| POLYMERS Vol.73 No.6 |
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COVER STORY
Front Line of Analytical Techniques Supporting Polymer Sciences: Special Issue on Leading-edge Analysis of Spectroscopy |
| COVER STORY: Topics and Products |
| Terahertz and Low-Frequency Raman Spectroscopy of Polymers | Harumi SATO |
| <Abstract> Infrared, Raman, and near-infrared spectroscopy are well known as vibrational spectroscopy methods, and recently, in addition to these methods, terahertz (THz) and low-frequency Raman spectroscopy have been used in a variety of fields. THz and low-frequency Raman spectroscopy mainly deal with the region below 300 cm－1. Since molecular skeletal and intermolecular vibrations are observed, and the spectra observed in these regions are very sensitive to the higher-order structure of polymer compounds and intermolecular interactions. Recently, authors have attempted to study the higher-order structures and intermolecular interactions of semi-crystalline polymers and biodegradable polymers as well as low-frequency imaging and marine degradation processes of polymers. Here, we present some applications of these vibrational spectroscopic techniques to polymers. Keywords: Terahertz Spectroscopy / Low-Frequency Raman Spectroscopy / Intermolecular Hydrogen Bonding |
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| Evaluation of the Surface/Interface by Sum-Frequency Generation (SFG) Spectroscopy | Takayuki MIYAMAE |
| <Abstract> Sum frequency generation (SFG) spectroscopy is widely recognized as a surface and interface specific vibrational spectroscopic technique. Various physical and chemical properties at the polymers and liquid interfaces are strongly correlated with the molecular behavior at the surfaces and interfaces, and it is essential to observe their behavior in-situ. In this paper, we present (1) the analysis of buried epoxy polymer/metal interfaces, (2) charged polymer surfaces and their charged mapping, (3) molecular orientation of saponin aqueous interfaces, and (4) the relationship between molecular orientation of isohumulones on beer surface and the foam stability. Keywords: Sum Frequency Generation / Interface / Polymer / Liquid Interfaces / Electrification |
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| Energy Transfer in Biohybrid Photosynthetic Antenna Studied by Transient Absorption Spectroscopy | Yutaka NAGASAWA |
| <Abstract> LH2 is the periferal light-harvesting antenna complex of the photosynthetic purple bacteria. It contains two types of bacteriochlorophyll groups called B800 and B850 that absorbs light at 800 nm and 850 nm. While the light around 500 nm could be absorbed by the carotenoids, absorbance of LH2 is weak around 650 nm. Hence, biohybrid antenna (LH2-Alexa) with an artificial dye, Alexa 647 (Alexa), attached to LH2 was developed. In order to investigate the energy transfer dynamics of the biohybrid, femtosecond time-resolved transient absorption spectroscopy was performed. As a result, the energy transfer from Alexa to LH2 occurred multiexponentially with four major components with time constants ranging from 440 fs to 23 ps. The multiexponentiality of the energy transfer is due to the heterogeneous attachment of Alexa to the cystein residue of LH2. Keywords: Ultrafast Spectroscopy / Transient Absorption Spectroscopy / Photosynthesis / Light-Harvesting Anntena Complex / Biohybrid / Energy Transfer / Förster Theory |
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| Aging of Polypropylene Probed by Near Infrared Spectroscopy | Hideyuki SHINZAWA |
| <Abstract> This paper describes the attempt to characterize thermally induced aging of polypropylene (PP) samples by near infrared (NIR) spectroscopy. Significant levels of variation in NIR bands associated with short (amorphous-dominated) and long (crystalline-dominated) helices was readily captured when PP samples were subjected to thermal aging treatment. A regression model derived from the NIR spectra indicated a significant level of correlation between the actual and predicted elongations of the samples. Thus, by utilizing the NIR spectra, it becomes possible to predict the change in the elongation property of the aged PP sample without conventional mechanical testing. Keywords: NIR Spectroscopy / Polymer / PP / Aging |
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| Dynamic Light Scattering: Molecular-Selective Dynamic Light Scattering | Takashi HIROI |
| <Abstract> Dynamic light scattering (DLS) is a technique that has been widely used for the characterization of diffusion dynamics for polymer solutions and soft materials. In DLS measurement, the fluctuation of Rayleigh scattering is recorded as a form of the time correlation function. One of the major disadvantages of DLS is the absence of molecular selectivity, which limits the application of DLS to multi-component materials. To solve this problem, we have conceived a new measurement technique combining DLS and Raman scattering. Raman scattering is a scattering process whose wavelength is shifted depending on the molecular vibrational frequency of the target molecule. A simple combination of DLS and Raman scattering is the measurement of the fluctuation of Raman scattering from the target species. However, this strategy does not work because the intensity of Raman scattering does not fluctuate at all since conventional Raman scattering is an incoherent process. We solved this problem by utilizing coherent anti-Stokes Raman scattering. Keywords: Dynamic Light Scattering / Raman Scattering / Molecular Selectivity |
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| Polymer Strucutres As Explored by State-of-The-Art Solid-state NMR Spectroscopy | Shunya ORIUCHI, Toshikazu MIYOSHI |
| <Abstract> Combined use of state-of-the-art solid state NMR spectroscopy with 13C isotope labeling enable ones to detect unique polymer strucutre such as chain folding strucutre of semicrystalline polymers (intramolecular packing) after crystalization as well as to separately observe intramolecular and intermolecular chemical reactions of solid polymers. Here, we in triduce two examples of i) chain folding strucutre of isotacitc-poly(1-butene) solution-grown crystals as a function of kinetics and ii) chemical reactions of polyacrylonitrile during stabilization process. Keywords: Solid-State NMR / Isotope Labeling / Intermolecular and Intermolecular Intereaction / Polymer Crystallization / Chemica Reaction / Carbon Fiber / Polyacrylonitrile |
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| Next-Generation High-Speed Infrared Spectrosocpy and Super-Resolution Infrared Microscopy | Takuro IDEGUCHI |
| <Abstract> In the field of laser physics, we have recently witnessed remarkable developments in lasers and optical technologies in the infrared spectral region. These advancements have led to the creation of innovative spectroscopic and microscopic measurement techniques. This paper introduces our recently developed technologies on high-speed infrared spectroscopy and super-resolution infrared microscopy. We anticipate that the high-performance vibrational spectroscopy and microscopy will pioneer new trends in polymer chemistry. Keywords: Laser / Infrared / Spectroscopy / Microscopy |
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| Water Structure in Polymers Observed by Thermal Analysis via Variable-Temperature Mid-Infrared Spectroscopy | Makoto GEMMEI-IDE, Shigehiro KAGAYA |
| <Abstract> The water structure in polymer-water systems was observed based on heat flux measurements such as differential scanning calorimetry，DSC, has been discussed on the assumption that the heat flux is a state change between liquid water and ice, that is, freezing of water and melting of ice. However, variable-temperature mid-infrared spectroscopy, VT-mid-IR method, has revealed that water in polymer solids can undergo not only freezing and melting, but also state changes including condensation, deposition, sublimation, and evaporation, as well as deposition during heating (re-deposition). The combination of DSC and VT-mid-IR methods to study the water structure in polymer solids is currently limited, but it is expected to contribute to a deeper understanding of the relationship between function of polymers and the water structure. Keywords: Free Water / Intermediate Water / Non-Freezing Water / State Changes / Polymer Solids |
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| Polymer Science and I: A Personal Account |
| What Can Be Gained by Changing Environments | Yuya DOI |
| <Abstract> I have learned a lot in my life as a researcher (especially after obtaining my Ph.D.) by changing my environment. In this article, I introduce some of my experiences so far. |
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| Front-Line Polymer Science |
| Assembly and Functionalization of Colloidal Particles Using Interfaces | Yui MAEJIMA, Michinari KOHRI |
| <Abstract> This topic summarizes recent trends in the fabrication of colloidal particle assemblies using interfaces and their functions, focusing on research from the past few years. Particle assemblies have many attractive and unique features not found in other materials, and coupled with advances in particle fabrication methods, research in this area is progressing rapidly. The particle-assembling process at the interface is dynamic, and advances in analytical techniques are essential to understanding the process. We look forward to further developing this field through interdisciplinary research. Keywords: Colloidal Particles / Interface / Assembly / Colloidal Crystals |
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