Grafting behavior of n-butyl acrylate onto poly(butadiene-co-styrene) latexes

The radical-induced grafting of n-butyl acrylate (BA) onto poly(butadiene-co-styrene) [(P(Bd-S)] latexes during seeded emulsion polymerization was studied. This P(Bd-S)/PBA rubber/rubber core/shell latex system exhibited unique grafting behavior as compared to other extensively studied rubber/glass core/shell latex systems, such as poly(butadiene-co-styrene)/poly(methyl methacrylate) [P(Bd-S)/PMMA], poly(butadiene-co-styrene)/polystyrene [P(Bd-S)/PS] and poly(butadiene-co-styrene)/poly(acrylonitrile)[P(Bd-S)/PAN]. These composite latexes were characterized by the formation of a highly grafted/crosslinked P(Bd-S)/PBA interphase zone generated during the seeded emulsion polymerization process. Although both of the individual core and shell polymers studied were “soft” themselves, the resulting P(Bd-S)/PBA composite latex particles were found to be rather “hard.” The formation of the interphase zone was studied by using techniques such as solvent extraction, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:511–523, 1997     

Effects of compatibilizing agents in poly(n-butyl acrylate)/poly(methyl methacrylate) composite latexes

Graft copolymers with poly(n-butyl acrylate) (PBA) backbones and poly(methyl methacrylate) (PMMA) macromonomer side chains are used as compatibilizing agents for PBA/PMMA composite latexes. The composite latexes are prepared by seeded emulsion polymerization of methyl methacrylate (MMA) in the presence of PBA particles. Graft copolymers were already incorporated into the PBA particles prior to using these particles as seed via miniemulsion (co)polymerization of n-butyl acrylate (BA) in the presence of the macromonomers. Comparison between size averages of composite and seed particles indicates no secondary nucleation of MMA during seeded emulsion polymerization. Transmission electron microscopy (TEM) observations of composite particles show the dependence of particle morphologies with the amount of macromonomer (i.e., mole ratio of macromonomer to BA and molecular weight of macromonomer) in seed latex. The more uniform coverage with the higher amount of macromonomer suggests that graft copolymers decrease the interfacial tension between core and shell layers in the composite particles. Dynamic mechanical analysis of composite latex films indicates the existence of an interphase region between PBA and PMMA. The dynamic mechanical properties of these films are related to the morphology of the composite particles, the arrangement of phases in the films, and the volume of the interphase polymer. © 1997 John Wiley & Sons, Inc.     

Morphologies of polybutylacrylate/poly(styrene‐co‐methyl methacrylate) latex prepared by starved emulsion polymerization Part I. Thermodynamics equilibrium morphology

Heterogeneous latexes were prepared by a semicontinuous seeded emulsion polymerization process under monomer starved conditions at 80 °C using potassium persulfate as the initiator and sodium dodecyl sulfate as the emulsifier. Poly(butyl acrylate) latexes were used as seeds. The second‐stage polymer was poly(styrene‐co‐methyl methacrylate). By varying the amounts of methyl methacrylate (MMA) in the second‐stage copolymer, the polarity of the copolymer phase could be controlled. Phase separation towards the thermodynamic equilibrium morphology was accelerated either by ageing the composite latex at 80 °C or by adding a chain‐transfer agent during polymerization. The morphologies of the latex particles were examined by transmission electron microscopy (TEM). The morphology distributions of latex particles were described by a statistical method. It was found that the latex particles displayed different equilibrium morphologies depending on the composition of the second‐stage copolymers. This series of equilibrium morphologies of [poly(butyl acrylate)/poly(styrene‐co‐methyl methacrylate)] (PBA/P(St‐co‐MMA)) system provides experimental verification for quantitative simulation. Under limiting conditions, the equilibrium morphologies of PBA/P(St‐co‐MMA) were predicted according to the minimum surface free energy change principle. The particle morphology observed by TEM was in good agreement with the predictions of the thermodynamic model. Therefore, the morphology theory for homopolymer/homopolymer composite systems was extended to homopolymer/copolymer systems. © 2002 Society of Chemical Industry     

Preparation of core–shell latex particles by emulsion co-polymerization of styrene and butyl acrylate,and evaluation of their pigment properties in emulsion paints

A series of core–shell polymeric particles with poly(n-butyl acrylate-co-methacrylic acid-co-ethylene glycol dimethylacrylate) as core and poly(styrene-co-methyl methacrylate) as shell were prepared by seeded emulsion polymerization. The role of ethylene glycol dimethylacrylate (EGDMA) is to crosslink the core so as to avoid any probability of gel formation and to bind both the core and the shell phase together. The spherical morphology of the core–shell structure was achieved at 60:40 core to shell ratio. The core–shell morphology was confirmed by SEM and TEM analyses. GPC analysis of the particles reveals that the polymer shows a bimodal mode. The first peak has M _w = 382700 and M _n = 245200 with polydispersity index of 1.6, and the second peak has M _w = 21200 and M _n = 14800 with polydispersity index of 1.4. These core–shell latexes were applied as a pigment/binder in emulsion paint and the paint properties like gloss, rock hardness, washability, opacity, etc. were compared with the standard. The results show that these core–shell latexes can provide similar hiding power with 17% reduction of TiO₂ in the paint formulation.     

硅溶胶／聚丙烯酸酯乳液型压敏胶的制备与性能

采用半连续加料乳液聚合方法制备了硅溶胶／聚丙烯酸酯核／壳结构聚合物,采用动态光散射方法跟踪了复合乳胶粒的粒径随反应进程的变化,其理论粒径与实测值基本一致,说明该聚合过程没有明显的二次成核过程。考查了壳层硬单体-甲基丙烯酸甲酯（MMA）含量对乳液聚合的影响,通过动态热机械分析仪（DMA）对聚合物的黏弹性能进行了表征,对制成的胶粘剂进行了压敏特性的测定,并与复合粒子的分子结构进行了关联。研究表明,随着MMA含量的增加,压敏胶的初粘性略有下降,而持粘性显著提高,剥离强度呈先升后降的趋势。     

Effect of particle size on the mechanical properties of polystyrene and poly(butyl acrylate) core/shell polymers

The effects of particle size and polymer location (core or shell) on the mechanical properties of core/shell materials composed of polystyrene (PST) and poly(butyl acrylate) (PBA) made by a two-stage emulsion or microemulsion polymerization process are reported. Low-seed content (LSC) latexes were made by batch polymerization in microemulsions stabilized with DTAB in the presence of an organic salt (dibutyl phosphite). High-seed content (HSC) latexes were produced by microemulsion or emulsion polymerization in semi-continuous process. These latexes were subsequently used to form core/shell particles of PST/PBA or PBA/PST and their mechanical properties were examined and compared. Our results indicate that core/shell particle size and the location of the polymers have important effects on the mechanical properties.     

Preparation and characterization of composite resin by vinyl chloride grafted onto poly(BA-EHA)/poly(MMA-St)

Crosslinked poly(butyl acrylate-co-2-ethylhexyl acrylate)/poly(methyl methacrylate-co-styrene) (ACR I) latex was synthesized by multi-stage emulsion polymerization. A series of grafting vinyl chloride (VC) composite latices were prepared by emulsion copolymerization in the presence of core-shell ACR I latex. The effects of ACR I amount and its core/shell ratio on particle diameters of the composite latices and mechanical properties of the prepared materials were investigated. The grafting efficiency (GE) of VC grafted onto ACR I increases with an increasing ACR I content. Transmission electron microscope (TEM) study indicates that ACR I latex particles have a regular core-shell structure obviously. However, when styrene content in the shell of ACR I is more than 70 percent of the shell by weight, ACR I latex particles have an irregular core-shell morphology like sandwich. The composite latex particles synthesized by core-shell ACR I latex grafting VC have a clear three-layered core-shell structure. Dynamic mechanical analysis (DMA) study reveals that the compatibility between ACR I and PVC is well improved. With increasing ACR I content, the loss peak in low temperature range for every composite sample becomes stronger and stronger and gradually shifts to a higher temperature. Scanning electron microscope (SEM) graphs showed that the fractured surface of the composite sample exhibited better toughness of the material. TEM graphs showed that ACR I was uniformly dispersed in the PVC matrix.     

Silicone-polyacrylate composite latex particles. Particles formation and film properties

Composite latex particles with a polydimethylsiloxane PDMS core and a poly(methyl methacrylate-co-n-butyl acrylate) P(MMA-BA) copolymer shell were synthesized by seeded emulsion polymerization using the PDMS latex as the seed. The compatibility between the two polymer phases was changed by introducing vinyl groups in the latex core. Monomer conversions and particle size evolution were monitored to see the influence of the nature of the core functionality on the polymerization kinetics and on the extent of secondary nucleation. Particle morphology was characterized by cryo-transmission electron microscopy. The P(MMA-BA) copolymer formed a regular shell around the PDMS seed, whereas nonuniform coatings were formed when vinyl functionalities were introduced into the seed. Films were produced from the latexes, and their surface property was analyzed by X-ray photoelectron spectroscopy and contact angle measurements. It was shown that the PDMS component segregated to the polymer/air interface and that the extent of segregation depended on the original particles structure. Because PDMS has a very low glass transition temperature, it can easily diffuse throughout the film material. However, protected by an acrylic shell, polymer diffusion is significantly hindered and the film then displays all the characteristic properties of the acrylic copolymer. The surface composition of the films formed by the structured particles which PDMS core was not totally covered by the polyacrylate, was found to be intermediate between the composition of the films issued from the core-shell latexes and that of the films produced from blends of pure polyacrylate and PDMS latexes.     

Enhanced toughness for polyamide 6 with a core-shell structured polyacrylic modifier

Polyamide 6 (PA 6) is an important thermoplastic with excellent strength, stiffness, and good chemical resistance. The notch sensitivity and low notch impact toughness of PA 6, however, limit its application. A core-shell structured polyacrylic modifier, poly(n-butyl acrylate)/poly(methyl methacrylate-co-methacrylic acid) modifier (PBM-co-MAA), was used to toughen PA 6. To study the effect of PBM-co-MAA particles on the toughness of PA 6, various contents of poly(BA) in PBM-co-MAA latexes of 300 nm were synthesized by seed emulsion polymerization. The results showed that polymerization had an instantaneous conversion higher than 95 wt% and an overall conversion higher than 97 wt%. The PBM-co-MAA particles had a clear core–shell structure confirmed by transmission electron microscope (TEM). The mechanical properties of PA 6/PBM-co-MAA blends showed that the notch impact strength of PA 6/PBM-co-MAA blends with 85 wt% poly(BA) and 0.5 wt% MAA in PBM-co-MAA was nearly six times greater than that of pure PA 6, being consistent with the scanning electron microscope (SEM) observations on the fractured surfaces. The notch impact strengths of PA 6/PBM-co-MAA blends were also better than that of PA 6/PBM blend, which did not contain MAA functional group in the modifier. Dynamic mechanical analysis (DMA) results showed improved compatibility between PA 6 matrix and core-shell toughening modifier, which should contain a functional group in the shell layer and a suitable core rubbery content to toughen PA 6 effectively.     

粒径可控的聚丙烯酸丁酯/聚甲基丙烯酸甲酯核壳乳液的制备及表征

采用种子乳液聚合法制备了聚丙烯酸丁酯(PBA)乳液,然后通过第二单体甲基丙烯酸甲酯的预溶胀法聚合制备了PBA/聚甲基丙烯酸甲酯(PMMA)乳液,用激光散射粒度仪和透射电子显微镜对乳液粒径和结构进行了表征.结果表明,当乳化剂十二烷基硫酸钠质量分数为丙烯酸丁酯的1.5%时,可制备粒径为53.6 nm且分布窄的PBA种子乳液;通过调整补加乳化剂、单体与种子乳液的用量,可制得粒径为53.6～443.8 nm的一系列单分散PBA乳液;PBA/PMMA乳液具有完善的核壳结构,且在核壳两相间存在着一个过渡层.     

Effect of initiator on morphology in poly(vinyl acetate)/polystyrene and poly(butyl acrylate)/polystyrene composite latexes

Summary A simple method of related sensitivity range to predict thermodynamic equilibrium morphology of a core-shell latex particle (J Appl Polym Sci. 2004, 92, 3144), is recently explored. The article proposed that it is necessary to classify core-shell latex systems as sensitivity and no-sensitivity by their equilibrium morphology sensitivity to initiator and emulsifier. As for the sensitivity system, the final morphology may change by adjusting initiator and emulsifier, whereas, for the no-sensitivity system, it is hard to change its final morphology in this way. Equilibrium morphologies in system poly(vinyl acetate) (PVAc)/polystyrene (PSt) and poly(butyl acrylate) (PBA)/ PSt composite latexes particles were observed by changing initiator. Composite latexes of the two systems were synthesized by two-stage semi-continuous emulsion polymerization. The types or/and concentration of initiator changed in two stages in which the oil-soluble initiator 2,2-azobis(isobutyronitrile) (AIBN) and the water-soluble initiator potassium persulfate (KPS) were used respectively, the concentration of which was 0.5% or 2% based on the weight of monomer. The results showed that the two systems had different characteristics. At different experiment conditions designed, the same equilibrium morphologies with PSt as core and PVAc as shell were obtained in system PVAc/PSt, whereas, three different equilibrium morphologies, core-shell, inverted core-shell and hemisphere, were obtained in system PBA/PSt. The equilibrium morphology in system PVAc/PSt is no-sensitive to initiator, and the equilibrium morphology in system PBA/PSt is sensitive to initiator.     

Polymer blend latex films: Miscibility and polymer diffusion studied by energy transfer

Fluorescence non-radiative energy transfer experiments were used to study latex blend films composed of high molar mass poly(butyl acrylate-co-methyl methacrylate) (PBA-co-MMA) and much lower molar mass PBA-co-MMA latex of the same chemical composition (50:50 BA:MMA by weight). These blends take advantage of the strong chain length dependence of T_g so that the particles consisting of oligomeric polymer (“low-M”) have a much lower T_g than the corresponding high-M latex. This type of blend represents a useful strategy for obtaining latex coatings with a reduced VOC content. Here we report on experiments which follow the rate at which the low-M polymer mixes via diffusion with the high-M polymer in the latex films. The high-M latex are doubly labeled, containing both donor and acceptor dyes covalently bound to the PBA-co-MMA backbone. Diffusion of the unlabeled low-M polymer into this phase dilutes the dyes, increasing their separation and lowering the quantum efficiency for energy transfer.     

Effect of the Crosslinking Agent Content on the Emulsion Polymerization Process and Adhesive Properties of Poly(N-Butyl Acrylate-Co-Methacrylic Acid)

A series of poly(n-butyl acrylate-co-methacrylic acid) with different contents of acrylic crosslinking agent (1,4-butanediol dimethacrylate, BDDA) latexes, named as poly(BA-co-MAA-co-BDDA), PBMABD, were synthesized via a two-stage sequential emulsion polymerization. During the polymerization, the particle sizes of the PBMABD latexes and conversions including instantaneous conversion and overall conversion of monomers were monitored online by dynamic light scattering (DLS) technology and gravimetric analysis in half-hour intervals, respectively. The overall conversions at the end of emulsion polymerization with different crosslinking agent contents were high, and the latex particles grew in a spherical shape without secondary particles during the growth process. The adhesive properties, including loop tack force, peel force and shear resistance, were evaluated systematically according to Fédération Internationale des Fabricants et Transformateurs d'Adhésifs et Thermocollants sur Papiers et Autres Supports (FINAT) test methods. When the content of the crosslinking agent was 0.5?wt%, a best equilibrium among the adhesive properties could be achieved. The adhesive properties of the PBMABD polymer were closely related to its viscoelastic behaviour and molecular structure, such as gel content and various molecular weight parameters.     

Double-responsive core-shell-corona micelles from self-assembly of diblock copolymer of poly(t-butyl acrylate-co-acrylic acid)-b-poly(N-isopropylacrylamide)

Self-assembly of poly(t-butyl acrylate-co-acrylic acid)-b-poly(N-isopropylacrylamide) [P(tBA-co-AA)-b-PNIPAM], which was obtained from part hydrolysis of PtBA-b-PNIPAM synthesized by sequential atom transfer radical polymerization (ATRP) was studied. Thermo- and pH-responsive core-shell-corona (CSC) micelles with different structures were formed from (PtBA-co-PAA)-b-PNIPAM in aqueous solution. At pH 5.8 and 25 °C, the block copolymer self-assembled into spherical core-shell micelles with hydrophobic PtBA segments as the core, hydrophilic PAA/PNIPAM segments as the mixed shell. Increasing temperatures, core-shell micelles converted into CSC micelles with PtBA as the core, collapsed PNIPAM as the shell and soluble PAA as the corona. Moreover, decreasing pH at 25 °C, PAA chains collapsed onto the core resulting in CSC micelles with PtBA as the core, PAA as the shell and PNIPAM as the corona.     

About morphology in ethylene-propylene(-diene) copolymers-based latexes

Coatings and engineering plastics often require high impact strength. This property can be achieved with tougheners. For the present paper, core-shell impact modifiers were synthesized using ethylene-propylene copolymers (EPM), ethylene-propylene-diene copolymers (EPDM) or a mixture of both types (EP(D)M) as core material, as well as poly(methyl methacrylate) (PMMA) as shell material.EP(D)M-based polymers were dispersed in water using an Ultra-Turrax^® and a high pressure homogenizer. The prepared artificial latexes were used, either without further treatment or after crosslinking, as seed latexes in the emulsion polymerization of methyl methacrylate (MMA). The free radical seeded emulsion polymerization of MMA was investigated in the presence of an oil-soluble initiator, i.e. cumene hydroperoxide (CHP), combined with a redox system, i.e. sodium formaldehyde sulfoxylate hydrate (SFS), disodium salt of ethylenediamine tetra-acetic acid (EDTA), iron (II) sulfate heptahydrate (FeSO₄). This initiation system promotes polymerization of MMA near the surface of the seed particles, partially suppressing homogeneous secondary nucleation and polymerization in the aqueous phase.Kinetic and thermodynamic considerations were used to predict the particle morphology. The monomer type, the monomer-to-rubber ratio, the monomer feed type, and crosslinking of the seed latex particles were investigated, to optimize the polymerization kinetics and the properties of the resulting dispersions. The particle morphology was determined by cryo-transmission electron microscopy (cryo-TEM). Monomer-flooded conditions led to the formation of inverted core-shell particles, whereas starved-feed MMA or MMA/styrene mixtures gave rise to partially engulfed structures, i.e. snowman-like. Crosslinking of the EP(D)M seed particles was found to be required to provide the desired core-shell structures.Finally, the obtained core-shell structured particles were used to toughen a PMMA matrix. The tensile properties of the modified PMMA matrix were investigated. The micro-morphology of modified PMMA was studied by scanning electron microscopy (SEM). Tensile tests as well as TEM and SEM analyses demonstrated that the main mechanism of deformation operating in the EP(D)M-toughened PMMA matrix is shear yielding, accompanied by debonding and cavitation processes.     

Morphologies and dynamic mechanical properties of core‐shell emulsifier‐free latexes and their copolymers for P(BA/MMA)/P(MMA/BA) and P(BA/MMA)/PSt systems in the presence of AHPS

Different poly(methyl methacrylate/n‐butyl acrylate)/poly(n‐butyl acrylate/methyl methacrylate) [P(BA/MMA)/P(MMA/BA)] and poly(n‐butyl acrylate/methyl methacrylate)/polystyrene [P(BA/MMA)/PSt] core‐shell structured latexes were prepared by emulsifier‐free emulsion polymerization in the presence of hydrophilic monomer 3‐allyloxy‐2‐hydroxyl‐propanesulfonic salt (AHPS). The particle morphologies of the final latexes and dynamic mechanical properties of the copolymers from final latexes were investigated in detail. With the addition of AHPS, a latex of stable and high‐solid content (60 wt %) was prepared. The diameters of the latex particles are ～0.26 μm for the P(BA/MMA)/P(MMA/BA) system and 0.22–0.24 μm for the P(BA/MMA)/PSt system. All copolymers from the final latexes are two‐phase structure polymers, shown as two glass transition temperatures (T_gs) on dynamic mechanical analysis spectra. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3078–3084, 2002     

Effect of amount of emulsifier added in the second stage on morphology of composite latex particles

In this article, PBA/P(MMA–crosslinking agent)-composite particle latexes were prepared by semicontinuous seeded emulsion polymerization. To determine the seed emulsion's saturating capacity of an emulsifier, a mathematical model was built to simulate the changes of the seed PBA emulsion's surface tension with the amount of emulsifier added dropwise. The effects of the emulsifier amount added in the second stage and the addition method on the morphology of the composite particles were studied. The results were shown as follows: If the amount of emulsifier added in one batch to the seed emulsion in the second stage was less than or equal to the saturating capacity of emulsifier of the seed emulsion (Cs), the morphology of the particles was “core–shell”; otherwise, a few particles were of a core–shell structure. However, if shell materials were preemulsified and added dropwise at an appropriate rate, the latex particles were still of a core–shell structure, even when the amount of emulsifier added to the seed emulsion was greater than the Cs. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 969–975, 1998     

Preparation and characterization of nano‐CaCO3 encapsulated with polyacrylic and its application in PVC toughness

The properties and morphology of nano‐calcium carbonate (nano‐CaCO₃) modified with the titanate coupling agent isopropyl trioleoyl titanate (IPTT) were characterized by Fourier transform infrared, thermogravimetric analyses, surface tension, and transmission electron microscopy. The results showed that the grafting ratio of IPTT on the surface of nano‐CaCO₃ (IPTT‐Ca) increased with IPTT content. IPTT‐Ca/PBA/PMMA (IPTT‐Ca/ACR, PBA/PMMA core‐shell polymer, referred to ACR) latexes were prepared by seeded emulsion polymerization. They were then used to mix with PVC resin. The outer layer (PMMA) enhanced the dispensability of IPTT‐Ca/ACR in the PVC matrix by increasing the interfacial interaction of these composite particles with PVC. The notched impact strengths of the blends were influenced by the weight ratio of IPTT‐Ca to BA/MMA monomers, the weight ratio of BA/MMA. The relationships between the mechanical properties and the core‐shell composite structures were elaborated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A study on the synthesis of acrylic composite particles and investigation of their characterization

Core-shell latexes were synthesized by sequential emulsion polymerization of methyl methacrylate (MMA), styrene (St), and ethyl acrylate (EA) in the presence of anionic surfactant, and the characteristics of these latexes were evaluated. The core latex had to be synthesized carefully to avoid the formation of secondary particles. The sequential polymerization method adopted for this synthesis took advantage of stabilizing particles grown during shell polymerization. In core-shell latex polymerization, to suppress the generation of new particles and to minimize the gelation during the shell polymerization, the amount of surfactant (Sodium dodecyl benzene sulfonate: SDBS) should be reduced to the minimum, 0.01 wt% and 0.02 wt% of SDBS to amount of monomer, respectively, when the Polymethyl methacrylate (PMMA) and Polystyrene (PSt) core latexes are prepared. In addition, the monomer pre-emulsion method is better than monomer-add method. The core-shell structure for composite latex synthesized was demonstrated by Particle Size Analysis (PSA), Differential Scanning Calorimeter (DSC), Transmission Electron Microscope (TEM), formability of film, and hydrolysis under NaOH solution.     

Synthesis and characterization of poly(butyl acrylate)/silica and poly(butyl acrylate)/silica/poly(methyl methacrylate) composite particles

Poly(butyl acrylate)/poly(methyl methacrylate) (PBA/PMMA) core–shell particles embedded with nanometer‐sized silica particles were prepared by emulsion polymerization of butyl acrylate (BA) in the presence of silica particles preabsorbed with 2,2′‐azobis(2‐amidinopropane)dihydrochloride (AIBA) initiator and subsequent MMA emulsion polymerization in the presence of PBA/silica composite particles. The morphologies of the resulting PBA/silica and PBA/silica/PMMA composite particles were characterized, which showed that AIBA could be absorbed effectively onto silica particles when the pH of the dispersion medium was greater than the isoelectric potential point of silica. The critical amount of AIBA added to have stable dispersion of silica particles increased as the pH of the dispersion medium increased. PBA/silica composite particles prepared by in situ emulsion polymerization using silica preabsorbed with AIBA showed higher silica absorption efficiency than did the PBA/silica composite particles prepared by direct mixing of PBA latex and silica dispersion or by emulsion polymerization in which AIBA was added after the mixing of BA and silica. The PBA/silica composite particles exhibited a raspberrylike morphology, with silica particles “adhered” to the surfaces of the PBA particles, whereas the PBA/silica/PMMA composite latex particles exhibited a sandwich morphology, with silica particles mainly at the interface between the PBA core and the PMMA shell. Subsequently, the PBA/silica/PMMA composite latex obtained had a narrow particle size distribution and good dispersion stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3425–3432, 2006