Highly crosslinked micron‐sized,monodispersed polystyrene particles by batch dispersion polymerization,Part 1: Batch,delayed addition,and seeded batch processes

The seeded batch dispersion polymerization with or without monomer absorption was compared with the batch polymerization and delayed addition by batch polymerization, to prepare the highly crosslinked, monodispersed polystyrene (PS) particles. The seeded batch polymerization was carried out under the variation of styrene (in second stage)/styrene (in PS seed) (St/St) ratio, divinylbenzene (DVB) concentration, and polymerization temperature using 1.9‐μm monodispersed PS seed particles. The experimental results imply that the seeded batch process is more efficient method that could avoid the sensitive particle nucleation step in the presence of the crosslinker than the batch and delayed addition processes. Without monomer absorption, 2.3‐μm uniform crosslinked PS particles with 7 wt % of the DVB were prepared in 1/1 (St/St) ratio. In comparison, with the monomer absorption, monodispersed and smooth‐surfaced PS particles containing 20 wt % of the DVB were formed. A total of 5% weight loss of the crosslinked PS particles determined by TGA occurred from 353.8 to 374.8°C, and the degree of swellability in toluene decreased from 150 to 104.5% with increasing the DVB concentration from 5 to 20 wt % because of the increase of the crosslink density of the particles. The seeded polymerization, especially through monomer absorption procedure, is a novel way to obtain highly crosslinked, monodispersed PS particles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

2‐Hydroxyethylmethacrylate carrying uniform porous particles: preparation and electron microscopy

Uniform macroporous particles carrying hydroxyl groups have been obtained in the size range 3–11.5 µm by seeded polymerization. For this purpose, uniform polystyrene particles in the size range 1.9–6.2 µm were used as seeds. The seed particles were successively swollen by dibutyl phthalate (DBP) and a monomer mixture comprising styrene, 2‐hydroxyethylmethacrylate (HEMA) and a crosslinker. Two different crosslinkers, divinylbenzene (DVB) and ethylene glycol dimethacrylate (EGDMA), were tested. Size distribution properties together with bulk and surface structures of the particles have been characterized by both scanning and transmission electron microscopy. While EGDMA provides uniform particles with a non‐porous surface, DVB produces uniform particles having a highly porous surface and interior. The comparison of FTIR and FTIR‐DRS spectra shows that the HEMA concentration is higher on the particle surface than within the particle interior. Seed latex size and monomer/seed latex ratios are identified as the most important variables affecting the final particles. Different seed latexes have been tried; the result is that highly macroporous particles with a sponge‐like pore structure both on the surface and in the particle interior have been obtained by use of the seed latex with the largest particles and the lowest molecular weight. An increase in the HEMA feed concentration leads to final particles with a non‐porous surface and a crater‐like porosity in the particle interior. The average pore size significantly decreases with increasing DBP/seed latex and monomer/seed latex ratios. © 2001 Society of Chemical Industry     

Preparation of polyaniline coated polystyrene‐poly(styrene‐co‐sodium 4‐styrenesulfonate) microparticles and the further fabrication of hollow polyaniline microspheres

In this article, the microparticles of polystyrene‐poly(styrene‐co‐sodium 4‐styrenesulfonate) (PS‐PSS) coated by polyaniline (PANI) were prepared and hollow PANI microspheres were further obtained by dissolving the core. First, surface‐sulfonated monodispersed PS was prepared by copolymerization of sodium 4‐styrenesulfonate (SSS) and styrene with dispersion polymerization method. Then aniline was polymerized on the surface of the surface‐sulfonated PS (PS‐PSS) by chemical oxidative polymerization. After purification, we prepared core‐shell (PS‐PSS)/PANI particles. Hollow PANI microspheres were prepared by dissolving the plastic PS core of the (PS‐PSS)/PANI particles in chloroform. The growth process of PANI on the surface of PS‐PSS particles was investigated and the hollow PANI microspheres were characterized. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and application of partially porous poly(styrene‐divinylbenzene) particles for lipase immobilization

Partially porous poly(styrene‐divinylbenzene) (PS‐DVB) particles in the micron size range were prepared by the method of multistep swelling and polymerization involving the use of polymeric porogens. Polystyrene (PS) seeds prepared by dispersion polymerization were expanded in particle size by absorbing styrene and initiator, and then polymerized to form polymeric porogen particles. The newly synthesized PS chains served as the porogens of the PS‐DVB particles, resulting from the copolymerization of styrene and divinylbenzene in the swollen polymeric porogen particles. PS‐DVB particles with a specific surface area of up to 34 m²/g and a pore volume of up to 0.15 cm³/g were obtained. The average pore diameter of PS‐DVB particles was in the range of 15–24 nm. An increasing amount of toluene used in the copolymerization step increased the pore volume and specific surface area. Lipase from Candida rugosa was immobilized on the prepared PS‐DVB by physical adsorption. The optimum temperature for enzymatic activity was increased and the thermal deactivation of enzyme in organic solvent was slowed down by the immobilization. However, compared with soluble enzyme, the immobilized lipase on PS‐DVB retained a less activity after the first stage deactivation, suggesting a possible change in the conformation of enzyme molecule by immobilization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 39–46, 2001     

Production of micron-size monodisperse polymer particles by seeded polymerization utilizing dynamic swelling method with cooling process

Monodisperse polystyrene particles (6.6 μm diameter) were produced by seeded polymerization utilizing the dynamic swelling method with cooling process as follows. Monodisperse polystyrene seed particles (1.8 μm diameter) were dispersed in ethanol/water (3/4 w/w) medium containing styrene monomer, benzoyl peroxide as initiator and poly(vinyl alcohol) as stabilizer at 65d?C. By lowering the temperature to ?5d?C at a speed of ?1d?C/min the polystyrene seed particles were swollen from 1.8 to 7.7 μm by the absorption of styrene monomer, keeping the high monodispersity. An appropriate amount of water was then added to the dispersion at ?5d?C to depress the redissolution of styrene from the swollen particles into the medium. By elevating the temperature the seeded polymerization was carried out at 70d?C. The production of submicron-size polystyrene new particles as a by-product was depressed by the addition of NaNO₂ to the medium.     

Small‐angle X‐ray scattering study of modified porous suspension–poly(vinyl chloride) particles

Small‐angle X‐ray scattering (SAXS) was applied to investigate the microstructure of unmodified and modified porous commercial suspension‐type poly(vinyl chloride) (PVC) particles. The modified PVC particles were prepared by an in situ stabilizer‐free polymerization/crosslinking of particles absorbed with a monomer/crosslinker/peroxide solution. The modifying polymers include styrene with or without divinyl benzene (DVB) as a crosslinker and methyl methacrylate (MMA) with or without ethylene glycol dimethacrylate (EGDMA) as a crosslinker. The SAXS method was used to highlight the effect of polystyrene (PS) on the microstructure of PVC particles and to evaluate the characteristic lengths, both in the PVC/PS and the PVC/XPS (PS crosslinked with 0 and 5% DVB, respectively) systems. A model is suggested, where during the synthesis modification process, swelling of PVC by styrene and styrene polymerization occur simultaneously. PVC swelling by styrene causes destruction of the PVC subprimary particles, whereas styrene polymerization leads to phase separation resulting from incompatibility of the polymers. It was further suggested that because of PVC swelling by styrene, structure of the subprimary particles is lost. Therefore the characteristic lengths of PVC/PS and PVC/XPS, as calculated from the SAXS measurements, were attributed to the size of the phase‐separated PS and XPS inclusions, respectively. The SAXS method also shows that PMMA and XPMMA do not influence the PVC microstructure. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1024–1031, 2005     

Deformation mechanism of polystyrene toughened with sub‐micrometer monodisperse rubber particles

Core–shell polybutadiene‐graft‐polystyrene (PB‐g‐PS) rubber particles with different ratios of polybutadiene to polystyrene were prepared by emulsion polymerization through grafting styrene onto polybutadiene latex. The weight ratio of polybutadiene to polystyrene ranged from 50/50 to 90/10. These core‐shell rubber particles were then blended with polystyrene to prepare PS/PB‐g‐PS blends with a constant rubber content of 20 wt%. PB‐g‐PS particles with a lower PB/PS ratio (≤70/30) form a homogeneous dispersion in the polystyrene matrix, and the Izod notched impact strength of these blends is higher than that of commercial high‐impact polystyrene (HIPS). It is generally accepted that polystyrene can only be toughened effectively by 1–3 µm rubber particles through a toughening mechanism of multiple crazings. However, the experimental results show that polystyrene can actually be toughened by monodisperse sub‐micrometer rubber particles. Scanning electron micrographs of the fracture surface and stress‐whitening zone of blends with a PB/PS ratio of 70/30 in PB‐g‐PS copolymer reveal a novel toughening mechanism of modified polystyrene, which may be shear yielding of the matrix, promoted by cavitation. Subsequently, a compression‐induced activation method was explored to compare the PS/PB‐g‐PS blends with commercial HIPS, and the result show that the toughening mechanisms of the two samples are different. Copyright © 2006 Society of Chemical Industry     

Synthesis of well‐defined poly(vinyl ether)‐based macromonomers having pendant glycerols via living cationic polymerization and their application to the preparation of core−shell polymer particles

A new vinyl ether monomer bearing a glycerol pendant moiety protected with an isopropylidene group (2‐(2,2‐dimethyl‐[1,3]dioxolan‐4‐ylmethoxy)‐ethyl vinyl ether, IpGEVE) was designed as the precursor of a novel type of hydrophilic poly(vinyl ether) containing glycerol pendants. It was found that the polymerization of IpGEVE proceeded in a controlled manner, and the protecting groups of isopropylidene moieties could be cleaved with trifluoroacetic acid. Living cationic polymerization of IpGEVE with an initiator bearing a methacryloyl group (VEM‐HCl) and subsequent deprotection of the pendant isopropylidene groups of the resultant precursor afforded a glycerol‐substituted hydrophilic macromonomer MA‐PGEVE. Nearly monodispersed polymer particles in the submicron size range were successfully obtained via dispersion copolymerization of MA‐PGEVE with styrene.© 2013 Society of Chemical Industry     

Ab initio reversible addition–fragmentation chain transfer emulsion polymerization of styrene/butyl acrylate mediated by poly(acrylic acid)‐block‐polystyrene trithiocarbonate

Ab initio reversible addition–fragmentation chain transfer (RAFT) emulsion polymerization of styrene/butyl acrylate was investigated with the trithiocarbonate macro‐RAFT agent poly(acrylic acid)‐block‐polystyrene (PAA‐b‐PS) as a stabilizer and a RAFT agent. Influences of the amount of ammonium persulfate (APS), the amount of PAA‐b‐PS and the mass ratio of monomers on emulsion polymerization and film properties are discussed. The particle morphology exhibited spherical‐like structure with particles of about 90 nm in diameter and relatively narrow particle size distribution characterized using transmission electron microscopy and dynamic laser scattering. Fourier transform infrared and ¹H NMR spectra showed that the styrene/butyl acrylate emulsion was successfully synthesized. The monomer conversion increased initially with increasing amount of APS, from 0.4 up to 0.8 wt%, and then decreased. The particle size increased and its distribution decreased gradually with increasing amount of APS. The monomer conversion increased from 76.83 to 94.21% as the amount of PAA‐b‐PS increased from 3 to 4 wt%, and then decreased with further increase of PAA‐b‐PS. The particle size decreased and its distribution increased with increasing amount of PAA‐b‐PS. The water resistance and solvent resistance of the polymer films initially increased and then decreased with decreasing mass ratio of butyl acrylate to styrene. © 2014 Society of Chemical Industry     

Attapulgite@polymer particles with double‐layer polymer shell via soapless seeded emulsion polymerization

Attapulgite needle encapsulated with double‐layer polymer shell (ATP@DP) were prepared by the soapless seeded emulsion polymerization of the second monomer styrene in the dispersion of the attapulgite needle encapsulated with poly(methyl methacrylate) (ATP@PMMA), which was also conducted by the soapless seeded emulsion polymerization of the first monomer methyl methacrylate with the cetyltrimethylammonium bromide (CTAB) modified attapulgite needle (org‐ATP) as seeds. The different morphologies of ATP, ATP@PMMA particles, and ATP@DP particles were characterized by transmission electron microscopy, and the encapsulation mechanism was also discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of spike‐ball‐like polystyrene/poly(methyl methacrylate) composite particles via seeded polymerization

A synthesis method for the production of novel spike‐ball‐like polymer particles is presented based on seeded dispersion polymerization of methyl methacrylate monomer in the presence of polystyrene seeds with poly(vinyl alcohol) as stabilizer and myristyl peroxydicarbonate as initiator. The particles resulting from the controlled aggregation of swollen particles during polymerization showed a salami‐like morphology with polystyrene cores and poly(methyl methacrylate) shells. The long spikes had the same morphology and were formed by the step‐by‐step addition of smaller particles on the surface of the larger particles during polymerization. The resulting particles have potential applications as templates to make micron‐sized electronics and biomaterials. © 2017 Society of Chemical Industry     

Microporous polypropylene fibers containing fine particles of poly(styrene‐co‐divinylbenzene) or poly(glycidylmethacrylate‐co‐divinylbenzene)

Styrene‐divinylbenzene or glycidylmethacrylate‐divinyl‐benzene were copolymerized in powdery polypropylene suspended in water and the resultant polymer composites were blended with a definite amount of polypropylene. The products consisted of polypropylene and the fine particles of the copolymer, which were uniformly dispersed in polypropylene phase. These products were melt‐spun to prepare polypropylene fibers containing the fine particles and then the fibers were stretched to make the fibers microporous. Some properties were estimated: porosity, 1.6–19.7%; average pore size, 0.004–0.009 µm; and specific surface, 9–137 m²/g. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 722–727, 1999     

Preparation of micron‐size monodispersed PS/P(St/MAA) microspheres by seeded dispersion polymerization

Uniform polystyrene (PSt) particles with the size of 1.9 μm were first prepared via dispersion polymerization, and then used as the seeds in a second‐stage dispersion copolymerization of styrene (St) and methacrylic acid (MAA) to produce carboxyl‐carrying microspheres. The PSt seed particles were swollen by monomer mixture of St and MAA, including an oil‐soluble initiator 2,2′‐azobisiso‐butyronitrile (AIBN), before polymerization. Finally, uniform PS/P(St/MAA) (polydispersity index, PDI = 1.02) microspheres with the size of 2.2 μm were obtained. The average particle size and size distribution of the final microspheres were investigated. MAA contents between 54 and 97 mg/g were detected from the PS/P(St/MAA) particles produced under different conditions. Dispersion medium has great influence on the kinetics of polymerization, due to its effect on the partitioning of monomers, solvents, and initiator in the particle phase, probably as well as on the conformation of the dispersion agent on the surface of the particles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3586–3591, 2006     

Monodisperse‐porous poly(styrene‐co‐divinylbenzene) beads providing high column efficiency in reversed phase HPLC

A multistage polymerization protocol, the so‐called “modified seeded polymerization,” was developed for the production of monodisperse‐porous poly(styrene‐co‐divinylbenzene) providing high column efficiency as a packing material in reversed phase high performance liquid chromatography (RPLC). In the first stage of the multistage production, uniform polystyrene seed particles, produced by dispersion polymerization, were swollen by an organic agent (i.e., the diluent) and then by a monomer mixture containing styrene and divinylbenzene. The final porous particles were obtained in the monodisperse form by the polymerization of monomer mixture in the seed particles. By the use of a small size seed latex with low molecular weight and by the selection of the appropriate diluent, relatively small monodisperse‐porous particles with suitable pore structure could be achieved. In the reversed phase separation of alkylbenzenes, under isocratic conditions, theoretical plate numbers up to 40,000 plates/m were achieved by using 5.2 μm porous particles, obtained by a toluene‐dibutyl phthalate mixture as the diluent. No significant decrease in the resolution power was observed by the fourfold increase in the mobile phase flow rate. The column efficiency and the resolution observed with 5.2 μm monodisperse‐porous particles were significantly higher with respect to the currently available polymer based packing materials used in the reversed phase HPLC. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1430–1438, 2005     

Morphology development of 10‐μm scale polymer particles prepared by SPG emulsification and suspension polymerization

Classicalparticle morphologies, core‐shell, hemisphere, sandwich, and so on, were all reproducible by starting from ca. 10‐μm uniform droplets composed of monomers, initiator, solvents, and polymer, and polymerizing them by subsequent suspension polymerization. SPG (Shirasu porous glass) membrane was employed to form uniform size droplets having the coefficient of variation (CV) around 10%. Styrene (ST) and acrylic monomers were used as monomers, and their polymers were dissolved in the droplets to investigate the development of phase separation. When hydrophilic methyl methacrylate (MMA) was polymerized in the droplets with a mixed solvent consisting of hydrophilic hexanol (HA) and hydrophobic benzene and hexadecane (HD), the resulting morphology shifted from hemisphere to sandwich and eventually to PMMA/solvent core‐shell with increasing hydrophilicity of the mixed solvent. The sandwich was converted to the core‐shell after several weeks elapsed. As styrene was added to MMA, the morphology shifted from hemisphere core/solvent shell to raspberry core/solvent shell as the fraction of ST increased. The domain of the mixed solvent in the raspberry core was reduced with increasing the hydrophilicity of the mixed solvent. All these morphologies were eventually converted to the copolymer core/solvent shell. When a mixed monomer of styrene and MMA dissolving polystyrene (PS) was polymerized, the resulting morphology shifted from salami to core‐shell with increasing the MMA fraction in the comonomer. The salami particles were then swollen with toluene, and after the swelling, toluene was removed under the different temperature and pressure. The final particle morphology converted to the core‐shell with a milder rate of toluene removal which was predicted from the thermodynamic model. When styrene and cyclohexyl acrylate (CHA), a pair with widely different reactivity ratios, were copolymerized, salami morphologies, with tiny CHA‐rich domains dispersed in the matrix, were obtained even at a higher fraction of CHA in comonomer. Effects of glass transition temperature of the polymers, molecular weight, and the composition of copolymers were taken in consideration whenever the final morphologies were discussed. By these experiments, the authors tried to demonstrate an advantage of using large uniform spheres for the particle morphology studies. SPG emulsification technique was a potential tool because of its free formulation of the droplets, and the subsequent polymerization could undergo without the breakup or coalescence of the droplets. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2200–2220, 2001     

Preparation of polystyrene/poly(methyl methacrylate) core‐shell composite particles by suspension‐emulsion combined polymerization

Suspension‐emulsion combined polymerization process, in which methyl methacrylate (MMA) emulsion polymerization constituents (EPC) were drop wise added to styrene (St) suspension polymerization system, was applied to prepare polystyrene/poly(methyl methacrylate) (PS/PMMA) composite particles. The influences of the feeding condition and the composition of EPC on the particle feature of the resulting composite polymer particles were investigated. It was found that PS/PMMA core‐shell composite particles with a narrow particle size distribution and a great size would be formed when the EPC was added at the viscous energy dominated particle formation stage of St suspension polymerization with a suitable feeding rate, whereas St‐MMA copolymer particles or PS/PMMA composite particles with imperfect core‐shell structure would be formed when the EPC was added at the earlier or later stage of St suspension polymerization, respectively. It was also showed that the EPC composition affected the composite particles formation process. The individual latex particles would exist in the final product when the concentrations of MMA monomer, sodium dodecyl sulfate emulsifier, and potassium persulfate initiator were great in the EPC. Considering the feature of St suspension polymerization and the morphology of PS/PMMA composite particles, the formation mechanism of PS/PMMA particles with core‐shell structure was proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Chromatographic performance of monodisperse–macroporous particles produced by “modified seeded polymerization.” I: Effect of monomer/seed latex ratio

In this study, the monodisperse–macroporous particles produced by a relatively new polymerization protocol, the so‐called, “modified seeded polymerization,” were used as column‐packing material in the reversed phase chromatography (RPC) of proteins. The particles were synthesized in the form of styrene‐divinylbenzene copolymer approximately 7.5 μm in size. In the first stage of the synthesis, the monodisperse polystyrene particles 4.4 μm in size were obtained by dispersion polymerization and used as the “seed latex.” The seed particles were swollen by a low‐molecular‐weight organic agent and then by a monomer mixture. The monodisperse–macroporous particles were obtained by the polymerization of monomer mixture in the seed particles. In the proposed polymerization protocol, the number of successive swelling stages was reduced with respect to the present techniques by the use of sufficiently large particles with an appropriate average molecular weight as the seed latex. A series of particles with different porosity properties was obtained by varying the monomer/seed latex ratio. The separation behavior of HPLC columns including the produced particles as packing material was investigated in the RPC mode using a protein mixture including albumin, lysozyme, cytochrome c, and ribonuclease A. The chromatograms were obtained with different flow rates under an acetonitrile–water gradient. The theoretical plate number increased and chromatograms with higher resolutions were obtained with the particles produced by using a lower monomer/seed latex ratio. The separation ability of the column could be protected over a wide range of flow rates (i.e., 0.5–3 mL/min) with most of the materials tested. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 607–618, 2004     

Preparation and characterization of imidazole‐functionalized microspheres

The preparation of imidazole‐functionalized latex microspheres by a two‐stage emulsion copolymerization process and their characterization are reported on. Emulsifier‐free emulsion copolymerization of styrene (St) and 1‐vinyl imidazole (VIMZ) exhibited bimodal particle size distributions caused by secondary homogeneous nucleation process. However, secondary nucleation can be avoided by using cetyltrimethylammonium bromide (CTAB) as a stabilizer at a concentration below its cmc (critical micelle concentration). This would result in the formation of monodisperse latex particles. The final particle size diameter depended on the concentration of CTAB as well as the amount of VIMZ. To control the amount of the functional imidazole groups on the latex particle surfaces, independent of the latex diameters, without secondary nucleation of particles, the seeded emulsion copolymerization of styrene and VIMZ was explored as a second‐stage polymerization at different concentrations and ratios of monomers in the presence of the previously prepared monodisperse poly(styrene‐co‐1‐vinyl imidazole) seed latex particles. The concentration of imidazole functional groups on the surface of the latex particles could also be varied through the rearrangement of hydrophilic imidazole groups by varying the second‐stage monomer addition process such as the utilization of monomer‐swollen seed particles or a shot addition of monomers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 120:5753–5762, 2006     

Self‐assembly morphology evolution of the polyamide 6 (PA6) component in the PA6/polyethylene glycol system by in situ polymerization of ϵ‐caprolactam monomer

This paper describes the morphology evolution of polyamide 6 (PA6) components in the presence of polyethylene glycol (PEG) by self‐assembly via in situ anionic ring‐opening polymerization of ?‐caprolactam (CL) monomer and expands the study of morphology changes of PA6 in the PA6/PEG system. With a fixed mass ratio of [CL]/[PEG], it was found that by simply changing the reaction conditions the morphology of PA6 components could be changed from nano‐sized microspheres to regular 3D microsphere structured polyhedrons to 3D nano‐sized particle clusters to micro‐scale microspheres. The morphologies of the PA6 components were investigated by SEM and TEM analyses. The diameter range of the PA6 nano‐sized microspheres was controlled within 400 nm. The side length of an individual polyhedron could be effectively tuned from 10 µm to 100 µm. The diameter range of micrometer microspheres was about 5–8 µm. The results suggest that this strategy for self‐assembly can be applied to design materials with complex geometric structures. © 2018 Society of Chemical Industry     

Synthesis of polystyrene/poly(butyl acrylate) core–shell latex and its surface morphology

A polystyrene (PS)/poly(butyl acrylate) (PBA) composite emulsion was produced by seeded emulsion polymerization of butyl acrylate (BA) with PS seed particles which were prepared by emulsifier‐free polymerization of styrene with potassium persulfate (KPS) under a nitrogen atmosphere at 70°C for 24 h with stirring at 60 rpm and swelled with the BA monomer in an ethanol/water medium. The structure of the PS/PBA composite particles was confirmed by the presence of the characteristic absorption band attributed to PS and PBA from FTIR spectra. The particles for pure PS and PS/PBA with a low content of the BA monomer were almost spherical and regular. As the BA monomer content was increased, the particle size of the PS/PBA composite particles became larger, and more golf ball‐like particles were produced. The surface morphology of the PS/PBA composite particles was investigated by AFM and SEM. The T_g's attributed to PS and PBA in the PS/PBA composite particles were found at 110 and ?49°C, respectively. The thermal degradation of the pure PS and PS/PBA composite particles occurred in one and two steps, respectively. With an increasing amount of PBA, the initial thermal decomposition temperature increased. On the contrary the residual weight at 450°C decreased with an increasing amount of PBA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 595–601, 2003