POLYMERS Vol.59　No.3 March 2010
POLYMERS　Vol.59　No.3
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COVER STORY
Polymers Reproduced by Processing Technology
Growing Polymers: A Personal Account
Dendrimer + Bio + α → Next Generation Biomaterials Chie KOJIMA
<Abstract> I graduated in dendrimer chemistry and received my Ph.D. in cell biology. As dendrimer molecular chains grow divergently, I am going to make progress in my interdisciplinary research by harmonizing my backgrounds and collaborating with some researchers in other fields.
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Helix Lover Koichi SAKAJIRI
<Abstract> Through the studies on biological and synthetic helical polymers, I have gained an increasing interest in chiral architectures exhibiting liquid crystalline properties based on the stiff helical backbones and/or structural changes in helical sense and conformation. Now, I am working on helical supramolecular systems showing such behaviors.
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COVER STORY: Highlight Reviews
Precision Polymer Processing and Its Structure Development Hiroshi ITO
<Abstract> In recent years, quality improvement and higher performance of plastics molded products were keenly required, especially for precise and micro- or nano-scale products, such as optical devices, medical applications, information and communication applications, and others. In this paper, strategy and present research work on micro/nano-moldings are reported. The higher-order structure and properties relationship in micro- and nano-molding is also introduced.
Keywords: Micro- and Nano-Moldings / Injection Molding / Thermal Imprinting / Replication Accuracy / Skin-Shear-Core Internal Structure
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Analysis of Pore Formation Mechanism and Control of Porous Structure in Polymeric Membranes Hideto MATSUYAMA
<Abstract> Recently, much attention was paid to water treatment by porous membranes. For these membranes, the control of porous structure is crucial to have a better membrane performance. However, porous polymeric membranes were sometimes prepared by “trial and error method”. In this paper the analysis of pore formation mechanism in the porous membrane preparation is briefly reviewed.
Keywords: Porous Membrane / Thermally Induced Phase Separation / Nonsolvent Induced Phase Separation / Water Treatment / Simulation of Pore Formation Process
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Polymer Foaming Technology: Foaming Mechanism and its Applications Shin-ichi KIHARA, Masashi HARUKI, and Shigeki TAKISHIMA
<Abstract> Polymer foams are functional materials which are composed of gas phase, polymer phase and the interface. The materials are used in various applications that make use of their new features like their high impact strength and lightness, high insulation or absorbents functions. However, it is not easy to control the foam structure and morphology in the processing stage. This is due to the fact that bubble nucleation phenomena occur on the nano-meter scale and bubble growth and bubble coalescence phenomena on the micro-meter scale and they are simultaneously occuring in the foaming process. These complex phenomena are known since long time but new scientific and technological studies are required to overcome the difficulty to handle them at the same time. For this reason, an outline about analysis of foaming mechanism mainly on homogeneous nucleation and bubble growth are given.
Keywords: Plastic Foaming / Supercritical Fluids / Homogeneous Nucleation / Heterogeneous Nucleation / Bubble Growth / Decompression / Crystallization
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Attempts to Simulate an Elongational Process Toshiro YAMADA
<Abstract> Simulation models are introduced which are applicable to wider process conditions for the prediction of molecular orientation axis and retardation on retardation films in the tentering process by using results of elasto-plastic analysis. The simulation model, a stress-strain hybrid model, proposed in this study consists of a principal stress term and a principal plastic strain term. The principal stress term is based on stress-optical law, whereas, the principal plastic strain term is based on affine deformation. The contribution ratio of the stress term and the plastic strain term changes with both temperature and stretching ratio. We assume that the formation of molecular orientation depends on temperature and stretching ratio. As a result, a better agreement is obtained between the simulated and experimental results for the transverse distribution of molecular orientation axes and retardation under the constant stretching ratio and constant temperature over a wider range of temperature than reported in previous simulation models.
Keywords: Simulation / Stress-Strain Hybrid Model / Elasto-plastic Analysis / Molecular Orientation / Retardation / Tentering Process
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Nanostructure Control by Reactive Polymer Blending Takashi INOUE
<Abstract> The reactive blending of dissimilar polymers yields block or graft copolymers. By an emulsifying effect of the in situ-formed copolymer, the size of dispersed particles can be reduced down to sub-μm. Another interfacial behavior is the pull-out of the in situ-formed copolymer by the external shear forces. The copolymer is also pulled into the dispersed particles, depending on the molecular architecture. Such interfacial phenomena can be applied for a new approach to the 10 nm morphology control, leading to a variety of high performance materials.
Keywords: Reactive Blending / in situ-Formed Copolymer / Pull-Out / Pull-In / Nano-Structure
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COVER STORY: Topics and Products
Laser Direct Joining Technology of Plastic to Metal Seiji KATAYAMA
<Abstract> Novel laser joining technology was newly developed to directly bond an industrial plastic to a metal surface. The joints possessed high tensile shear strength and fractured in the base plastic plates. The mechanisms of high strengths were attributed to chemical, mechanical and physical bonding.
Keywords: Laser Joining / Lap Joining / Plastics / Metals / Tensile Shear Test / Joints / Bubbles
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Novel Technique for Surface-Modification of Nanoparticles via Block Polymer-Assisted Emulsification Yoshihiko MURAKAMI
<Abstract> The novel facile technique for preparing surface-modified nanoparticles is described. The technique can be used even though reactive groups are not present on the surface.
Keywords: Nanoparticle / Surface Modification / Block Polymer / Drug Delivery Systems
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Enhanced Recycling of FRP Using Subcritical Water Takaharu NAKAGAWA
<Abstract> Subcritical water was applied to hydrolyze thermo-setting resin of FRP (Fiber Reinforced Plastics) into resin raw materials and styrene-fumaric acid copolymer (SFC). In 1-octanol the modified SFC showed an equivalent shrinkage control performance comparable to a commercial low profile additive for FRP forming. This process is suggested for use in “Enhanced Recycling.” A pilot test was also performed successfully.
Keywords: Subcritical Water / Fiber Reinforced Plastics / Chemical Recycling / Thermo-setting Resin / Styrene-fumaric Acid Copolymer / Unsaturated Polyester / Hydrolysis / Low Profile Additive
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Front-Line Polymer Science
π-Stacked Polymers Tamaki NAKANO
<Abstract> π-Stacked structures are characterized by multiple π-electron groups in the side or main chain of a polymer chain regularly stacked on top of each other. This structure type has been realized for various polymers including vinyl polymers and foldamers and is also found in naturally occurring DNAs and RNAs. Some π-stacked polymers exhibit photoelectronic properties such as energy transfer, charge transfer, and electroluminescence based on the interaction between stacked π-electronic systems. In addition to π-stacked polymers where π-electron systems are densely stacked, π-layered polymers whose π-electron systems are not in close contact but are regularly aligned with the aid of rigid scaffold moieties in the polymer chain, have been synthesized. This article reviews the synthesis, structure, and properties of these polymers. It is important to note the fact that electronic properties including conduction that have been studied mainly using main-chain conjugated polymers such as polyacetylenes and polythiophenes can be also achieved using π-stacked and related polymers.
Keywords: π-Stacked Structure / Conformation / Energy Transfer / Charge Transfer / Conduction / Dibenzofulvene / DNA / Cyclophane / Photoelectronic Property / π-Layered Structure
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