The competitive reactions of initiator fragments and growing polymer chains against the surface of carbon black

The reactivity of free radicals generated by the thermal decomposition of 2,2′-azobisisobutyronitrile (AIBN) is compared with that of the free radicals from 2,2′-azobis-2,4-dimethyl valeronitrile in nitrogen atmosphere at 60°C, and the reaction mode of the free radicals with carbon black surface is discussed. Also bulk polymerization of vinyl monomers such as styrene and methyl methacrylate was performed in the presence of furnace black in nitrogen at 60°C using AIBN as initiator. Typical retardation is found in the course of conversion of methyl methacrylate into the polymer, whereas inhibition is observed in the conversion of styrene which results in an induction period of the reaction. In addition, inhibition by carbon black is also found in the copolymerization of methyl methacrylate with a small amount of styrene. On the basis of the results of the conversions of different kinds of monomers, competitive reactions of 2-cyano-2-propyl radicals from AIBN and growing polymer radicals are suggested to occur preferentially on the surface of carbon black. The results are supported by the observation of the stability of the dispersion of the resulting carbon black in adequate solvents and also by gas chromatographic analysis of the pyrolysis products of the polymers bound to the surface of carbon black.     

甲基丙烯酸甲酯-苯乙烯共聚物的悬浮聚合工艺

采用无机／有机三元复合分散体系进行了甲基丙烯酸甲酯与苯乙烯悬浮聚合的研究。对影响共聚物珠粒形成的因素进行了考察，得到了合成共聚物的优化工艺条件。用博立叶红外光谱（FT-IR）方法表征了珠状共聚物的结构，并用热分析仪考察了共聚物的热性能。结果表明，在以有机蒙脱土为分散剂的优化工艺条件下，合成的甲基丙烯酸甲酯／苯乙烯共聚物的热性能有明显提高。     

Phase separation of some clear polyblends

By using variations of elution and precipitation techniques, a clear ABS resin is found to be a mixture of a styrene–butadiene rubbery copolymer, a methyl methacrylate–styrene–acrylonitrile copolymer, and a graft of the methyl methacrylate–styrene–acrylonitrile copolymer onto the styrene–butadiene rubber. A clear impact acrylic is separated into a methyl methacrylate–styrene–acrylonitrile copolymer and a methyl methacrylate–butadiene rubbery copolymer. Photomicrographs indicate that clarity in the clear ABS and impact acrylic is achieved by matching refractive indices of the continuous and dispersed polymer phases.     

PAS、PASM共聚物的合成及流变性

以丙烯腈,苯乙烯和甲基丙烯酸甲酯为原料,经乳液聚合合成丙烯腈－苯乙烯二元共聚物、丙烯腈－苯乙烯－甲基丙烯酸甲酯三元共聚物。研究了ＰＡＳ、ＰＡＳＭ的组成与流变性能和粘流活化能的关系。     

Use of poly(styrene)-block-poly(ethyleneoxide) as emulsifier in emulsion polymerization

Summary Poly(styrene)-block-poly(ethyleneoxide), abbreviated as (PS-b-PEO) were used as emulsifiers in emulsion polymerization of styrene and methyl methacrylate. The block copolymers had a poly(styrene) block with M_n=1000 g/mol and a poly(ethyleneoxide) block with M_n=1000, 3000 or 5000 g/mol, respectively. Stable dispersions were obtained when the PEO block molecular weight was higher than 1000 g/mol. Also the amphiphilic properties of the copolymers depended on the PEO chain length. Block copolymer micelles with hydrodynamic radii between 11 and 17nm were observed. Emulsion polymerization was performed at different block copolymer concentration at 60 and 80°C. Particle size varied between 50 and 300nm and decreased with increasing copolymer concentration. The particle size was larger at higher temperature, but the size distribution was narrower. Polymerization of methyl methacrylate gave smaller particles when compared to styrene. The dispersions were very stable towards high electrolyte concentration, but flocculation occurred at elevated temperatures. Both observations indicate that the dispersions are sterically stabilized.     

悬浮接枝共聚合成POE-g-MAS及其表征

用悬浮接枝法合成了乙烯-辛烯共聚物（POE）和甲基丙烯酸甲酯（MMA）-丙烯腈（AN）-苯乙烯（St）的接枝共聚物（POE-g-MAS）。研究了单体比率、POE／单体的比率、引发剂浓度和反应时间等因素对接枝共聚合反应的影响。从聚合产物中用丙酮抽提得到接枝共聚物POE-g-MAS,并用傅立叶变换红外光谱（FTIR）和差示扫描量热法（DSC）对POE-g-MAS进行了分析。实验证明MMA-AN-St已经接枝在POE分子链上。接枝链MAS在一定程度上影响了POE的结晶相,降低了POE的熔融温度和熔融热。     

Mechanochemical copolymerization of methyl methacrylate and styrene initiated by the grinding of quartz

The copolymerization of methyl methacrylate and styrene mechanochemically initiated by the grinding of quartz in the monomer mixture was investigated by using a vibrating ball mill. The effect of the grinding of quartz on the copolymerization was investigated by characterizing both the polymer formed and the ground quartz. The copolymerization proceeds apparently from the quartz grindings and was closely related to the total surface area of the ground quartz. The molecular weight distributions of the copolymers formed were unimodal as found in a homopolymer of only methyl methacrylate. It was clear from the composition analysis of the copolymer that the mechanochemical copolymerization of methyl methacrylate and styrene proceeded with a radical polymerization mechanism because of radicals on the quartz surface produced by the grinding. The monomer reactivity ratios obtained by the Fineman‐Ross method suggested that the copolymers formed were alternating copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2011–2017, 2002; DOI 10.1002/app.10544     

Enthalpy relaxation of filled copolymers

Excess enthalpy following annealing at various periods of time at T_g ?10°C was measured by differential scanning calorimetry of electrophotographic toners, copolymers of styrene and butyl methacrylate containing carbon black. An approximate equilibrium enthalpy relaxation after annealing the pure copolymers for one month was 3.30 kJ/kg for a copolymer with 66.5% styrene and 2.72 kJ/kg for a copolymer containing 49.8% styrene. The rate of enthalpy relaxation was reduced by increasing the styrene content of the pure copolymer. The incorporation of a carbon black with high surface area reduces the rate of enthalpy relaxation, increasing in effectiveness with butyl methacrylate concentration.     

四官能度过氧化物JWEB50引发的PS-b-PMMA合成与表征

引言嵌段共聚物是具有两种或两种以上不同链段的聚合物,不同链段间存在的化学键限制了聚合物的相分离程度,易形成微相分离结构[1],而嵌段共聚物能作为聚合物共混体系的相容剂,只需加入少量     

Multiblock copolymers by polymeric initiators via free radical mechanism

Polymeric peroxycarbamate initiators containing polyazoester or polyethylene adipate blocks were synthesized. They can be used to prepare multiblock copolymers by radical polymerization in a procedure involving several steps. Bulk and solution polymerizations are suitable techniques in these steps. The polymerization of styrene with these initiators was investigated over a wide range of conversion. Longer polymerization times led to an expected decrease in peroxygen contents of the active polystyrenes. Styrene/methyl methacrylate/n-butyl methacrylate, polyethylene adipate/styrene/methyl methacrylate, polyethylene adipate/styrene/methyl methacrylate/n-butyl methacrylate and polyethylene adipate/styrene/methyl methacrylate/acrylonitrile multiblock copolymers were obtained in this way.     

Anionic polymerization of p-(2,2′-diphenylethyl)styrene and applications to graft copolymers

Well-controlled anionic polymerization of an initiator-functionalized monomer, p-(2,2′-diphenylethyl)styrene (DPES), was achieved for the first time. The polymerization was performed in a mixed solvent of cyclohexane and tetrahydrofuran (THF) at 40 °C with n-BuLi as initiator. When the volume ratio of cyclohexane to THF was 20, the anionic polymerization of DPES showed living polymerization characteristics, and well-defined block copolymer PDPES-b-PS was successfully synthesized. Furthermore, radical polymerization of methyl methacrylate in the presence of PDPES effectively afforded a graft copolymer composed of a polystyrene backbone and poly(methyl methacrylate) branches. The designation of analogous monomers and polymers was of great significance to synthesize a variety of sophisticated copolymer and functionalize polymer materials.     

Polymerization initiated with polymeric compounds,II

The polymerization of methyl methacrylate initiated by the copolymers methacrylaldehyde — styrene — divinylbenzene and acrylaldehyde — ethylene dimethacrylate in the absence of usual initiators was investigated. The polymerization was found to proceed fairly readily and fast. Acceleration can be achieved by adding glycerylaldehyde. An increase in the surface of the initiating copolymer favourably influences the reaction rate; at the same time, however, physical trapping of ungraft poly(methyl methacrylate) molecules in the macroporous initiator seems likely to occur. It was also found that only copolymers containing aldehyde groups could be used for initiation and that besides MMA some other monomers could be polymerized in this way, such as glycidyl methacrylate, acrylic and methacrylic acid, acrylonitrile, and alkyl acrylate.     

Synthesis of block copolymers by using polysilanes

Poly(methyl phenyl silane) was used to photoinitiate the polymerization of methyl methacrylate. Poly(methyl methacrylate) (PMMA), obtained this way, contains remaining polysilane chains. Photolysis of this PMMA in the presence of vinyl monomers such as styrene makes it possible to prepare block copolymers. Such PMMA prepolymers were also used to induce the polymerization of cyclohexene oxide through formation of PMMA-attached silyl radicals and subsequent oxidation to the corresponding ions in the presence of N-ethoxy-2-methylpyridinium hexafluorophosphate resulting in the formation of a block copolymer.     

Radical polymerization of vinyl monomers in the presence of carbon black initiated by 2,2'‐azobisisobutyronitrile and benzoyl peroxide in ionic liquid

The radical polymerization behavior of vinyl monomers, such as styrene, methyl methacrylate (MMA), and vinyl acetate (VAc), in the presence of carbon black initiated by benzoyl peroxide (BPO) and 2,2'‐azobisisobutyronitrile (AIBN) in ionic liquid (IL) was compared with those in toluene. 1‐Butyl‐3‐methylimidazolium hexafluorophosphate was used as IL. The radical polymerization of vinyl monomers initiated by BPO and AIBN in the presence of carbon black was remarkably retarded in toluene. On the contrary, the retardation of the polymerization by carbon black was considerably reduced in IL. During the radical polymerization in the presence of carbon black, a part of polymer formed was grafted onto carbon black surface based on the termination reaction of the growing polymer radicals with carbon black surface. The percentage of grafting and molecular weight of polymer in IL were much higher than those in toluene. This may be due to the fact that lifetime of the growing polymer radical is prolonged because of high viscosity of IL. Therefore, the growing polymer radicals with higher molecular weight were trapped by carbon black surface, because of stabilization of polymer radicals. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

甲基丙烯酸甲酯与苯乙烯共聚物的研究

本文着重阐述了甲基丙烯酸甲酯与苯乙烯共聚反应，以及采用连续溶液聚合方法生产甲基丙烯酸甲酯与苯乙烯聚物的工艺过程，它对科研和实际应用都有指导作用。     

Cardanyl acrylate/methacrylate based cross-linked copolymers as novel supports: Synthesis and characterization

Cardanyl acrylate/methacrylate on suspension polymerization with methyl methacrylate, styrene, and acrylonitrile yielded copolymer beads. The beads were almost uniform in size and cross-linked in nature. The copolymers synthesized were characterized by infrared, thermogravimetric analysis, scanning electron and optical microscopy, and swelling studies. © 1994 John Wiley & Sons, Inc.     

Preparation of copoly(vinyl alcohol–styrenesulfonic acid) resin and its catalytic activity on hydrolysis of carbohydrates. II. Two-step polymerization using tetraethylthiuram disulfide as an initiator

Copoly(vinyl alcohol–styrenesulfonic acid) resin was prepared by a two-step polymerization, consisting of a suspension polymerization of styrene containing divinylbenzene using tetraethylthiuram disulfide as an initiator and a subsequent block copolymerization of vinyl acetate to the crosslinked polystyrene obtained, followed by sulfonation and saponification. Some reaction conditions in the polymerization of styrene were investigated to obtain copolymer containing more vinyl alcohol units. The catalytic activity of the copolymer on the hydrolysis of dextrin was investigated and found to be increased with increasing amount of vinyl alcohol units and with a lowering degree of crosslinking of the copolymer. The maximum acceleration of rate obtained in the presence of the copolymer was about six times that in the presence of Amberlite 120B. Catalytic activity of the copolymer on hydrolysis of sucrose and methyl acetate were also investigated and found to be comparable each other and lower than that for dextrin. The difference between the activities for dextrin and for sucrose and methyl acetate increased with an increasing amount of vinyl alcohol units in the copolymer.     

Synergism effect between modified carbon black and organic ultraviolet absorber in polymer matrix for ultraviolet protection

Modified carbon black (MCB) was obtained by oxidization and hydroxymethylation reactions with conductive carbon black (CB); in the MCB, some hydroxyl groups were introduced on the surface of the CB particles. CB, MCB, and a kind of organic ultraviolet absorber (UA) were used as UV antidotes, and binary composites and ternary composites were prepared by solvent casting with polystyrene, styrene–butadiene–styrene triblock copolymer, and poly(methyl methacrylate) as the matrix, respectively. In the binary composites, only one kind of UV antidote was used, whereas in the ternary composites, the organic and inorganic UAs were combined. The ultraviolet–visible absorption spectra of the composites were investigated extensively, and it was found that no synergism occurred when CB was combined with the organic absorber; on the other hand, an obvious synergism effect emerged when MCB was combined with the organic absorber in the same matrix, which was attributed to the formation of hydrogen bonds between MCB and UA. The interaction between MCB and UA was studied by Fourier transform infrared spectroscopy, differential scanning calorimetry, and transmission electron microscopy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Metal-containing initiator systems

Summary The polymerization of vinyl monomers with the initiator systems of ferrocene and acid anhydrides were investigated. The initiator activity for radical polymerization of methyl methacrylate (MMA) was higher than that for styrene (St). However, isobutyl vinyl ether was not polymerized. The rate of polymerization of MMA with ferrocene/benzoic anhydride system was in proportional to the square root concentrations of both compounds of the initiator system, indicating the mechanism of radical polymerization. When an alternating copolymer of ethylene with maleic anhydride was used as an acid anhydride, a graft copolymer, which was soluble in dimethylformamide and tetrahydrofuran, was produced from radical polymerization of MMA.     

Polymers with acyloxime ester groups in the main chain. 2. Photochemical synthesis of block copolymers

Block copolymers of styrene and methyl methacrylate (MMA) were prepared in a two-stage free-radical polymerization by means of an azo-acyloxime ester (AOE) initiator. In the first stage, photosensitive styrene prepolymers were synthesized by using AOE initiator. These polymers were photolysed in the presence of MMA in the second stage to form block copolymers. The block copolymer structure was elucidated by means of extraction by appropriate solvents, GPC analysis and IR and NMR spectral measurements.