POLYMERS Vol.63 No.2
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Extremely Thin Polymer Films
COVER STORY: Highlight Reviews
Glass Transition of Polymer Thin Filmes Toshiji KANAYA, Rintaro INOUE
<Abstract> Polymer thin films show interesting but unusual properties different from those of bulk. In this article we review the recent progress in research on polymer thin films, especially focusing on the glass transition temperature.
Keywords: Polymer Thin Film / Glass Transition Temperature / Confinmemt / Surface Effect / Interfacial Effect / Distribution of Glass Transition Temperature
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Nano-Architectures and Dynamics of Polymer Chains Adsorbed on Planar Solid Surfaces Tadanori KOGA
<Abstract> It is known that polymer chains adsorb even onto weakly attractive surfaces, forming three types of segment sequences, “trains” (adsorbed segments), “loops” (sequences of free segments connecting successive trains), and “tails” (non-adsorbed chain ends). There is now growing evidence that the polymer/substrate interface plays a crucial role in the physical and mechanical properties of polymeric materials confined at the nanometer scale. However, the mechanism associated with the structure and dynamics at the interface still remains unsolved due to the lack of suitable experimental tools. In order to provide a better understanding of the interfacial behavior at the nanometer scale, we have integrated a suite of in-situ and real-time X-ray/neutron scattering techniques. Here, I review our recent experimental results on the revealed nano-architectures and dynamics of adsorbed polymer chains at the interface. In addition, the impact of the nanometer thick adsorbed layer at the interface on the local property of polymer thin films is also discussed.
Keywords: Adsorbed Layer / Polymer Melt / Solid Interface / Flattened Conformation / Nanoconfinement Effects / Long-Range Perturbations
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Ultrafine Fabrication Using Self-Assembled Polymer Thin Film Koji ASAKAWA
<Abstract> The technology driver for higher performance of electronic devices has been miniaturization. Recently, the cost of apparatus and materials for the conventional top-down approaches are surging as the fabrication size closes to 10 nm-scale. A low cost nano-fabrication technology is desire and bottom-up approaches recently become quite attractive.
Since self-assembled lithography was demonstrated that could fabricate nm-scale pattern by simple process, several kinds of devices have been demonstrated. For example, patterned magnetic media for a hard disk drive (HDD) was the first trial of the block copolymer lithography. Fabrication of light extraction and anti-reflection structures are common attempts for optical devices.
Development for memory devices are also in progress. The directed self-assembly (DSA) is a key technique, that the larger guides are made by the conventional top-down methods then the bottom-up self-assembled structures are formed along the guides. A multiple line/space pattern for wires and slinked hole pattern for vias were fabricated by the method.
Keywords: Block Copolymer Lithography / Directed Self-Assembly / Electronic Device Fabrication / Hard Disk Drive / Optical Device / Memory Device
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COVER STORY: Topics and Products
Hybrid Polymer Nanoassembly Masaya MITSUISHI, Tokuji MIYASHITA
<Abstract> We demonstrate flexible design of hybrid polymer nanoassemblies based on nanoparticle arrays and polymer nanosheets. Using excellent film formation ability of acrylamide-based amphiphic polymers at the air-water interface, well defined hybrid polymer nanoassemblies were constructed at the monoparticle layer level. Hybrid polymer nanoassemblies enable to elucidate the structure-property relationship in terms of light-matter interaction at confined spaces as well as open up a new scientific field for nanophotonics and nanoelectronics applications. Several examples such as luminescence oxygen sensor application and emission control of hybrid polymer nanoassemblies assembled on a silver grating surface are described.
Keywords: Polymer Nanosheet / Hybrid Polymer Nanoassembly / Localized Surface Plasmon / Waveguide / Nanoparticle
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End-On Orientation of Semiconducting Polymers in Thin Films Induced by Surface Segregation Keisuke TAJIMA
<Abstract> Controlling the orientation of highly anisotropic semiconducting polymers in thin films is important for the high performance of organic electronic devices. We have recently developed simple ways to achieve unique end-on (vertical) orientation by utilizing the surface segregation of the end-fluoroalkylated poly(3-butylthiophene) (P3BTF). In P3BTF/polystyrene (PS) blend films, a highly ordered end-on orientation of the conjugated backbone was observed in the surface-segregated layer of the crystalline P3BT-F. Furthermore, when the film was spin-coated from a mixture of P3BT-F and poly(3-butylthiophene) (P3BT), the chain orientation of P3BT-F at the surface forced the P3BT in the bulk of the film to adopt the end-on orientation because of the high crystallinity of P3BT. The electronic conductivity measured perpendicular to the film surface also reflected the end-on orientation in the bulk, resulting in a more than 30-fold enhancement of the hole mobility. This strategy could be applied to other crystalline semiconducting polymers and has great promise for controlling the optical and electronic properties of polymer films.
Keywords: Semiconducting Polymers / Chain Orientation / Thin Films / Surface Segregation / Self-Assembly / Anisotropy / Charge Mobility / Crystalization
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Structure Analysis of Polymer Thin Film Using Neutron Reflectometry Norifumi L. YAMADA
<Abstract> Neutron reflectometry is one of the powerful tools to investigate surface and interfacial structures of materials in the spatial range from nm to sub-μm. Because hydrogen and deuterium atoms have different scattering length for neutrons, this method can distinguish deuterated materials from normal ones in the mixture of soft-condensed matters, such as polymer blends, bio-mimic membranes, and so on. Furthermore, high transmissivity of neutrons to materials enables us to probe deeply-buried interfaces such as solid/liquid interfaces in a non-destructive way. SOFIA is a horizontal type neutron reflectometer in Japan Proton Accelerator Research Complex (J-PARC). Thanks to a careful treatment for background, we can measure a reflectivity profile down to 10-7. Furthermore, the high-flux pulsed neutron beam at J-PARC enables us to perform a time-slicing measurement with a wide wavelength band and short time slices. In this paper, I introduce a specification of SOFIA and some usage examples of SOFIA for polymer samples.
Keywords: Surface and Interfacial Structures / Soft Matter / Neutron Reflectometry
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Liquid Crystalline Block Copolymer Thin Film Dominated by Liquid Crystal Motonori KOMURA
<Abstract>Liquid crystalline block copolymer, PEO-b-PMA(Az), forms a highly ordered microphase separated film with perpendicularly oriented cylinders on various substrates by thermal annealing, because homeotropic anchoring of the liquid crystalline mesogens to air-film interface induces nucleation of liquid crystallization and simultaneous order-order transition from sphere to cylinder microphase separations from the interface. In the case of a thick film, homogeneous anchoring of the mesogens to a Si substrate was also observed. Based on this phenomenon, we succeeded in direct observation of both, perpendicular and parallel cylinder formations by temperature-controlled atomic force microscopy with introduction of a temperature gradient between sample stage and cantilever tip. Furthermore, the liquid crystalline block copolymer shows the smallest microphase separated structures because of the exclusion effect of other materials by liquid crystallization that added to thermodynamic repulsive force between blocks represented by χ parameter. Hierarchical microphase separated structures of such a well-designed block copolymer will afford a further progress in block copolymer lithography and fabrication of functional nanomaterials.
Keywords: Microphase Separation / Liquid Crytal / Cylinder / Order-Order Transition / In-situ Observation
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Studies on Polymer Thin Film Structure by Grazing Incidence Small Angle X-ray Scattering at SPring-8 Hiroki OGAWA
<Abstract> To gain a better understanding of the function of polymer thin films, one should measure the multi-scale structures from the surface roughness down to the atomically truncated structures at micro area as well as the formation process inside the film. In this article, structural studies of polymer thin films using synchrotron radiation grazing incidence (GI) small-angle X-ray scattering (SAX) is reviewd, and recent development of GI ultra SAX and in-situ GISAX measurement during spin-coating process is also introduced.
Keywords: Polymer Thin Film / GISAXS / GIUSAXS / Dewetting / Spin-Coating
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Polymer Science and I: A Personal Account
Towards Construction of Functional Materials for Effectively Promoting Living Tissues Motohiro TAGAYA
<Abstract> This manuscript introduces interfacial biological phenomena, preparative nanobiomaterials, and the biomedical applications, leading to functional nanobiosystems as enhanced biocompatibility. In future, the author’s work will contribute to the biomedical fields such as biosensor, drug delivery system, bioimaging and tissue engineering materials.
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Front-Line Polymer Science
Novel Development of Cellulose Nanocrystals Takeshi SERIZAWA
<Abstract> Cellulose composed of β-1,4-linked anhydro-d-glucose repeating units is the most abundant organic polymer in the biosphere. In nature, crystalline elementary fibrils are formed during biosynthesis, and are hierarchically assembled into larger fibers with other biomolecules. Acid treatment of natural cellulose sources isolates cellulose nanocrystals (CNCs) with rod-like shapes. In this review, the preparation, physical/chemical properties, surface functionalization, and composite materials of CNCs are described. Then, the hydrolytic activities of CNCs, recently developed by our group as their novel functions, are introduced.
Keywords: Cellulose / Nanocrystal / Acid Treatment / Suspension / Surface Functionalization / Composite Material / Hydrolytic Activity
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