Synthesis of core–shell microspheres with active hydroxyl groups by two‐stage precipitation polymerization

Monodisperse micrometer microspheres having active hydroxyl groups with a dense core and a lightly crosslinked functional shell were prepared by two‐stage precipitation polymerization in the absence of any stabilizer. Commercial divinylbenzene (DVB), containing 80 % of DVB was polymerized by precipitation in acetonitrile without any stabilizer as the first stage polymerization and used as the core. When the conversion of DVB was about 60 % in the first stage, hydroxyethyl methacrylate (HEMA) and azobisisobutyronitrile (AIBN) were introduced into the reaction system and copolymerized with unreacted DVB on the core surface to form a lightly crosslinked functional shell with hydroxyl groups formed on the surface during the second stage precipitation polymerization. Both the crosslinking degree and the thickness of the shell layer depend on HEMA loading. The kinetic study demonstrated that the conversion of HEMA increased slightly with increasing HEMA loading. Higher HEMA loading and AIBN concentration increased the reaction rate significantly and formed more soluble oligomers, which resulted in secondary initiation with high HEMA loading. The resulting core–shell polymer particles were characterized with scanning electron microscopy (SEM), and FTIR. Copyright © 2004 Society of Chemical Industry     

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     

Narrow‐disperse or monodisperse crosslinked and functional core–shell polymer particles prepared by two‐stage precipitation polymerization

Narrow‐disperse and monodisperse cross‐linked core–shell polymer particles containing different functional groups, such as esters, hydroxyls, chloromethyls, carboxylic acids, amides, cyanos, and glycidyls, in the shell layers in the micrometer size range were prepared by a two‐stage precipitation polymerization in the absence of any stabilizer. Commercial divinylbenzene (DVB), containing 80% DVB, was precipitation polymerized in acetonitrile without any stabilizer as the first‐stage polymerization and was used as the core. Several functional monomers, including methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2‐hydroxyethyl methacrylate, glycidyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, t‐butyl acrylate, i‐octyl acrylate, acrylic acid, acrylamide, acrylonitrile, styrene, and p‐chloromethyl styrene, were incorporated into the shells during the second‐stage polymerization. The resulting core–shell polymer particles were characterized with scanning electron microscopy and Fourier transform infrared spectroscopy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1776–1784, 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     

Facile synthesis of silica/polymer hybrid microspheres and hollow polymer microspheres

Monodisperse silica/polydivinylbenzene (SiO₂/PDVB) and silica/poly(ethyleneglycol dimethacrylate) (SiO₂/PEGDMA) core-shell hybrid microspheres were prepared by a two-stage reaction with silica particles' grafting of 3-(methacryloxy)propyltrimethoxysilane (MPS) as core and PDVB or PEGDMA as shell, in which the MPS-modified silica core with diameter of 238 nm was synthesized by Stöber method and subsequently grafted with MPS as the first-stage reaction. The PDVB or PEGDMA shell was then encapsulated over the MPS-modified silica core by distillation precipitation polymerization of divinylbenzene (DVB) or ethyleneglycol dimethacrylate (EGDMA) in neat acetonitrile with 2,2′-azobisisobutyronitrile (AIBN) initiator as the second-stage reaction. The encapsulation of PDVB and PEGDMA on modified silica core particles was driven by the capture of DVB or EGDMA oligomer radicals via the vinyl groups on the surface of the modified silica cores during the second-stage polymerization in the absence of any stabilizer or surfactant. The shell thickness of the core-shell hybrid particles was controlled by the feed of DVB or EGDMA monomer during the polymerization. Hollow PDVB or PEGDMA microspheres with various shell thickness were further developed after selective removal of the modified silica cores with hydrofluoric acid. The resultant core-shell hybrid materials and hollow microspheres were characterized by transmission electron microscopy (TEM), and Fourier transform infrared spectra (FT-IR).     

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     

Preparation of monodisperse hydrophilic polymer microspheres with N,N′‐methylenediacrylamide as crosslinker by distillation precipitation polymerization

Highly crosslinked cauliflower‐like poly(N,N′‐methylenebisacrylamide) particles were prepared by distillation precipitation polymerization in neat acetonitrile with 2,2′‐azobisisobutyronitrile as initiator. Monodisperse hydrophilic polymer microspheres with various functional groups, such as amide, pyrrolidone and carboxylic acid, with a spherical shape and smooth surface in the size range 120–600 nm were prepared by distillation precipitation copolymerizations of functional comonomers including N‐isopropylacrylamide, N‐vinylpyrrolidone, methacrylic acid with N,N′‐methylenebisacrylamide as crosslinker. The polymer particles were formed and precipitated out from the reaction medium during the distillation of the solvent from the reaction system through an entropic precipitation manner. The effects of the solvent and the degree of crosslinking on the morphology and the loading capacity of the functional groups of the resultant polymer particles were investigated. The resulting polymer particles were characterized with scanning electron microscopy, transmission electron microscopy, dynamic light scattering and Fourier transform infrared spectroscopy. Copyright © 2007 Society of Chemical Industry     

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     

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).     

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     

Synthesis of monodisperse porous poly(divinylbenzene) microspheres by distillation-precipitation polymerization

Highly crosslinked monodisperse porous poly(divinylbenzene) (PDVB) microspheres were prepared by distillation-precipitation polymerization in acetonitrile containing up to 25 vol% of toluene as porogen with 2,2′-azobisisobutyronitrile (AIBN) as initiator in the absence of any stabilizer or surfactant. The porous polymer microspheres were formed through a precipitation manner during the distillation of the solvent from the reaction system. Monodisperse porous polymer particles with spherical shape and smooth surface were synthesized with diameters in the range of 1.86 and 3.06 μm, total porosity of up to 0.30 cm³/g and specific surface area as high as 762 m²/g. The growth procedure of porous PDVB microsphere was characterized by SEM technique for morphological observation and isotherm nitrogen adsorption for the determination of the special surface area and porosity. The resultant porous polymer microspheres had a novel structure with the gradual increasing of pore volume during distillation of the solvent out of the reaction system.     

Synthesis and analysis of properties of a new core–shell silicon‐containing fluoroacrylate latex

BACKGROUND: Silicon‐containing fluoroacrylate copolymers are potential materials for use in the protection of ancient stone buildings. In the work reported in this paper, a new core–shell silicon‐containing fluoroacrylate latex was prepared through grafting of a fluoroacrylate copolymer latex with polysiloxane. RESULTS: The core–shell silicon‐containing fluoroacrylate latex was successfully synthesized by seed emulsion polymerization and octamethylcyclotetrasiloxane (D₄) ring‐opening polymerization in the presence of a mixed emulsifier consisting of a non‐ionic emulsifier and a novel fluorine‐containing anionic emulsifier sodium perfluoro‐octane sulfonate. Transmission electron microscopy, X‐ray photoelectron spectroscopy, static contact angle measurements and scanning electron microscopy‐energy dispersive X‐ray analysis showed that when the D₄ content was controlled at 2.84–4.36 wt%, the silicon‐containing fluoroacrylate latex presented a uniform sphere core‐shell structure and had strong hydrophobic and oleophobic characters due to the association of both fluorine and silicon atoms on the latex film surface. The film cross‐section exhibited uniform and dense microstructure without any phase segregation. Additionally, thermogravimetric analysis and tensile test results indicated that all the silicon‐containing fluoroacrylate copolymers displayed better thermal stability and higher flexibility. CONCLUSION: The synthetic core–shell silicon‐containing fluoroacrylate latex showed excellent surface properties, thermal stability and flexibility, and has encouraging prospects in application as a protective coating. Copyright © 2009 Society of Chemical Industry     

Preparation of core–shell glass bead/polysulfone microspheres with two‐step sol–gel process

Core–shell microspheres made from glass beads as the core phase and polysulfone (PSf) as the shell phase can act as an absorbent in the separation process or a supporter for chemical reactions. Based on phase‐inversion principles, a two‐step sol–gel method was developed in this work in which ether was added first and H₂O was added second to a PSf‐containing dimethyformamide (DMF) solution to help PSf solidify on the surface of glass beads. The results from scanning electron microscopy, Fourier transform IR, and X‐ray photoelectron spectroscopy showed that a dense layer of PSf (thin to several microns) was coated on the glass beads and the core–shell microspheres were almost monodispersed. The utilization percentages of the glass beads and PSf were high as 100 and 80%, respectively. The thickness of the PSf membrane was calculated to be about 4.3 μm. To obtain well‐monodispersed microspheres, the practical volume ratio of ether to DMF was recommended to be larger than 4.5. The results suggested that the two‐step sol–gel method is a highly efficient process for preparation of glass bead/PSf core–shell microspheres. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3365–3369, 2006     

Study on synthesis and morphology control of poly(4‐vinylpyridine‐co‐butyl acrylate)/poly(styrene‐co‐butyl acrylate) composite microspheres

Monodispersed crosslinked cationic poly(4‐vinylpyridine‐co‐butyl acrylate) [P(4VP‐BA)] seed latexes were prepared by soapless emulsion polymerization, using 2,2′‐azobismethyl(propionamidine)dihydrochloride (V₅₀) as an initiator and divinylbenzene (DVB) or ethylene glycol dimethacrylate (EGDMA) as a crosslinker. The optimum condition to obtain monodispersed stable latex was investigated. It was found that the colloidal stability of the P4VP latex can be improved by adding an adequate amount of BA (BA/4VP = 1/4, w/w), and adopting a semicontinuous monomer feed mode. Subsequently, poly(4‐vinylpyridine‐co‐butyl acrylate)/Poly(styrene‐co‐butyl acrylate) [P(4VP‐BA)/P(ST‐BA)] composite microspheres were synthesized by seeded polymerization, using the above latex as a seed and a mixture of ST and BA as the second‐stage monomers. The effects of the type of crosslinker, the degree of crosslinking, and the initiators (AIBN and V₅₀) on the morphology of final composite particles are discussed in detail. It was found that P(4VP‐BA)/P(ST‐BA) composite microspheres were always surrounded by a PST‐rich shell when V₅₀ was used as initiator, while sandwich‐like or popcorn‐like composite particles were produced when AIBN was employed. This is because the polarity of the polymer chains with AIBN fragments is lower than for the polymer with V₅₀ fragments, hence leading to higher interfacial tension between the second‐stage PST‐rich polymer and the aqueous phase, and between PST‐rich polymer and P4VP‐rich seed polymer. As a result, the seed cannot be engulfed by the PST‐rich polymer. Furthermore, the decrease of T_g of the second‐stage polymer promoted phase separation between the seeds and the PST‐rich polymer: sandwich‐like particles formed more preferably than popcorn‐like particles. It is important knowledge that various morphologies different from PST‐rich core/P4VP‐rich shell morphology, can be obtained only by changing the initiator, considering P4VP is much more hydrophilic than PST. The zeta potential of composite particles initiated by AIBN in seeded polymerization shifted from a positive to a negative charge. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1190–1203, 2002     

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 Narrow or Monodisperse Polymer Microspheres with Cyano Group by Distillation-Precipitation Polymerization

Summary Narrow- or monodisperse poly(divinylbenzene-co-acrylonitrile) (poly(DVB-co-AN)) microspheres with reactive cyano group were prepared by distillation-precipitation polymerization of divinylbenzene (DVB) and acrylonitrile (AN) in neat acetonitrile with 2,2′-azobis(isobutyronitrile) (AIBN) as initiator in the absence of any stabilizer or additive without stirring. The effects of the comonomer feed on the morphology and the size of poly(DVB-co-AN) microspheres were investigated. All the polymer microspheres were characterized with scanning electron microscopy and FT-IR spectra.     

Synthesis of monodisperse crosslinked poly(styrene‐co‐divinylbenzene) microspheres by precipitation polymerization in acetic acid

Poly(styrene‐co‐divinylbenzene) microspheres with size ranging from 1.6 to 1.8 μm were prepared in acetic acid by precipitation polymerization. The particle size and particle size distribution were determined by laser diffraction particle size analyzer, and the morphology of the particles was observed with scanning electron microscope. Besides, effects of various polymerization parameters such as initiator and total monomer concentration, divinylbenzene (DVB) content, polymerization time and polymerization temperature on the morphology and particle size were investigated in this article. In addition, the yield of microspheres increased with the increasing total monomer concentration, initiator loading, DVB concentration and polymerization time. In addition, the optimum polymerization conditions for synthesis of monodisperse crosslinked poly(styrene‐co‐divinylbenzene) microspheres by precipitation polymerization in acetic acid were obtained. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of poly(methyl methacrylate–butyl acrylate–acrylic acid)/polyaniline core–shell nanoparticles in miniemulsion media

Conductive polymer particles, polyaniline (PANI)‐coated poly(methyl methacrylate–butyl acrylate–acrylic acid) [P(MMA–BA–AA)] nanoparticles, were prepared. The P(MMA–BA–AA)/PANI core–shell complex particles were synthesized with a two‐step miniemulsion polymerization method with P(MMA–BA–AA) as the core and PANI as the shell. The first step was to prepare the P(MMA–BA–AA) latex particles as the core via miniemulsion polymerization and then to prepare the P(MMA–BA–AA)/PANI core–shell particles. The aniline monomer was added to the mixture of water and core nanoparticles. The aniline monomer could be attracted near the outer surface of the core particles. The polymerization of aniline was started under the action of ammonium persulfate (APS). The final product was the desired core–shell nanoparticles. The morphology of the P(MMA–BA–AA) and P(MMA–BA–AA)/PANI particles was characterized with transmission electron microscopy. The core–shell structure of the P(MMA–BA–AA)/PANI composites was further determined by Fourier transform spectroscopy and ultraviolet–visible measurements. The conductive flakes made from the core–shell latexes were prepared, and the electrical conductivities of the flakes were studied. The highest conductivity of the P(MMA–BA–AA)/PANI pellets was 2.05 S/cm. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of novel hybrid inorganic–organic hollow microspheres via a self‐template approach

BACKGROUND: Hollow microspheres, especially biodegradable polymeric microspheres, have attracted considerable attention due to their particular characteristics. Up to now, microspheres have been prepared via various strategies, for instance the template synthesis method and the self‐assembly process. However, economic, novel and simple methods to prepare hollow microspheres are still being sought. RESULTS: Phosphazene‐containing microspheres, which contain self‐assembled core‐shell structures, were prepared at high colloid contents using an ultrasonic bath via a self‐template approach. Along with the controlled self‐degradation of the internal core, the corresponding hybrid inorganic–organic hollow microspheres appeared. The mechanism was evidenced by means of transmission and scanning electron microscopy, cross‐polarization with magic angle spinning NMR, Fourier transform infrared spectroscopy, X‐ray diffraction and thermogravimetric analysis. CONCLUSION: It was clarified that the phosphazene‐containing microspheres could be formed and stably dispersed without aggregation even at high colloid contents using the ultrasonic bath method and the microspheres contain self‐assembled core–shell structures. Along with the controlled self‐degradation of the internal core, the corresponding hollow microspheres appeared. The mechanism of this preparation is of great significance because it is completely different from the conventional template synthesis method and the self‐assembly process. The absence of any stabilizing agent and special templates might inspire creative imagination in the design of new morphologies of micro‐ and nanostructures. Copyright © 2007 Society of Chemical Industry