Faculty Profiles - NAKANISHI Kazuki

Papers - NAKANISHI Kazuki

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Functional porous materials via sol-gel with phase separation Reviewed

Kazuki Nakanishi

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN Vol. 115 ( 1339 ) page： 169 - 175 2007.3

Language：English Publishing type：Research paper (scientific journal) Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

Variety of functional porous materials in metal oxide, metalloxane polymer and even pure organic polymer compositions obtained by a sol-gel process are reviewed. Specifically, processes including polymerization-induced phase separation have been extensively introduced from theories to practices. The basic concept of hierarchical pore architecture in monolithic materials is explained, together with several examples of successful applications. Depending on the hierarchy, single, double and triple, unique family of materials can be fabricated. Existing and prospective applications and future challenges of the materials are also shown.

DOI： 10.2109/jcersj.115.169

High-throughput protein digestion by trypsin-immobilized monolithic silica with pipette-tip formula Reviewed

Shigenori Ota, Shota Miyazaki, Hideo Matsuoka, Kei Morisato, Yukihiro Shintani, Kazuki Nakanishi

JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS Vol. 70 ( 1 ) page： 57 - 62 2007.2

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Based on the monolithic silica gel materials with hierarchical pore structure and on the SPE devices (MonoTip (R)) developed thereof, a trypsin-immobilized monolithic silica in a pipette tip (MonoTip (R) Trypsin) suitable for digesting proteins has been newly developed. The surface of monolithic silica fixed into the tip was chemically modified with trypsin via an aminopropyl group. Trypsin-immobilized monolith successfully performed a rapid digestion of reduced and alkylated proteins with only a few times pipetting operation for the pre-treatment procedure of chromatographic analysis. The novel solid-phase digestion tool using monolithic silica allows a high-throughput trypsin proteolysis of bio-substances in proteomics. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jbbm.2006.10.005

Size-exclusion effect and protein repellency of concentrated polymer brushes prepared by surface-initiated living radical polymerization Reviewed

Chiaki Yoshikawa, Atsushi Goto, Norio Ishizuka, Kazuki Nakanishi, Akio Kishida, Yoshinobit Tsujii, Takeshi Fukuda

MACROMOLECULAR SYMPOSIA Vol. 248 page： 189 - 198 2007

Language：English Publishing type：Research paper (international conference proceedings) Publisher：WILEY-V C H VERLAG GMBH

The adsorption of proteins on poly(2-hydroxyethyl methacrylate) (PHEMA) brushes was systematically investigated from the viewpoint of the size-exclusion effect of the concentrated brushes. By use of surface-initiated atom transfer radical polymerization, well-defined, concentrated PHEMA brushes were successfully grafted on the inner surface of the silica monolithic column with meso pores of ca. 80 nm as well as a silicon wafer and a quartz crystal microbalance (QCM) chip. By eluting low-polydispersity pullulans with different molecular weight through the modified monolithic column, the concentrated PHEMA brush was characterized and demonstrated to sharply exclude solute molecules with the critical molecular size (size-exclusion limit) comparable to the distance between the nearest-neigh boring graft points d. The elution behaviors of proteins with different sizes were studied with this PHEMA-grafted column: the protein sufficiently larger than the critical size was perfectly excluded from the brush layer and separated only in the size-exclusion mode by the meso pores without affinity interaction with the brush surface. Then, the irreversible adsorption of proteins on PHEMA brushes was investigated using QCM by varying graft densities (or = 0.007, o.M, and 0.7 chains/nm(2)) and protein sizes (effective diameter = 2-13 nm). A good correlation between the protein size and the graft density was observed: proteins larger than d caused no significant irreversible adsorption on the PHEMA brushes. Thus, we experimentally substantiated the postulated size-exclusion effect of the concentrated brushes and confirmed that this effect plays an important role for suppressing protein adsorption.

DOI： 10.1002/masy.200750220

Monolithic TiO2 with controlled multiscale porosity via a template-free sol-gel process accompanied by phase separation Reviewed

Junko Konishi, Koji Fujita, Kazuki Nakanishi, Kazuyuki Hirao

CHEMISTRY OF MATERIALS Vol. 18 ( 25 ) page： 6069 - 6074 2006.12

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

This article describes the fabrication of multiscale porous nanocrystalline TiO2 monoliths through a one-step method that combines a sol-gel process and phase separation in template-free conditions. A large-dimension monolith with well-defined macropores and a mesostructured anatase-type TiO2 gel skeleton is spontaneously obtained by controlling the solution pH during the hydrolysis and polycondensation reactions of titanium alkoxides. The size of the macropores is adjusted by the starting composition, and a crystallized anatase TiO2 skeleton is formed without heat treatment. The use of titanium alkoxide strengthens the gel network by the formation of chemical bonding in the condensation reaction, which yields porous monoliths with higher mechanical strength than for the case of porous monoliths derived from colloidal TiO2 using freeze drying to maintain the porous morphology. The average crystallite size of anatase TiO2 nanocrystals was found to be about 3.6 nm for the dried gel and about 5.0 nm for the gel calcined at 300 degrees C. As a result of the growth of the anatase TiO2 nanoparticles, the mesopores with a median size of 5.0 nm are obtained. The high surface area (similar to 150 m(2)/g) is maintained even after the heat treatment at 300 degrees C.

DOI： 10.1021/cm0617485

New macroporous crosslinked polymer gels prepared via living radical polymerization

K. Kanamori, K. Nakanishi, T. Hanada

Materials Research Society Symposium Proceedings Vol. 947 page： 66 - 71 2006.12

Language：English Publishing type：Research paper (scientific journal)

Macroporous crosslinked polymer gels have been prepared via TEMPO-mediated living radical polymerization of divinylbenzene (DVB) in a solvent with a counter polymer. Incorporating a counter polymer, poly(dimethylsiloxane) (PDMS), induced macroscopic spinodal-type phase separation during the course of polymerization of DVB while suppressing the segregation of DVB-derived particles from the solution by living polymerization. Well-defined macroporous morphologies comprising continuous DVB-derived skeletons have thus obtained. Macropore volume and diameter were independently controlled by altering the concentrations of PDMS and the solvent. Since the present polymer gels are prepared using only the multifunctional "crosslinker", mechanical durability against bending and compression was found to be as high as inorganic ceramics with similar morphologies and porosities. © 2007 Materials Research Society.

Performance of octadecylsilylated monolithic silica capillary columns of 530 mu m inner diameter in HPLC Reviewed

Masanori Motokawa, Masayoshi Ohira, Hiroyoshi Minakuchi, Kazuk Nakanishi, Nobuo Tanaka

JOURNAL OF SEPARATION SCIENCE Vol. 29 ( 16 ) page： 2471 - 2477 2006.11

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

Monolithic silica capillary columns were successfully prepared in a fused silica capillary of 530 mu m inner diameter and evaluated in HPLC after octadecylsilylation (ODS). Their efficiency and permeability were compared with those of columns pakked with 5-mu m and 3-mu m ODS-silica particles. The monolithic silica columns having different domain sizes (combined size of through-pore and skeleton) showed 2.5-4.0-times higher permeability (K = 5.2-8.4 x 10(-14) m(2)) than capillary columns packed with 3-mm particles, while giving similar column efficiency. The monolithic silica capillary columns gave a plate height of about 11-13 mu m, or 11200-13400 theoretical plates/150 mm column length, in 80% methanol at a linear mobile phase velocity of 1.0 mm/s. The monolithic column having a smaller domain size showed higher column efficiency and higher pressure drop, although the monolithic column with a larger domain size showed better overall column performance, or smaller separation impedance (E value). The larger-diameter (530 gm id) monolithic silica capillary column afforded a good peak shape in gradient elution of proteins at a flow rate of up to 100 mu L/min and an injection volume of up to 10 mu L.

DOI： 10.1002/jssc.200600335

Thick silica gel coatings on methylsilsesquioxane monoliths using anisotropic phase separation Reviewed

Kazuyoshi Kanamori, Kazuki Nakanishi, Teiichi Hanada

JOURNAL OF SEPARATION SCIENCE Vol. 29 ( 16 ) page： 2463 - 2470 2006.11

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

Silica gel coatings on methyltrimethoxysilane (MTMS)-derived monoliths have been studied using wetting transition. Wetting transition is observed in a small confined space, where a coating solution phase-separates into a well-coarsened dimension, making all the phase-separating polymerizing silica phase dynamically flow onto the existing surface of a mold. Bulk coating experiments have shown reductions of both macropore volume and diameter due to the coated layer. Comparing HPLC efficiencies of the coated monolith with those of the non-coated MTMS monolith revealed that the retention factors drastically increased in both normal- and reversed-phase modes. This is attributed to the existence of considerable amounts of accessible micropores left inside the coated layer, where analyte molecules travel and adsorb for a considerable period of time.

DOI： 10.1002/jssc.200600163

Living radical polymerization in size-exclusion silica gel column reactors

Masao Katsube, Makoto Ouchi, Tsuyoshi Ando, Mitsuo Sawamoto, Kazuki Nakanishi, Norio Ishizuka

Polymer Preprints, Japan Vol. 55 page： 150 2006.10

Language：English Publishing type：Research paper (scientific journal)

This work was aimed to development of continuous-flow living radical polymerization in a silica-gel column, "Chromolith", focusing its separation function by combination of surface chemical absorption and size-exclusion via uniquely shaped mesopores, Thus, living radical copolymerization of two monomers with different polarities, methyl methacrylate (MMA) and 2(dimethylamino)ethyl methacrylate (DMAEMA) was performed with a catalyst [2; Ru(Ind)Cl(PPh3)2] coupled with an initiator (1). Copolymers were continuously produced, and molecular weight distributions were narrower than that in the corresponding batch process.

Morphological control and strong light scattering in macroporous TiO2 monoliths prepared via a colloid-derived sol-gel route Reviewed

Koji Fujita, Junko Konishi, Kazuki Nakanishi, Kazuyuki Hirao

SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS Vol. 7 ( 6 ) page： 511 - 518 2006.9

Language：English Publishing type：Research paper (scientific journal) Publisher：NATL INST MATERIALS SCIENCE

Macroporous titania (TiO2) monoliths have been prepared via the sol-gel route started from aqueous anatase-type titania colloid in the presence of poly(ethylene oxide) (PEO), and the light-scattering properties have been investigated by means of coherent backscattering. Well-defined macroporous bicontinuous structures are formed when the transient structure of phase separation is fixed as the permanent morphology by the sol-gel transition. The macroporous morphology, i.e., the size and volume fraction of continuous macropores, can be tailored by adjusting the amount and/or molecular weight of PEO and the TiO2 concentration in the starting solution. During the heat treatment at temperatures above 1000 degrees C, the skeleton is sintered into fully dense body, and the crystalline structure is transformed from anatase to rutile phases, while keeping the macroporous morphology. We show that the rutile-type TiO2-based macroporous monoliths are strongly scattering media for visible light and that the scattering strength can be controlled by the macroporous morphology. (c) 2006 NIMS and Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.stam.2006.04.014

Monolithic silica capillary column extraction of methamphetamine and amphetamine in urine coupled with thin-layer chromatographic detection Reviewed

Akihiro Nakamoto, Akira Namera, Manami Nishida, Mikio Yashiki, Takako Kuramoto, Yoshiyuki Takei, Masahiro Furuno, Hiroyoshi Minakuchi, Kazuki Nakanishi, Kojiro Kimura

Forensic Toxicology Vol. 24 ( 2 ) page： 75 - 79 2006.9

Language：English Publishing type：Research paper (scientific journal)

A monolithic silica capillary column was first developed in Japan in 2001 as a new tool for better liquid chromatographic separation. The column is made of C18-bonded monolithic silica packed into a capillary glass tube (0.20 mm i.d.). In this study, we used this column for solid-phase extraction of methamphetamine (MA) and amphetamine (AP) in urine. Chromatographic separation was achieved by thin-layer chromatography (TLC) with double-spray detection of each spot. For extraction of amphetamines in urine, samples were mixed with phosphate buffer (pH 3.0, containing 20mM sodium octanesulfate), and the analytes were adsorbed to the column by passing the mixture through it. They were then eluted with a 10-μl volume of ethyl acetate and directly spotted onto a TLC plate. After development, the detection of MA was performed with Simon's reagent. The plate was air-dried, and then over-sprayed with fluorescamine reagent for detection of AP. A fluorescent spot of AP was observed at 365 nm using an ultraviolet viewing system. The detection limits of MA and AP in urine were about 1.0 and 2.0μg/ml, respectively. To confirm the usefulness of this method, the eluent from the column was also analyzed by gas chromatography-mass spectrometry (GC-MS) after derivatization with heptafluorobutyric anhydride. In analysis of 30 actual urine samples, the results obtained by the monolith-TLC system were generally well in accordance with those obtained by GC-MS. © 2006 Japanese Association of Forensic Toxicology and Springer-Verlag Tokyo.

DOI： 10.1007/s11419-006-0009-z

Other Link： http://orcid.org/0000-0002-8069-4780

High-performance liquid chromatographic enantioseparations on capillary columns containing crosslinked polysaccharide phenylcarbamate derivatives attached to monolithic silica Reviewed

Bezhan Chankvetadze, Takateru Kubota, Tomoyuki Ikai, Chiyo Yamamoto, Masami Kamigaito, Nobuo Tanaka, Kazuki Nakanishi, Yoshio Okamoto

JOURNAL OF SEPARATION SCIENCE Vol. 29 ( 13 ) page： 1988 - 1995 2006.8

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

Monolithic capillary columns containing native silica gel were covalently modified with 3,5-disubstituted phenylcarbamate derivatives of cellulose and amylose and applied for enantioseparations in capillary LC. The method previously used for covalent immobilization of polysaccharide phenylcarbamate derivatives onto the surface of microparticulate silica gel was successfully adapted for in situ modification of monolithic fused-silica capillary columns. The effects of the nature of polysaccharide and the substituents, as well as of multiple covalent immobilization of polysaccharide derivative on chromatographic performance of capillary columns were studied. The capillary columns obtained using this technique are stable in all solvents commonly used in LC and exhibit promising enantiomer resolving ability.

DOI： 10.1002/jssc.200500388

Fabrication of Sm2+-doped macroporous aluminosilicate glasses with high alumina content Reviewed

Takayuki Hirao, Koji Fujita, Shunsuke Murai, Kazuki Nakanishi, Kazuyuki Hirao

JOURNAL OF NON-CRYSTALLINE SOLIDS Vol. 352 ( 23-25 ) page： 2553 - 2557 2006.7

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Macroporous Al2O3-SiO2 glasses doped with Sm2+ have been prepared from a sol-gel system containing aluminum sec-butoxide, tetramethoxysilane, samarium chloride hexahydrate, poly(ethylene oxide), nitric acid, and water. Monolithic gels having interconnected macropores and skeletons are formed by inducing the phase separation parallel to the gelation. The use of aluminum sec-butoxide preheated at 80 degrees C as the starting material enables the incorporation of Al3+ into the gel skeleton up to 20 mol% in cation ratio. The maximum amount of Al3+, i.e., 20 mol%, is twice as large as that reported in our previous study, where aluminum sec-butoxide was diluted with sec-butanol prior to the hydrolysis. Heat-treatment of Sm3+-doped 20AlO(3/2)center dot 80SiO(2) macroporous glass under the reducing atmosphere converts Sm3+ to Sm2+, which is confirmed by the appearance of intense emission peaks attributed to 4f-4f transitions of Sm2+. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnoncrysol.2006.02.101

Formation of photonic structures in Sm2+-doped aluminosilicate glasses through phase separation Reviewed

Koji Fujita, Shunsuke Murai, Kazuki Nakanishi, Kazuyuki Hirao

JOURNAL OF NON-CRYSTALLINE SOLIDS Vol. 352 ( 23-25 ) page： 2496 - 2500 2006.7

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Sm2+-doped Al2O3-SiO2 glasses with three-dimensionally interconnected macroporous morphology have been prepared via the alkoxide-derived sol-gel process containing poly(ethylene oxide) and SmCl3 center dot 6H(2)O. The macroporous morphology is obtained by concurrently inducing the phase separation and sol-gel transition. When the macroporous aluminosilicate glasses doped with Sm2+ are irradiated with a visible light laser at the wavelength of 488 nm, a hole or a dip appears in the plot of fluorescence intensity versus the incident angle of laser beam, indicating that the valence state of Sm2+ is spatially modulated through the interference of multiply scattered light. The hole profile can be controlled by adjusting the macroporous morphology. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnoncrysol.2006.03.024

Anisotropic siloxane-based monolith prepared in confined spaces Reviewed

Y Suzumura, K Kanamori, K Nakanishi, K Hirao, J Yamamichi

JOURNAL OF CHROMATOGRAPHY A Vol. 1119 ( 1-2 ) page： 88 - 94 2006.6

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

When bicontinuous gels are prepared via sol-gel method in a 2-dimensionally (21)) confined space, the gel skeletons in the vicinity of interface of a mold are elongated perpendicular to the interface. This phenomenon was attributed to the dynamic wetting of polymerizing siloxane phase onto the interface of the mold under gravity. In this paper, we report the successful preparation of monolithic columns with an oriented pillar structure in a variety of 2D confined spaces. Starting from a solution, which consists of methyltrimethoxysilane (MTMS), the macroporous structure is prepared in situ by a completely spontaneous process. In the oriented pillar structure, bicontinuous siloxane skeletons deformed or disappeared and most pillars are oriented along the direction of gravity. Gel morphologies with the pillar structure were examined by scanning electron microscopy (SEM) and laser scanning confocal microscopy (LSCM). Geometrical information on gel morphologies was numerically derived from the obtained 3D LSCM images. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.chroma.2006.02.059

Mutual consistency between simulated and measured pressure drops in silica monoliths based on geometrical parameters obtained by three-dimensional laser scanning confocal microscope observations Reviewed

Haruko Saito, Kazuki Nakanishi, Kazuyuki Hirao, Hiroshi Jinnai

JOURNAL OF CHROMATOGRAPHY A Vol. 1119 ( 1-2 ) page： 95 - 104 2006.6

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

The geometrical properties of co-continuous macroporous silica monoliths have been studied by laser scanning confocal microscopy (LSCM) and a comparison has been made with those obtained by conventional mercury intrusion method. Tetrahedral skeleton model (TMS), which mimics the gel skeleton shape of monoliths, was compared with real monoliths in terms of macropore and porosity using the geometrical parameters extracted from the LSCM observations. Liquid flow behavior through the macroporous silica monoliths was examined in comparison with those simulated using TSM, based on the geometrical properties obtained from LSCM observations. Heterogeneity in macropore topology and connectivity in pores and skeletons are suggested to contribute to the improvement of the model structure for macroporous monoliths. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.chroma.2006.03.087

Sol-gel process of oxides accompanied by phase separation Reviewed

Kazuki Nakanishi

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN Vol. 79 ( 5 ) page： 673 - 691 2006.5

Language：English Publishing type：Research paper (scientific journal) Publisher：CHEMICAL SOC JAPAN

A versatile sol-gel method for fabricating porous oxide materials with well-defined co-continuous macropores has been reviewed. The chemical instability, in many cases induced by polymerization of the network-forming components, triggers the formation of biphasic morphologies, followed by an irreversible freezing of the transient morphology by the sol-gel transition of the gelling phase. Upon removal of the non-gelling phase, an oxide framework comprising of controlled macropores can be obtained. The mesopore system of such macroporous materials can be further modified either by a physico-chemical treatment or a supramolecular templating technique. Pure silica and siloxane-based organic-inorganic hybrids with a hierarchical pore system in monolithic form have been successfully applied to the novel type of separation medium for high performance liquid chromatography, HPLC. Additional topics are also described including recent advances in the 3D-analysis of the interfacial properties of macroporous systems, extended compositional variations in the network-forming phase, and emerging applications in areas of biochemistry.

DOI： 10.1246/bcsj.79.673

High-performance liquid chromatographic enantioseparations on capillary columns containing monolithic silica modified with amylose tris(3,5-dimethylphenylcarbamate) Reviewed

B Chankvetadze, C Yamamoto, M Kamigaito, N Tanaka, K Nakanishi, Y Okamoto

JOURNAL OF CHROMATOGRAPHY A Vol. 1110 ( 1-2 ) page： 46 - 52 2006.3

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Monolithic capillary columns containing native silica were modified by in situ coating with amylose tris(3,5-dimethylphenylcarbamate) and applied for enantioseparations in capillary liquid chromatography. Capillary columns were examined for 10 standard racemic compounds in order to compare the performance of monolithic silica columns with the common, 4.6 mm I.D. high-performance liquid chromatographic columns packed with particulate silica. The effects of polysaccharide coating and of the linear velocity of the mobile phase on peak performance were studied. Enantioseparations with an analysis time below 1 min were achieved for some chiral analytes. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.chroma.2006.01.076

Phase-separation-induced Titania monoliths with well-derined macropores and mesostructured framework from colloid-derived sol-gel systems Reviewed

J Konishi, K Fujita, K Nakanishi, K Hirao

CHEMISTRY OF MATERIALS Vol. 18 ( 4 ) page： 864 - 866 2006.2

Direct observation of the spatial distribution of samarium ions in alumina-silica macroporous monoliths by laser scanning confocal microscopy Reviewed

S Murai, K Fujita, K Nakanishi, K Hirao

JOURNAL OF ALLOYS AND COMPOUNDS Vol. 408 page： 831 - 834 2006.2

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE SA

We have investigated the spatial distribution of Sm2+ inside macroporous alumina-silica (Al2O3-SiO2) glasses having three-dimensionally interconnected skeletons. The Sm2+-doped Al2O3-SiO2 glasses are prepared via an alkoxy-derived sol-gel route in the presence of poly (ethylene oxide) and SmCl3.6H(2)O. The well-defined macroporous morphology is obtained by the concurrence of the phase separation and the sol-gel transition. The reduction of Sm3+ to Sm2+ is accomplished by heat treatment under a reducing atmosphere. Two-dimensional images of the fluorescence due to the 4f-4f transition of Sm2+ with the aid of a laser scanning confocal microscope reveal the spatially uniform dispersion Of Sm2+ inside the Al2O3-SiO2 skeleton. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jallcom.2005.01.085

Basic study of the gelation of dimethacrylate-type crosslinking agents Reviewed

H Aoki, K Hosoya, T Norisuye, N Tanaka, D Tokuda, N Ishizuka, K Nakanishi

JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY Vol. 44 ( 2 ) page： 949 - 958 2006.1

Language：English Publishing type：Research paper (scientific journal) Publisher：JOHN WILEY & SONS INC

An investigation was made of the gelation of dimethacrylate-type crosslinking agents in view of an application for separation media. The study mainly centered on a crosslinking agent, glycerol dimethaerylate (GDMA), which is relatively hydrophilic because of a hydroxyl group in the middle of its structure. The gelation of GDMA was compared with that of other hydrophobic crosslinking agents such as ethylene glycol dimethacrylate and 1,6-hexanediol dimethacrylate. The diluents used in the study were toluene, toluene with methanol, and cyclohexanol. The gelation was observed in real time with a charge coupled device camera and dynamic light scattering (DLS). Also, the separated dry gels were extensively characterized with scanning electron microscopy, BET (N-2 absorption and desorption isotherm), and Fourier transform infrared. DLS analysis showed a stronger molecular interaction of GDMA gelation in toluene, whereas this interaction was much weaker in an alcoholic solvent such as toluene with methanol or cyclohexanol. This indicated that GDMA gelation might proceed through hydrogen bonding as well as a crosslinking reaction of vinyl groups. (c) 2005 Wiley Periodicals, Inc.

DOI： 10.1002/pola.21205

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