Synthesis and properties of soap-free poly(methyl methacrylate-ethyl acrylate-methacrylic acid) latex particles prepared by seeded emulsion polymerization

In order to obtain functional polymer latex particles with clean surface and with surface carboxyl groups, P(MMA-EA) seed particles with the diameter of 335 nm were first synthesized via soap-free batch emulsion polymerization of methyl methacrylate (MMA) and ethyl acrylate (EA), and then the seeded emulsion copolymerization of MMA, EA and MAA (methacrylic acid) onto the seed particles were performed in the absence of emulsifier. Influences of ingredients and conditions on polymerization, latex particle size (D_p) and its distribution were investigated. Results showed that most of the monomers polymerized onto the seed latex particles in the second step of polymerization by using drop-wise addition method, and D_p increased from 483 nm to 829 nm with the mass ratio of core/shell monomers [C]/[S] decreased from 1:2 to 1:15. It was found that D_p decreased with the increase of MAA and initiator amounts, and the size of the latex particles became uniform with the decrease of MAA amount and with the increase of [C]/[S] value.     

Preparation of multihollow P(St-MAA) particles by sequence soap-free/soap emulsion polymerization and followed by stepwise alkali/acid posttreatment

The effects of ionic emulsifier, sodium dodecylbenzene sulfate (SDBS), on the formation of the multihollow structures in sub-micron sized polymer particles produced by alkali/acid posttreatment were investigated. The original latex particles with narrow size distribution were synthesized by a new sequence emulsifier-free/emulsifier emulsion copolymerization of styrene (St) and methacrylic acid (MAA). Results indicated that the pore size decreased and the pore number increased with the increase of SDBS amount, and the morphology of the posttreated latex particles was also significantly influenced by the introducing time of SDBS in the preparation of the original latex particles, and a suitable introducing time was 3 h of polymerization.     

Morphology control in polystyrene/poly(methyl methacrylate) composite latex particles

The effect of the presence of different amounts of block copolymers [polystyrene-block-poly(methyl methacrylate)] on the morphology of polystyrene/poly (methyl methacrylate) composite latex particles was investigated. The block copolymers were produced in situ by controlled radical polymerization (CRP) through the addition of the second monomer to a seed prepared by miniemulsion polymerization with a certain amount of a CRP agent. With an increase in the amounts of the block copolymers, the particle morphology changed from a hemisphere morphology (for a latex without block copolymers, i.e., without the use of a CRP agent during the polymerization) to clear core–shell morphologies as a result of decreasing polymer–polymer interfacial tension © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2484–2493, 2007     

The properties of covalently immobilized trypsin on soap-free P(MMA-EA-AA) latex particles

The covalent immobilization of trypsin onto poly[(methyl methacrylate)-co-(ethyl acrylate)-co-(acrylic acid)] latex particles, produced by a soap-free emulsion polymerization technique, was carried out using the carbodiimide method. The catalytic properties and kinetic parameters, as well as the stability of the immobilized enzyme were compared to those of the free enzyme. Results showed that the optimum temperature and pH for the immobilized trypsin in the hydrolysis of casein were 55 degrees C and 8.5, both of which were higher than that of the free form. It was found that K(m) (Michaelis constant) was 45.7 mg . ml(-1) and V(max) (maximal reaction rate) was 793.0 microg . min(-1) for immobilized trypsin, compared to a K(m) of 30.0 mg . ml(-1) and a V(max) of 5 467.5 microg . min(-1) for free trypsin. The immobilized trypsin exhibited much better thermal and chemical stabilities than its free counterpart and maintained over 63% of its initial activity after reusing ten times.     

交联剂对无皂P(MMA-EA-MAA)种子聚合乳胶粒成孔的影响

采用完全无皂种子乳液聚合技术合成了粒径窄分布的P(MMA-EA-MAA)乳胶粒,通过对上述胶乳进行碱处理,制备出了具有空腔结构和多孔结构的聚合物乳胶粒,研究了交联剂的种类和用量对聚合过程、胶粒特性及胶粒结构形态的影响.结果表明,体系中加入交联剂后,单体转化率都有不同程度的提高;随交联剂用量的增加,乳胶粒粒径略有减小,交联剂用量较高时,乳胶粒粒径分布加宽;二乙烯基苯(DVB)的交联效率稍高于双甲基丙烯酸乙二醇酯(EGDMA);不加入交联剂及EGDMA用量低于0.5%时,处理后乳胶粒呈空腔结构,加入DVB及EGDMA用量高于1.0%时,处理后乳胶粒呈多孔结构,并且乳胶粒体积增量随交联剂用量的增加而减小.     

Production of multihollow polymer particles by the stepwise alkali/acid method IV. Acid treatment process

The effects of pH, temperature and time in the acid-treatment process on the multihollow structure formed within submicron-sized monodispersed polymer particles by the stepwise alkali/acid method proposed by the authors were examined in detail. The original particles were produced by emulsifier-free emulsion terpolymerization of styrene, butyl acrylate, and methacrylic acid. It was clarified that the number and the size of hollows per particle were drastically changed by the acid treatment conditions as well as those in the alkali treatment process.Part CXLV of the series Studies on Suspension and Emulsion     

Fluorinated monomer–styrene copolymer latex particles: I. kinetic studies in a soap-free aqueous medium

Soap-free emulsion copolymerization of 2, 2, 2-trifluoroethyl acrylate (3FEA) with styrene was carried out by using potassium persulfate as an initiator, and the effects of the weight fraction of 3FEA in the monomer feed on the kinetics and the particle size were investigated. Monomer conversions were followed by a gravimetric method, revealing that the overall polymerization rate increased exponentially with an increase in the weight fraction of 3FEA. According to dynamic light scattering measurement, the final particle size was found to decrease with an increase in the weight fraction of 3FEA. The number of particles for 3FEA homopolymerization was roughly twice as large as that at the fraction of 0.9, although both fractions had the almost same polymerization rates. These results indicate that soap-free emulsion homopolymerization of 3FEA would proceed not only inside the polymer particles but also in the aqueous phase throughout the polymerization.     

Production of submicron-sized multihollow polymer particles by alkali/cooling method

Submicron-sized styrene-methacrylic acid copolymer particles, which were produced by emulsion copolymerization, were changed to those having multihollow structure by treating stepwise the emulsion as follows. First alkali treatment was carried out at higher temperature than the glass transition temperature and subsequently the emulsion was cooled by keeping it at room temperature. This was named alkali/cooling method. The effects of methacrylic acid content, pH, time and temperature in the alkali treatment on the formation of multihollow structure were clarified.Part CLV of the series Studies on suspension and emulsion     

A New Kind of Void Soap-free P（MMA-EA-MAA） Latex Particles

Soap-flee P(MMA-EA-MAA) particles with narrow size distribution were synthesized by seeded emulsion polymerization of methyl methacrylate (MMA), ethyl acrylate (EA) and methacrylic acid (MAA), and large voids inside the particles were generated by alkali posttreatment in the presence of 2-butanone. Results indicated that the size of void and theparticle volume were related with the amount of 2-butanone. The generation mechanism of voids was proposed.     

Production of submicron-sized multihollow polymer particles having high transition temperatures by the stepwise alkali/acid method

Submicron-sized multihollow styrene-methacrylic acid (92.6/7.4, molar ratio) copolymer particles having high transition temperature above 100°C were produced by using the stepwise alkali/acid method proposed by the authors. The original particles were prepared by emulsion copolymerization of styrene and methacrylic acid. The effects of pH, temperature and time in the alkali treatment process as the first step on the multihollow structure were clarified under the same acid treatment conditions.Part CLII of the series Studies on Suspension and Emulsion     

Preparation and characterization of submicron hybrid magnetic latex particles

Micrometer magnetic hybrid particles are of great interest in biomedical field, and various morphologies have been prepared via encapsulation processes. Regarding submicron, only few processes have been investigated and the most recent one leading to highly magnetic submicron magnetic hybrid particles is based on oil in water magnetic emulsion (MES) transformation. The encapsulation of magnetic iron oxide nanoparticles forming oil in water MES was investigated using different styrene/cross‐linker divinylbenzene volume ratio in the presence of potassium persulfate initiator. The encapsulation performed in this work is basically conducted by using well‐defined oil in water MES as a seed in radical emulsion polymerization. The chemical composition, morphology, iron oxide content, magnetic properties, electrokinetic properties, particle size, and size distribution of the prepared magnetic hybrid particles were examined using various techniques. The desired perfect magnetic core and polymer shell morphology were successfully obtained, and the final magnetic hybrid particles are superparamagnetic in nature and exhibit high iron oxide content (64 wt %). Copyright © 2015 John Wiley & Sons, Ltd.     

Tailoring of carboxyl‐decorated magnetic latex particles using seeded emulsion polymerization

In this research, submicron and carboxyl‐functionalized magnetic latex particles were elaborated by using seeded emulsion polymerization technique in presence of oil‐in‐water (o/w) magnetic emulsion as seed. The polymerization conditions were optimized in order to get well‐defined latex particles with magnetic core and polymer shell bearing carboxylic (–COOH) functionality. Starting from (o/w) magnetic emulsion as seed, synthesis process was performed by copolymerization of styrene (St) monomer with the cross‐linker divinylbenzene (DVB) in presence of 4,4′‐azobis(4‐cyanopentanoic acid) (ACPA) as a carboxyl‐bearing initiator. The prepared magnetic latex particles were first characterized in terms of particle size, chemical composition, morphology, magnetic properties, magnetic content, and colloidal stability using various techniques, e.g. particle size analyzer using dynamic light scattering (DLS) technique, Fourier transform infrared, transmission electron microscopy, vibrating sample magnetometer, thermogravimetric analysis, and zeta potential measurements as a function of pH of the dispersion media, respectively. The prepared magnetic latex particles were then used as second seed for further functionalization with methacrylic acid (MAA) in order to enhance carboxylic groups on the magnetic particle's surface. The results showed that final magnetic latex particles possessed spherical morphology with core‐shell structure and enriched carboxylic acid functionality. More importantly, they exhibited superparamagnetism with high magnetic content (58.42 wt%) and high colloidal stability, which considered as the main requirements for their application in the biomedical diagnostic domains. Copyright © 2017 John Wiley & Sons, Ltd.     

Study on soap‐free P(MMA‐EA‐AA or MAA) latex particles with narrow size distribution

Soap‐free poly(methyl methacrylate‐ethyl acrylate‐acrylic acid or methacrylic acid) [P(MMA‐EA‐AA or MAA)] particles with narrow size distribution were synthesized by seeded emulsion polymerization of methyl methacrylate (MMA), ethyl acrylate (EA) and acrylic acid (AA) or methacrylic acid (MAA), and the influences of the mass ratio of core/shell monomers used in the two stages of polymerization ([C/S]_w) and initiator amount on polymerization, particle size and its distribution were investigated by using different monomer addition modes. Results showed that when the batch swelling method was used, the monomer conversion was more than 96.0% and particle size distribution was narrow, and the particle size increased first and then remained almost unchanged at around 600 nm with the [C/S]_w decreased. When the drop‐wise addition method was used, the monomer conversion decreased slightly with [C/S]_w decreased, and large particles more than 750 nm in diameter can be obtained; with the initiator amount increased, the particle size decreased and the monomer conversion had a trend to increase; the particle size distribution was broader and the number of new particles was more in the AA system than in the MAA system; but the AA system was more stable than the MAA system at both low and high initiator amount. Copyright © 2006 John Wiley & Sons, Ltd.     

Preparation of sulphonate-containing core/shell latex particles via seeded emulsion copolymerization

<正>In this study,P(St-MAA) seed latex particles were first prepared via soap-free emulsion polymerization of styrene(St) and methacrylic acid(MAA),then the seed particles were allowed to swell with St at room temperature,and the P(St-MAA)/P(StNaSS) core/shell latex particles were then synthesized via seeded emulsion copolymerization of St and sodium styrene sulphonate (NaSS) using AIBN as initiator in the presence of N,N'-methylenebisacrylamide(BAA,water-soluble crosslinker).Results showed that the polymerization could be carried out smoothly when the ratio of BAA to total monomers was less than 3 mol%,the narrow dispersed P(St-MAA) seed particles with the diameter of 150 nm and the P(St-MAA)/P(St-NaSS) core/shell latexes with the particle size of about 200 nm were synthesized.When the 25/75 mole ratio of NaSS/(St + MAA) and 2 mol%of BAA were used in the seeded emulsion polymerization,the resulted P(St-MAA)/P(St-NaSS) latex product showed a low weight loss after water extraction,and the NaSS unit content in the whole particle and in the shell reached 11.7 mol%and 34.6 mol%,respectively.     

Agitation requirement for synthesis of micron-sized monodisperse polymer particles in soap-free polymerization method

Single-stage polymerization recently proposed for producing micron-sized polymer particles in aqueous media by Gu, Inukai and Konno (2002) was carried out under the control of agitation with styrene monomer, an amphoteric initiator, 2,2′-azobis [N-(2-carboxyethyl)-2-methylpropionamidine] tetrahydrate and a pH buffer NH₃/NH₄Cl at a monomer concentration of 1.1 kmol/m³ H₂O, an initiator concentration of 10 mol/m³ H₂O and a buffer concentration of [NH₃] = [NH₄Cl] = 10 mol/m³ H₂O. In the polymerizations, impeller speed was ranged from 300 to 500 rpm to satisfy complete dispersion of the monomer phase and not to introduce the gas phase from the free surface. Polymerization experiments under steady agitation indicated that impeller speed was an important factor for size distribution of polymer particles. An increase in impeller speed promoted particle coagulation during the polymerization to enlarge the average size of polymer particles but widen the size distribution. To produce polymer particles with narrow size distribution, stepwise reduction in impeller speed was examined in the polymerization experiments. It was demonstrated that this method was more effective than the steady agitation. The impeller speed reduction could produce highly monodisperse particles with an average size of 2 μm and a coefficient of variation of size distributions of 2.2% that was much smaller than typical monodispersity criterion of 10%.     

Reactive blends of thermoplastics and latex particles

Monodisperse homogeneous and core–shell latex particles of various sized between 200 and 600 nm were synthesized by emulsion copolymerization. Some of the core–shell particles were functionalized with epoxy groups at their peripheries upon introduction of glycidyl methacrylate (GMA) during the synthesis. The core consisted of crosslinked polybutylacrylate and the shell polymethylmethacrylate. Synthesis conditions at high and low temperatures were optimized to obtain coreshell particles with a well-defined morphology. The particles were characterized by quasi-elastic light scattering, scanning electron microscopy and transmission electron microscopy. The latex particles functionalized with GMA were then dispersed into a reactive matrix (styrene and maleic anhydride copolymer) using a batch mixer to obtain blends with well-defined and stabilized morphology. 4 Dimethylaminopyridine was used as a catalyst. The reaction between the epoxy groups at the particle surface and the maleic anhydride or diacid groups of the matrix was evaluated by torque and extraction techniques. A small amount of conversion generates sufficient amounts of grafted species at the matrix and particle interfaces to ensure a good interfacial adhesion.     

Preparation of micron-sized nonspherical polystyrene/poly(styrene-<Emphasis Type="Italic">co</Emphasis>-ethyleneglycol dimethacrylate) particles by seeded soap-free emulsion polymerization

Micron-sized nonspherical polymer particles having different morphologies were synthesized by seeded soap-free emulsion polymerization of styrene(St) and ethyleneglycol dimethacrylate(EGDMA,used as a crosslinker) on spherical, linear polystyrene(PS) seed particles.The morphology of the resulting PS/poly(St-co-EGDMA) particles was dependent on the crosslinker concentration and polymerization temperature.     

Synthesis of submicron-sized peanut-shaped poly(methyl methacrylate)/polystyrene particles by seeded soap-free emulsion polymerization

Submicron-sized peanut-shaped poly(methyl methacrylate)/polystyrene(PMMA/PS) particles were successfully synthesized by seeded soap-free emulsion polymerization of styrene on the spherical crosslinked PMMA seed particles.The obtained peanut-shaped particles showed a novel internal morphology:PS phase formed one domain which linked to the other domain having PMMA core encased by PS shell.     

A small-angle X-ray scattering study of bromine-containing latex particles

A small-angle X-ray scattering (SAXS) study of two-stage latices (TSL), composed of polystyrene (PS) and polytribromostyrene (PTBrS), is presented. The analysis of the scattering curves leads to the conclusion that the TSL particles have a concentric core-shell structure. When a PTBrS latex was used as a seed, its particles were overcoated with a PS shell during the second-stage polymerization. However, only a small portion of the seed particles were overcoated with a PTBrS shell when using a PS seed. The size distributions of the TSL and the PTBrS latex particles were determined from the scattering curves, using the method of Indirect Fourier Transformation. The resulting average radii were in good agreement with the values obtained from TEM observations. © 1996 John Wiley & Sons, Inc.     

Surface functionalization of styrene/butyl acrylate latex with a water‐soluble monosaccharide monomer. Synthesis and morphology of the polymer particles

New polymer latexes bearing saccharide moieties on the particle surface were synthesized by using a water‐soluble sugar monomer, such as 1‐deoxy‐1‐methacryl‐amido‐D ‐glucitol, (MAG). All the latexes were prepared by a two‐stage emulsion polymerization technique. In the first step, the core was prepared with butyl acrylate (BA) and styrene (St). In the second step, the seed latex was polymerized with ethyl acrylate (EA) and MAG. The influence of a bifunctional monomer such as allyl methacrylate (ALMA), introduced at various concentrations, on the final latexes morphologies and properties was investigated. It was found that the latex particles exhibit a core‐shell structure. The mass balance of MAG showed that the main part of the sugar moiety is on the shell layer. The molecular properties, such as structure, composition, and molecular weight, were determined by elemental analysis, ¹H‐ and ¹³C‐NMR spectroscopy. Colloidal (particle size and their distributions), thermal, and rheological properties were also studied. Copyright © 2003 John Wiley & Sons, Ltd.