| POLYMERS Vol.67 No.11 |
| >> Japanese | >> English |
COVER STORY
Attractive Behavior of Dispersing System |
| COVER STORY: Highlight Reviews |
| Precise Control of Spontaneous Emulsification and Novel Method for Preparing Porous Ultra-Low-Density Biomaterials | Yoshihiko MURAKAMI |
| <Abstract> The spontaneous emulsification is the phenomenon that droplet formation is achieved by contacting two immiscible solutions that are not in equilibrium. The paper provides a brief review on recent efforts to develop the porous ultra-low-density biomaterials and their perspective. Keywords: Spontaneous Emulsification / Porous Biomaterials / Pulmonary Drug Delivery |
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| Metal Particle Dispersion Systems by using Polymers for Surface Coating and Their Applications | Tetsu YONEZAWA, Masaki MATSUBARA |
| <Abstract> In many cases, metal fine particles and nanoparticles are stabilized by organic substances and stably dispersed in dispersion media. Polymers are known as an excellent dispersing agents and are frequently used. Their unique functions can also be added to the particles. In this paper, synthesis and function of polymer-stabilized particle dispersed systems and their applications to the filed of electronics is discussed. Keywords: Polymer-Stabilized / Dispersion / Nanoparticle / Graft Polymerization / Surface Coating / Gelatins |
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| Polymerization-Induced Self-Assembly for Nanomolecular Materials | Shinji SUGIHARA |
| <Abstract> The reproducible synthesis of bespoke organic nanoparticles of controlled size, morphology and surface functionality in concentrated solution is widely regarded to be a formidable technical challenge. In the recent years, polymerization-induced self-assembly (PISA) has become widely recognized as the efficient route to produce such block copolymer nano-objects; spherical micelles, stable or metastable worm-like micelles or vesicles, and non-spherical strange assemblies such as jellyfish and lumpy rod composed of well-defined block copolymers. Among them, RAFT dispersion polymerization is a much simpler formulation for self-assembly since the initial reaction solution is homogeneous and block copolymer architecture can be directly applied. This brief review focuses on the various advantages of the nano-objects offered by RAFT aqueous dispersion polymerization for promising future research directions. Keywords: Polymerization-Induced / Self-Assembly / Nano-objects / RAFT Polymerization / Dispersion Polymerization / Emulsion Polymerization / Block Copolymer |
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| COVER STORY: Topics and Products |
| Development of Polyester Resin Particles for Toner | Hideo NAKANISHI |
| <Abstract> We developed new polyester resin particles for use in toner that are prepared by an advanced dissolution suspension method. The new resin particles have excellent characteristics, such as a narrow particle size distribution, a uniform and non-spherical particle shape, and high melt elasticity at high temperature with low-temperature meltability. The narrow particle size distribution, which has a coefficient of variation (CV) under 20%, is obtained by using nanoscale styrene-acrylic particles during the particle formation of the dissolution suspension process. The particle shape is controlled variously from spherical to non-spherical forms, such as spindle or dimple shapes, during the solvent removal process. Moreover, a melting property suitable for toner application is achieved by the elongation reaction of the polyester prepolymer proceeding simultaneously during the particle formation process. Keywords: Resin Particle / Polyester / Toner / Particle Size Distribution / Shape / Prepolymer |
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| Characteristics of Association and Emulsification Ability of Water-Soluble Amphiphilic Polysaccharides | Eri AKIYAMA |
| <Abstract> We investigated solution properties of water-soluble amphiphilic polysaccharides. They formed sub-micron sized self-aggregates in dilute aqueous solution through the association of hydrophobic moieties. The size, density, aggregation number of self-aggregate, aggregation number and mobility of alkyl chains in each associating hydrophobic microdomain differed by molecular structures. These association characteristics were controlled by the balance of affinity of hydrophilic main chain to water and aggregation strength of hydrophobic moieties. In the semi-dilute regime, these water-soluble amphiphilic polysaccharides formed a macrogel network and showed a viscosity-increase as revealed by rheological measurements. Rheological properties of these macrogels also differed by the characteristics of sub-micron sized self-aggregates. We also evaluated the emulsification ability of these polymers. Elastic macrogel stabilized emulsions by preventing creaming and coalescence of emulsified particles. Keywords: Water-Soluble Amphiphilic Polymer / Self-Assembly / Sub-Micron Sized Self-Aggregate / Association Characteristic / Thickening Property / Emulsification Ability |
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| Interaction Forces between Particles in Polymer Solutions | Takeshi MORI |
| <Abstract> Since the performances of composite materials containing particles dispersed in a polymer resin might be changed depending on the particle dispersibility, it is important to obtain a stable dispersion state. Particle dispersibility in polmer solution could be evaluated from the viewpoint of the surface interaction force, which can be measured using a colloidal probe atomic force microscope (CP-AFM). In this article, a method to measure interaction forces in polymer solutions by the CP-AFM method was explained, and the results of measurement of interaction forces between silica particles in various concentration of PVA solution was introduced. From this study, it was confirmed that the interaction forces were changed depending on the concentration of PVA solutions, and adsorption of PVA on the surface of silica particle influences on interaction forces. Keywords: Composite Materials / Particle Dispersivility / Interaction Forces / Colloidal Probe AFM |
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| Polymer Science and I: A Personal Account |
| Memoir | Hironori ATARASHI |
| <Abstract> When I was an undergraduate student, I was impressed with interfacial polycondensation, which is my first impression of polymer science. So far I have been fascinated with many different research areas in articles and textbooks. In this essay, I review my research life and express my hope for future success. |
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| Front-Line Polymer Science |
| Self Assembly and Structure Formation of Colloids | Junpei YAMANAKA, Tohru OKUZONO, Akiko TOYOTAMA |
| <Abstract> Colloidal self-assembly has drawn an increasing attention as a bottom-up technique to fabricate mesoscopically ordered materials. In this review, we describe recent advances of colloidal assembly routes to precisely assemble clusters and complex structures, as well as our relevant studies on clustering and crystallization. In particular, we report on (1) colloidal clusters due to electrostatic interaction, DNA hybridization, and depletion interaction, (2) eutectic crystals in multicomponent colloids with depletion interaction, and (3) open crystalline lattices of colloids with interparticle interaction having specificity and directionality. The examples of complex lattice structures include diamond lattices, which have been expected as 3D photonic crystals having a full band gap. Keywords: Colloid / Self-Assembly / Colloidal Cluster / Colloidal Crystal / Electrostatic Interaction / Depletion Interaction / DNA hybridization / Diamond Lattice |
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