Sulfur-Containing Vinyl Monomers. XIX. Radical Polymerization of 2-Mercaptobenzothiazolyl Methacrylate

2-Mercaptobenzothiazolyl methacrylate (MBTM) was synthesized by the reaction of 2-mercaptobenzothiazole and methacrylyl chloride in tetrahydrofuran at -18°C. MBTM was found to polymerize in the presence of 2,2′-azobisisobutyronitrile (AIBN), n-BuLi, and UV light. From the kinetic studies of radical polymerization of MBTM with AIBN in benzene at 60°C, the overall activation energy was determined to be 18.9 kcal/mole, and the rate of polymerization (R) was expressed as R_p = k[AIBN]^0.5 [MBTM], where k is the overall polymerization rate constant. From these results this polymerization was confirmed to proceed via an ordinary radical mechanism. This monomer (M₂) was also copolymerized radically with styrene (M₁) at 60°C, and the resulting copolymerization parameters were determined as r₁ = 0.042, r₂ = 0.20, Q₂ = 4.09, and e₂ = 1.39. The thermal stability and the photodegradation behavior of the polymers were examined, and they were compared with those of the related polymers.     

Sulfur-Containing Vinyl Monomers. XV. Kinetic Study of Radical Polymerization of Vinyl Mercaptobenzothiazole and Its Copolymerization

A kinetic study of radical polymerization of vinyl mercaptobenzothiazole (VMBT) with α,α′-azobisisobutyonitrile (AIBN) at 60°C was carried out. The rate of polymerization (R_p) was found to be expressed by the rate equation: R_p = k[AIBN]^0.5 [VMBT]^1.0, indicating that the polymerization of this monomer proceeds via an ordinary radical mechanism. The apparent activation energy for overall polymerization was calculated to be 20.9 kcal/mole. Moreover, this monomer was copolymerized with methyl methacrylate, acrylonitrile, vinyl acetate, phenyl vinyl sulfide, maleic anhydride, and fumaronitrile at 60°C. From the results obtained, the copolymerization parameters were determined and discussed.     

Cyclodimerizations and Copolymerizations of Vinyl Ketones with Vinyl Monomers

Stable high-molecular-weight polyacetals can be prepared from formaldehyde or from its trimer trioxane.     

Metal-Containing Initiator Systems. IX. Radical Polymerizations of Vinyl Monomers by Various Metal Acetylacetonates

Abstract

A study of the polymerization of styrene, methyl methacrylate, acrylonitrile, vinyl acetate, and vinyl chloride initiated by various metal acetylacetonates [Me(acac)_x] has been made. It was found that Mn(acac)₃ was the most effective initiator, and Co(acac)₃, Mn(acac)₂, Cu(acac)₂, and Cr(acac)₃ showed moderate activity for the polymerization of methyl methacrylate at 60°C. However, the other, Me(acac)_x, had no effect or served as inhibitors. The addition of some additives such as halogen compounds did not accelerate polymerization of methyl methacrylate by Mn(acac)₃, From the results of polymerization and copolymerization of methyl methacrylate by Mn(acac)₃, it was concluded that the polymerization proceeded via an ordinary radical mechanism and the activation energy for initiation was 25.2 kcal/mole. The initiation mechanism of vinyl polymerization by Me(acac)_x was studied on the basis of the complex formation with the monomer.     

Radical Photopolymerization of Vinyl Monomers

Abstract

Photopolymerization is the initiation by light of a chain polymerization process. In the more general sense, photopolymerization implies the increase of molecular weight caused by light. Photopolymerization is not only useful for the detection and identification of photochemically produced free radicals; since photopolymerization reactions can be started or stopped at will by the simple expedient of turning on or off light, a means is provided for studying the nonsteady-state kinetics of polymerization [1]. Photopolymerization also allows for the subtle control of molecular weight and molecular weight distribution by varying the intensity of light. Photopolymerization can be confined to local regions since the light can be spatially controlled. Photopolymerization can be carried out at very low temperatures. Hence, chain-transfer processes leading to branched macromolecules will be absent. Photopolymerization at low temperature yields the low-energy stereospecific polymeric species, namely the syndiotactic configuration of the polymer [2]. Certain monomers can only be polymerized at low temperature, i.e., they have low ceiling temperatures; the photopolymerization offers this possibility [3]. Because photopolymerization need not be carried out at elevated temperatures, it has applications to biochemistry. One important application of the method is in disk electrophoresis [4]. Photopolymerization played an important role in the early development of polymer chemistry. One of the first procedures for polymerizing vinyl monomers was to expose the monomer to sunlight. Blyth and Hoffman [5] reported the polymerization of styrene by this method in 1845.     

QSPR Modeling of the Reactivity Parameters of Monomers in Radical Copolymerizations

For a series of monomers, QSPR test analysis is performed by optimizing the correlation weights of the local invariants of molecular graphs representing monomer structures in order to construct models of the reactivity parameters of monomers Q and e. This approach may be used as a tool in reactivity predictions for monomers for which no experimental data on Q and e are available.Original Russian Text Copyright © 2004 by A. A. Toropov, V. O. Kudyshkin, N. L. Voropaeva, I. N. Ruban, and S. Sh. Rashidova__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 994–998, November–December, 2004.     

乙烯基二联苯单体的螺旋选择性自由基聚合

为了深入理解乙烯基二联苯单体自由基聚合过程中的手性传递,进行了手性单体(+)-2-[(S)-异丁氧羰基-5-(4′-己氧基苯基)苯乙烯、非手性单体2-丁氧羰基-5-(4′-己氧基苯基)苯乙烯的均聚反应及它们二者的共聚反应,探讨了聚合温度和溶剂性质对手性单体均聚物旋光活性、手性单体含量对共聚物旋光活性以及聚合反应溶剂的超分子手性对共聚物旋光活性的影响.研究发现,降低聚合温度、采用液晶性反应介质有利于得到旋光度大的聚合物;少量手性单体的引入即可诱导共聚物形成某一方向占优的螺旋构象,比旋光度随手性单体的含量增加呈线性增长;在胆甾相液晶中制备的非手性单体聚合物不具有光学活性.这些结果表明,该类乙烯基二联苯聚合物具有动态螺旋构象,其光学活性主要依赖于主链的立构规整度和侧基不对称原子的手性.     

Microwave‐Assisted Free Radical Polymerizations and Copolymerizations of Styrene and Methyl Methacrylate

Summary: Radical homopolymerizations and copolymerizations of styrene were performed in toluene and N,N‐dimethylformamide (DMF) as solvents using different initiators with and without microwave irradiation. Only the homopolymerization of styrene under microwave irradiation in DMF with DtBP showed significantly enhanced styrene conversion whereas other initiators resulted in no or only slight increase of styrene conversion under microwave irradiation. In any case, DMF was required to gain in styrene conversion under microwave irradiation. Significantly higher monomer conversions were observed under otherwise comparable conditions in the copolymerization of styrene and methyl methacrylate (MMA) in DMF. Microwave‐induced selectivity of monomers was not observed in copolymerizations.

Yield of styrene polymerizations under varying reaction conditions initiated by DtBP.     

Radical Polymerization of Vinyl Monomers in Porous Organic Cages

The radical polymerization of vinyl monomers was performed in a tetrahedral imine‐linked organic cage with extrinsic porosity (CC3). Because of its dynamic and responsive packing structure, CC3 endowed the polymerization with specific behaviors. The adsorption of styrene triggered a change in the CC3 assembly, resulting in a monomer arrangement that was suitable for polymerization within the host matrix. The polymerization reaction was strongly dependent on the crystallinity of CC3 and was promoted by amorphization of the host in a cooperative manner, which is not possible with conventional rigid porous materials. Furthermore, CC3 can recognize the polarity of substrates, and thus polar monomers, such as methyl methacrylate and acrylonitrile, could not induce the structural changes in CC3 that are required for polymerization. This monomer specificity governed by the flexibility of CC3 is useful to the prevent incorporation of unfavorable monomers into the polymeric products.     

Conventional Radical and RAFT Alternating Copolymerizations of Hydroxyalkyl Vinyl Ethers and Dialkyl Maleates

The alternating copolymerization of hydroxyalkyl vinyl ethers and dialkyl maleates is investigated by conventional radical polymerization and reversible addition-fragmentation chain transfer polymerization(RAFT). The influence of comonomer structure, comonomer feeding ratios, and monomer concentrations on the copolymerization and the copolymer structure have been investigated systematically. With 2-hydroxyethyl vinyl ether(HEVE) and dimethyl maleates(DMM) as comonomers, a well-defined alternatin...     

氧气分子参与的乙烯基单体自由基聚合

尽管被公认在自由基聚合中往往起着缓聚、阻聚或链转移的作用,越来越多的结果表明,在某些情况下,如高温、高压,或当某些催化剂存在时,氧气分子(O2)可以参与甚至加速乙烯基单体的自由基聚合。本文综述了上世纪90年代以来,O2参与的乙烯基单体的热/光诱导自由基聚合、化学引发自由基聚合、氧载体催化自由基聚合以及可逆加成-断裂链转移自由基聚合。以上结果表明,在上述情况下,O2,作为一个普通不饱和单体,可以与苯乙烯、甲基丙烯酸甲酯等乙烯基单体形成交替共聚物(聚过氧化物),而此类聚过氧化物均可裂解为自由基。     

Free Radical Grafting of Polyethylene with Vinyl Monomers by Reactive Extrusion

The free radical grafting of polyethylene with vinyl monomers by reactive extrusion was studied numerically. Numerical computation expressions of key variables, such as the concentrations of the initiator and polymer, grafting degree, average molecular weight and apparent viscosity, were deduced. The evolutions of the above variables were predicted by means of an uncoupled semi‐implicit iterative algorithm. The monomer conversion monotonically increases with decreasing throughput or increasing initial initiator concentration; with increasing barrel temperature, the monomer conversion first increases then decreases. The simulated results are nearly in good agreement with the experimental results.

     

Preparations and Polymerizations of p-Substituted Phenyl Vinyl Sulfides. Vinyl Polymerization 168

Abstract

p-Substituted phenyl vinyl sulfides (PVS) were prepared and their radical polymerizations were investigated dilatometrically to determine some kinetic constants and to deduce the influences of the sulfur atom and p-substituents of PVS. It was found that PVS could be easily homopolymerized by ordinary radical polymerization mechanisms in the presence of 2,2′-azobisisobutyronitrile, contrary to the case of phenyl vinyl ethers, which do not homopolymerize.

From the rates of polymerization (R_p H) of PVS and those of p-substituted PVS (R_p X) under the same conditions, the plot of log (R_p H/R_p X) against the Hammett's equation was found to give a parabola curve. When these results were plotted by the modified Hammett's equation [log (k_p X/k_p H) = ρσ + γE_R ], however, a straight line with γ = ?4.5 and ρ = 0.35 was obtained. From these results it was concluded that the 3d orbital resonance was important in the transition state of the polymerization of these monomers.     

Vinyl Polymerization 204. Initiation Mechanism of the Radical Polymerization of Vinyl Monomers by p-Methoxy -p'-nitrobenzoyl Peroxide and Tertiary Amines

Abstract

A study of the reaction of tertiary amines with p-methoxy-p'-nitrobenzoyl peroxide in the presence of styrene was made in benzene. Anisic acid and p-nitrobenzoic acid were obtained from the reaction product. Using gas chromatography, the molar ratio of the amount of the above two acids was measured and classified into three types, according to the kind of amine used. From the results the reaction mechanism was discussed, and it was concluded that the oxygen which stands adjacent to the p-methoxybenzoyl group may be charged more positively and may be the more predominantly attacked by tertiary amine.     

多官能团乙烯基单体原子转移自由基交联聚合机理

乙烯基单体;原子转移自由基交联聚合;聚合机理;交联网络     

Free Radical Copolymerizations of N-Arylmaleimides

The free radical copolymerization of methyl acrylate (MA) with N-phenylmaleimide (NPMI) and N-p-tolylmaleimide (NPTMI) at 75° C in cyclohexanone solution initiated by AZBN was studied. The copolymer composition has been calculated from the nitrogen content estimated by the micro-Kjeldahl's method and by NMR spectral studies. The reactivity ratios have been calculated by Mayo and Lewis, Fineman and Ross, Glen and Tüdös, and Joshi and Joshi methods. Q and e values of NPMI and NPTMI were also calculated. Since the reactivity ratios are the measure of distribution of monomer units in a copolymer chain, the values obtained are compared and discussed.     

Radical Copolymerization of Allyl and Vinyl Monomers Derived from 1,4-Benzoquinone with Acrylic Acid

Radical copolymerization of allyl and vinyl redox monomers derived from 1,4-benzoquinone with acrylic acid in dimethylformamide was studied.     

Vinyl polymerization. 178. Copolymerizations of p-substituted phenyl vinyl sulfides

The copolymerizations of p-substituted phenyl vinyl sulfides (M₂) having OCH₃, CH₃, H, Cl, and Br substituents with styrene and methyl methacrylate (M₁) and their intercopolymerizations at 60°C. were studied. From the results of copolymerizations with styrene and methyl methacrylate, the monomer reactivity ratios and the Q₂e₂ values were determined. For example, the Q and e values for unsubstituted phenyl vinyl sulfide were 0.45 and ?1.26 in the copolymerization with methyl methacrylate. This result indicated the importance of the 3d orbital resonance between the sulfur atom and the adjacent carbon atom in the transition state of copolymerizations. The relative reactivities of these monomers toward the polymer radicals were found to be correlated with the Hammett σ constants of the substituents. In the intercopolymerizations of these monomers, it was also found that the relative reactivities followed the Hammett equation approximately.     

Anionic Polymerizations and Copolymerizations of Methacrylates-Reactivity of Monomer and Tacticity of Polymer

The anionic polymerizations and copolymerizations of methacrylates were investigated. The studies were focused on the stereoregularity of the polymers and the relative reactivity of the monomers in relation to the stereospecificity of polymerization.