单体预聚乳化法合成水性苯丙乳液及性能研究

采用单体预聚乳化法,以苯乙烯(St)、丙烯酸(AA)、丙烯酸丁酯(BA)为原料,过硫酸钾(KPS)为引发剂,十二烷基硫酸钠(SDS)和聚氧乙烯醚烷基酚(Op-10)的混合物为复合乳化剂合成绿色水性苯丙乳液。对该苯丙乳液附着力、DSC、涂膜硬度等进行表征,并对该乳液的机械稳定性、抗化学试剂的稳定性、黏度等进行测试。研究表明,单体V(苯乙烯St):V(丙烯酸丁酯BA)=1∶1时,乳化剂m(OP-10)∶m(SDS)=2∶1时,此时苯丙乳液黏度最大,附着力最好;通过DSC、涂膜耐酸碱测试,玻璃化温度低于理论值,表明该产品具有很好的涂膜性能和机械稳定性。     

Continuous emulsion polymerisation of styrene and methyl acrylate

An investigation of continuous emulsion polymerisation kinetics was carried out using a series of three continuous stirred tank reactors (CSTR), and styrene and methyl acrylate as types of monomer with different solubilities in water. Steady-state conversion fluctuations reported in the literature could be suppressed by holding the feed rates constant. The results obtained are only partly in agreement with the theory proposed by Gershberg & Longfield, who combined the basic assumptions of the Smith-Ewart theory with steady-state CSTR kinetics. An explanation for the deviations from this theory is therefore suggested which takes into account the tendency of relatively water-soluble monomers to form particles from the homogeneous solution and to undergo so-called interparticle termination as a result of migration of radicals between the latex particles.     

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.     

Studies of 2-hydroxyethyl methacrylate and ethyl acrylate copolymers as negative photoresists

The potential of 2-hydroxyethyl methacrylate and ethyl acrylate copolymers as negative photoresists was studied. Negative photoresist solution was prepared by esterfication of copolymers with cinnamoyl chloride. The effects of photosensitizer concentration, copolymer composition, and exposure time were investigated. A resolution of 30 μm was attained from these photoresists.     

Study on emulsion copolymerization of styrene andn-butyl acrylate

Summary The emulsion copolymerization of styrene and n-butyl acrylate has been investigated. Copolymers were obtained at 70°C in the presence of sodium lauryl sulfate, an anionic micelle generator and ammonium persulfate as initiator. The ideal time of reaction, the effect of the amount of initiator, temperature and comonomer composition were also studied. The copolymers have been characterized through gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR).     

Microstructure study of styrene/n-butyl acrylate emulsion copolymers by 13C nuclear magnetic resonance spectroscopy

A detailed study of the sequence distribution in styrene (S)/n-butyl acrylate (A) emulsion copolymers using ¹³C nuclear magnetic resonance spectroscopy is reported. From the interpretation of the spectra of the homopolymers and copolymers, assignment of the carbonyl (A) and quaternary (S) carbon atom resonances has been made. This provides a quantitative estimation of the compositional triad distributions in the copolymers. The results were found to be in relatively good agreement with calculated triad fractions deduced from a simulation program taking into account the actual reactivity ratios and type of emulsion process.     

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.     

Aluminum triflate-cocatalyzed radical copolymerization of styrene and ethyl acrylate

Polymer Bulletin - Various random copolymers, poly(styrene-co-ethyl acrylate), were synthesized by free radical bulk copolymerization cocatalyzed by aluminum triflate (Al(OTf)3). The experimental...     

Graft copolymers with hydrophilic and hydrophobic polyether side chains

Poly(ethylene glycol)methyl ether methacrylate (PEOMA) and oligo(propylene glycol)-4-nonylphenyl ether acrylate (OPOPhNA) were copolymerized by atom transfer radical polymerization (ATRP). Grafting through method was employed in the presence of CuBr/HMTETA or CuBr/PMDETA catalyst/ligand complex in anisole at 70 °C. It yielded a heterografted copolymers containing hydrophilic PEO and hydrophobic OPOPhNA side chains with polymerization degree DP = 68-315 in the presence of PMDETA and DP = 48-195 in the presence HMTETA. Moreover, higher reactivity of PEOMA than OPOPhNA (r_methacrylate > r_acrylate), which was observed during copolymerization, suggested the formation of copolymers with a spontaneous gradient composition starting from the grafted segment of P(PEOMA). The molecular weight distribution (MWD) was increased with DP in the range 1.2-1.6. The X-ray diffraction analysis (WAXS) indicated that larger number of PEO segments generated crystalline properties in the copolymers with amorphous OPOPhNA.     

苯丙共聚物乳液合成研究

以苯乙烯,丙烯酸酯类为共聚单体,采用乳液聚合合成了低成本的苯丙共聚乳液。讨论了单体共聚比,ｐＨ调节剂,乳化剂等对乳液聚合的影响。     

Ionomer synthesis by emulsion polymerization of styrene and sodium acrylate

The emulsion copolymerization of styrene and sodium acrylate is reported using either a water-soluble initiator (potassium persulfate, or KPS), or an oil-soluble one [2,2-azoisobutyronitrile (AIBN)]. Reaction rates are fast with both KPS and AIBN. With KPS, conversions >90% are achieved in 50 min, with AIBN, conversions reach 85% in 100 min. Particle size, measured by quasielectric light scattering (QLS), increases with conversion. Particle size in final latices is ∼ 70–80 nm. Copolymer formation is confirmed by infrared (IR) spectroscopy, plasma emission spectroscopy (PES), and scanning electron microscopy (SEM). IR and PES indicate that mainly sodium acrylate reacts at the beginning of the reaction and then styrene is incorporated in the copolymer backbone. The copolymer produced with KPS contains more sodium acrylate than the one made with AIBN. These differences can be explained in terms of the reactivities and partitioning (local concentrations) of the monomers and of the type of initiator used. Thermomechanical analysis (TMA) of the copolymers reveals two transitions: one at ∼ 100°C, which is due to the glass transition temperature (T_g) of polystyrene blocky segments in the copolymer, and another one at higher temperatures, which is associated to the T_g of segments composed of alternated sodium acrylate and styrene units. The higher-temperature transition shifts to lower values as the reaction proceeds because these segments become richer in styrene. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 879–889, 1997     

丙烯酸甲酯和丙烯酸全氟烷基乙酯嵌段共聚物的合成和表面性能

用原子转移自由基聚合法合成了丙烯酸甲酯和丙烯酸全氟烷基乙酯的两嵌段共聚物,研究了嵌段共聚物的表面性能。结果表明,嵌段共聚物具有低表面能特性。且X射线光电子光谱法证明氟烷基链有强烈的趋于表面的特性。     

Effect of emulsifiers on emulsion copolymerization of styrene and n-butyl acrylate

Summary The emulsion copolymerization of styrene and n-butyl acrylate was conducted at 70°C using anionic or nonionic emulsifiers, or a mixture of both at different concentrations. The effect of the emulsifiers on the overall conversion was examined. The latex morphology with special attention to average particle diameter and particle diameter distribution was also studied. The latexes were characterized by LASER light scattering (LLS) and transmission electron microscopy (TEM).     

Molecular weight distribution of polystyrene and of butadiene–styrene copolymers prepared in emulsion systems

Polystyrene and butadiene–styrene copolymers (SBR) were prepared in emulsion systems with a homologous series of commercial mercaptan modifiers. The molecular weight distribution (MWD) of the sets of polymers changed in a consistant manner when the regulating index of the mercaptan was relatively low. However the shape of the MWD curves appeared distorted in comparsion to theoretical curves when the modifier depleted rapidly and when divinylbenzene was present in the system. The divergence from the theoretical curve is attributed to a higher degree of branching in the high molecular weight fractions. Differences in MWD of SBR made with n- and tert- dodecyl mercaptans was marked. Notable differences were also found for SBR 1500 samples from the industry at random, but only slight differences were seen in a set of SBR 1503 samples. This study shows how the MWD of polymers prepared in emulsions can be varied simply by use of modifiers with different regulating indexes.     

苯乙烯改性丙烯酸酯类乳液的合成及性能研究

采用半连续预乳化聚合方法合成苯丙乳液,研究了聚合温度、反应时间、乳化剂用量及引发剂用量对单体转化率和聚合稳定性的影响;探讨了不同MMA／St配比对单体转化率、乳液粒径、胶膜吸水性及耐热性的影响。对共聚物进行了红外分析。结果表明,当乳化剂用量为2．5％、引发剂0．5％、聚合温度为80℃、反应时间120min、mMMA／mSt=6：4时,能得到各项性能指标优异的苯丙乳液,合成产品的耐水性和耐热性都较纯丙乳液有明显提高,产品可用作静电植绒粘合剂。     

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.     

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      

Lipase-catalyzed synthesis and characterization of copolymers from ethyl acrylate as the only monomer starting material

Several acrylic copolymers containing, at random, sequences of poly(ethyl acrylate) and poly(N-(2-hydroxyethyl)acrylamide) were obtained from ethyl acrylate as the only monomer starting material in a chain polymerization process, catalyzed by Candida antarctica lipase B. In the presence of ethanolamine, the enzyme not only catalyzes the chain polymerization of ethyl acrylate but also aminolysis the pendant ester groups. The products, characterized by FTIR, ¹H and ¹³C NMR and UV-MALDI-TOF-MS, show low molecular weight and high monodispersity. The activity showed by C. antarctica lipase B in the polymerization reaction is a new example of enzyme promiscuity.     

Semicontinuous emulsion copolymerization to obtain styrene–methyl acrylate copolymers with predetermined chemical composition distributions

Four types of emulsion copolymerization processes were applied to produce various styrene–methyl acrylate copolymer latices. (1) Batch emulsion copolymerization. (2) Monomer starved semicontinuous emulsion copolymerization, i.e., a monomer mixture of constant composition was fed to the reactor at a constant rate. Sufficiently low addition rates led to homogeneous copolymers. (3) Optimal addition rate profiles were used to produce homogeneous emulsion copolymers in relatively short times. The profiles were determined in a semiempirical way, and applied to three different copolymer compositions. (4) We made an attempt to determine an addition rate profile to produce a heterogeneous emulsion copolymer with predetermined heterogeneity, i.e., a copolymer of which the chemical composition distribution (CCD) did not consist of one narrow peak, as with homogeneous copolymers, but had a predetermined broadness profile. Strategies (2) and (3) were used to produce homogeneous emulsion copolymers with varying fractions of styrene. Strategy (3) was also used to demonstrate the influence of the monomer ratio on the kinetics. The advantage of this method is that the monomer ratio is constant over the whole conversion range in the latex particles. High performance liquid chromatography (HPLC) was used to determine the homogeneity/heterogeneity of the copolymers produced, and proved to be invaluable in determining the optimal addition rate profile. The final goal will be to study the influence of the chemical composition distribution (CCD) on mechanical properties of these copolymers, as both homopolymers used in this study have quite differentglass transition temperatures; the results will be published later. © 1993 John Wiley & Sons, Inc.     

丙烯酸丁酯/苯乙烯/功能单体多元共聚乳液的合成

通过一步加料和滴加引发剂的方法合成了丙烯酸丁酯、苯乙烯和功能单体的多元共聚乳液,对其性能进行了表征。结果表明:在合适的单体配比条件下,可以得到一种较高固含量、低粘度,且具有良好稳定性的共聚乳液。