AMPS作用下无皂醋丙乳液的合成

在不加入任何传统乳化剂的情况下,以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为表面活性功能单体(surfmer),作用于乙酸乙烯酯(VAc)与丙烯酸丁酯(BA)的共聚乳化体系中,成功制备了一种新型的P(VAc/BA/AMPS)三元无皂乳液,该乳化体系在聚合以及贮存过程中都表现出良好的稳定性。考查了单体配比、AMPS用量、引发剂用量、反应温度和反应时间等条件对乳液性能的影响。确定的最佳单体配比为mVAc:mBA=8:2,AMPS用量为单体质量的1.0%,引发剂过硫酸钾(KPS)用量为单体质量的0.6%,反应温度为80℃。所制得的乳液粒径约为144nm,且单分散性好,固含量在42%以上。     

Semicontinuous heterophase copolymerization of vinyl acetate and butyl acrylate

Vinyl acetate (VAc) and butyl acrylate (BuA) were copolymerized in heterophase by a semicontinuous process (unseeded) and compared with the seeded semicontinuous microemulsion polymerization of the same monomers. A mixture of sodium dodecyl sulfate (SDS) and poly(ethylene oxide) dodecyl ether (Brij‐35®) were used as surfactants. The effects of monomer addition rate (R_a) and surfactants concentrations (4 or 1 wt % with respect to the initial mixture of reaction) on polymer and latex properties were studied. High copolymer content latexes (24–36 wt %) with average particle diameters (D_p) from 38 to 55 nm and relatively narrow particle size distributions, high polymerization rates, weight ratios of polymer to surfactant (P/S) from 13.3 to 32.8 were obtained. The number‐average molecular weights (M_n) were between 96,000 and 188,000 g/mol. Homogeneous copolymer compositions were obtained throughout the reaction for both, seeded and unseeded processes, which is not possible by the usual batch microemulsion process. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Concentrated emulsion copolymerization of butyl acrylate and vinyl acetate initiated by a redox initiator at lower temperature

The concentrated emulsion copolymerization of butyl acrylate and vinyl acetate with an ammonium persulfate/sodium hydrogen sulfate mixture as a redox initiator, with a sodium dodecyl sulfate/cetyl alcohol mixture as a compound surfactant, and with poly(vinyl alcohol) as a liquid film reinforcer was carried out at lower temperature. In less than 3 h, the polymerization conversion was greater than 95%. The effects of the surfactant, the initiator, the volume fraction of the monomer, and the temperature on the stability of the concentrated emulsion, the kinetic process, and the average size of the latices were examined. The morphology of the polymer particles was observed by transmission electron microscopy, and the average size and distribution of the particle diameter were measured by photon correlation spectroscopy. The kinetic equation was R_p = k[M]^0.38[I]^0.89[E]^?0.80 at 30°C (where R_p is the polymerization rate, [I] is the initiator concentration, [M] is the monomer concentration, and [E] is the concentration of the compound surfactant), and the apparent activation energy was 22.69 kJ/mol. The thin‐layer polymerization of the concentrated emulsions, which enabled the removal of the heat of polymerization, was performed first. In comparison with test‐tube polymerization, thin‐layer polymerization provided a more regular morphology of the polymer particles. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 570–576, 2004     

醋酸乙烯酯/马来酸/丙烯酸丁酯无皂共聚乳液研究

采用无皂乳液聚合方法合成聚醋酸乙烯酯/马来酸/丙烯酸丁酯乳液。以透射电镜观察乳胶粒的表面形态并测量粒径,对乳胶粒的增长机理进行了分析。以转化率、吸水性、拉伸强度和乳液的稳定性为主要指标考查了共聚单体用量、pH等因素对乳液性能的影响。结果表明,马来酸占总单体量的3%,丙烯酸丁酯占8%,pH为6时共聚乳液具有良好的性能。     

Semicontinuous emulsion copolymerization of styrene and butyl acrylate

Semicontinuous emulsion copolymerization of styrene and butyl acrylate with a constant rate of feed of monomer emulsion was investigated. The integral composition of the copolymer at the end of the feeding was different from the feed composition, and the difference was proportional to the monomer feeding rate. The closer the feed composition was to the composition at the azeotropic point, the lower was the sensitivity of the system to the feeding rate. At low feeding rates, the copolymerization proceeded at conversions of about 90–95%, and the composition of the copolymer was practically equal to that of the monomer feed. The reactivity ratios determined under these conditions were probably influenced by diffusion inside the growing polymer–monomer particles.     

Free radical copolymerization behavior of vinyl acetate with butyl acrylate in the presence of GeCl4 and BCl3

No alternating copolymers of vinyl acetate (VAc) and butyl acrylate (BA) were obtained by free radical copolymerization in the presence of GeCl₄ and BCl₃ (compared with the acrylic acid–vinyl acetate copolymerization system). By ultraviolet spectral analysis, it was concluded that both BCl₃ and GeCl₄ can form complexes with butyl acrylate. The BA–BCl₃ complex constants were determined by ¹H NMR; K_B=33·2 (25°C). The reason for the gel formation in the BA–Vac–BCl₃ copolymerization system was discussed. When vinyl acetate reacted with BCl₃, cationic polymerization probably occurred. A white gel product probably resulted from the polymerization of the BA–BCl₃ complex. © 1998 SCI.     

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.     

Reactivity ratios and monomer partitioning in the microemulsion copolymerization of vinyl acetate and butyl acrylate

The true monomer reactivity ratios for the vinyl acetate/butyl acrylate system were determined with experimental data from the cumulative copolymer composition at low, intermediate, and high conversions and with the monomer partitioning among the aqueous, microemulsion droplet, and polymer particle phases taken into account. A mixture of sodium dodecyl sulfate and poly(ethylene oxide) (23) dodecyl ether (Brij‐35; 3 : 1 w/w) was used as a stabilizer. Potassium persulfate was used as an initiator. The true values of the monomer reactivity ratios were 0.028 ± 3.2 × 10^?3 for vinyl acetate and 6.219 ± 3.1 × 10^?1 for butyl acrylate, and these were in agreement with those reported in the literature for bulk copolymerizations but differed from values reported for other compartmentalized copolymerizations. Thus, these results indicate that the monomer partitioning and cumulative copolymer composition throughout the reaction have to be duly accounted for in the determination of monomer reactivity ratios in heterogeneous polymerizations. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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.     

Nonlinear model order reduction and control of particle size distribution in a semibatch vinyl acetate/butyl acrylate emulsion copolymerization reactor

This paper addresses the control of the full particle size distribution (PSD) in a semibatch emulsion copolymerization reactor. The numerical approximation of a fundamental population balance model results in a high order system to accurately describe the distribution of particle size; therefore, model order reduction is required. Pseudo random input signals are input to the mechanistic model to generate a data set which covers the reachable region of the system, on the basis of which the transformation matrices are calculated by principal component analysis (PCA). A linear time varying model with reduced order obtained from the transformation matrices is augmented in the prediction equation of linear model predictive control. The performance of the controller is evaluated to drive the particle size distribution at the final time of the batch to the desired distribution in the presence of disturbances. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from the Seoul National University.     

Off‐line monitoring of butyl acrylate and vinyl acetate homopolymerization and copolymerization in toluene

A study of butyl acrylate (BA) and vinyl acetate (VAc) solution homopolymerization and copolymerization in toluene was carried out. The conversion and copolymer composition were monitored using traditional techniques (gravimetry and ¹H‐NMR spectroscopy) and attenuated total reflectance‐Fourier transform IR (ATR‐FTIR) spectroscopy with a diamond‐composite probe and light conduit technology. The peak height of the characteristic absorbances of the monomer(s) during the course of the reaction was used to calculate the conversion and copolymer composition for the ATR‐FTIR monitoring. The data obtained using a ReactIR? 1000 reaction analysis system in the off‐line mode showed very good agreement with data obtained using traditional techniques. The solvent effects on BA and VAc solution homopolymerizations and copolymerizations in toluene were also investigated. Improvement to model predictions was obtained by allowing the lumped constant (k_p/k) to vary with the solvent concentration. Experimental data and model predictions of the number‐ and weight‐average molecular weights for the investigated systems are also presented. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2958–2977, 2001     

Semicontinuous emulsion copolymerization of ethyl acrylate and butyl acrylate at high conversions

Semicontinuous emulsion copolymerization of ethyl acrylate and butyl acrylate was studied at conversions higher than 0.9. It was found that, in the cases in which the mole fraction of ethyl acrylate in the reaction mixture was over 0.65, the copolymerization diagram differs from the one given by the reactivity ratios. It was suggested that this deviation was caused by the diffusion control of the process. This suggestion was also supported by the differences in the free-monomer composition of the systems with and without seed latex, respectively, at the beginning of the copolymerization.     

Microemulsion copolymerization of vinyl acetate and butyl acrylate using a mixture of anionic and non-ionic surfactants

Monomer mixtures of vinyl acetate (VAc)/butyl acrylate (BuA) were polymerized in batch reactions at 60 °C with potassium persulfate as the initiator in microemulsions consisting of VAc:BuA (85:15 wt/wt)/water/sodium dodecyl sulfate (SDS)/polyoxyethylene (23) dodecyl ether (3:1 wt/wt). The effect of the concentration of the monomer mixture on the kinetics was studied. It was found that, as the total monomers concentration ([M]₀) increases, the polymerization rate increases also, and that the maximum polymerization rate is proportional to [M]₀^1.26. Particle size increases with total monomers concentration. In all cases, final average particle diameter was less than 50 nm. Particle number density is independent of total monomers concentration. A mathematical model that takes into account the partition of monomers between the different phases during polymerization using a minimum of adjustable parameters was applied to simulate the experimental data. A correlation for the radical desorption coefficient, which is a function of the rate of monomer chain transfer and of the probability of desorption, was used in the model. Radical capture by micelles and particles was assumed to occur by diffusion. The model takes into account both micellar and homogeneous nucleation. Good agreement between the model and the experimental results was observed.     

Stability and copolymerization of concentrated emulsion of styrene and butyl acrylate in the presence of polyurethane macromonomer

A study has been made of the stability and copolymerization of concentrated emulsion of styrene (St) and butyl acrylate (BA) in the presence of polyurethane macromonomer (DPUA), which contains C?C at one end. First, the DPUA macromonomer was synthesized from the appropriate amount of 2,4‐diisocyanate (TDI), polypropylene glycol (PPG), 2‐hydroxyethyl methylacrylate (HEMA), dimethylolpropionic acid (DMPA), and triethylamine (TEA) by four steps. Then, the DPUA was dissolved in St‐BA monomer mixtures. The DPUA/St‐BA concentrated emulsion copolymerization using sodium dodecyl sulfate/cetyl alcohol (SDS/CA) as composite surfactant and polyvinyl alcohol (PVA) as liquid film reinforcer, and ammonium persulfate/sodium hydrogen sulfate (APS/SHS) as redox initiator system was carried out at 30°C. The effect of NCO/OH molar ratio, surfactants' concentration, mass ratio of DPUA/St‐BA, initiators' concentration, volume fraction of the monomer phase (Φ), and temperature on the stability or the copolymerization of the concentrated emulsion of DPUA/St‐BA were investigated. The average size and distribution of the latex particles obtained under different conditions were also analyzed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1992–1999, 2007     

Effect of initiators and ethoxylation degree of non‐ionic emulsifiers on vinyl acetate and butyl acrylate emulsion copolymerization in the loop reactor

Vinyl acetate and butyl acrylate copolymers were synthesized in the presence of ammonium persulfate and potassium persulfate initiators, mixture of non‐ionic and anionic emulsifiers, and polyvinyl alcohol as protective colloid in a loop reactor. The monomer ratio was chosen 85:15. The series of non‐ionic emulsifiers, which have 10–40 moles ethoxylated nonyl phenol, were combined with Nansa 66 (sodium dodecyl benzene sulfonate). The effects of the initiators on the physicochemical properties of copolymers were investigated by measuring conversion, viscosity, molecular weight, molecular weight distribution, and surface tension, respectively by using gravimetric method, Brookfield viscometer, gel permeation chromatograpy (GPC), and ring method. The effects of ethoxylation degrees of the non‐ionic emulsifiers to the same properties of copolymers were also investigated. It was determined that the copolymer viscosities showed different tendency for two initiators. They were increased by the increasing ethoxylation degree of the non‐ionic emulsifier for ammonium persulfate. In contrast, latex viscosity was decreased by increasing the ethoxylation degree in presence of potassium persulfate. Similar changes were also found in number average molecular weights of copolymers. On the other hand, weight average molecular weights of copolymers increased by increasing the ethoxylation degree of the non‐ionic emulsifier for both initiators. In the case of potassium persulfate, the surface tension values of copolymers increased by increasing the ethoxylation degree, but generally increasing the ethoxylation degree did not affect the surface tension of copolymer very seriously for two initiators. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 537–543, 2003     

Emulsifier-free emulsion copolymerization of styrene and butyl acrylate with cationic comonomer

Emulsifier-free emulsion copolymerization of styrene (St) and butyl acrylate (BA) in the presence of a cationic functional comonomer, N-dimethyl, N-butyl, N-ethyl methacrylate ammonium bromine (DBMA) was carried out using azobis(isobutyl-amidine hydrochloride) (AIBA) as an initiator. The surface properties of particles were studied by testing the actual value of on the surface of the particles and the surface charge density. The copolymer particles were characterized using transmission electron microscopy (TEM). The effects of reaction temperature, DBMA content, AIBA content, ionic strength, etc., on the conversion of the monomer and the average diameter (D¯w) and number (Np) of copolymer particles were investigated. Under constant ionic strength, the average diameter of copolymer particles (D¯w) decreased with increasing AIBA and DBMA concentrations and decreased with increasing reaction temperature also. Moreover, it increased with increasing St content in the monomer feeding. Under a constant concentration of the co-monomer and initiator as well as the constant monomer composition, D¯w shows a change process of increase-decrease-increase in the ionic strength plot. The polymerization reaction rate increased with increasing the DBMA content, AIBA content, and increasing temperature. The surface charge properties of the particles were mainly decided by the DBMA content, AIBA content, ionic strength, etc. The methods of feeding the monomer affects the morphology, structure, size, and surface charge density of the particles. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1–9, 1997      

Semicontinuous emulsion copolymerization of acrylonitrile,butyl acrylate,and styrene

Semicontinuous emulsion copolymerization of acrylonitrile (M₁), butyl acrylate (M₂), and styrene (M₃) was investigated. The copolymerization proceeded under the conditions used with a high degree of conversion, whereby a stationary state characterized by a constant monomer mixture composition and a constant composition of the arising copolymer was achieved. From the analytically estimated free monomers and arising copolymer compositions, the reactivity ratios for the pair AN/BA r₁₂ = 0.71, r₂₁ = 1.17 and for the pair AN/Sty r₁₃ = 0.06, r₃₁ = 0.28 were calculated. The applicability of the reactivity ratios found was verified also for the ternary system acrylonitrile/butyl acrylate/styrene.     

醋酸乙烯-丙烯酸无皂乳液共聚的研究

研究了以醋酸乙烯(VAc)为主单体,丙烯酸(AA)为改性功能单体,以“半连续”加料方式进行无皂乳液共聚合过程,得到了稳定的乳液。并探讨了功能单体AA含量、反应温度等对共聚的影响。采用FTIR、粒度分析等方法对共聚物的组成、乳胶粒子的尺寸及分布进行了分析表征。结果表明:在(65±2)℃的温度下聚合,所得乳液稳定性好、转化率高,反应完全,且随着功能单体AA含量的增加,乳液粘度上升,单体转化率下降,乳胶粒粒径变小且粒径呈单分散性。     

醋酸乙烯-丙烯酸无皂乳液共聚的研究

研究了醋酸乙烯(VAc)与丙烯酸(AA)以“半连续”加料方式进行无皂乳液共聚合。探讨了功能单体AA用量、反应温度等对共聚的影响。采用FTIR、粒度分析等测试方法对共聚物的组成、乳胶粒子的粒径及分布进行了分析表征。结果表明,在(65±2)℃的温度下聚合,所得乳液稳定性好、转化率高,反应完全,且随着功能单体AA用量的增加,乳液黏度上升,单体转化率下降,乳胶粒粒径变小且粒径单分散性好。     

Solvent effects in butyl acrylate and vinyl acetate homopolymerizations in toluene

A series of butyl acrylate (BA) and vinyl acetate (VAc) homopolymerizations in toluene was conducted to investigate the effect of solvent at different solvent and chain transfer agent (CTA) concentrations. Because the experimental determination of the individual propagation and termination rate constants for these systems is challenging, experimental observations were limited to the lumped rate constant (k_p/k). Differences in the lumped rate constant, at different solvent and CTA concentrations, were assumed to be attributed to the effect of solvent on the termination rate constant. Our hypothesis was that the termination rate constant k_t was affected by the presence of solvent. At higher solvent concentrations, chain transfer to solvent occurs more frequently and leads to the formation of shorter chains, which move more easily and are able to terminate more quickly compared to longer chains. Thus, k_t will increase, leading to a decrease in the lumped rate constant. The experimental results confirmed the presence of a solvent effect on the lumped rate constant. This effect was more pronounced in the case of VAc compared to BA solution homopolymerizations. Under the investigated conditions, increased CTA concentrations did not substantially affect the rate of BA homopolymerizations, whereas a slight synergistic effect between the CTA and solvent at higher CTA and solvent concentrations was apparent for VAc homopolymerizations. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 871–876, 2004