P(MMA‐EA‐AA or MAA)] particles with narrow size distribution were synthesized by seeded emulsion polymerization of methyl methacrylate (MMA), ethyl acrylate (EA) and acrylic acid (AA) or methacrylic acid (MAA), and the influences of the mass ratio of core/shell monomers used in the two stages of polymerization ([C/S]_w) and initiator amount on polymerization, particle size and its distribution were investigated by using different monomer addition modes. Results showed that when the batch swelling method was used, the monomer conversion was more than 96.0% and particle size distribution was narrow, and the particle size increased first and then remained almost unchanged at around 600 nm with the [C/S]_w decreased. When the drop‐wise addition method was used, the monomer conversion decreased slightly with [C/S]_w decreased, and large particles more than 750 nm in diameter can be obtained; with the initiator amount increased, the particle size decreased and the monomer conversion had a trend to increase; the particle size distribution was broader and the number of new particles was more in the AA system than in the MAA system; but the AA system was more stable than the MAA system at both low and high initiator amount. Copyright © 2006 John Wiley & Sons, Ltd.     

Investigation of the radical copolymerization and terpolymerization of maleic anhydride and norbornenes by an in situ 1H NMR analysis of kinetics and by the mercury method: Evidence for the lack of charge‐transfer‐complex propagation

The radical copolymerization of electron‐deficient maleic anhydride (MA) and electron‐rich norbornene (NB) derivatives with 2,2′‐azobis(isobutyronitrile) (AIBN) in dioxane‐d₈ has been monitored in situ by ¹H NMR spectroscopy with free induction decays recorded every 30 min at 60, 70, or 84 °C. The ratios of the monomer pairs were varied in some cases. The NB derivatives employed in this study included bicyclo[2.2.1]hept‐2‐ene (NB), t‐butyl 5‐norbornene‐2‐carboxylate, methyl 5‐norbornene‐2‐methyl‐2‐carboxylate, and ethyl tetracyclo[4.4.0.1^2,5.1^7,10]dodec‐3‐ene‐8‐carboxylate. Decomposition of AIBN, consumption of the monomers, feed ratios, endo/exo ratios, copolymer compositions, and copolymer yields were studied as a function of polymerization time. Furthermore, a homopolymerizable third monomer (t‐butyl methacrylate, methacrylic acid, t‐butyl acrylate, or acrylic acid) was added to the NB/MA 1/1 system, revealing that the methacrylic monomer polymerizes rapidly in the early stage and that the ratio of MA to NB in the terpolymer strongly deviates from 1/1. In contrast, however, the acrylic monomers are more uniformly incorporated into the polymer. Nevertheless, these studies indicate that MA and NB do not always behave as a pair in radical polymerization and disproves the commonly believed charge‐transfer mechanism. Electron‐deficient fumaronitrile was also included in the kinetics study. To further understand the copolymerization mechanism, MA and NB were competitively reacted with a cyclohexyl radical generated by the treatment of cyclohexylmercuric chloride with sodium borohydride (mercury method). A gas chromatographic analysis of the reaction mixtures has revealed that a cyclohexyl radical reacts with MA almost exclusively in competition and that the cyclohexyl adduct of MA essentially accounts for all the products in a mass balance experiment, eliminating a possibility of the formation of an adduct involving the MA–NB charge‐transfer complex. Thus, the participation of a charge‐transfer complex in the copolymerization of MA and NB cannot be important. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3521–3542, 2000     

Controlled radical (co)polymerization of (meth)acrylic esters via the reversible addition-fragmentation chain-transfer mechanism

The homopolymerization of acrylic and fluoroacrylic esters mediated by benzyl dithiobenzoate and dibenzyl trithiocarbonate proceeds in the controlled mode via the reversible addition-fragmentation chain-transfer mechanism, while the controlled radical polymerization of methacrylic esters is not effected under these conditions. The molecular-mass characteristics of the copolymers of acrylic and methacrylic esters may be satisfactorily controlled by benzyl dithiobenzoate-mediated copolymerization when the content of acrylic esters is no less than 50 mol %. If a reversible addition-fragmentation chain-transfer agent active with respect to only one of the monomers is used, compositionally homogeneous narrowly dispersed copolymers are formed via the azeotropic copolymerization of the monomers up to high conversions. The controlled copolymerization of N-vinylpyrrolidone and fluoroacrylates allows the synthesis of alternating narrowly dispersed amphiphilic copolymers with properties different from those of alternating copolymers with a broad molecular-mass distribution.