A comprehensive kinetic model for high‐temperature free radical production of styrene/methacrylate/acrylate resins

n‐Butyl methacrylate/styrene/n‐butyl acrylate (BMA/ST/BA) high‐temperature starved‐feed solution semibatch copolymerization and terpolymerization experiments with varying monomer feed composition, final polymer content, monomer feed time, and reaction temperature were carried out. A comprehensive mechanistic terpolymerization model implemented in PREDICI includes methacrylate depropagation, acrylate backbiting, chain scission, and macromonomer propagation, as well as penultimate chain‐growth and termination kinetics. The generality of the model was verified by comparison with terpolymerization data sets from two laboratories that demonstrate the impact of high‐temperature secondary reactions on polymerization rate and polymer molecular weight. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Emulsifier‐minor emulsion copolymerization of BA‐MMA‐St‐MAA (or AA)‐N‐MA

A novel emulsion polymerization technique referred to as emulsifier‐minor emulsion polymerization was achieved by the copolymerization of methyl methacrylate, butyl acrylate, and styrene (MMA‐BA‐St) with a combination of water‐soluble ionic monomers [methacrylic acid (MAA) or acrylic acid (AA)] and nonionic monomers (N‐methylol acrylamide). In the technique, water‐soluble monomers play a crucial role in the stabilization of the latex particles as they can be bound to the particle surface and form a hydrate protective layer, which exhibits steric and/or electrostatic effects to prevent particle coagulation. The minor but over its critical micelle concentration emulsifier sodium alkylated diphenyl ether disulfonate (DSB) results in the nucleation of particles mainly by the micelle nucleation mechanism and thus determines the polymerization rate, the particle size, and the number. The film water resistance of the latices can be improved, and the foaming capacity of can be lowered by using technique instead of conventional emulsion polymerization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2923–2929, 2004     

丙烯酸/丙烯酸甲酯共聚物聚合工艺研究及其表征

以丙烯酸(AA)、丙烯酸甲酯(MA)为共聚单体,以过硫酸铵和亚硫酸氢钠为氧化还原体系引发剂,异丙醇为链转移剂,以水为溶剂,采用溶液聚合方法,合成P(AA-MA)共聚物,利用红外光谱对合成的共聚物结构和组成进行表征,研究了各因素对共聚物的特性粘数的影响程度,确定了最佳聚合条件为:单体比例为8∶1,加料时间0.5 h,聚合温度80℃,聚合时间2.5 h,过硫酸铵用量6%,亚硫酸氢钠用量2%,异丙醇100%(以单体质量计)。     

Synthesis,characterization, and antitumor activity of poly(maleic anhydride‐co‐vinyl acetate‐co‐acrylic acid)

The ternary copolymerization of maleic anhydride (MA), vinyl acetate (VA), and acrylic acid (AA) [P(MA‐co‐VA‐co‐AA)], which is considered to be an acceptor–donor–acceptor system, was carried out in 1,4‐dioxane with benzoyl peroxide as an initiator at 70°C under a nitrogen atmosphere. Constants of complex formation for the monomer systems in the study were determined by UV–visible (hydrogen‐bonding complex) and ¹H‐NMR (charge transfer complex) methods, respectively. The results show that polymerization of the P(MA‐co‐VA‐co‐AA) system proceeds by an alternating terpolymerization mechanism. It is shown that the synthesized copolymers have typical polyelectrolyte behavior, ability for reversible hydrolysis–anhydrization reactions, and semicrystalline structures. In these cases, including radical polymerization, and formation of semicrystalline structures, the hydrogen‐bonding effect plays a significant role. The in vitro cytotoxicities of the synthesized terpolymer and alternating copolymer were evaluated using Raji cells (human Burkitt lymphoma cell line). The antitumor activities of prepared anion‐active copolymers were studied using methyl–thiazol–tetrazolium colorimetric assay and 50% of the cytotoxic dose of each copolymer and terpolymer were calculated. Hydrolyzed P(MA‐co‐VA‐co‐AA) and P(MA‐alt‐AA) copolymers have sufficiently high antitumor activity, which depends on the amount of hydrogen‐bonding carboxylic groups and their regular distribution in the side chain of functional macromolecules. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3425–3432, 2006     

Comparative study of copolymerization and terpolymerization of ethylene/propylene/diene monomers using metallocene catalyst

(Ind)₂ZrCl₂ catalyst was synthesized and used for copolymerization of ethylene and propylene (EPR) and terpolymerization of ethylene propylene and 5‐ethyldiene‐2‐norbornene (ENB). Methylaluminoxane (MAO) was used as cocatalyst. The activity of the catalyst was higher in copolymerization of ethylene and propylene (EPR) rather than in terpolymerization of ethylene, propylene and diene monomers. The effects of [Al] : [Zr] molar ratio, polymerization temperature, pressure ratio of ethylene/propylene and the ENB concentration on the terpolymerization behavior were studied. The highest productivity of the catalyst was obtained at 60°C, [Al] : [Zr] molar ratios of 750 : 1 and 500 : 1 for copolymerization and terpolymerization, respectively. Increasing the molar ratio of [Al] : [Zr] up to 500 : 1 increased the ethylene and ENB contents of the terpolymers, while beyond this ratio the productivity of the catalyst dropped, leading to lower ethylene and ENB contents. Terpolymerization was carried out batchwise at temperatures from 40 to 70°C. Rate time profiles of the polymerization were a decay type for both copolymerization and terpolymerization. Glass transition temperatures (T_g) of the obtained terpolymers were between ?64 and ?52°C. Glass transition temperatures of both copolymers and terpolymers were decreased with increased ethylene content of the polymers. Dynamic mechanical and rheological properties of the obtained polymers were studied. A compounded EPDM showed good thermal stability with time. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanism of the copolymerization of styrene with methyl,ethyl, and n-butyl acrylates in the presence of zinc chloride

The complexes of methyl acrylate (MA), ethyl acrylate (EA) and n-butyl acrylate (BA) with zinc chloride (ZnCl₂) were prepared at 300 K and found to be polar in nature. The viscosity and density of the complexes increased while the tendency to form a binary complex decreased with increase in size of the alkyl substituents of the acrylate monomers. The copolymerization of MA and BA with styrene (Sty) followed a cross-propagation mechanism, whereas the copolymerization of EA with Sty followed a radical-complex mechanism in the presence of their complexes with ZnCl₂.     

Monomer-to-water ratios as a tool in controlling emulsion copolymer composition: The methyl acrylate–indene system

A drifting copolymer composition as a function of conversion is an aspect typical of copolymerization. Reducing this so-called composition drift in batch copolymerizations will lead to a decrease in chemical heterogeneity of the copolymers formed. For monomer systems in which the more water-soluble monomer is also the more reactive one, theory predicts that composition drift in emulsion copolymerization can be reduced or even minimized by optimizing the monomer-to-water ratio. The monomer combination methyl acrylate–indene (MA–Ind) meets the requirements needed to minimize composition drift in batch emulsion copolymerization. Therefore, this monomer combination is chosen as a model monomer system in order to verify this theoretical prediction. Reactivity ratios needed for model predictions have been determined by low conversion bulk polymerization, resulting in r_MA = 0.92 ± 0.16 and r_Ind = 0.086 ± 0.025. Furthermore, emulsion copolymerization reactions at the same monomer mole fraction are performed at different monomer to water ratios. From the good agreement between experiments and theoretical predictions for MA–Ind, it was concluded that control and even minimization of composition drift in batch emulsion copolymerization for monomer systems in which the more water-soluble monomer is also the more reactive one is indeed possible by changing the initial monomer-to-water ratio of the reaction mixture provided that the reactivity ratios of both monomers are not too far from unity. © 1994 John Wiley & Sons, Inc.     

Copolymerization of norbornene and methyl acrylate catalyzed by Nd(naph)<Subscript>3</Subscript>–Al(i-Bu)<Subscript>3</Subscript>

The copolymerization of norbornene (NB) and methyl acrylate (MA) catalyzed by Nd(naph)₃–Al(i-Bu)₃ and the structure of the copolymers are studied in this article. All polymerization reactions were carried out under nitrogen atmosphere using syringe technique. The copolymers are characterized by IR, ¹H NMR, ¹³C NMR, GPC, and TGA. Norbornene and methyl acrylate are 22.2 and 77.8 mol%, respectively, in the copolymer. The molecular weight distribution is M_w/M_n < 2.0. The molecular weight of copolymer changes with the change of NB/MA in molar ratio. Molecular weight and its distribution of copolymer decrease as molar ratio of NB/MA increases. The copolymerization can be performed in solvents such as aromatic hydrocarbon. The copolymerization can be obtained at room temperature, whereas the copolymer yield increases with increasing reaction temperature. The yield of copolymer changes with the Al/Nd molar ratio with a preferable Al/Nd molar ratio of 30.     

Synthesis and Swelling Behavior of Superabsorbents Cross-Linked with N-Maleyl Chitosan

A kind of superabsorbent based on the monomers maleic anhydride (MA) and acrylic acid (AA) was prepared by solution polymerization using ammonium peroxodisulfate (AP) and sodium bisulfite (NaHSO₃) as initiator, and N-maleyl chitosan (N-MACH) as cross-linker. Effects of process parameters such as the amount of cross-linker, mass ratio of MA to AA, and neutralization degree of AA on the water absorbency of superabsorbents are discussed. The results indicated the water absorbency of superabsorbents increased and then decreased with the increase of MA content, the amount of the N-MACH cross-linker, and the neutralization degree of AA. Under the optimal conditions, the water absorbency of superabsorbents could reach l560.42 g/g and 83.7 g/g in distilled water and in 0.9% NaCl solution, respectively. In addition, to enhance the water absorbency of superabsorbents in 0.9% NaCl solution, polyvinyl alcohol (PVA) was introduced as interpenetrating polymer in the network and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) was introduced as comonomer. It was proved that PVA and AMPS could effectively improve the water absorbency of superabsorbents both in distilled water and 0.9% NaCl solution.     

马来酸酐水溶液共聚体系的研究

选择不同配比和用量的 2 丙烯酰胺基 2 甲基丙基磺酸 (AMPS)、2 丙烯酰胺基 2 甲基丙基膦酸 (AMPP)、丙烯酸 (AA)、丙烯酰胺 (AM)、丙烯酸甲酯等 5种聚合单体和过硫酸盐 -Fe2 + 、过氧化氢 -Fe2 + 、过硫酸盐 -次磷酸盐、过氧化氢 -次磷酸盐等 4组引发体系与马来酸酐共聚合成一系列共聚物 ,并对其性能进行分析比较。结果表明 ,AMPS可作为此共聚体系第二单体 ,在所考察的第三单体、引发体系中 ,以AMPP、过氧化氢 次磷酸盐为最佳。当引发剂用量为单体总质量的 10 % [以次磷酸盐的质量计 ,m(过氧化氢 )∶m(次磷酸盐 ) =1.0∶1.2 ],m(MA)∶m(AMPS) =8∶6时合成的共聚物聚合率达 93.41% ,在加药质量浓度分别为 12mg/L和 18mg/L条件下 ,该共聚物对CaCO3 和Ca3(PO4 ) 2 垢的阻垢率分别为 6 6 .2 9%和 10 0 % ;在相同引发剂用量和加药质量浓度下 ,m(MA)∶m(AMPS)∶m(AMPP) =10∶4∶1时合成的三元共聚物的聚合率为 92 80 % ,对CaCO3和Ca3(PO4 ) 2 垢的阻垢率分别为 97.6 1%和 95 .92 %     

Experimental study of the spontaneous thermal homopolymerization of methyl and n‐butyl acrylate

This article presents an experimental study of the spontaneous thermal homopolymerization of methyl acrylate (MA) and n‐butyl acrylate (nBA) in the absence of any known added initiators at 120 and 140°C in a batch reactor. The effects of the solvent type, oxygen level, and reaction temperature on the monomer conversion and polymer average molecular weights were investigated. Three solvents, dimethyl sulfoxide (DMSO; polar, aprotic), cyclohexanone (polar, aprotic), and xylene (nonpolar) were used. The spontaneous thermal polymerization of MA and nBA in DMSO resulted in a lower conversion and higher average molecular weights in comparison to polymerization in cyclohexanone and xylene under the same conditions. The highest final conversion of both monomers was obtained in cyclohexanone. The high polymerization rate in cyclohexanone was most likely due to an additional initiation mechanism where cyclohexanone complexed with the monomer to generate free radicals. Bubbling air through the mixture led to a higher monomer conversion during the early stage of the polymerization and a lower polymer average molecular weight in xylene and cyclohexanone; this indicated the existence of a distinct behavior between the air‐ and nitrogen‐purged systems. Matrix‐assisted laser desorption/ionization time‐of‐flight analysis of the polymer samples taken from nitrogen‐bubbled batches did not reveal fragments from initiating impurities. On the basis of the identified families of peaks, monomer self‐initiation is suggested as the principal mode of initiation in the spontaneous thermal polymerization of MA and nBA at temperatures above 100°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of the MMA content on the emulsion polymerization process and adhesive properties of poly(BA‐co‐MMA‐co‐AA) latexes

In the past work, the shear resistance of pure poly(n‐butyl acrylate) was low, even incorporation of inorganic filler, silica in the composition. It is well‐known that the copolymerization of n‐butyl acrylate (BA) with methyl methacrylate (MMA) will increase the glass transition temperature, and enhance the shear resistance of acrylic polymers. In the current work, the preparation of a series of acrylic water‐borne pressure‐sensitive adhesives (PSAs) with the controlled composition and structure for the copolymerization of BA and acrylic acid (AA) with different MMA contents, poly(BA‐co‐MMA‐co‐AA) was reported and its effects on adhesive properties of the latices were investigated. The latices of poly(BA‐co‐MMA‐co‐AA) were prepared at a solid content of 50% by two‐stage sequential emulsion polymerization, and this process consisted of a batch seed stage giving a particle diameter of 111 nm, which was then grown by the semicontinuous addition of monomers to final diameter of 303 nm. Dynamic light scattering (DLS) was used to monitor the particle diameters and proved that no new nucleation occurred during the growth stage. Copolymerization of BA with MMA raised the glass transition temperature (T_g) of the soft acrylic polymers, and had the effect of improving shear resistance, while the loop tack and peel adhesion kept relatively high. The relationship between pressure‐sensitive properties and molecular parameters, such as gel content and molecular weight, was evaluated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of Gemini‐Like Methyl Acrylate‐Acrylic Acid‐Methyl Acrylate Triblock Copolymers Surfactants by RAFT Polymerization in Solution and Investigation of their Behavior at the Air–Water Interface

A series of methyl acrylate‐acrylic acid amphiphilic triblock copolymers (PMA‐PAA‐PMA) were prepared by solution polymerization using S,S′‐bis (α,α‐dimethy1acetic acid) trithiocarbonate (BDAT) as a reversible addition fragmentation chain transfer (RAFT) agent and methyl acrylate (MA) as the first monomer. The triblock copolymers and their common MA homopolymer precursors were characterized in terms of their compositions, molecular weights and behavior at the air–water interface using ¹H‐NMR spectroscopy, thermogravimetric analysis, gel permeation chromatography, surface tension, transmission electron microscopy (TEM) and dynamic light scattering respectively. The results indicated that PMA‐PAA‐PMA was successfully synthesized through RAFT polymerization. The polydispersity index (PDI) decreased when the molar ratio [n(MA)/n(AA)] increased, the lowest PDI was obtained at 5.23 wt% RAFT and the molecular weights were consistent with the theoretical value as the RAFT agent percentage varied. The polymer neutralized by sodium hydroxide solution shows a low critical micelle concentration (CMC), which was <10^?2 mol L^?1 in water. The A_min values increased and showed a maximum with decreased AA chain length. TEM showed that the neutralized polymer formed a special vesicle structure with large pore structure which led to a low CMC and surface tension of water.     

Toward an understanding of the role of water‐soluble oligomers in the emulsion polymerization of styrene–butadiene–acrylic acid. Function of carboxylic acid

In a further effort to understand the role of water‐soluble oligomers formed during the emulsion terpolymerization of styrene/butadiene/acrylic acid (St/Bu/AA), the reaction temperature, initiator concentration, and ionic strength were varied and the kinetics and resulting oligomers were characterized as a function of reaction time. The rate of polymerization (R_p) was observed to increase with increasing temperature and initiator concentration; the reasons for this vary. The increase in R_p with increasing initiator concentration is mainly attributed to the increase in the number of oligomeric radicals formed and, subsequently, the resulting number of particles (N_p). Increasing the temperature increases the water solubility of both monomers and polymers, which results in changes in the composition and molecular weight of the oligomeric radicals being formed. The primary reaction locus in the St/Bu/AA system was noted to shift to the aqueous phase after most of the styrene and butadiene had reacted, based on the unreacted AA profile. The role of water‐soluble oligomers (both oligomeric radicals and dead oligomers) during the emulsion polymerization of St/Bu with acrylic acid can be described by three periods: (1) particle generation and (2) before and (3) after the critical surface saturation concentration (CSSC) is reached during the particle growth period. The incorporation of AA monomer into the oligomer chains after the CSSC may cause destabilization of the latexes through a bridging flocculation mechanism. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1988–1999, 2003     

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     

Kinetics and mechanism of free radical grafting of methyl acrylate onto sago starch

The graft copolymerization was carried out by methyl acrylate with sago starch in which ceric ammonium nitrate was used as an initiator. It has been found that the rates of graft polymerization and grafting efficiency were dependent upon the concentration of ceric ammonium nitrate (CAN), methyl acrylate (MA), sago starch (AGU, anhydro glucose unit), mineral acid (H₂SO₄), and as well as reaction temperature and period. A rate equation of polymerization was established from the proposed reaction mechanism, and the rate of polymerization (R_p) was the first‐order dependence of the MA monomer concentration and square root of the CAN concentration. A new kinetic model of the grafting reaction has been proposed, and a normal kinetics of methyl acrylate polymerization was observed. An equation of a predicted model relating the graft fraction of poly(methyl acrylate) with the sago starch has been derived, and validity of the predicted model was verified by the experimental results. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 784–791, 2000     

Seeded emulsion terpolymerization of dimethyl meta-isopropenyl benzyl isocyanate (TMI®) with acrylic monomers

Dimethyl meta-isopropenyl benzyl isocyanate (TMI®) is a novel bifunctional monomer. It has a double bond and an isocyanate group. The seeded emulsion terpolymerization of TMI with the acrylic monomers, methyl methacrylate and n-butyl acrylate, has been studied. A copolymer of methyl methacrylate and n-butyl acrylate was used as the seed latex. In order to minimize the risk of hydrolysis of TMI, polymerizations were carried out at 40°C using redox initiators. No additional surfactant was added during the second-stage polymerization in order to avoid the nucleation of secondary particles. TMI was found to retard the polymerization kinetics. The effect of variables, such as the total number of particles, initiator concentration, and the monomer feed rate on polymerization kinetics, was investigated. The composition of the second-stage polymer could be controlled by running the polymerization under monomer-starved conditions. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 685–694, 1998     

Complex-radical terpolymerization of styrene, maleic anhydride, and N-vinyl pyrrolidone via γ-ray radiation: Synthesis, characterization, and micellization

Radical terpolymerization of donor–acceptor monomers, i.e. styrene (St), maleic anhydride (MA) and N-vinyl pyrrolidone (NVP) were carried out in methyl ethyl ketone(MEK) under γ-ray radiation at room temperature. Constants of copolymerization, complex formation, and some kinetic parameters for the monomer systems were studied by UV, ¹H NMR, Kelen-Tüdöş and Fineman-Ross methods, respectively. Obtained results show that terpolymerization proceeded mainly through ‘complex’ mechanisms in the state of near-binary copolymerization of StMA and MANVP complexes. The homo-polymerization of St and NVP and the copolymerization between St and NVP could hardly be occurred. The possible reason is the effect of protection from radiation by styrene with its aryl-ring structure and/or the much larger reactivity of the complex copolymerization between the donor–acceptor monomers. The terpolymer self-assembles into micelles in aqueous solution. Polymeric micelles, composed of chains of St–MA and MA–NVP with equal molar ratio, displayed narrow size distribution of about 120 nm. The critical association concentration of micelles was determined to be around 3 mg/L.     

Graft copolymerization of methyl acrylate onto silk sericin initiated by tert‐butyl hydroperoxide

A novel redox system, tert‐butyl hydroperoxide (TBHP)–silk sericin (SS), was used to initiate the graft copolymerization of methyl acrylate (MA) onto silk sericin in an aqueous medium. The graft copolymer, consisting of nanoparticles with a fine core–shell structure, was characterized using Fourier transfer infrared spectroscopy. The effects of the concentrations of MA and TBHP, reaction temperature and time on the grafting parameters of the copolymerization were studied in detail. In terms of grafting percentage and grafting efficiency, the optimum reaction conditions were obtained as follows: [MA] = 0.465 mol L^?1, [TBHP] = 3.884 × 10^?4 mol L^?1, T = 80 °C, t = 150 min. Transmission electron microscopy images of the particles showed a core–shell morphology, where poly(methyl acrylate) cores were covered with SS shells. A possible initiation mechanism is proposed. Copyright © 2006 Society of Chemical Industry     

VAc-2EHA-NMA-AA四元共聚乳液的制备

以醋酸乙烯(VAc)、丙烯酸异辛酯(2-EHA)、N-羟甲基丙烯酰胺(NMA)和丙烯酸(AA)为单体,采用预乳化工艺合成了理论玻璃化转变温度Tg为-16℃的自交联共聚乳液;确定了乳液的固含量,考察了表面活性剂用量及pH、聚合温度和聚合时间对乳液质量的影响。