Synthesis and properties of branched organosilicon-acrylate copolymer latexes

Summary Stable organosilicon-acrylate copolymer latexes with high silicon content were prepared by seeded semibatch emulsion polymerization of butyl acrylate (BA), methyl methacrylate (MMA) with a novel branched organosilicon monomer 3-methacryloxypropyl tris(trimethylsiloxy) silane (MPTS). Monomer conversion, evolution of the particle size and its distribution were monitored by dynamic light scattering. The effects of MPTS on the polymerization kinetics, the nucleation mechanism and properties of latex were investigated. The results indicated that, in addition to micellar nucleation, a coagulative nucleation step was also observed as a result of the addition of the organosilicon monomer, accordingly, the particle number of the silicon-acrylate latexes increased, the average particle diameter decreased and the polymerization rate accordingly increased compared to those of the acrylate latexes without organosilicon monomer. Moreover, the particle size distribution presented bimodal curves, which indicated that there were large particles formed at an early stage. However, the particle size distribution curves became monomodal at the later stage, and the final latex shows a narrow particle size distribution. It was found that the properties of latex and latex film were obviously influenced by MPTS content. With increasing MPTS content, latex film glass transition temperature and water absorption ratio decreased, the degradation temperature and water contact angle were increased. Hence, the resulting latex films containing MPTS showed lower glass transition temperature and excellent water-resistance, which probably due to the incorporation of the bulky branched hydrophobic group of MPTS into the copolymer chains.     

Synthesis of well‐defined,functionalized polymer latex particles through semicontinuous emulsion polymerization processes

The design of a semicontinuous emulsion polymerization process, primarily based on theoretical calculations, has been carried out with the objective of achieving overall independent control over the latex particle size, the monodispersity in the particle size distribution, the homogeneous copolymer composition, the concentration of functional groups (e.g., carboxyl groups), and the glass‐transition temperature with n‐butyl methacrylate/n‐butyl acrylate/methacrylic acid as a model system. The surfactant coverage on the latex particles is very important for maintaining a constant particle number throughout the feed process, and this results in the formation of monodisperse latex particles. A model has been set up to calculate the surfactant coverage from the monomer feed rate, surfactant feed rate, desired solid content, and particle size. This model also leads to an equation correlating the polymerization rate to the instantaneous conversion of the monomer or comonomer mixture. This equation can be used to determine the maximum polymerization rate, only below or at which monomer‐starved conditions can be achieved. The maximum polymerization rate provides guidance for selecting the monomer feed rate in the semicontinuous emulsion polymerization process. The glass‐transition temperature of the resulting carboxylated poly(n‐butyl methacrylate‐co‐n‐butyl acrylate) copolymer can be adjusted through variations in the compositions of the copolymers with the linear Pochan equation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 30–41, 2003     

Control of monodisperse particle size of styrenic–acrylate copolymers in dispersion copolymerization

Syntheses of monodisperse poly[(styrene)‐co‐(n‐butyl acrylate)] and poly[(styrene)‐co‐(2‐ethylhexyl acrylate)] were carried out by dispersion polymerization. The reactions were performed in the mixed solvent of ethanol–water in the presence of azo‐bisisobutyronitrile and poly(N‐vinylpyrrolidone) as the initiator and dispersant, respectively. The effects of reaction parameters, that is the type and concentration of dispersant, ratio of the mixed solvent, reaction temperature, agitation rate, monomer composition between styrene and n‐butyl acrylate or 2‐ethylhexyl acrylate, crosslinking agent and reaction time on the particle size, size distribution and average molecular weights of the resulting copolymer were thoroughly investigated. The resulting copolymer particles were smooth on their spherical surface and the sizes were in the range 0.6–1.8 µm with a narrow size distribution. In most cases, a correlation between small particle sizes with high average molecular weights was observed. The average particle size generally increased with increasing reaction temperature, time and acrylate monomer content. In contrast, the particle size decreased as the molecular weight, concentration of dispersant, polarity of the medium or agitation rate was increased. The glass transition temperature (T_g) of the copolymers can be controlled by the mole ratio of the comonomer. The T_g values decreased when the content of acrylate monomers in the copolymer increased, and T_g values of the synthesized copolymer were in the range 66–102 °C. Instead of using n‐butyl acrylate monomer in the copolymerization, 2‐ethylhexyl acrylate copolymerization with styrene resulted in insignificant changes in the particle sizes but there were significant decreases in T_g values. In this study, the monodisperse particles can be obtained by monitoring the appropriate conditions regarding PVP K‐30 (2–8 wt%), ethanol/water (90/10 wt%), the reaction temperature (70 °C) and the agitation rate (100 rpm). © 2000 Society of Chemical Industry     

High‐temperature solution polymerization of butyl acrylate/methyl methacrylate: Reactivity ratio estimation

Solution copolymerizations of butyl acrylate/methyl methacrylate in toluene were performed over an expanded temperature range (60–140°C) compared to more typical ranges that do not exceed 80°C. From a large amount of data collected independently at two laboratories, reactivity ratios were estimated at five different temperatures. The reactivity ratios were estimated from low conversion copolymer composition data using both the error‐in‐variables model method and a nonlinear parameter estimation based on the integrated copolymer composition equation. Using all of the available data, temperature‐dependent expressions were developed for the reactivity ratios and compared to previously published bulk copolymerization values. No significant differences appeared to exist between the bulk and solution polymerization reactivity ratios. Furthermore, the copolymer composition data conformed to the Mayo‐Lewis kinetic model over the entire temperature range. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 602–609, 2000     

Synthesis and property behavior of dioctyl phthalate plasticized styrene–acrylate particles by Shirasu porous glass emulsification and subsequent suspension copolymerization

Two‐phase model styrene–acrylate copolymers were synthesized with a soft phase consisting of methyl acrylate, butyl acrylate, and butyl methacrylate. Besides the styrenic copolymers, copolymers containing a hard phase of methyl methacylate and methyl acrylate were also synthesized. Comonomer droplets with a narrow size distribution and fair uniformity were prepared using an SPG (Shirasu porous glass) membrane having pore size of 0.90 μm. After the single‐step SPG emulsion, the emulsion droplets were composed mainly of monomers, hydrophobic additives, and an oil‐soluble initiator, suspended in the aqueous phase containing a stabilizer and inhibitor. These were then transferred to a reactor, and subsequent suspension polymerization was carried out. Uniform copolymer particles with a mean diameter ranging from 3 to 7 μm, depending on the recipe, with a narrow particle size distribution and a coefficient of variation of about 10% were achieved. Based on the glass‐transition temperatures, as measured by differential scanning calorimetry, the resulting copolymer particles containing a soft phase of acrylate were better compatibilized with a hard phase of methyl methacrylate than with styrene with dioctyl phthalate (DOP) addition. Glass‐transition temperatures of poly(MMA‐co‐MA) particles were strongly affected by the composition drift in the copolymer caused by their substantial difference in reactivity ratios. Incorporation of DOP in the copolymer particles does not significantly affect the glass‐transition temperature of MMA‐ or MA‐containing copolymer particles, but it does affect the St‐containing copolymer and particle morphology of the copolymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3037–3050, 2003     

Thermal and sonochemical degradation kinetics of poly(n‐butyl methacrylate‐co‐alkyl acrylates): Variation of chain strength and stability with copolymer composition

The thermal degradation of poly(n‐butyl methacrylate‐co‐alkyl acrylate) was compared with ultrasonic degradation. For this purpose, different compositions of poly (n‐butyl methacrylate‐co‐methyl acrylate) (PBMAMA) and a particular composition of poly(n‐butyl methacrylate‐co‐ethyl acrylate) (PBMAEA) and poly(n‐butyl methacrylate‐co‐butyl acrylate) (PBMABA) were synthesized and characterized. The thermal degradation of polymers shows that the poly(alkyl acrylates) degrade in a single stage by random chain scission and poly(n‐butyl methacrylate) degrades in two stages. The number of stages of thermal degradation of copolymers was same as the majority component of the copolymer. The activation energy corresponding to random chain scission increased and then decreased with an increase of n‐butyl methacrylate fraction in copolymer. The effect of methyl acrylate content, alkyl acrylate substituent, and solvents on the ultrasonic degradation of these copolymers was investigated. A continuous distribution kinetics model was used to determine the degradation rate coefficients. The degradation rate coefficient of PBMAMA varied nonlinearly with n‐butyl methacrylate content. The degradation of poly (n‐butyl methacrylate‐co‐alkyl acrylate) followed the order: PBMAMA < PBMAEA < PBMABA. The variation in the degradation rate constant with composition of the copolymer was discussed in relation to the competing effects of the stretching of the polymer in solution and the electron displacement in the main chain. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

原位乳液聚合制备聚合墨粉用含蜡苯丙复合乳液及其性能研究

采用核壳乳液聚合的方法,以苯乙烯、丙烯酸丁酯和丙烯酸为共聚单体,原位制备了聚合墨粉用含蜡苯丙复合乳液。探讨了巴西棕榈蜡用量对单体转化率、凝聚率、复合乳液粒径及其分布、Zeta电位、共聚物的玻璃化转变温度以及相对分子质量及其分布的影响。结果表明,巴西棕榈蜡的加入对聚合稳定性影响不大;随着其用量的增加,乳液粒径、Zeta电位、聚合物玻璃化转变温度降低,而相对分子质量增大。当其用量为3%(wt)时,聚合物具有较适宜的Tg和相对分子质量,分别为65.9℃和89,000。     

Synthesis and characterization of tall oil fatty acids-based alkyd resins and alkyd–acrylate copolymers

The polymerization and properties of environmentally friendly waterborne binders for wood coatings were studied. Conjugated and non-conjugated tall oil fatty acids-based alkyd resins were synthesized and further copolymerized via miniemulsion polymerization with acrylates (butyl acrylate and methyl methacrylate). The ratio between alkyd resin and acrylate monomers was varied and the effect on copolymerization and the copolymer binder properties, such as particle size, molecular weight, grafting of acrylate to alkyd resin and reaction of double bonds, were studied. It was observed that the use of MMA influenced on the degree of grafting of acrylate and monomer conversion because the steric hindrances prevent MMA to react with alkyd double bonds as eagerly as BA. The increasing amount of alkyd resin was noticed to decrease the polymerization rate. The research showed that it was possible to prepare stable hybrids, alkyd–acrylate copolymers, with varied chemical composition.     

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。     

氯乙烯-丙烯酸丁酯共聚树脂的性能优化及应用

通过调整生产工艺或聚合配方,对氯乙烯-丙烯酸丁酯共聚树脂(以下简称氯丙树脂)中丙烯酸丁酯的含量及分布,氯丙树脂的分子质量及其分布、颗粒特性、热稳定性进行了优化;比较了优化后的氯丙树脂与普通PVC树脂的加工性能和力学性能,并将其应用于PVC型材和注塑管件的生产。结果表明:①氯丙树脂中丙烯酸丁酯的质量分数以5%～10%为宜;②通过调整生产工艺或聚合配方,可制得丙烯酸丁酯分布均匀、分子质量分布集中、粒度分布集中、热稳定性优良的氯丙树脂;③氯丙树脂可提高PVC树脂的加工性能和力学性能,可部分替代ACR或CPE等助剂;④经氯丙树脂改性生产的PVC型材和注塑管件性能合格,可简化注塑生产工艺,提高碳酸钙的用量,从而降低产品成本。     

Synthesis and characterization of styrene‐butyl acrylate polymers,varying feed composition in a semicontinuous emulsion process

Two‐stage polymerization has been used to improve properties of two‐component polymers. In this work, a semicontinuous emulsion process varying feed composition along the reaction is used to produce copolymer chains of different composition as conversion proceeds. Polymer composition and evidence of branching were determined by ¹H‐NMR. Polymer molecular weight values determined by GPC are beyond the range where mechanical properties depend on molecular weight. Mechanodynamic properties show a copolymer type behavior with a synergistic effect around the 50/50 styrene/butyl acrylate composition ratio. For such composition, mechanical performance superiority of variable composition copolymer with respect to two‐stage polymer was confirmed with stress–strain tests carried out at several temperatures. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3964–3971, 2007     

Revisiting emulsion polymerization to produce stable,translucent, nanolatex of partially water‐soluble monomers,ethylacrylate–methylmethacrylate

Stable, translucent nanolatex with monomer weight % as high as 25 was obtained through emulsion copolymerization of partially water‐soluble monomers, ethyl acrylate and methylmethacrylate. The kinetics of reaction, studied at monomer/surfactant (M/S) ratio 10 and 50 showed two intervals and higher rate of particle nucleation for KPS initiated systems. However, AIBN initiated system showed phase separation. The copolymer composition was determined through ¹H‐NMR studies and copolymers showed two glass transition temperatures. Dynamic light scattering studies indicated bimodal distribution of polymer particle size. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2593–2603, 2003     

A kinetic investigation of styrene/butyl acrylate copolymerization

An experimental investigation of the kinetics of the bulk free radical copolymerization of styrene/butyl acrylate initiated with 2,2′-azobisisobutyronitrile (AIBN) was conducted at 50°C using various initiator concentrations and initial monomer ratios including the azeotropic composition. Reactivity ratios were determined by analyzing composition data using the error-in-variables model. The experiments, designed using the Tidwell-Mortimer criterion, were conducted in sealed ampoules at 50°C to low conversion levels (< 7%). From the calculated reactivity ratios, the azeotropic composition was determined and further experiments were run at these conditions as well as at two other initial monomer feed compositions in order to collect composition, rate and molecular weight data. The experiments were run through the full conversion range at two different initiator concentrations.     

Influence of Particle Size Distribution of Bimodal Reactive Alumina on Properties of LCC Refractory Castables

The effect of particle size distribution of alumina has been investigated for silica-free tabular alumina low cement castables( LCC). Three different combinations of alumina have been included in the matrix formulation of the castables. All the three combinations are composed of a bimodal reactive alumina and a fine ground monomodal reactive alumina. The first A1 and second A2 combinations are respectively composed of bimodal and monomodal aluminas from Alteo,with a different fine /coarse particles ratio for the bimodal alumina. The two Alteo combinations have been compared with a third combination C composed of a bimodal commercially available grade and a monomodal commercially available grade. Optimization of particle size packing has been performed for the three different formulations using the Dinger and Funk model. With this optimization,the two formulations based on Alteo material( PFR,PBR and PFR40) achieve the same level of performance in applicative tests( flowability,cold physical properties,mechanical resistance,crystalline phases,thermal shocks and corrosion) as reference solutions on the market.     

Modeling and experimental studies of emulsion copolymerization systems. III. Acrylics

Using a previously published model and continuing the series of papers started with styrenic copolymers, predictions for evolution of conversion and average particle diameter in batch experiments are compared against experimental data for four emulsion copolymerizations involving at least one acrylic monomer: (1) methyl methacrylate/butyl acrylate, (2) methyl methacrylate/butadiene, (3) methyl methacrylate–vinyl acetate, and (4) butyl acrylate/vinyl acetate. For each system a fraction of factorial experiments were run covering simultaneous variations in five variables: initiator [I] and surfactant [E] concentrations, water to monomer ratio (W/M), monomer composition, and temperature. Data fitting is performed to represent the experimental data as several parameters are not available from independent experimental sources. The model is able to explain the effects of simultaneous changes in emulsifier concentration, initiator concentration, and water to monomer ratio on conversion and average particle size histories, although in some cases only qualitatively. An assessment of the degree in which a general emulsion copolymerization model is useful for practical applications is made. Physical insight is also gained by observing the trends of adjusted parameters with temperature and copolymer composition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1320–1338, 2002; DOI 10.1002/app.10003     

Novel methods for synthesis of high‐impact polystyrene with bimodal distribution of rubber particle size

By using in situ prepolymerization and radiation curing, high‐impact polystyrene (HIPS) with a bimodal distribution of the size of the rubber particles (bimodal HIPS) was synthesized in the presence of ultrafine full‐vulcanized powdered styrene–butadiene rubber (UFPSBR) and polybutadiene rubber (BR). TEM photographs indicated that UFPSBR was dispersed uniformly as a single particle with a diameter of about 100 nm. On the other hand, bimodal HIPS with different rubber particle size distributions could also be obtained by blending HIPS and UFPSBR grafting styrene (UFPSBR‐g‐St) with different grafting yields. The bimodal HIPS with the smallest rubber particle size, at about 100 nm, could be prepared by blending the monomodal HIPS containing big rubber particles with polystyrene/UFPSBR. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of morphology on mechanical and rheological properties of butyl acrylate–methyl methacrylate multiphase polymers

Polymers of butyl acrylate–methyl methacrylate with different morphologies were synthesized by emulsion polymerization. Four types of polymers were obtained: copolymer, core–shell, three layer, and a core–shell with a copolymer layer of variable composition (gradient). The effect of the morphologies on the mechanical and rheological properties of these polymers was studied. It was found that when the same overall composition was used the properties of the polymer can be varied from those of rigid plastic to those of an elastomeric material. It was found that increasing the content of butyl acrylate (BA) improves the mechanical properties and the presence of a copolymer zone improves the impact resistance of the material. © 1995 John Wiley & Sons, Inc.     

用阴离子Gemini 9 B-6-9 B乳化剂合成苯乙烯-丙烯酸丁酯共聚物纳米乳液

以壬基酚、1,6-二溴己烷、氯磺酸为主要原料合成的阴离子Gemini磺酸盐表面活性剂9 B-6-9 B为乳化剂,苯乙烯(St)、丙烯酸丁酯(BA)为单体,合成了乳胶粒径小于100 nm且分布均匀的苯乙烯-丙烯酸丁酯共聚物纳米乳液,考察了聚合温度、乳化剂用量、引发剂用量、单体配比、单体含量对乳液的影响,探讨了乳胶粒子成核机理。结果表明,随着温度的升高,乳胶粒子的平均粒径减小,转化率与凝胶率增大;随着乳化剂或引发剂用量的增加,乳胶粒子的平均粒径和凝胶率减小,转化率增大;随着软单体比例的增加,乳胶粒子的平均粒径与转化率增大,粒径分布变宽,凝胶率减小;单体用量增大,乳胶粒子的平均粒径与凝胶率增大,转化率降低;乳胶粒子的粒径呈单峰分布,可能是按胶束成核机理形成的。     

Effect of SiCp multimodal distribution on pitting behavior of Al/SiCp composites prepared by reactive infiltration

The effect of coated-SiC_p multimodal-size-distribution on the pitting behavior of Al/SiC_p composites was investigated. α-SiC powders (10, 54, 86, and 146 μm) were properly mixed and coated with silica to produce porous preforms with 0.6 volume fraction of the reinforcement with monomodal, bimodal, trimodal, and cuatrimodal size distribution. The preforms were infiltrated with the alloy Al–13 Mg–1.8Si (wt.%) in argon followed by nitrogen at 1100 ºC for 60 min. The composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) before and after cyclic polarization measurements in 0.1 M NaCl de-aerated solutions. Results show that whereas corrosion and passivation potentials are not influenced with increase in SiC_p particle size distribution, favorably, the susceptibility to pitting corrosion decreases. This beneficial effect is ascribed to the smaller area of the alloy matrix exposed to the chloride solution with augment in particle size distribution, substantially when going from monomodal to bimodal SiC_p particle size distribution.     

不同粒径含氟丙烯酸酯共聚乳液的合成及膜表面疏水性能研究

采用半连续种子乳液聚合的方式,以丙烯酸丁酯、甲基丙烯酸甲酯和甲基丙烯酸六氟丁酯为原料制备了粒径分别为30nm、75nm、210nm左右的含氟丙烯酸酯共聚物乳液。通过乳胶粒核壳结构设计与大小粒径乳液机械共混改性2种方法研究了如何在较少含氟单体用量的情况下达到较好的表面疏水性能。利用X射线光电子能谱、动态光散射仪、接触角测定仪等分析手段,研究了共聚物膜的表面性能和共聚物乳液粒径的大小及分布,测试结果表明,核壳结构乳液成膜后壳层含氟量较高,膜表面接触角大于90,°疏水性能强;而大小粒径乳液共混物成膜后表面含氟量较低,却仍能得到90°以上的接触角,表明乳胶膜表面具有粗糙结构,具有一定的仿荷叶效应。