Semicontinuous emulsion polymerization of methyl methacrylate,ethyl acrylate,and methacrylic acid

By a semicontinuous emulsion polymerization method with a variable monomer feed rate, a terpolymeric latex of methyl methacrylate and ethyl acrylate functionalized with methacrylic acid was synthesized. Conversion and reactor temperature vs. time were followed during the reaction. Characterization of the latex system was performed by particle-size measurements, scanning electron microscopy, infrared spectroscopy, viscometric molecular weight, glass transition temperature measurement, and rheological behavior. © 1996 John Wiley & Sons, Inc.     

Modelling of a continuous kneader reactor for the polymerization of partially neutralized acrylic acid

A mathematical model and analysis of the continuous polymerization of partially neutralized acrylic acid (AA) in a continuous kneader reactor is presented here as an initial attempt to simulate the synthesis of a superabsorbent polymer. A detailed kinetic model has been used to describe the copolymerization of AA and sodium acrylate (NaA) in aqueous medium. This model is used to describe batch and continuous operations. The polymerization is initiated by a mixture of potassium persulphate (K₂S₂O₈, KPS) and hydrogen peroxide (H₂O₂) as oxidizing agent and ascorbic acid (AsA) as reducing agent. A novel set of kinetic parameters has been estimated by fitting experimental data from different literature sources. The operation of a continuous kneader reactor modelled as a plug-flow reactor with axial dispersion is theoretically investigated to predict temperature profile, total and individual monomer conversion, consumption of KPS, H₂O₂, and AsA, and polymer average molecular weights. The simulation results show the presence of a hot spot close to the reactor entrance that could be potentially severe during startup and could have a detrimental impact on polymer quality. This model is a first step in the direction of achieving optimal operating protocols and exploring improved polymerization reactor designs.     

Salt-resistant superabsorbents from inverse-suspension polymerization of PEG methacrylate,acryamide and partially neutralized acrylic acid

The Superabsorbent resin was synthesized based on poly(ethylene glycol) methacrylate (PEGMA), acrylic acid(AA) and acrylamide(AM) by inverse suspension polymerization. By plenty of trial and error in previous works, we used mono-octadecyl phosphate as the dispersant to stabilize the suspension system effectively. In addition, the monomer we employed, PEGMA, also took a role as dispersant, this resulted in the shortage of mono-octadecyl phosphate to reduce the consumption of raw materials effectively. The effects of temperature, the concentration of monomers, the dosage of initiator, crosslinking agent and marcomonomer on the absorbency were studied. At the same time, the kinetics of swelling also was studied. The maximum absorption of the resin reached 930 mL/g and 94 mL/g for deionized water and 0.9 wt % NaCl solution, respectively.     

Soap-free emulsion polymerization of styrene using poly(methacrylic acid) macro-RAFT agent

A well-defined poly(methacrylic acid) (PMAA) macro-RAFT agent has been synthesized by the bulk polymerization using 4-toluic acid dithiobenzoate as a RAFT agent and successfully employed as a reactive emulsifier in the soap-free emulsion polymerization of styrene, leading to a formation of stable latex. The amphiphilic block copolymer, prepared from the in situ micelle formation, contains a hydrophilic PMAA block and a hydrophobic PS block, via styrene monomer transfer reaction to the dithioester function in PMAA macro-RAFT agent during the nucleation step. The chemical structure of the synthesized PS with the PMAA macro-RAFT agent was confirmed using FTIR and NMR. In addition, it was confirmed that the macro-RAFT agent is present on the particle surface via the ESCA measurement. The reaction mechanism was proposed that the stable spherical particles enlarged by the aggregation of small particles, which were also produced by the chemical or physical bonding between the tiny small particles. The results indicate that the PMAA macro-RAFT agent is used as emulsifier for the formation of PS particles and block copolymer [P(S-b-MAA)] in situ.     

Preparation of partially neutralized poly(acrylic acid) microspheres via inverse pickering suspension polymerization

Partially neutralized poly(acrylic acid) (PAA) microspheres have been prepared by Inverse Pickering Suspension Polymerization (IPSP) using 1,2‐dichlorobenzene (DCB) and hydrophobic fumed silica nanoparticles (HFSi‐NPs) as organic dispersing media and dispersing agent respectively. As crosslinker N,N'‐methylene bisacrylamide (MBAc), as initiator potassium persulfate (KPS) and sodium metabisulfite (SMBS) redox couple were used. Neutralization degrees were adjusted using 8N NaOH solution and polymerizations were initiated at 34°C. Water/oil phase ratio was set to 1/7 for all polymerizations. Morphology of prepared dry poly(acrylic acid) beads was examined by two microscopic methods, scanning electron microscopy (SEM) and optical microscopy. Prepared microsized polymer beads were observed as smooth and spherical in shape. Effect of neutralization degree (α) varied from 70% to 90% on absorptions in both distilled water and saline solutions, absorption under load (AUL) and crosslink density (CD) results were also investigated. POLYM. ENG. SCI., 59:162–169, 2019. © 2018 Society of Plastics Engineers     

Emulsifier‐free emulsion copolymerization of styrene with methacrylic acid

The study on batch emulsifier‐free emulsion copolymerization of styrene with methacrylic acid was conducted. The copolymerization process was followed by gravimetry, infrared, and transmission electron microscopy. The copolymerization mechanism differs from that of styrene with acrylic acid. The effect of solid content on particle size was examined, and it was found that the particle size was increased as the solid content was increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1747–1751, 2003     

Stability of nanoparticles during semibatch emulsion polymerization of butyl methacrylate,in the presence of methacrylic acid via RSM

The size and stability of latex particles in the semibatch emulsion polymerization of butyl methacrylate (BMA), in the presence of 0–10% methacrylic acid (MAA), were investigated. Response surface methodology (RSM), as a design of experiment, was used to obtain a more systematic understanding of the role of emulsifier and MAA in the stability of the particles. The amount of coagulum can be greatly reduced by increasing the concentration of sodium lauryl sulfate (SLS) in the monomer emulsion feed (MEF) and initial reactor charge (IRC). On the other hand, increasing the concentration of SLS in the IRC can result in a decrease of the particles size. According to the experimental data, the yield of reaction can be improved with incorporation of MAA into the emulsion polymers. The size and morphology of particles were obtained by scanning electron microscopy (SEM). FTIR and titration were used to determine the percentage of MAA in the copolymer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Studies of the polymerization of methacrylic acid via free-radical retrograde precipitation polymerization process

In this paper, we present some new results of our work in a novel polymerization process (called the free-radical retrograde precipitation polymerization, or FRRPP, process) that occurs at temperatures above the lower critical solution temperature. Our polymerization experiments basically involve the methacrylic acid–poly(methacrylic acid)–water system. Experimental results indicate a gradual increase in conversion with time after what seemingly is the onset of phase separation. In an equivalent solution polymerization system, conversion of methacrylic acid reaches almost 100% at a much shorter time than in the FRRPP system. Molecular weights of poly(methacrylic acid) at different times for the FRRPP system are not dramatically different from those obtained in the solution system. However, the FRRPP system yields a relatively narrow molecular weight distribution at a wide range of conversion compared to that obtained in the equivalent solution system. The unique characteristics of the FRRPP process is shown in the asymptotic time behavior of the free-radical concentration compared to the decay behavior in other polymerization systems. © 1996 John Wiley & Sons, Inc.     

Microsphere synthesis by emulsion copolymerizations of styrene with poly(methacrylic acid) macromonomers

The polymer microspheres were synthesized by emulsion copolymerizations of styrene with vinyl benzyl terminated poly(methacrylic acid) (PMA) macromonomers in an aqueous ethanol solution. In these copolymerization systems, the macromonomer acted not only as a comonomer but also as a stabilizer. The particle diameters obtained from the water‐soluble initiator system showed smaller values than those obtained from the water‐insoluble initiator system. These polymer microspheres had a very narrow particle‐size distribution. The particle diameters depended strongly on the feed amount and molecular weight of PMA macromonomers, water fraction in the mixed solvent, and pH in the medium. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 900–905, 2002     

Crosslinking of partially neutralized carboxyl-terminated liquid rubbers with bisepoxide and anhydride

Crosslinking of partially neutralized carboxyl-terminated liquid rubbers (PNCTLR) with bisepoxide and anhydride was investigated by the PNCTLR–bisepoxide–anhydride reactions. The PNCTLR were prepared, by the partial neutralization with MgO and CaO, from a polymer of butadiene (Hycar CTB 2000X162) and a copolymer of butadiene–acrylonitrile (Hyca? CTBN 1300X8). As the bisepoxide, bisphenol-A diglycidyl ether was used, and hexahydrophthalic anhydride was the anhydride used. It was found that the metal carboxylate groups of PNCTLR catalyze the crosslinking reactions, and, further, the Mg carboxylate group showed higher catalytic activities than the Ca carboxylate group. As for the physical properties of the cured rubbers obtained, the rubbers containing Mg showed higher tensile strength and Shore A hardness than those containing Ca. In addition, the CTBN-series cured rubbers showed better physical properties than those of the CTB-series, because of a polarity effect of nitrile groups in the former rubbers. Resistances to water and chemical attack, thermal behavior, and stress relaxation are also discussed.     

Chain extension of partially neutralized carboxyl-terminated liquid polybutadiene with bisepoxide

Chain extension of partially neutralized carboxyl-terminated liquid polybutadiene (PB) with bisepoxide was investigated by the carboxyl–epoxide reaction. The partially neutralized liquid PB were prepared, by the partial neutralization with MgO and CaO, from a carboxyl-terminated liquid PB (Hycar CTB 2000X162). As the bisepoxide, hydroquinone diglycidyl ether was used. The metal carboxylate groups in the system catalyzed the reaction and, further, the Mg carboxylate group showed higher catalytic activity than the Ca carboxylate group. The chain-extended metal-containing PB obtained by the reaction were found to be elastic when subjected to a rapid impact, but plastic under slowly applied stress and their solution behavior in pyridine was examined. The viscosities were very low at very low concentrations but increased markedly as the concentration increased. This solution behavior is attributed to ionic associations of carboxylate anions and metal cations to longer chains. Further, thermal and other properties were evaluated.     

乳液聚合法聚丙烯酸树脂的制备研究

介绍了以丙烯酸、苯乙烯、丙烯酸丁酯、丙烯酸羟丙酯为单体,采用过硫酸铵作为引发剂,以非离子乳化剂聚氧乙烯醚(OP-10)和阴离子乳化剂十二烷基硫酸钠(SDS)作为复合乳化剂,经过乳液聚合,制得了一种水性涂料用缔合型增稠剂.考察了丙烯酸单体含量、乳化剂用量对乳液性能和增稠剂黏度的影响.优化了反应条件,反应过程和最终乳液都很...     

无皂乳液聚合法制备丙烯酸改性聚醋酸乙烯酯乳液的研究

以丙烯酸(AA)为改性单体,过硫酸铵(APS)为引发剂,采用无皂乳液聚合法制备了AA改性PVAc(聚醋酸乙烯酯)乳液。着重探讨了AA和APS含量对乳液凝胶率、转化率、固含量、粒径分布以及耐水性等影响。研究结果表明:该乳液是由3种单体共聚而成的;当w(AA)=20%、w(APS)=0.5%(均相对于混合单体总质量而言)时,聚合反应转化率(为82.5%)相对最大、凝胶率(为0.81%)相对最小、乳液平均粒径为2.17μm且粒径分布较窄,胶膜的耐水性较佳(吸水率仅为17.35%)。     

Synthesis of syndiotactic poly(methacrylic acid) by free‐radical polymerization of the pseudo‐divinyl monomer formed with methacrylic acid and catechol

Syndiotactic poly(methacrylic acid) (Syn‐PMAA, r diad = 91 mol %) was synthesized by free radical polymerization of methacrylic acid (MAA) with catechol. The pseudo‐divinyl monomer was formed with one catechol and two MAA molecules by the hydrogen bonding between OH groups of catechol and COOH group of MAA. When the free radical polymerization of the pseudo‐divinyl monomer was carried out, intra‐ and intermolecular addition proceeded with racemic addition. The hydrogen bonding was the driving force to control tacticity. We discussed the effects of solvent, temperature, and the concentrations of MAA and catechol on the pseudo‐divinyl monomer formation. The highly syndiotactic PMAA was successfully obtained. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

High solid content multisized emulsion copolymerization of styrene,butyl acrylate,and methacrylic acid

Polymer lattices with a multimodal particle size distribution (PSD) polymer latex were prepared by introducing additional surfactants during the semicontinuous emulsion polymerization of styrene, butyl acrylate, and methacrylic acid. The polymerization was investigated by following the variation of the particle size, the size distribution, the number of particles, the T_g of the different particle sizes, and the total conversion at different steps of the polymerization process. The results show that bimodal and trimodal PSD polymer lattices can be obtained by this method and that the secondary generation of particles is greatly influenced by the nature and the amount of additional surfactants, as well as the moment when they are introduced. When the amount of additional surfactants is increased, the diameters of both the small and large particles decrease and the number of particles in each of the populations increases. Earlier introduction of these surfactants favors the generation and the growth of the small particles and thereby leads to a reduction of the relative fraction of large particles in the final latex. On introduction of 7 wt % of additional surfactants, based on the total monomers, 100% of the monomers of the second-stage polymerization were consumed to form the small particles. This fraction decreases with a decreasing amount of the additional surfactants. These results were further demonstrated by measuring the T_g's of both the large and the small particles of two lattices, in which the T_g's of the copolymers produced in each of the stages were different. High solid content (>65%), low viscosity, and coagulum-free lattices have been obtained through secondary nucleation, and a minimum in viscosity was found when the weight fraction of the large particles was around 80%. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2667–2677, 1998     

The intrinsic viscosity of poly(acrylic acid) and partially neutralized poly(acrylic acid) by isoionic dilution

The isoionic dilution method has been used to measure the intrinsic viscosity, [η], of a poly(acrylic acid) (PAA) sample as a function of neutralization degree, i, at low ionic strength, I = 1.0 × 10. The results obtained for the counterion activity are in close agreement with Manning's theory for counterion condensation. The influence of the ionic strength, I, on [η] and on the Huggins coefficient, k', was also examined and the exponents of the scaling laws relating these two parameters with I were found.     

Incorporation of nonionic emulsifiers inside styrene–methacrylic acid copolymer particles during emulsion copolymerization

Emulsion copolymerizations of styrene and methacrylic acid with polyoxyethylene nonylphenyl ether nonionic emulsifiers having various hydrophilic–lipophilic balance (HLB) values (13.7, Emulgen 911; 15.5, Emulgen 920; 17.2, Emulgen 931) were performed. The incorporation behavior of the nonionic emulsifiers, comprising polydisperse poly(ethylene oxide) (PEO) chain lengths, inside the particles was investigated. At the completion of the polymerization, the incorporated percentage of the lowest HLB emulsifier was 61%, much higher than that of the highest HLB one (10%). In both polymerizations, the amounts of the incorporated emulsifiers increased with conversion, and shorter PEO chain (i.e., lower molecular weight) components were predominantly incorporated over longer PEO chain components.     

Preparation and characterization of porous poly(methacrylic acid) gel by dispersion polymerization

Porous poly(methacrylic-co-glycidylmethacrylate) (MAA-GM) was prepared by dispersion polymerization using benzoyl peroxide as an initiator and methacrylate terminated phthalate glycol polyester as a steric stabilizer in polar organic medium (chloroform–ethanol mixture). The prepared poly(methacrylic acid) dispersion was crosslinked by glycidylmethacrylate oligomers. The crosslinked copolymer (MAA-GM) was base hydrolyzed using hydroxyl amine, sodium methoxide, and triethyl amine. The metal binding behavior of the prepared polymer was examined by means of atomic absorption spectrophotometer. The thermal stability of the prepared polymers was examined by thermal gravimetric analysis (TGA). © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1793–1798, 1999     

Preparation,characterization, and performance of poly(acrylamidocaproic acid) partially neutralized with calcium for use in nanofiltration

The preparation, characterization, and application to nanofiltration of a membrane made of poly(acrylamidocaproic acid) partially neutralized with calcium using the thin-film composite membrane technique are reported in this study. The long hydrophobic side substituent prevents excessive swelling with water and binds the chain. The neutralized ionic group is designed to enhance the affinity of the membrane to water. By controlling the degree of neutralization, the performance of the membrane could be adjusted. The amount of water molecules participating in the hydration shell surrounding an ionic group was increased with increasing ionic concentration in the membrane. The exponential increase of flux with increasing degree of neutralization is due to the increase of the number and size of the hydration shell. The effect of the pressure and molecular weight of the solute on performance was also investigated. The surface interaction between the solute and the membrane seemed to mainly affect the characteristics of performance. © 1996 John Wiley & Sons, Inc.     

丙烯酸改性聚醋酸乙烯酯乳液聚合的研究

通过丙烯酸与聚乙二醇共聚合成了具有反应活性的丙烯酸聚氧乙烯酯（简称大单体）,将大单体作为表面活性剂对醋酸乙烯酯乳液聚合的动力学进行了研究;同时在性能上与普通的乳液聚合体系进行了比较。实验结果表明聚合速率随亲水链长度、乳化剂浓度、引发剂浓度、温度的增大而增大,pH值的减小而加快,乳液性能也有了很大的改善．