桑折 道済

Polydopamine (PDA) is of interest as a mimetic material of melanin to produce structural color materials. Herein, to investigate the influence of the material composition of the artificial melanin particles on structural color, we demonstrated the preparation of core-shell particles by polymerization of norepinephrine or 3,4-dihydroxyphenylalanine, which are melanin precursors similar to dopamine, in the presence of polystyrene particles. It was revealed that the arrays of the prepared particles produce high-visibility structural color because of absorption of scattering light. Although poly(3,4-dihydroxyphenylalanine) showed the same tendency as PDA which was previous studied, polynorepinephrine can easily produce a smooth and thick shell layer compared with that of PDA, and pellets consisting of the particles showed angle-dependent structural color. Therefore, the artificial melanin particles that produce angle-dependent structural color became stable than ever before. These results indicated that material compositions of artificial melanin particles have influence on structural color, and an important finding for application as a coloring material was obtained.

Holmium (Ho), one of the lanthanide elements, shows a high magnetic moment. Here we present a simple, yet highly potential approach for preparing polymer-based magnetic materials from a three-dimensional polymer network composed with poly(acrylic acid) and Ho showing trivalent nature. We have successfully prepared a magnetic polymer network that reacts directly to a magnet by three-dimensionally immobilizing Ho in the polymer matrix. The present method allowed a preparation of wide range of magnetic materials using polymeric scaffolds, e.g., polymer-grafted particles and cross-linked polymer gels. As a result of the high Ho content, these materials responded quickly to the magnet. The discovery of a method to prepare magnetic materials will provide flexibility in materials design and greatly expand the scope of application of magnetic materials.

Biomimetic material design is a useful method for producing new functional materials. In recent years, catecholic polymers inspired from the adhesion mechanism of marine organisms have attracted attention. Here, we demonstrated the preparation of catecholic polymers by reversible addition-fragmentation chain transfer (RAFT) polymerization of an acetonide-protected catecholic monomer, that is, N-(2-(2,2-dimethylbenzo-1,3-dioxol-5-yl)ethyl)-acrylamide (DDEA). By selecting the specific RAFT reagents, well-defined branched PDDEA and linear PDDEA were obtained. These PDDEA samples showed stronger adhesion strength after deprotection by acid stimulation compared with that before deprotection. In addition, we demonstrated the adhesion control of synthetic polymers by photoirradiation in the presence of photoacid generators, which decompose under light and release an acid.

By selecting the core materials and grafted-hair polymers, hairy particles with polymer brushes can create various types of functional materials. In recent years, polydopamine (PDA) particles that are obtained by polymerizing dopamine, which is an amino acid derivative, have attracted attention for various applications. Herein, we present a novel approach for creating photonic and magnetic materials from hairy PDA particles. By grafting a hydrophilic hair polymer, we have succeeded in producing photonic materials capable of structural color changes. Furthermore, we have demonstrated the preparation of magnetic materials by immobilizing holmium, which is one of the lanthanide elements, by electrostatic interactions onto a cationic hair polymer. These results demonstrate the possibility of hairy PDA particles for a wide range of applications, such as for photonic and magnetic materials.

A metal-lustrous self-standing film, named "porphyrin foil", was formed from a glass-forming polymeric porphyrin. The amorphous glass nature of the porphyrin foil played a key role in spontaneously producing a smooth surface. Its sharp contrast in intense absorption and specular reflection of light at each wavelength provided a brilliant metallic lustre.

Novel C-2-symmetric chiral dopant derivatives, namely, N-substituted (2R, 3R)-2,3-bis(4-(4-octyloxyphenyl)benzoyloxy)succinimides1a-h, were synthesised, and the effects of the N-substituent and imide-carbonyl groups on the helical twisting powers (HTPs) were investigated in two nematic liquid crystalline compounds, 4-n-pentyl-4'-cyanobiphenyl (5CB) and N-(4-ethoxybenzylidene)-4-n-butylaniline (EBBA). As a result, it was clarified that the bulkiness of the N-substituents has a significant correlation with the HTPs, and the imide-carbonyl group interacts strongly with the cyano group of 5CB to give high HTPs in the nematic phases. However, it is assumed that the imide-carbonyl groups of the dopants do not have strong electrostatic attractive interactions with EBBA molecules in the nematic phase to afford the moderate HTPs. [GRAPHICS] .

The structural color of Rock Pigeon feathers is produced by thin-layer interference, which occurs in the cortex layer of the barbule. Furthermore, melanin granules, which exist below the cortex layer, absorb scattered light to reduce the background reflection. In this paper, we describe the preparation of structural color materials from combined use of polydopamine-inorganic thin films (PDA/GOPTS thin film) and black particles (PDA/GOPTS particles) that mimic the coloration mechanism of Rock Pigeon feathers. A hierarchical structure of thin films and particles was created to endure the polymerization solution of DA and DA-GOPTS. The obtained materials showed beautiful structural colors and the colors were controlled by film thicknesses.

We present the ability to tune structural colors by mixing colloidal particles. To produce high-visibility structural colors, melanin-like core shell particles composed of a polystyrene (PSt) core and a polydopamine (PDA) shell, were used as components. The results indicated that neutral structural colors could be successfully obtained by simply mixing two differently sized melanin-like PSt@PDA core shell particles. In addition, the arrangements of the particles, which were important factors when forming structural colors, were investigated by mathematical processing using a 2D Fourier transform technique and Voronoi diagrams. These findings provide new insights for the development of structural color-based ink applications.

In achiral rod-like molecules, a nematic phase is the most disordered liquid crystal phase, which only has onedirectional order in the direction of the molecular long axis. A dumbbell-shaped molecule (compound 3: R C6H10 @ CH=C-C6H4-CH=CH-C6H10-R, (R=nC(5)H(11))), and its liquid crystal phase (X phase) are reported, which exhibit high scattering without thermal fluctuation between two nematic phases under a polarized light optical microscope. TheXphase was investigated by X-ray diffraction, scanning electron microscopy, atomic force microscopy, and molecular dynamics simulation. A layered structure was ascertained for which a molecular self-organization mechanism was postulated in which the super-structure is based on lateral intermolecular interlocking. A second nematic phase above the X phase consisted of "rice grain"-shaped particles.

We describe a facile and simple method to prepare colloidal architectures by the in situ assembly of amphiphilic diblock copolymers onto submicron-sized core particles. Polystyrene-b-poly(acrylic acid) diblock copolymers (PSt(m)PAA(n)) were directly assembled onto hydrophobic silica (SiO2) core particles,. forming spherical core-shell particles. By varying the surface hydrophobicity of the core particles and the compositions of the diblock copolymers, core-shell particles with tailored shell thickness were observed. Furthermore, we demonstrated the preparation of ellipsoidal particles, which containing two core particles, based on this strategy. (C) 2016 Elsevier B.V. All rights reserved.

Blue phases (BPs) obtained by doping a commercially available liquid crystalline compound (4-butyl-N-(4-ethoxybenzylidene)aniline (EBBA)) with (2R,3R)-2,3-bis(4-octyloxyphenylbenzoyloxy)-N-(hydroxydecyl)succinimide (1) were highly stabilised by the addition of a small amount of alkane diols. Especially, addition of only 0.5mol% of octane-1,8-diol increased the BP-Iso transition temperature by 10K and widened the BP temperature range up to 35K. A model stabilisation mechanism based on the construction of a hydrogen bond network in each disclination zone in BPs was proposed. [GRAPHICS] .

Some beautiful structural colorations found in nature are produced by microstructures of melanin. Polydopamine (PDA), produced by the self-oxidative polymerization of dopamine, is known as a mimetic material of melanin. Previous experiments by our group have shown that PDA-based structural color materials produced bright structural colors upon enhancing the color saturation through the absorption of light scattering. Herein, we describe the preparation of structural color films by a dip-coating of biomimetic melanin-like particles with PDA shell layers. Various parameters of the dip-coating method influencing the structural coloration were investigated in detail. Experimental results revealed that the obtained films exhibited bright and angle-dependent structural colors independent of a background color, i.e., black or white background. These findings provide new insights for the development of dye-free ink technologies. (C) 2017 Elsevier B.V. All rights reserved.

A metal-lustrous self-standing film, named "porphyrin foil'', was formed from a glass-forming polymeric porphyrin. The amorphous glass nature of the porphyrin foil played a key role in spontaneously producing a smooth surface. Its sharp contrast in intense absorption and specular reflection of light at each wavelength provided a brilliant metallic lustre.

<p>This article describes a simple procedure to fabricate magnetically-responsive particles from as-prepared particles. Firstly, a magnetically-responsive, holmium-containing surfactant (DDAH) was prepared by mixing a commercially available surfactant and holmium(III) chloride hexahydrate. Subsequently, polydopamine (PDA) particles, which exhibit beautiful structural colors, were modified using the DDAH to afford PDA/DDAH particles. The magnetic behavior of the obtained PDA/DDAH particles was investigated. Furthermore, structural color changes of the materials prepared by PDA/DDAH particles under magnetic fields were also investigated.</p>

Luminescent particles have been attracting significant attention because they can be used in biochemical applications, such as detecting and imaging biomolecules. In this study, luminescent polystyrene latex particles were prepared through miniemulsion polymerization of styrene with dissolved europium complexes in the presence of bovine serum albumin (BSA) and poly(ethylene glycol) monomethoxy methacrylate as surfactants. The solubility of the europium complex in styrene has a strong effect on the yield of the particle. Europium tris(2-thenoyl trifluoroacetonate) di(tri-n-octyl phosphine oxide), which has a high solubility in styrene, was sufficiently incorporated into the polystyrene particles compared to europium tris(2-thenoyl trifluoroacetonate), which has a low solubility in styrene. The luminescence property of the europium complex could remain intact even after its incorporation through the miniemulsion polymerization. In the aqueous dispersion, the resulting particles could emit strong luminescence, which is a characteristic of the europium complex. The antibody fragments were covalently attached to BSA-covered particles after a reaction with a bifunctional linker, N-(6-maleimidocaproyloxy)succinimide. The time-resolved fluoroimmunoassay technique showed that 3.3 pg/mL of human ct-fetoproteins (AFP) can be detected by using the resulting luminescent particles. An immunochromatographic assay using the resulting particles was also performed as a convenient method to qualitatively detect biomolecules. The detection limit of AFP measured by the immunochromatographic assay was determined to be 2000 pg/mL. These results revealed that the luminescent particles obtained in this study can be utilized for the highly sensitive detection of biomolecules and in vitro biochemical diagnosis. (C) 2016 Elsevier B.V. All rights reserved.

"Pickering-type" emulsions were prepared using polydopamine (PDA) particles as a particulate emulsifier and n-dodecane, methyl myristate, toluene or dichloromethane as an oil phase. All the emulsions prepared were oil-in-water type and an increase of PDA particle concentration decreased oil droplet diameter. The PDA particles adsorbed to oil-water interface can be crosslinked using poly(ethylene imine) as a crosslinker, and the PDA particle-based colloidosomes were successfully fabricated. Scanning electron microscopy studies of the colloidosomes after removal of inner oil phase revealed a capsule morphology, which is strong evidence for the attachment of PDA particles at the oil-water interface thereby stabilizing the emulsion. The colloidosomes after removal of inner oil phase could retain their capsule morphology, even after sonication. On the other hand, the residues obtained after oil phase removal from the PDA particle-stabilized emulsion prepared in the absence of any crosslinker were broken into small fragments of PDA particle flocs after sonication.

We present a method for fabricating photonic crystals (PCs) by polymerization-induced microphase separation of block copolymers (BCPs). Molecular weight of BCP for PCs is so large that it has been difficult for conventional solution casting and annealing methods to complete the microphase separation to form periodically ordered submicron structures. Our method overcomes the difficulty by inducing the microphase separation and transitions during the polymerization, when the molecular weight of the BCPs is small enough for the microphase separation and transitions. The microphase-separated structure is then enlarged while maintaining the self-similarity. We succeeded in fabricating PCs with reflection wavelength lambda(m) approximate to 1000 nm and a full width at half-maximum Delta lambda = 0.05 lambda(m) by living-radical bulk block copolymerization of poly(methyl methacrylate)-block-polystyrene.

Glycopolymers bearing carbohydrates have an advantage in protein recognition that is attributable to the multivalent effect (cluster effect) of side-chain carbohydrates. A variety of surface-modified polymer particles have been prepared concurrently with the development of new synthetic technology. Here we describe a synthetic method of glycopolymer-grafted polymer particles by surface-initiated living radical polymerization, i.e., atom-transfer radical polymerization (ATRP) and photoiniferter polymerization, for specific lectin recognition.

The beautiful structural colors in bird feathers are some of the brightest colors in nature, and some of these colors are created by arrays of melanin granules that act as both structural colors and scattering absorbers. Inspired by the color of bird feathers, high-visibility structural colors have been created by altering four variables: size, blackness, refractive index, and arrangement of the nano-elements. To control these four variables, we developed a facile method for the preparation of biomimetic core-shell particles with melanin-like polydopamine (PDA) shell layers. The size of the core-shell particles was controlled by adjusting the core polystyrene (PSt) particles' diameter and the PDA shell thicknesses. The blackness and refractive index of the colloidal particles could be adjusted by controlling the thickness of the PDA shell. The arrangement of the particles was controlled by adjusting the surface roughness of the core-shell particles. This method enabled the production of both iridescent and non-iridescent structural colors from only one component. This simple and novel process of using core-shell particles containing PDA shell layers can be used in basic research on structural colors in nature and their practical applications.

<p>A novel approach for creating non-iridescent bright structural color materials from polydopamine (PDA) black particles that mimic melanin granules found in nature is presented.</p>

Polystyrene latex particles with controlled size were prepared by polymerization of oil-in-water (O/W) emulsion styrene droplets obtained through the phase inversion temperature (PIT) emulsification using amphiphilic comb-like block polymers, polystyrene-b-poly[oligo(ethylene glycol) methyl ether methacrylate] (PSt(n)-b-POEGMA(m)-Cl). PSt(n)-b-POEGMA(m)-Cl block polymers were synthesized by sequential atom transfer radical polymerization (ATRP) of St and OEGMA. The interfacial properties of PSt(n)-b-POEGMA(m)-Cl in aqueous media were investigated by means of surface tension measurement, fluorescence probe technique, and transmittance measurement. The length of hydrophobic PSt block chain was found to affect the critical micelle concentration, the micelle aggregation number, and the cloud point. O/W emulsions were obtained through the PIT process using PSt(n)-b-POEGMA(m)-Cl as a surfactant by lowering the temperature of emulsions below the PIT in an ice bath. PSt particles with precisely controlled size in a range between 30 and 120nm were successfully prepared by a free radical polymerization of St droplets initiated by the water- or oil-soluble initiators. FE-SEM observation revealed that the morphology of polystyrene particles was found to depend on the relative PSt chain length of PSt(n)-b-POEGMA(m)-Cl. (C) 2015 Elsevier B.V. All rights reserved.

Biaxial smectic A (SmA(b)) and biaxial nematic (N-b) liquid crystal (LC) phases using achiral straight-rod molecules were realized through perfluoroarene-arene (PFA-A) and CH/F interactions. Compounds 1a, 1b and 1c, 4,4'-bis(2,3,4-trifluorobenzoyloxy)biphenyl, 4,4'-bis(2,3-difluorobenzoyloxy)biphenyl and 4,4'-bis(2-fluorobenzoyloxy)biphenyl, were synthesized. The liquid crystallinity of these compounds was investigated using polarized light optical microscopy (POM) and differential scanning calorimetry (DSC). Furthermore, the ferroelectric switching behaviors of 1a in the nematic (N) and smectic A (SmA) LC phases and 1b in the N phase were confirmed by applying a triangular wave voltage in electro-optic experiments. Then, the values of spontaneous polarization (P-s) in the LC phases of 1a were investigated as functions of frequency, voltage, and temperature. It was strongly hypothesized that the semiperfluorinated phenyl (SFP) groups rotate around the molecular long axes and change pairs in the CH/F interacting sites, and this cooperative movement of the SFP groups is repeated during the switching process.

Herein, we describe a general and versatile procedure to fabricate hierarchically structured coatings onto material surfaces using colorless polydopamine (PDA) thin layer and polymer brush layer. Firstly, atom transfer radical polymerization (ATRP) initiator-containing colorless PDA layer was coated onto various types of material surfaces. Then, surface-initiated ATRP was conducted to produce functional polymer brush layer. This methodology will be applied to a broad range of materials to modification of surface properties. Furthermore, one-step hierarchically structured coatings of materials surface were also investigated.

Herein, we describe a facile and green method to prepare fluorescent polymer particles by combined use of enzymatic miniemulsion polymerization and click reaction. Firstly, alkyne-bearing polymer particles were prepared by HRP-mediated miniemulsion polymerization of styrene with clickable surfmer (surfactant + monomer) 1. Then, azide-bearing fluorescence compound, i.e., dansyl azide compound 2, was introduced to polymer particles surface via click reaction using Cu(I) catalyst. This methodology will be applied to a broad range of azide-bearing compounds to generate functional polymer particles. Since both enzymatic miniemulsion polymerization and click reaction are conducted at room temperature in water, present method offers a practical and environmental friendly method for preparation of functional polymer particles.

The facile preparation of nonspherical raspberry-like particles composed of a polystyrene (PSt) core and polydopamine (PDA) nodules was described. Various polymerization parameters influencing the PDA nodules were investigated in detail. It was found that raspberry-like particles were obtained in a 1:1 water/methanol solution in the presence of compounds with carboxylic acid groups, e.g., caffeic acid (CF). The raspberry-like particles obtained were characterized in terms of their size, morphology, and chemical composition using scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared (IR) spectroscopy, elemental analysis, and solid-state nuclear magnetic resonance (NMR) measurements. Finally, the formation mechanism was discussed. Because PDA may be used to cover a variety of particle surfaces, the present method has great potential for fabricating many types of raspberry-like particles. (C) 2014 Elsevier B.V. All rights reserved.

A simple chiral dopant molecule (R)-1 with both rod- and arch-like units was prepared, and extremely large helical twisting powers (+123 to +228 mu m(-1)) in nematic liquid crystal phases were achieved. We have demonstrated that the introduction of an arch-like unit in addition to rod- like units is highly effective in controlling the helical molecular alignment. As an application of the dopant, induction of blue phases by addition of a small amount of it was achieved.

Blue phases (BPs) have received considerable attention as light shutters in the next generation of liquid crystal (LC) displays. However, no simple and efficient chiral dopant for induction of BPs of commercially available rodlike LC compounds has been reported. In this study, both (R) and (S) forms of novel chiral dopants were synthesized, showed extremely high helical twisting power values in nematic LC compounds, and induced stable BPs with a small amount of our chiral dopants (3-5 mol %). In enantiomeric excess controlled experiments, we found novel phenomena in their physical properties, such as generation of a metastable chiral nematic phase between an isotropic state and a BP.

We prepared the novel fluorescent polymer latex particles which can change their fluorescence intensity in response to the increasing NaCl concentration in water. Core polymer latex particles were synthesized by emulsifier-free emulsion polymerization of styrene and 2-(2-chloroisobutyroyloxy)ethyl methacrylate. Hydrophilic polymer chains containing epoxy groups were grafted from the core particles by surface-initiated atom transfer radical copolymerization of methoxy polyethyleneglycol methacrylate (MEO(x)MA, x = 4 or 9) and glycidyl methacrylate in aqueous media. After azidation of epoxy groups in graft chains, a water-soluble fluorescent dansyl derivative was successfully coupled with the graft chains by copper-catalyzed azide-alkyne cycloaddition in aqueous media. The wavelength of maximum fluorescence intensity of polymer particles carrying graft chains with longer PEG side chains (x = 9) was slightly blue-shifted (7 nm) and the fluorescence intensity increased (1.35 times) with an increase in NaCl concentration as opposed to polymer particles with shorter PEG chains (x = 4). (C) 2014 Elsevier Ltd. All rights reserved.

To investigate the effect of the number of chiral mesogenic units and their spatial arrangement in dopant molecules on the induction of blue phases (BPs), and widening the temperature ranges of these phases, six benzene derivatives possessing (cholesteryloxycarbonyl)pentyloxy groups (monosubstituted (1), 1,2-disubstituted (2), 1,3-disubstituted (3), 1,4-disubstituted (4), 1,2,3-trisubstituted (5) and 1,3,5-trisubstituted (6) compounds) were prepared. Their helical twisting powers (HTPs) in 4-cyano-4 '-pentylbiphenyl (5CB) were proportional to the number of the chiral mesogenic units in each molecule. Furthermore, the minimum amount of the chiral dopant necessary for the induction of BPs was almost inversely proportional to its HTP value in this series.

Enzymatic polymerization is a powerful tool for the synthesis of functional polymeric materials. Horseradish peroxidase (HRP)-mediated vinyl polymerization in the presence of hydrogen peroxide (H2O2) and beta-diketone has been successfully applied to the synthesis of functional polymer particles as follows: (i) monodisperse polymer particles were prepared by enzymatic miniemulsion polymerization using surfmer (surfactant + monomer). (ii) Polymer particles stabilized by beta-diketone moieties were prepared by enzymatic emulsifier-free emulsion polymerization. (iii) A novel method of surface-initiated enzymatic graft polymerization was used to synthesize core-shell particles. These methods could offer a practical approach for the synthesis of functional polymer particles because the polymerizations can be conducted at room temperature using a mild enzymatic process.

We developed a novel fluorescence labeling technique for quantification of surface densities of atom transfer radical polymerization (ATRP) initiators on polymer particles. The cationic P(St-CPEM-C(4)DMAEMA) and anionic P(St-CPEM) polymer latex particles carrying ATRP-initiating chlorine groups were prepared by emulsifier-free emulsion polymerization of styrene (St), 2-(2-chloropropionyloxy)ethyl methacrylate (CPEM), and N-n-butyl-N,N-dimethyl-N-(2-methacryloyloxy)ethylammonium bromide (C(4)DMAEMA). ATRP initiators on the surface of polymer particles were converted into azide groups by sodium azide, followed by fluorescent labeling with 5-(N,N-dimethylamino)-N-(prop-2-yn-1-yl)naphthalene-1-sulfonamide (Dansyl-alkyne) by copper-catalyzed azide-alkyne cycloaddition (CuAAC). The reaction time required for both azidation of ATRP-initiating groups and successive fluorescence labeling of azide groups with Dansyl-alkyne by CuAAC were investigated in detail by FTIR and fluorescence spectral measurement, respectively. The ATRP initiator densities on the cationic P(St-CPEM-C(4)DMAEMA) and anionic P(St-CPEM) particle surfaces were estimated to be 0.21 and 0.15 molecules nm(-2), respectively, which gave close agreement with values previously determined by a conductometric titration method. The fluorescence labeling through click chemistry proposed herein is a versatile technique to quantify the surface ATRP initiator density both on anionic and cationic polymer particles. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4042-4051

Organic/inorganic hybrids were prepared by catalytic hydrolysis and subsequent polycondensation of tetra-n-butyl titanate (TnBT) in shell layers grafted on core particles. The core particles were synthesized by emulsifier-free emulsion polymerization of styrene, N-n-butyl-N-2-methacryloyloxyethyl-N,N-dimethylammonium bromide (C(4)DMAEMA), and 2-chloropropionyloxyethyl methacrylate using 2,2'-azobis(2-amidinopropane) dihydrochloride as an initiator. The core diameters were controlled in the range of 70-550 nm by adjusting a C(4)DMAEMA feed concentration. The core-shell particles were prepared by surface-initiated activator generated electron transfer-atom transfer radical polymerization of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA). The sizes of core-shell particles were found to increase monotonically with an increase in a DMAEMA concentration. The hybrid particles were fabricated by adding TnBT into a water/ethanol dispersion of core-shell particles. The amounts of titania deposited increased in proportion to the grafted amounts of poly[2-(N,N-dimethylamino)ethyl methacrylate] on the core particles. The X-ray diffraction measurement revealed that the hollow titania particles obtained by heat treatment of hybrids have an anatase crystallographic phase.

A free-standing polymer brush film with tailored thicknesses based on a colorless polydopamine (PDA) thin layer is prepared and characterized. The surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate (HEMA) is performed on a PDA layer with thickness of ca. 6 nm, which generated an optically transparent and colorless free-standing PHEMA brush film (1.5 cm x 1.5 cm). Because the cross-linked PDA layer is used as the base for the polymer brushes, the reported method does not require cross-linking the polymer brushes. The free-standing film thicknesses of approximate to 16-75 nm are controlled by simply changing the ATRP reaction time. The results show that the free-standing PHEMA brush film transferred onto a plate exhibits a relatively smooth surface and is stable in any solvent.

Polystyrene particles were prepared via the horseradish peroxidase (HRP)-mediated emulsifier-free emulsion polymerization of styrene. A mixture of styrene and deionized water was placed into a three-necked flask. The mixture was deoxygenated using an argon purge for 15 min. HRP was dissolved in a small amount of deionized water and purged with nitrogen for 10 min. Some of the HRP solution was injected into the mixture at room temperature. H2O 2 and a β-diketone were added. The polymerization solution was stirred for 6 h under nitrogen, and aliquots were withdrawn periodically. The monomer conversion was determined by freeze drying and then weighing aliquots that were periodically withdrawn from the polymerization medium. Adding H 2O2 to the reaction mixture all at once caused a significant amount of the monomer to remain in the reaction mixture, which resulted in a lower conversion rate of the polymers. The conversion significantly increased as the reaction time increased, and then reached a plateau after approximately 180min.

Enzymatic polymerization is a powerful tool for synthesizing functional polymeric materials. HRP-mediated vinyl polymerization in the presence of hydrogen peroxide (H2O2) and beta-diketone has been successfully applied to the synthesis of functional polymer particles. In this review, three topics are discussed: (i) Monodisperse polymer particles were prepared using enzymatic miniemulsion polymerization using surfmers. The H2O2 to HRP initial concentration ratio (alpha) was important for the optimization of the reaction. (ii) Polymer particles were prepared by enzymatic emulsifier-free emulsion polymerization. The results indicate that the beta-diketone moieties, which were located on the surface of the particles, influenced the particle formation and stability. (iii) A novel method of surface-initiated enzymatic vinyl polymerization was used to synthesize core-shell particles. These methods might offer a practical method for preparing functional polymer particles because polymerizations can be conducted at room temperature using a mild enzymatic process. The author hopes that these novel methods for polymer particle synthesis will contribute to the progress of environmentally benign industrial processes.

Herein, we describe a facile method to prepare a colorless functional polydopamine (PDA) thin layer by the in situ oxidative copolymerization of dopamine (DA) and ATRP initiator-bearing DA (DA-BiBB) onto polystyrene (PSt) core particles: PSt@PDA/BiBB2. Surface-initiated ATRP of 2-hydroxyethyl methacrylate (HEMA) was performed on PSt@PDA/BiBB2 particles, followed by the removal of the template particles, which generated PHEMA capsules that were based on a colorless PDA thin layer and have tailored hollow core sizes and capsule wall thicknesses. The PDA thin layer is used as a basis for polymer brushes. The present method does not require cross-linking the polymer brushes. Furthermore, subsequent preparation of functional PHEMA capsules by post-functionalization of hydroxy groups of PHEMA chains was successful.

A novel method of surface-initiated enzymatic vinyl polymerization was used to synthesize organic-inorganic hybrid core-shell particles comprising a silica core and a polyacrylamide shell covalently attached to the core surface.

We have investigated the origin of a specific polymerization loci that yielded copolymer particles with a bimodal gel permeation chromatographic profile in the early stage of miniemulsion polymerization of styrene (St) with the polymerizable surfactant N-n-dodecyl-N-2-methacryloyloxyethyl-N,N-dimethylammonium bromide (C(12)DMAEMA). The formation of particles by miniemulsion polymerization using C(12)DMAEMA was investigated as a function of the polymerization time (t(p)) and was compared with that using the nonpolymerizable surfactant cetyltrimethylammonium bromide (CTAB). St was miniemulsified with C(12)DMAEMA or CTAB and was polymerized with either a water-soluble initiator, 2,2'-azobis(2-amidinopropane) dihydrochloride (V50), or an Oil-soluble initiator, 2,2'-azobis(isobutyronitrile) (AIBN), at 60 degrees C in the presence of polystyrene (PSt) as a hydrophobe. Gel permeation chromatography (GPC) and elemental analysis indirectly predicted two different polymerization loci in the St/C(12)DMAEMA/V50 polymerization system. Time-resolved small-angle neutron scattering (SANS) was used to directly observe and examine the specific polymerization loci in the miniemulsion polymerization solutions. The droplets formed in the St/C(12)DMAEMA/V50/PSt at the initial stage of the polymerization were not fully stabilized by C(12)DMAEMA and poly(C(12)DMAEMA-ran-St) and were found to build up the large aggregates. The spherical droplets were stabilized later in the polymerization (t(p) &gt; 20 min) by forming a homogeneous dispersion in the water phase. In contrast, the droplets stabilized by CTAB in St/CTAB/V50/PSt maintained their size and shape throughout the polymerization. As a result, in both polymerization systems of St/C(12)DMAEMA/V50/PSt and St/CTAB/V50/PSt, the particle size was found to depend strongly on the size of the droplets formed in the early stage of polymerization. Porod analysis of the power law scattering observed by SANS provided direct evidence for the specific polymerization loci, which appeared in the early stage of the polymerization system of St/C(12)DMAEMA/V50/PSt on the surface of the droplet, and was the origin of the bimodal peaks in the GPC chromatogram.

The organic/inorganic hybrid particles PSt/P(St-CPEM)(theta)-g-PDMAEMA/SiO2 were prepared by catalytic hydrolysis and subsequent polycondensation of tetraethoxysilane in the poly[2-(N,N-dimethylamino)ethyl methacrylate] (PDMAEMA) layers grafted on the PSt/P(St-CPEM)(theta) core/shell heterocoagulates. The micron-sized PSt core and the submicron-sized P(St-CPEM) shell particles bearing ATRP initiating groups were synthesized by dispersion polymerization of styrene (St) and emulsifier-free emulsion polymerization of St with 2-chloropropionyloxyethyl methacrylate (CPEM), respectively. The raspberry-shaped PSt/P(St-CPEM)(theta) heterocoagulates with a controlled surface coverage (theta = 0.51, 0.81) were prepared by hydrophobic coagulation between the core and the shell particles in an aqueous NaCl solution near the T-g of P(St-CPEM). Surface modification of heterocoagulates was carried out by ATRP of DMAEMA from the shell particles adsorbed on the core particles. Silica deposition was performed by simply adding tetraethoxysilane to a water/methanol dispersion of PSt/P(St-CPEM)(theta)-g-PDMAEMA. The SEM and TGA revealed that the resulting PSt/P(St-CPEM)(theta)-g-PDMAEMA/SiO2 composites maintain a raspberry-like morphology after deposition of silica onto the PDMAEMA layer grafted on heterocoagulates. The micron-sized, raspberry-shaped or the submicron-sized, hole-structured silica hollow particles were obtained selectively by thermal decomposition of the PSt/P(St-CPEM)(theta)-g-PDMAEMA/SiO2. The oriented particle array was fabricated by dropping anisotropically perforated silica particles onto a glass substrate settled at the bottom of a bottle filled with chloroform. Crown Copyright (C) 2011 Published by Elsevier Inc. All rights reserved.

One-pot regio- and stereospecific synthesis of chitoheptaose ((GlcNAc)(7)) has been achieved by using chitopentaose ((GlcNAc)(5)) and chitobiose ((GlcNAc)(2)) as starting materials. The key intermediate, 1,2-oxazoline derivative of (GlcNAc)(5), could be directly prepared in water and successfully transglycosylated to (GlcNAc)(2) catalyzed by a mutant chitinase with lower hydrolyzing activity.

Enzymatic polymerization is a powerful tool for synthesizing useful polymeric materials. However, the preparation of polymer particles by enzymatic polymerization has been reported only rarely. We demonstrated herein the preparation of polystyrene particles by enzyme-mediated miniemulsion polymerization with a polymerizable surfactant, i.e., N, N-dimethyl-N-n-dodecyl-N-2-methacryloyloxyethylammonium bromide (C-12-DMAEMA), using a horseradish peroxidase (HRP)/H2O2/beta-diketone system in water. Effects of various amounts of HRP, H2O2, and beta-diketone on styrene conversion and particle size were investigated. The obtained polystyrene particles were characterized using DLS, GPC, and SEM measurements, and the polymerization kinetics was examined. Comparison of five beta-diketones was also conducted: acetylacetone (ACAC), ethylacetoacetate (EAA), 1,3-cyclopentanedione (CP), tetronic acid (TA), and dibenzoylmethane (DM), for enzymatic miniemulsion polymerization.

The influence of surfactant type on monomer conversion and particle size of polystyrene particles prepared by horseradish peroxidase (HRP)-mediated miniemulsion polymerization was investigated.

The organic/inorganic composites were fabricated by catalytic reduction of tetrachloroaurate ions in poly[2-(N,N-dimethylamino)ethyl methacrylate] shell layers on polystyrene core particles. The core-shell particles were prepared by emulsifier-free emulsion polymerization of styrene (St) with 2-chloropropionyloxyethyl methacrylate (CPEM) using potassium persulfate as an initiator, followed by surface-initiated activator generated electron transfer-atom transfer radical polymerization (AGET-ATRP) of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) on core particles dispersed in aqueous media. The concentration effect of both DMAEMA (x) and copper complex (y) on a shell thickness of P(St-CPEM)-g-PDMAEMA(x/y) core-shell particles was investigated by light scattering technique. The amount of grafted DMAEMA units with respect to (wrt) St was determined by H-1 NMR spectra measurement. The P(St-CPEM)-g-PDMAEMA(x/y)/Au-z hybrid particles were successfully obtained by loading with hydrogen tetrachloroaurate (HAuCl4) into the P(St-CPEM)-g-PDMAEMA aqueous dispersions. The particle size and shape of gold nanoparticles (NPs) generated by catalytic reduction in the poly[2-(N,N-dimethylamino)ethyl methacrylate] (PDMAEMA) shell layers were evaluated by both UV/vis absorption spectra measurement and TEM observation. The size and the number of gold NPs increased with increasing HAuCl4 concentration (z) below 75 mM. Interestingly, 60-80 nm sized, trigonal or polygonal, plate-like gold NPs were generated in the PDMAEMA shell by adding HAuCl4 of 100 mM. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.

Polystyrene particles bearing ATRP initiating groups, obtained by emulsifier-free emulsion polymerization of styrene (St) and 2-chloropropyloxyethyl methacrylate (CPEM), were subjected to surface-initiated activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP) using glycomonomers, i.e., 4-vinylbenzenesulfonamidoethyl 1-thio-beta-D-glucopyranoside (1) and 4-vinylbenzenesulfonamidoethyl 1-thio-beta-D-lactoside (2). The glycopolymer-grafted polystyrene particles obtained Gp1 and Gp2 were shown to have hydrated graft layers of 15-65 nm in thickness on the cores of 370 nm in diameter. Gp1 and Gp2 coagulated in the presence of concanavalin A (Con A) and that of peanut agglutinin (PNA), respectively, showing highly specific response toward lectins. (C) 2011 Elsevier Ltd. All rights reserved.

A new family of activated glycosidic compounds has been designed and synthesized: (2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl)-2-nitrophenylmethane (1). It is stable in conditions commonly used for synthesis, and it can be converted to a sugar lactone derivative merely by photoirradiation (lambda = 365 nm): 2,3,4,6-tetra-O-acetyl-D-glucono-1,5-lactone (2). A mechanism for the reaction is proposed. The photochemical conversion of 1 in the presence of methanol has also been demonstrated, giving rise to methyl 2,3,4,6-tetra-O-acetyl-D-gluconate (3). (C) 2011 Elsevier Ltd. All rights reserved.

The synthesis of polyarbutin by oxidative polymerization using polyethylene glycol-containing hematin (PEGylated hematin) as a biomimetic catalyst was examined. Diethyl azodicarboxylate was added to PEG, triphenylphosphine and hematin (190mg, 0.30mmol) suspended in N,N-dimethylformamide in a dropwise manner at 0°C under a nitrogen atmosphere. The catalyst (PEGylated hematin, hematin or HRP) was added to arbutin (30mg, 0.1mmol) dissolved in a phosphate buffer solution (pH 7.0, 300 ml) and an aqueous H2O2 solution (6wt%) was then added dropwise. The polymerization process was followed by gel permeation chromatography (GPC) using UV detection of the hydroquinone absorption at 285 nm. The product obtained by the Mitsunobu reaction, crude PEGylated hematin, was soluble in water, and in organic solvents such as toluene, acetone, chloroform and tetrahydrofuran. PEGylated hematin showed high catalytic activity for arbutin polymerization, and the molecular weight (M n) of polyarbutin reached ~5100.

An organic-inorganic hybrid amorphous molecular material, carbazole-substiuted double-decker-shaped silsesquioxane (DDSQ-4Cz) was synthesized, and an organic light-emitting diode was fabricated using the spin-coated DDSQ-4Cz film as a hole transport layer

Organic/inorganic composites were prepared by catalytic hydrolysis and subsequent condensation of tetraethoxysilane (TEOS) in a shell layer of core-shell polymer particles. First, core-shell particles were prepared by emulsifier-free emulsion polymerization of styrene (St) with 2-chloropropionyloxyethyl methacrylate (CPEM) using potassium persulfate as an initiator, followed by surface-initiated activator generated electron transfer-atom transfer radical polymerization (AGET-ATRP) of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA). Dynamic light scattering revealed that hydrodynamic diameter of the particle increased from 482 to 931 nm after AGET-ATRP of DMAEMA. The amount of grafted DMAEMA was determined to be ca. 10 mol% with respect to (wrt) St by H-1 NMR. Second, the composite particles were prepared by adding TEOS into a water/methanol dispersion of the P(St-CPEM)-g-P(DMAEMA). The P(St-CPEM)-g-P(DMAEMA)-SiO2 composite particles containing ca. 50 wt.% of silica wit the total weight were obtained. Hollow silica shell particles were also obtained by extraction of polymer components from the composites with tetrahydrofuran. Crown Copyright (C) 2010 Published by Elsevier Inc. All rights reserved.

In this paper, a simple method for fabrication of glycopolymer hollow particles was demonstrated. The P(St-CPEM)-g-PVBSAELA core-shell particles were prepared by emulsifier-free emulsion polymerization of styrene (St) with 2-chloropropionyloxyethyl methacrylate (CPEM) using potassium persulfate as an initiator, followed by surface-initiated activator generated electron transfer-atom transfer radical polymerization (AGET-ATRP) of a styrene derivative bearing a lactose residue, i.e., N-2-4-(vinylbenzenesulfonamido)ethyl lactobionamide (VBSAELA). Dynamic light scattering measurement showed that the P(St-CPEM)-g-PVBSAELA core-shell particles possess graft layers of ca. 160 nm in thickness on the P(St-CPEM) core of 455 nm in diameter. By taking advantages of large difference in solubility between the PSt-based core and the PVBSAELA shell, the submicron-sized PVBSAELA hollow particles were obtained through a selective extraction of the core part from the P(St-CPEM)-g-PVBSAELA particles in tetrahydrofuran. The hydrodynamic diameter of the resulting hollow particles decreased by 15% compared to that of the corresponding core-shell particles. Finally, the micron-sized, raspberry-shaped, PVBSAELA hollow particles were successfully fabricated by a sacrificial dissolution of the PSt-based components from the PVBSAELA-grafted, core/shell heterocoagulates. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.