Batch and semicontinuous emulsion copolymerization of vinylidene chloride and butyl methacrylate. II. Physical and mechanical properties of copolymer latex films

Vinylidene chloride (VDC)–butyl methacrylate (BMA) copolymer latex films of various compositions (83 : 17, 60 : 40, 33 : 67 in mol %), prepared by batch and semicontinuous processes, were investigated for their physical properties by infrared spectroscopy, ¹³C solidstate NMR spectroscopy, X-ray diffraction, solubility in various solvents, differential scanning calorimetry (DSC), and water vapor transmission rates (WVTR), and for their mechanical properties by dynamic mechanical spectroscopy (DMS), and tensile strength measurements. Semicontinuous latex films were found to be homogeneous in composition and amorphous in character. On the other hand, batch latex films containing high VDC monomer content were heterogeneous in composition and crystalline in character. These differences were found to reflect the effect of mode of monomer addition during the emulsion polymerization process, and correlated well to the results on kinetics, colloidal, and surface properties of the VDC-BMA copolymer latexes, as described in the first part of this study.     

偏氯乙烯乳液聚合

对偏氯乙烯乳液聚合配方如引发剂，乳化剂，共聚单体，pH值调节剂，聚合工艺如聚合温度、搅拌强度和聚合方式等进行了较全面的叙述。     

Semibatch emulsion copolymerization of methyl methacrylate and butyl acrylate

The concentration of sodium lauryl sulfate (SLS) in the initial reactor charge is the most important parameter in determining the particle size of a semibatch emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA). The number of particles formed is proportional to the concentration of SLS to the 0.5–1.2 power and it is proportional to the concentration of the nonyl phenol–40 mol ethylene oxide adduct to the 0.014–0.72 power. The number of particles is almost independent of the concentration of the initiator. The solubility of monomer in water has an important effect on the nucleation mechanism according to the literature. However, the ratio of MMA to BA does not show any significant effect on the latex particle size in our laboratory. The particle size also increases with increasing ionic strength or agitation speed. Experimental data of particle-size distribution and molecular weight distribution support the coagulative nucleation mechanism when the concentration of SLS is way below its critical micelle concentration (CMC). © 1995 John Wiley & Sons, Inc.     

Mechanistic aspects of sonochemical copolymerization of butyl acrylate and methyl methacrylate

This paper attempts to get a physical insight into the sonochemical emulsion copolymerization using butyl acrylate (BA) and methyl methacrylate (MMA) as model monomers at low to moderate ultrasound intensity. The principal physical mechanism underlying beneficial effects of ultrasound on emulsion polymerization system is cavitation, which affects the system in both chemical (i.e. generation of radicals that can initiate/propagate polymerization process) as well as physical (i.e. emulsification of reaction mixture) way. By taking dual approach of coupling experiments with simulations of cavitation bubble dynamics, we have tried to justify the trends in experiments results. The role of cavitation in the present study is found to be only physical. Quite interestingly, the chemical effect of cavitation is found to have no role to play. Reactivity ratios of both monomers for applied experimental conditions have been found to be less than 1, which hints at moderately alternating behavior of copolymerization. Theoretically calculated copolymer composition using the reactivity ratios of copolymers matched well with experimental values. The copolymer composition for all monomer feed ratios is rich in MMA, due to higher reactivity of MMA than BA. The molecular weight of the copolymer reduced with greater fraction of MMA in the reaction mixture. This effect is attributed to nature of termination of the BA (i.e., combination) and MMA (i.e., disproportionation) monomer radicals.     

Semi-continuous emulsion copolymerization of butyl methacrylate with polymerizable anionic surfactants

Two polymerizable anionic surfactants sodium 4-(ω-acryloyloxyalkyl)oxy benzene sulfonate (SABS-n, n=8 or 10) have been successfully used in the semi-continuous emulsion copolymerization with butyl methacrylate (BMA). After generating seeding particles in an emulsion consisting SABS-8 or SABS-10 and small amount of BMA using a redox initiator ammonium persulfate (APS)/tetramethylethylenediamine (TMEDA) at room temperature, most of BMA was added drop-wise to the polymerizing emulsion system during a period of 4-8 h. These emulsion copolymerizations produced nanosized latexes with high polymer/surfactant weight ratios up to about 12/1 and nearly monodisperse particles ranging from 18 to 33 nm in diameter. X-ray photoelectron spectroscopy results showed that SABS-n was significantly enriched on the surface of latex particles. The effects of concentrations of SABS-n, BMA, and APS/TMEDA and the latex characteristics during the continuous addition of monomer were studied. A possible polymerization mechanism was proposed.     

Semibatch emulsion copolymerization of butyl acrylate and glycidyl methacrylate: Effect of operating variables

Semibatch emulsion copolymerization was carried out to prepare poly(butyl acrylate‐co‐glycidyl methacrylate) latexes at 75°C, using potassium persulfate as an initiator, sodium dodecylbenzene sulfonate as an emulsifier and sodium bicarbonate as a buffer. The reaction was conducted in three stages; a further stage (called the steady stage, 2 h) was added to the traditionally stages (i.e., feed and seed stages) to improve considerably the monomer conversion. The monomer conversion and particle size distribution were studied by gravimetric and laser light scattering methods, respectively. The effects of variables such as agitation speed, emulsifier concentration, initiator concentration, feeding rate and comonomers ratio were fully investigated based on the monomer conversion‐time profiles and the particle size distribution to find the optimized copolymerization conditions. Increasing the agitation speed had a negative effect on the monomer conversion, but reduced coagulation of polymer particles. Monomer conversion could be improved by increasing the initiator or emulsifier contents. Feeding rate increased the polymer particle size sharply; however, it showed no significant effect on conversion. The final conversions were as high as 97–99% and they were recognized to be independent of the comonomers ratios employed. Morphological studies by scanning electron microscopy showed nano‐sized isolated particles which were partially aggregated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

水溶性聚合物存在下的苯乙烯/丙烯酸丁酯乳液共聚合

以苯乙烯、丙烯酸丁酯为单体,以十二烷基硫酸钠为乳化剂,并向反应体系加入适量的水溶性苯乙烯-丙烯酸共聚物进行一次投料的间歇乳液聚合反应,详细分析了该体系的动力学规律和乳胶粒直径及分布的规律,通过乳液聚合的动力学模型探讨了水溶性聚合物及其它因素对聚合反应速率、乳液稳定性的影响.结果表明,该水溶性聚合物参与的乳液聚合反应规律与小分子乳化剂的乳液聚合基本相似,但聚合反应速率大大下降.     

Miniemulsion copolymerization of n‐butyl methacrylate with crosslinking monomers

Miniemulsion copolymerization of n‐butyl methacrylate and crosslinking monomers such as a macromonomer crosslinker (Mac), ethylene glycol dimethacrylate (EGDMA), or an aliphatic urethane acrylate macromonomer (AUA) was utilized to obtain crosslinked latex particles. The crosslinking monomers were added at 0.2 mol %, on the basis of the amount of n‐butyl methacrylate utilized in a polymerization. The development of the gel content during the copolymerization reaction differs depending on the type of the crosslinking monomer. In addition to the crosslinking reactions between the n‐butyl methacrylate and the crosslinking monomers, other kinetic events, such as microphase separation, may have occurred, giving rise to different particle morphologies, dependent on the type of initiator used (i.e., oil‐soluble or water‐soluble). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1721–1730, 2001     

Batch and semicontinuous emulsion copolymerization of vinylidene chloride and butyl methacrylate. I. Kinetics in VDC–BMA emulsion polymerization and surface and colloidal properties of VDC–BMA latexes

Vinylidene chloride (VDC)—butyl methacrylate (BMA) comonomer mixtures with various composition (83 : 17, 60 : 40, 33 : 67 in mol %) were polymerized at 25°C using redox catalyst by batch and seeded semicontinuous emulsion copolymerization. The reactivity ratios determined in VDC (M₁)—BMA (M₂) emulsion copolymerization system were r₁ = 0.22 and r₂ = 2.41. Seven 35% solids (83 : 17 mol %) VDC–BMA copolymer latexes were prepared: one batch (G), one seeded batch (F), and 5 seeded semicontinuous polymerizations of 5 different monomer feed rates ranging from 0.27 (A) to 1.10 wt %/min (E). The kinetic studies of seeded semicontinuous polymerizations A-E showed that the rates of polymerizations (R_p) were controlled by the monomer addition rates (R_a). The conversion versus time curves for the polymerizations of 0 : 100–100 : 0 VDC–BMA mixtures by batch polymerization showed that the rate of polymerization (R_p) was a function of the number of particles, and that the rate of polymerization in a latex particle (R_pp) increased with increasing proportions of butyl methacrylate in the monomer mixture. All of the latexes had narrow particle size distributions. The greater particle number density in VDC polymerization and the greater water solubility of VDC suggest that the homogeneous nucleation mechanism is operative in VDC–BMA copolymerizations. The latex copolymers prepared by semicontinuous polymerization had lower number-and weight-average molecular weights than those of the corresponding batch copolymers, resulting from the monomer starvation occurring during the semicontinuous polymerization. The surface characterization study of the cleaned latexes showed that for the latexes by batch process, the surface charge density derived from strong-acid groups decreased with increasing proportion of VDC in the monomer mixture. On the other hand, for the latexes prepared by semicontinuous polymerization, the surface charge density derived from strong-acid groups did not depend on the monomer composition of the copolymers.     

Emulsion copolymerization of styrene and butyl acrylate by reverse atom transfer radical polymerization

Reverse atom transfer radical copolymerization of styrene (St) and butyl acrylate was carried out in emulsion under normal emulsion conditions, using CuBr₂/bpy complex as catalyst. The effects of surfactant type, initiator type and concentration, and CuBr₂ addition on the system livingness, polymer molecular weight control, and latex stability were examined in detail. It was found that the Polysorbate 80 (Tween 80) and azodiisobutyronitrile gave the best exhibition in this system, polymer samples were got with narrow molecular‐weight dispersity (M_w/M_n = 1.1–1.2) and linear relationships of molecular weight versus monomer conversion, as well as a relatively low polydispersity index (<0.1). Through the GPC and SEM analysis, the polymerization processes under these conditions showed good living/control characteristics relative to the processes under normal emulsion polymerization, although the latex stability was susceptible to the CuBr₂ catalyst. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Sequencing of methyl methacrylate/vinylidene chloride copolymers by NMR spectroscopy

Methyl methacrylate/vinylidene chloride (M/V) copolymers of different monomer concentrations were prepared by photopolymerization using the uranyl ion as photosensitizer. The copolymer composition was determined by chlorine estimation of the copolymers. The complete assignment of the ¹³C{¹H} NMR spectra of these copolymers is made by comparison with the spectra of poly(methyl methacrylate) and observing the changes in the intensities of the resonances with copolymer composition. The quaternary carbon of V- and M- center resonances were used for determining the sequence in terms of the distribution of V- and M- centered triads. The triad fractions thus obtained were compared with theoretically determined triad concentrations. The Monte Carlo simulation method was also used for estimating the copolymerization behavior. The variation of V- and M- centered triad concentrations was reported as a function of fractional conversions. The comonomer reactivity ratios, determined by both Kelen Tudos and nonlinear error in variables methods are r_V = 0.26 ± 0.04 and r_M = 2.88 ± 0.23. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 373–381, 1998     

均相制备纤维素/丙烯酰胺/甲基丙烯酸丁酯接枝共聚物的研究

以氢氧化钠/硫脲/尿素新型溶液溶解纤维素,在均相条件下以丙烯酰胺(AM)、甲基丙烯酸丁酯(BMA)为接枝单体,过硫酸铵为引发剂,N,N′-亚甲基双丙烯酰胺(MBA)为交联剂,通过自由基聚合法制备出了纤维素/AM/BMA接枝共聚物。考察了聚合温度、时间以及(NH4)2S2O8、AM、BMA、MBA的用量对接枝效果的影响。利用红外光谱(FT-IR)、X射线衍射(XRD)和扫描电镜(SEM)对接枝产物进行了结构表征。实验结果表明,纤维素/AM/BMA接枝共聚物的最佳合成条件为:m(纤维素)∶m(AM)∶m(BMA)∶m[(NH4)2S2O8]∶m(MBA)=1∶4∶2∶0.05∶0.006,反应温度为65℃,反应时间为2h,在此条件下接枝率可达87%,接枝效率为36%。制备的纤维素/AM/BMA接枝共聚物的吸水倍率为583g/g。     

氯乙烯-丙烯酸丁酯-甲基丙烯酸甲酯三元共聚物的研究

讨论了氯乙烯 丙烯酸丁酯 甲基丙烯酸甲酯三元共聚物 3种共聚单体的投料比、反应温度、引发剂用量对共聚物树脂性能的影响。所得共聚树脂加工成片后 ,测量其各种物理性能 ,结果显示出低温韧性和抗冲击性等有了明显提高。     

偏氯乙烯-丙烯酸甲酯悬浮共聚树脂的研制

采用悬浮共聚的方法研制了偏氯乙烯/丙烯酸甲酯（VDC/MA）共聚树脂。考察了共聚配方、分散剂种类及用量、搅拌速度及聚合温度对VDC/MA共聚树脂的影响。结果表明,当VDC/MA=（92-96）/（8-4）、采用分散剂B（用量0.13%)、搅拌速度300-400r/min,并根据聚合温度调节分子量大小,制得的VDC/MA共聚树脂其膜光泽好、透时度高,热稳定性好。     

Organotin polymers. IV. Binary and ternary copolymerizations of tributyltin acrylate and methacrylate with styrene,allyl methacrylate,butyl methacrylate,butyl acrylate,and acrylonitrile

The monomer reactivity ratios for the copolymerization of tributyltin acrylate with styrene and allyl methacrylate have been found to be r₁ = 0.213, r₂ = 1.910 and r₁ = 0.195, r₂ = 2.257, respectively. Also, the copolymerization parameters of tributyltin methacrylate with styrene and allyl methacrylate were as follows: r₁ = 0.256, r₂ = 1.104 and r₁ = 2.306, r₂ = 1.013. Copolymerization reactions were carried out in solution at 70°C using 1 mole % AIBN, and the copolymer compositions were determined by tin analysis. Ternary copolymerization of the three systems butyl methacrylate–tributyltin methacrylate–acrylonitrile, butyl acrylate–tributyltin methacrylate–acrylonitrile, and styrene–tributyltin acrylate–acrylonitrile have been studied, and the terpolymer composition of each system was determined through tin and nitrogen analyses. The variation of instantaneous and average terpolymer composition with conversion fit satisfactorily the experimental results over a wide range of conversion.     

A re-evaluation of the reactivity ratios of 3-vinyl thiopene in copolymerization with butyl acrylate and methyl methacrylate

Summary The reactivity ratios of 3-vinyl thiophene in copolymerization with n-butyl acrylate and methyl methacrylate were determined by using a nonlinear least squares error-in-variables method coupled with an experimental design scheme. The values obtained were found to be significantly different than those previously reported.     

Polymerization in a magnetic field,part 17: Styrene copolymerization with 2,3‐epoxypropyl methacrylate

The article presents a comparative study regarding the magnetic field influence intervened during styrene copolymerization with 2,3‐epoxypropyl methacrylate using a radical emulsion polymerization procedure. The registered magnetokinetic effects were evidenced for different reaction compositions and temperatures. The field effect influenced the conversion, the polymerization rate, and activation energy of polymerization process. An efficiency of magnetic field from the kinetic parameters has been established. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007