Preparation of polymer/silica/polymer tri-layer hybrid materials and the corresponding hollow polymer microspheres with movable cores

Tri-layer poly(methacrylic acid-co-ethyleneglycol dimethacrylate)/silica/poly(ethyleneglycol dimethacrylate) (P(MAA-co-EGDMA)/SiO₂/PEGDMA) and P(MAA-co-EGDMA)/SiO₂/polydivinylbenzene hybrid microspheres were prepared by distillation precipitation polymerization of ethyleneglycol dimethacrylate (EGDMA) and divinylbenzene (DVB) in the presence of 3-(methacryloxy)propyl trimethoxysilane (MPS)-modified P(MAA-co-EGDMA)/SiO₂ microspheres as the seeds. The polymerization of EGDMA and DVB was performed in neat acetonitrile with 2,2′-azobisisobutyronitrile (AIBN) as initiator to coat the MPS-modified P(MAA-co-EGDMA)/SiO₂ seeds through the capture of EGDMA and DVB oligomer radicals with the aid of vinyl groups on the surface of modified seeds in the absence of any stabilizer or surfactant. Monodisperse P(MAA-co-EGDMA)/SiO₂ core-shell microspheres were synthesized by coating of a layer of silica onto P(MAA-co-EGDMA) microspheres via a sol-gel process, which were further grafted by MPS incorporating the reactive vinyl groups onto the surface to be used as the seeds for the construction of hybrid microspheres with tri-layer structure. Hollow poly(ethyleneglycol dimethacrylate) (PEGDMA) and poly(divinylbenzene) (PDVB) microspheres with movable P(MAA-co-EGDMA) core were subsequently developed after the selective etching of the silica mid-layer from the tri-layer hybrid microspheres in hydrofluoric acid. The morphology and structure of the tri-layer polymer hybrids and the corresponding hollow polymer microspheres with movable P(MAA-co-EGDMA) core were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectra and X-ray photoelectron spectroscopy (XPS).     

Preparation of ellipsoidal hematite/polymer hybrid materials and the corresponding hollow polymer ellipsoids

Ellipsoidal hematite/poly(ethyleneglycol dimethacrylate) core-shell hybrid materials were prepared by distillation precipitation polymerization of ethyleneglycol dimethacrylate (EGDMA) in the presence of 3-(methacryloxy)propyl trimethoxysilane (MPS)-modified hematite (α-Fe₂O₃) particles as the seeds. The polymerization of EGDMA was performed in neat acetonitrile with 2,2′-azobisisobutyronitrile (AIBN) as initiator to coat MPS-modified hematite seeds through the capture of EGDMA oligomer radicals with the aid of vinyl groups on the surface of the MPS-modified hematite particles in absence of any stabilizer or surfactant. The shell-thickness of the core-shell hybrid particles was controlled by the feed of EGDMA monomer during the polymerization. Other hematite/polymer core-shell hybrid particles, such as hematite/polydivinylbenzene (α-Fe₂O₃/PDVB) and hematite/poly(divinylbenzene-co- methacrylic acid) (α-Fe₂O₃/P(DVB-co-MAA)) were also prepared by this procedure. Hematite/poly(N,N′-methylenebisacrylamide-co-methacrylic acid) (α-Fe₂O₃/P(MBAAm-co-MAA)) were synthesized with unmodified hematite particles as the seeds. Hollow polymer ellipsoids were subsequently developed after the selective removal of the hematite core with hydrochloric acid (HCl) from hematite/polymer core-shell hybrids. The resultant core-shell hybrid particles and hollow polymer ellipsoids were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR) and vibrating sample magnetometer (VSM).     

A facile route to poly(divinylbenzene) hollow microspheres with pyridyl group on the interior surface

Poly(divinylbenzene) (PDVB) hollow microspheres with pyridyl group located on their interior surface were prepared by a facile route with the aid of the vinyl groups on the surface of poly(methacrylic acid) (PMAA) microspheres, which were incorporated through the hydrogen-bonding interaction between the carboxylic acid group and pyridyl group of 4-vinylpyridine (VPy). Poly(methacrylic acid)@polydivinylbenzene (PMAA@PDVB) core-shell structure microspheres with PMAA as core and PDVB as shell were synthesized by a two-stage distillation-precipitation polymerization technique through the capture of the DVB monomer from solution of the reactive vinyl groups on pyridyl-functionalized PMAA microspheres based on a seeded-nucleation mechanism during the second-stage polymerization. The PDVB hollow microspheres with different shell thicknesses were developed after the PMAA core particles were removed by selective dissolution under basic condition in ethanol, during which the pyridyl group was left on the interior surface of the shell layer in PDVB hollow microspheres. The resultant core-shell and hollow microspheres were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier transform infrared spectra (FT-IR) and elemental analysis.     

Synthesis of hollow polymer microspheres with movable polyelectrolyte core and functional groups on the shell-layer

Hollow polymer microspheres with movable quaternary pyridinium polyelectrolyte (PE) cores and various functional groups on the shell-layers, such as hydroxyl, amide, and carboxyl, were prepared by the selectively etching of mid-silica layer with hydrofluoric acid from the corresponding poly(ethyleneglycol dimethacrylate-co-methacrylic acid)@poly(ethyleneglycol dimethacrylate- co-4-vinylpyridinium benzylchloride)/silica/polymer (P(EGDMA-co-MAA) @P(EGDMA-co-VPyBzCl)/SiO₂/polymer) tetra-layer microspheres. The tetra-layer hybrid microspheres were synthesized by a multi-stage reaction process, which included the combination of distillation precipitation polymerization for the formation of polymer-layers and the hydrolysis of tetraethyl orthosilicate (TEOS) via a modified Stöber sol-gel procedure to afford silica layer. The efficient electrostatic interaction between the cationic pyridinium species on the surface of P(EGDMA-co-MAA)@P(EGDMA-co-VPyBzCl) cores and the negative charges on the silica species was essential to get monodisperse tri-layer P(EGDMA-co-MAA)@P(EGDMA-co-VPyBzCl)/SiO₂ microspheres during the hydrolysis of TEOS. The functional polymer shell was encapsulated over 3-(methacryloxy)propyl trimethacrylate (MPS) modified tri-layer polymer/silica seeds by distillation precipitation copolymerizations of N,N′-methylenebisacrylamide (MBAAm) crosslinker and comonomers with different functional groups, including N-isopropylacrylamide (NIPAAm), 2-hydroxyethylmethacrylate (HEMA) and methacrylic acid (MAA), with 2,2′-azobisisobutyronitrile (AIBN) as an initiator in neat acetonitrile. The morphology and structure of the tetra-layer hybrid microspheres and the corresponding hollow microspheres with movable PE core and functional polymer shell-layer were characterized by transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), ξ-potential, and dynamic light scattering (DLS).     

Preparation of narrow‐dispersion or monodisperse polymer microspheres with active hydroxyl group by distillation–precipitation polymerization

Narrow‐dispersion or monodisperse polymer microspheres with active hydroxyl groups were prepared by distillation–precipitation polymerization in the absence of any stabilizer. The monomer hydroxyethyl methacrylate (HEMA) was copolymerized with either commercial divinylbenzene (DVB) (containing 80 % of DVB isomers) or ethyleneglycol dimethacrylate (EGDMA) as crosslinker by distillation–precipitation polymerization technique with 2,2′‐azobisisobutyronitrile (AIBN) as initiator in neat acetonitrile. The effects of the crosslinker and the crosslinking degree on the morphology and the loading of the active hydroxyl group of the resultant microspheres were investigated. The agitation caused by distilling off a portion of the polymerization solvent during the polymerization avoided coagulation and resulted in the narrow‐dispersion or monodisperse polymer microspheres for the distillation precipitation technique. Copyright © 2005 Society of Chemical Industry     

Preparation of core–shell poly(acrylic acid)/polystyrene/SiO2 hybrid microspheres

Core–shell poly(acrylic acid)/polystyrene/SiO₂ (PAA/PS/SiO₂) hybrid microspheres were prepared by dispersion polymerization with three stages in ethanol and ethyl acetate mixture medium. Using vinyltriethoxysilane (VTEOS) as silane agent, functional silica particles structured vinyl groups on surfaces were prepared by hydrolysis and polycondensation of tetraethoxysilane and VTEOS in core stage. Then, the silica particles were used as seeds to copolymerize with styrene and acrylic acid sequentially in shell stage I and stage II to form PAA/PS/SiO₂ hybrid microspheres. Transmission electron microscope results show that most PAA/PS/SiO₂ hybrid microspheres are about 40 nm in diameter, and the silica cores are about 15 nm in diameter, which covered with a layer of PS about 7.5‐nm thick and a layer of PAA about 5‐nm thick. This core–shell structure is also conformed by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and differential scanning calorimetry. FTIR results show that silica core, PS shell, and PAA outermost shell are bonded by covalents. In the core–shell PAA/PS/SiO₂ hybrid microsphere, the silica core is rigidity, and the PAA outermost shell is polarity, while the PS layer may work as lubricant owning to its superior processing rheological property in polymer blending. These core–shell PAA/PS/SiO₂ hybrid microspheres have potential as new materials for polar polymer modification. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1729–1733, 2006     

Facile synthesis of high-magnetization Fe3O4@polydivinylbenzene core–shell submicrospheres

Fe₃O₄@polydivinylbenzene (PDVB) submicrospheres were prepared via distillation–precipitation polymerization of DVB in the presence of submicron magnetite colloid nanocrystal clusters (MCNCs) as seeds. The surface of the MCNCs was modified with vinyl groups before PDVB encapsulation. The resulting Fe₃O₄@PDVB particles showed a well-defined core–shell structure, and the shell thickness could be readily controlled by the DVB dosage. A lowly cross-linked poly(methacrylic acid) (PMAA) layer could be further coated onto the highly cross-linked PDVB shell via a second-stage DPP process, suggesting the presence of residual vinyl groups on the surface of the Fe₃O₄@PDVB particles. The hybrid particles showed rather high magnetization and near superparamagnetism, hence capable of easy magnetic separation.     

Degradable inorganic/polymer core-shell microspheres for pH-triggered release of indole-3-acetic acid

Abstract

The narrowly dispersed functional silica/poly(di(metacryloylooxy-1-ethoxy) methane-co-acryl amide) (SiO₂/P(DMOEM-co-AAm)) core-shell microspheres were synthesized by distillation precipitation polymerization of DMOEM as a degradable crosslinker and AAm as a functional monomer with the presence of 3-(methacryloxy)propyltrimethoxysilane (MPS) modified silica microspheres as seeds. Indole-3-acetic acid (IAA) can be efficiently loaded into the microspheres with a loading capacity of 37.5% via hydrogen-bonding interaction between the carboxylic acid group of IAA and the amide groups on the surface of SiO₂/P(DMOEM-co-AAm). The loaded IAA can be triggered released by pH due to the presence of pH-responsive crosslinker (DMOEM).     

Monodisperse hydrophilic polymer microspheres having carboxylic acid groups prepared by distillation precipitation polymerization

Monodisperse hydrophilic polymer microspheres having carboxyl acid group with spherical shape in the range of 160 nm and 1.52 μm were prepared by distillation copolymerizations of (meth)acrylic acid with either ethyleneglycol dimethacrylate (EGDMA) or divinylbenzene (DVB) as crosslinker. Polymerization was carried out with 2,2′-azobisisobutyronitrile (AIBN) as initiator in neat acetonitrile without stirring. The polymer microspheres were formed and precipitated out from the reaction medium during the distillation of the solvent from the reaction system through an entropic precipitation polymerization manner. The effects of the crosslinker degree on the morphology and the loading capacity of the carboxylic acid group of the resultant polymer microspheres were investigated. The growth procedures of poly(DVB-co-AA) microspheres were traced by SEM characterization. The steric stabilization through the pendent chains and surface gel and the electrostatic repulsion from the carboxyl acid groups contribute to the formation of monodisperse polymer microspheres.     

Preparation of uniform poly(glycidyl methacrylate) porous microspheres by membrane emulsification–polymerization technology

Uniform poly(glycidyl methacrylate‐divinyl‐benzene) (P(GMA‐DVB)) and poly(glycidyl methacrylate‐ethylene dimethacrylate) (P(GMA‐EGDMA)) porous microspheres with several 10 μm were successfully prepared by membrane emulsification–polymerization technology. Conventional suspension polymerization method was first investigated by examining the effects of recipe components on the morphologies of P(GMA‐DVB), including stabilizer, diluent, and crosslinker to select a optimum recipe. The membrane emulsification–polymerization process was developed to prepare uniform PGMA porous microspheres as the following: the oil phase composed of monomer, diluent and initiator was pressed through membrane pores into the aqueous phase to form uniform droplets, and subsequent suspension polymerization was carried out. GMA and 4‐methyl‐2‐pentanol in the selected recipe were relatively hydrophilic, and therefore oil phase could wet the hydrophilic glass membrane and bring about polydispersed droplets. However, when isooctane was added as a component of diluents, the uniform droplets could be prepared by membrane emulsification method. In the membrane emulsification–polymerization, the coagulation between microspheres obviously decreased while yield of microspheres slightly increased. To extend the application of PGMA, as a trail, uniform P(GMA‐EGDMA) porous microspheres were also successfully prepared by membrane emulsification–polymerization with a isooctane contained diluent, even though EGDMA was more hydrophilic than DVB. Therefore, recipe was found the important factor to prepare uniform PGMA porous microspheres using membrane emulsification–polymerization method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5018–5027, 2006     

Preparation of poly(divinylbenzene‐co‐N‐isopropylacrylamide) microspheres and their hydrogen‐bonding assembly behavior for raspberry‐like core‐corona polymer composite

Narrowdisperse poly(divinylbenzene‐co‐N‐isopropylacrylamide) (poly(DVB‐co‐NIPAM)) functional microspheres with the diameter in the range of 630 nm and 2.58 μm were prepared by distillation–precipitation polymerization in neat acetonitrile in the absence of any stabilizer. The effect of N‐isopropylacrylamide (NIPAM) ratio in the comonomer feed on the morphology of the resultant polymer particles was investigated in detail with divinylbenzene (DVB) as crosslinker and 2,2′‐azobisisobutyronitrile (AIBN) as initiator. The monodisperse poly(DVB‐co‐NIPAM) microspheres with NIPAM fraction of 20 wt % were selected for the preparation of raspberry‐like core‐corona polymer composite by the hydrogen‐bonding self‐assembly heterocoagulation with poly(ethyleneglycol dimethacrylate‐co‐acrylic acid) [poly(EGDMA‐co‐AA)] nanospheres. Both of the functional poly(DVB‐co‐NIPAM) microspheres and the core‐corona particles were characterized with scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), and elemental analysis (EA). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1350–1357, 2007     

Synthesis of pH-sensitive hollow polymer microspheres with movable magnetic core

The pH-sensitive hollow poly(N,N′-methylenebisacrylamide-co-methacrylic acid) (P(MBAAm-co-MAA)) microspheres with movable magnetic/silica (Fe₃O₄/SiO₂) cores were prepared by the selective removal of poly(methacrylic acid) (PMAA) layer in ethanol/water from the corresponding Fe₃O₄/SiO₂/PMAA/P(MBAAm-co-MAA) tetra-layer microspheres, which were synthesized by the distillation precipitation copolymerization of N,N′-methylenebisacrylamide (MBAAm) and methacrylic acid (MAA) in the presence of Fe₃O₄/SiO₂/PMAA tri-layer microspheres as seeds in acetonitrile with 2,2′-azobisisobutyronitrile (AIBN) as the initiator. The Fe₃O₄/SiO₂/PMAA tri-layer microspheres were afforded by the distillation precipitation polymerization of MAA with 3-(methacryloxy)propyl trimethoxysilane (MPS)-modified Fe₃O₄/SiO₂ core-shell particles as the seeds. The functional multi-layer inorganic/polymer microspheres and the corresponding hollow polymer microspheres with movable magnetic cores were characterized with transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectra, dynamic light scattering (DLS), and vibrating sample magnetometer (VSM).     

Stable poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) microspheres via precipitation polymerization

Narrow‐dispersion or monodisperse with stable and smooth surface polymer microspheres were prepared without a significant coagulum by precipitation polymerization in the absence of any stabilizer. The monomer glycidyl metharylate (GMA) was copolymerized with ethyleneglycol dimethacrylate (EGDMA) as crosslinker by precipitation polymerization technique with 2,2′‐azobisisobutyronitrile as initiator in neat acetonitrile. The effects of the content of EGDMA on the polymerization characteristics and size/uniformity of the microspheres were investigated. The onset of the thermal degradation temperature at higher temperature and the swelling test suggest that the prepared particles were highly crosslinked. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Monodisperse temperature-responsive hollow polymer microspheres: Synthesis, characterization and biological application

Temperature-responsive hollow poly(N-isopropylacrylamide) (PNIPAAm) microspheres were prepared by a two-stage distillation precipitation polymerization to afford a core-shell microspheres with subsequent removal of poly(methacrylic acid) (PMAA) core. PMAA@PNIPAAm core-shell microspheres were synthesized by the second-stage polymerization of NIPAAm in the presence of PMAA as core with N,N′-methylenebisacrylamide as crosslinker in acetonitrile, in which the hydrogen-bonding interaction between the carboxylic acid group of PMAA core and the amide group of NIPAAm as well as MBAAm played a key role to form the core-shell microspheres. The hollow PNIPAAm microspheres with different thicknesses, which were controlled by the monomer loading level and the crosslinking degree, were developed after the removal of PMAA core. The loading and controlled-release behavior of the drug on the hollow PNIPAAm microspheres was investigated with doxorubicin hydrochloride. The core-shell and hollow microspheres were characterized with transmission electron microscopy, scanning electron microscopy, dynamic light scattering, static light scattering, X-ray photoelectron spectroscopy, elemental analysis, and FT-IR spectra.     

Fabrication and characterization of multilayer SiO2/polymethacrylic acid/polypyrrole composites and hollow polypyrrole microspheres

Methacrylic acid was polymerized on the 3‐(methacryloxy)propyl trimethoxysilane‐modified silica core. The carboxylic acid groups of polymethacrylic acid (PMAA) not only provide the “active‐sites” for growth of the pyrrole monomers but also act as doping acids for polypyrrole (PPy). By in situ polymerization route, SiO₂/PMAA/PPy multilayer composites and hollow PPy microspheres with controllable shell thickness were fabricated. The morphologies, sizes, and structures of the nanocomposites were investigated in detail by transmission electron microscopy, scanning electron microscopy, Fourier‐transform infrared spectra, X‐ray photoelectron spectroscopy, and thermogravimetric analysis. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of narrow‐disperse or monodisperse poly{[poly(ethylene glycol) methyl ether acrylate]‐co‐(acrylic acid)} microspheres with ethyleneglycol dimethacrylate as crosslinker by distillation precipitation polymerization

Narrow‐disperse or monodisperse poly{[poly(ethylene glycol) methyl ether acrylate]‐co‐(acrylic acid)} (poly(PEGMA‐co‐AA)) microspheres were prepared by distillation precipitation polymerization with ethyleneglycol dimethacrylate (EGDMA) as crosslinker with 2,2′‐azobisisobutyronitrile as initiator in neat acetonitrile in the absence of any stabilizer, without stirring. The diameters of the resultant poly(PEGMA‐co‐AA‐co‐EGDMA) microspheres were in the range 200–700 nm with a polydispersity index of 1.01–1.14, which depended on the comonomer feed of the polymerization. The addition of the hydrogen bonding monomer acrylic acid played an essential role in the formation of narrow‐disperse or monodisperse polymer microspheres during the polymerization. Copyright © 2006 Society of Chemical Industry     

高分子微球的合成及其在密封剂中的应用

以亲水性4-乙烯基吡啶(4-Vp)为微球的壳层单体、苯乙烯(St)为微球的核层单体,采用一步无皂乳液聚合法制备了PS-P4V P[聚苯乙烯-聚(4-乙烯基吡啶)]微球;然后在该高分子微球表面覆盖了一层有机硅,合成了有机-无机杂化PS-P4VP-Si[有机硅包覆的聚苯乙烯-聚(4-乙烯基吡比啶)]微球;最后分别将两种微球与聚硫橡胶共混,制备相应的聚硫密封剂。研究结果表明:PS-P4VP、PS-P4VP-Si微球大小均一,两者粒径分别为290 nm和350 nm;两种微球分别作为聚硫密封剂的填料,既能提升密封剂的性能,又能降低密封剂本身的密度(比常规密封剂降低了15%～20%);同时,这两种微球填充的聚硫密封剂具有艮好的耐热性能和耐介质性能,特别是PS-P4VP-Si微球的综合性能更优异。     

Preparation of monodisperse fluorescent core–shell polymer microspheres with functional groups in the shell layer by two‐stage distillation–precipitation polymerization

Monodisperse crosslinked core–shell micrometer‐sized microspheres bearing a brightly blue fluorescent dye, carbazole, and containing various functional groups in the shell layers were prepared by a two‐stage distillation–precipitation polymerization in acetonitrile in the absence of any stabilizer. Commercial divinylbenzene (DVB), containing 80 vol.% of DVB, was polymerized by distillation–precipitation in acetonitrile without any stabilizer using 2,2′‐azobisisobutyronitrile (AIBN) as the initiator for the first stage of polymerization which resulted in monodisperse polyDVB microspheres used as the core. Several functional monomers, including 2‐hydroxyethyl methacrylate and acrylonitrile together with N‐vinylcarbazole blue fluorescent comonomer, were incorporated into the shell layers with AIBN as initiator during the second stage of polymerization. The resultant core–shell polymer microspheres were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, UV‐visible spectroscopy and fluorescence spectroscopy. Copyright © 2006 Society of Chemical Industry     

Fabrication and properties of polysilsesquioxane-based trilayer core–shell structure latex coatings with fluorinated polyacrylate and silica nanocomposite as the shell layer

Polysilsesquioxanes (PSQ)-based core–shell fluorinated polyacrylate/silica hybrid latex coatings were synthesized with PSQ latex particles as the seeds, and methyl methacrylate, butyl acrylate, 3-(trimethoxysilyl) propyl methacrylate (MPS)-modified SiO₂ nanoparticles (NPs), 1H,1H,2H,2H-perfluorooctyl methacrylate (PFOMA) as the shell monomers by emulsifier-free miniemulsion polymerization. The results of Fourier transform IR spectroscopy, transmission electron microscopy, and dynamic light scattering suggested the obtained hybrid particles emerged with trilayer core–shell pattern. Contact angle analysis, x-ray photoelectron spectroscopy, and atom force microscopy results indicated that the hybrid film containing SiO₂ NPs showed higher hydrophobicity, lower surface free energy and water absorption, in comparison with the control system (without SiO₂ NPs). Compared with the control system, the hybrid latex film containing SiO₂ NPs in the fluorinated polyacrylate shell layer showed the higher content of fluorine atoms and a rougher morphology on the film surface. Additionally, thermogravimetric analysis demonstrated the enhanced thermostability of PSQ-based nanosilica composite fluorinated polyacrylate latex film.     

Molecularly imprinted polymer microspheres prepared by precipitation polymerization using a sacrificial covalent bond

Molecularly imprinted polymer microspheres were prepared by precipitation polymerization using a sacrificial covalent bond. In the present model, cholesteryl (4‐vinyl)phenyl carbonate was used as a template monomer. The imprinted microspheres were prepared using ethylene glycol dimethacrylate (EDMA) and divinylbenzene (DVB) as crosslinker. The base‐labile carbonate ester bond was easily hydrolyzed to leave imprinted cavities in the resulting polymers. Radioligand binding analysis, elemental analysis, and scanning electron microscopy were used to characterize the imprinted materials. Imprinted microspheres prepared from DVB crosslinker had larger and more defined spherical shape, and displayed better imprinting effect than did the EDMA‐based microparticles. For comparison, imprinted bulk polymers were also prepared in the same reaction solvent as that used in precipitation polymerization. Elemental analysis results indicated that imprinted microspheres contained more template monomer units than bulk materials. The efficiency of template removal by hydrolysis treatment for microspheres was also higher than that for bulk polymers. For DVB‐based polymers, imprinted microspheres displayed higher specific cholesterol uptake than did the corresponding bulk polymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1390–1398, 2006