Fabrication of polymeric hollow spheres having macropores by a quenching and sublimation process

Im, Sang Hyuk; Park, Ok O; Kwon, Moo Hyun

doi:10.1007/bf03218987

Cited by 7 publications

(7 citation statements)

References 22 publications

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“…Chemical methods, therefore, are those whereby hollow spheres are prepared by the selective removal of spherical templates coated with polymers by chemical reactions [1][2][3] and/or by in situ polymerization of monomer; that is, by emulsion polymerization or suspension polymerization, [4][5][6] interfacial condensation polymerization, [7,8] radical polymerization of monomers entrapped in the bilayer membrane of vesicles, [9][10][11][12] or by the polymerization of monomers on spherical polymer templates that are removable by physical methods. [13] Preformed polymers are used in physical methods, and the spherical shapes of polymers are obtained in different ways; dispersing polymer solution droplets in immiscible media, [14] inducing the self-assembly of polymers in solutions, [15] coating polymers on physically removable spherical templates, [1,16] dispersing droplets of polymer melts in immiscible media, [17] and injecting polymer melts. [18] In all these processes, the preparation of hollow polymer spheres is carried out at elevated temperature or using organic solvents.…”

Section: Introductionmentioning

confidence: 99%

A Physical Method of Fabricating Hollow Polymer Spheres Directly from Oil/Water Emulsions of Solutions of Polymers

Kim

Yoon²

2004

Macromol. Rapid Commun.

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Summary: A new physical method of fabricating hollow spheres from different polymers has been developed. In this method, emulsions were prepared by mixing organic solutions of polystyrene, poly(D,L‐lactide‐co‐glycolide) (PLGA), and bacterial poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV), water, and surfactants. The evaporation of solvents at room temperature caused a phase separation that eventually yielded hollow spheres. Molecular weights, concentrations of polymers, and the natures of surfactant and solvent were important aspects of hollow sphere formation and structure. A mechanism for the formation of hollow spheres is proposed based on observations made using an optical microscope equipped with a digital camcorder and using scanning electron microscopy images of hollow spheres obtained under different conditions.A scanning electron microscopy image of a broken smaller hollow sphere prepared using a 7 wt.‐% polystyrene solution (diameter of the sphere ∼10 micrometers).magnified imageA scanning electron microscopy image of a broken smaller hollow sphere prepared using a 7 wt.‐% polystyrene solution (diameter of the sphere ∼10 micrometers).

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Section: Introductionmentioning

confidence: 99%

A Physical Method of Fabricating Hollow Polymer Spheres Directly from Oil/Water Emulsions of Solutions of Polymers

Kim

Yoon²

2004

Macromol. Rapid Commun.

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“…1 Nowadays, such polymer particles have broadened their applications to more advanced fields such as information technology, electric and electronic science, and biotechnology including biochemicals and biomedicals. [2][3][4][5][6] In accord with the explosive expansion of their applications, precise control of the properties of the polymer colloids has become more important. Their size, uniformity of size, functionality of the base polymer, morphology of the polymer beads, and the degree of crosslinking are the main concerns in controlling properties.…”

Section: Introductionmentioning

confidence: 99%

Thermally robust highly crosslinked poly(methyl methacrylate-co-divinyl benzene) microspheres by precipitation polymerization

et al. 2004

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We prepared thermally robust fully crosslinked poly(methyl methacrylate-co-divinyl benzene) [poly(MMAco-DVB)] microspheres successfully by precipitation polymerization in the absence of a stabilizing agent. The DVB concentration plays a pivotal role not only in the formation of the individually stable microspheres but also in the polymerization characteristics, including the particle size, the uniformity of size, the polymerization yield, and the thermal properties. The number-average diameter of the microspheres increased linearly, from 0.72 to 2.15 μm, and the particle size distribution became narrower, by elevating the uniformity from 1.35 to 1.12, as the DVB concentration increased from 20 to 75 mol%. In addition, the yield of the polymerization increased, from 73.4 to 98.6%, as the DVB concentration increased. Since the prepared particles possess fully crosslinked microstructures, no glass transition temperatures were observed, but all the samples prepared with DVB concentrations ranging from 20 to 75 mol% possess enhanced thermal properties. Based on the DSC and TGA data, the thermal stability of the microspheres prepared by the precipitation polymerization is significantly improved as a result of crosslinking with DVB.

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“…As polymeric microspheres have been used in wider fields of conventional 1 and more sophisticated [2][3][4][5][6] areas, the development of a new process to prepare such materials has received much attention. Polymer microspheres of a particular size and uniformity are generally obtained with one of the heterogeneous polymerizations, including suspension, emulsion, dispersion, seeded, and precipitation polymerizations.…”

mentioning

confidence: 99%

Synthesis of poly(acrylamide‐co‐divinylbenzene) microspheres by precipitation polymerization

Jin

Yang

Shim

et al. 2005

J. Polym. Sci. A Polym. Chem.

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The synthesis and application of polymeric microspheres are of great importance from both academic and industrial points of view. As polymeric microspheres have been used in wider fields of conventional 1 and more sophisticated 2-6 areas, the development of a new process to prepare such materials has received much attention. Polymer microspheres of a particular size and uniformity are generally obtained with one of the heterogeneous polymerizations, including suspension, emulsion, dispersion, seeded, and precipitation polymerizations. Moreover, each polymerization is branched to several subsidiary methods, such as macroemulsion, miniemulsion, microemulsion, and soap-free emulsion polymerizations.Fully crosslinked monodisperse polymer microspheres have unique applications because of their superior strength, thermal and solvent resistance, and antislip properties.7 However, the synthesis of such microspheres is limited to a few techniques, such as seeded polymerization, [8][9][10][11] Shirasu porous glass (SPG) membrane emulsification followed by postpolymerization, 12,13 and precipitation polymerization.14 Precipitation polymerization, in particular, has advantages over the other techniques because crosslinked microspheres can be readily prepared in a single process without any auxiliary apparatus to make the size distribution of the particles narrow. Therefore, homoand copolymerization systems have been thoroughly investigated, including poly(divinylbenzene), 15 poly (methacrylic acid-co-polyethylene oxide methyl ether methacrylate), 16 poly(methacrylate-co-divinylbenzene), 17 poly(chloromethylstyrene-co-divinylbenzene), 18 poly(divinylbenzene-co-maleic anhydride) 19 , poly(methyl methacrylate-co-divinylbenzene)[poly(MMA-co-DVB)], [20][21][22] and poly(styrene-co-divinylbenzene) [poly(St-co-DVB)]. 23In addition, mechanistic studies to elucidate the formation of stable microspheres in the absence of any stabilizer have been reported 24,25 in which the absorption of oligomeric species onto the nuclei and the high degree of crosslinking are the primary reasons for the formation and stable growth of the microspheres.Several examples of the copolymerization of the partially water-soluble monomer acrylamide (AAm) and oil-soluble monomers such as methacrylic acid 26 and styrene 27,28 have been recently reported with precipitation polymerization, 26 inverse microemulsion polymerization, 27 and water/oil/water emulsion by SPG membrane emulsification and subsequent suspension polymerization. 28In our previous studies, poly(St-co-DVB) and poly (MMA-co-DVB) microspheres containing various concentrations of divinylbenzene (DVB), from 5 to 75 mol %, were synthesized by precipitation polymerization, and their unexpected thermal properties, superior to those of crosslinked polymers prepared by emulsion and

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Fabrication of polymeric hollow spheres having macropores by a quenching and sublimation process

Cited by 7 publications

References 22 publications

A Physical Method of Fabricating Hollow Polymer Spheres Directly from Oil/Water Emulsions of Solutions of Polymers

A Physical Method of Fabricating Hollow Polymer Spheres Directly from Oil/Water Emulsions of Solutions of Polymers

Thermally robust highly crosslinked poly(methyl methacrylate-co-divinyl benzene) microspheres by precipitation polymerization

Synthesis of poly(acrylamide‐co‐divinylbenzene) microspheres by precipitation polymerization

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