Kobunshi - Vol. 59, No. 3 (March, 2010)

Hot Topics

Vol. 59, No. 3, March (2010)

Electromagnetic Response of Metallic Microcoils Fabricated through Biotemplating Process
Soichiro SUZUKI, Kaori ITO, and Tomokazu IYODA
Division of Integrated Molecular Engineering, Chem. Res. Lab., Tokyo Inst. of Tech.

Millimeter waves have been expected to be applied for next-generation wireless communications. It is now highly required to generate electromagnetic waves (EMWs) at specific frequency and to fabricate the wave absorbers in millimeter wave range due to serious problems in electromagnetic interference and the possible health hazard on exposure to EMWs. We have suggested the biotemplating process for the fabrication of microcoils, which has electromagnetic wave absorption properties in the range of millimeter and potentially subterahertz waves. We successfully demonstrated the fabrication of the microcoils with electroless plating and their characterization using vascular bundles of Lotus as biotemplates. For the mass-production, we include microorganisms like algae, which can be applied for the same biotemplating process. Polymer Preprints, Japan 2009, 58, 4607.

Recovery of Useful Resources from Waste Electric Boards by Liquefaction Using Biomass Derived Tar
Tohru KAMO
National Institute of Advanced Industrial Science and Technology (AIST)
Recovery of useful materials from end-of-life electric devices is very important not only for reducing the environmental load but also for securing indispensable resources. In this study, epoxy boards could be liquefied almost completely in a biomass derived tar at 210-300℃ for 60 min under atmospheric pressure, due to easy ester bond dissociation in the epoxy resin facilitated by cresol derivatives in the tar. Liquefied products can be used again as solvent or feedstock. Other plastics, like urethane, FRP, PET, and polycarbonate, were also liquefied in this tar. We propose a new way to use biomass as a renewable solvent, because it is very mottainai (wasteful) to use the natural resources as a fuel only for one time. Polymer Preprints, Japan 2009, 58, 5385.

Design of Multifunctional Liposomes for Temperature-Sensitive Drug Release and Imaging
Kenji KONO1, Seiji NAKASHIMA1, Atsushi HARADA1, Daisuke KOKURYO2, Ichio AOKI2, Sadahito AOSHIMA3, and Yukihito ISHIZAKA4
1Graduate School of Engineering, Osaka Prefecture University; 2National Institute of Radiological Sciences; 3Graduate School of Science, Osaka University; 4International Medical Center of Japan
We prepared multi-functional liposomes by surface modification of liposome with thermosensitive polymers and inclusion of Gd-bearing lipids in the liposomal membrane. We found that tumor growth was effectively suppressed by injection of the DOX-loaded thermosensitive polymer-modified liposomes and subsequent heating at 42-45℃. Furthermore the timing of the heat application after the liposome injection affected efficacy of tumor growth suppression. Inclusion of Gd-bearing lipids was shown to provide the temperature- sensitive liposomes with MR detection properties. Accumulation of the liposomes in the tumor was followed by using Gd-labeled liposomes and MRI. Liposomes having both the temperature-sensitive property and the imaging function might increase accuracy of antitumor drug delivery. Polymer Preprints, Japan 2009, 58, 5122.

Gold Nanoparticle in Nanogel for New NanoTherapy
Yukio NAGASAKI
Tsukuba Research Center for Interdisciplinary Materials Science, University of Tsukuba
Recently, we have been focusing on preparation of core-shell type polymeric nanogels, which possess a crosslinked polyamine core and a biocompatible poly(ethylene glycol) (PEG) shell. The obtained nanogels showed volume phase transition in a minute change in environmental pH and dispersed stable under physiological conditions. The cytotoxicity of polyamine core was reduced significantly by the crosslinking as well as PEG shell. Using the new nanogel as a nanoreactor, new gold colloid containing nanogel (GNG) was successfully synthesized through the self-reduction of Au(III) ions by tertiary amino group in nanogel. TEM images revealed that the synthesized GNPs located only in the nanogel core, indicating that nanogel acted as both nanoreactor and nanoreservoir for GNPs. Additionally, the number of GNPs in single nanogel could be easily arranged by changing N / Au (number of amino groups / number of Au atoms) ratio. The obtained gold nanoparticle containing nanogels (GNG) were applied for an enhancement of cancer photothermal therapy as well as radiotherapy in response to electromagnetic wave in cultured cancer cells. Polymer Preprints, Japan 2009, 58, 4283.

Excellent Blood Circulation of Concentrated Polymer Brush-Afforded Fine Particles
Kohji OHNO
Institute for Chemical Research, Kyoto University
Hydrophilic polymer brush-afforded silica particles were synthesized by surface-initiated living radical polymerization, varying the diameter of the silica core, the length of brush chain, and the graft density to obtain a series of samples with various structural features. The hybrid particles were intravenously injected into mice to investigate their blood circulation and biodistribution, so that the structure factors of the hybrid particles (size, surface elasticity, etc.) strongly affect their in vivo pharmacokinetics. Some hybrid particles showed an excellently prolonged blood circulation with a blood half-life of more than 24 h, which induced particle accumulation in tumor tissues due to the so-called EPR effect. Polymer Preprints, Japan 2009, 58, 5044.

Single-Molecules Imaging of the Unidirectional Molecular Motion Surfing the Longitudinal Wave in the Helical Polymer Chain as a Linear Motor
Ken-ichi SHINOHARA
School of Materials Science Japan Advanced Institute of Science and Technology (JAIST)
A motor driven by the thermal energy of room temperature was discovered at the nanometer scale. We succeeded in single-molecules imaging of a linear motor function as the unidirectional molecular motion surfing the longitudinal wave in a helical polymer chain of (－)-poly(MtOCAPA) repeatedly at the maximum velocity of 125 nm/s. We assume that the molecular motion is a kind of the bias Brownian motion based on a flexible asymmetric structure of a chiral helical polymer. The molecule is transported in the surfing by the unidirectional traveling wave of a coarse-dense helical structure in the polymer chain. This is the first epoch-making discovery of a linear motor that is made of a synthetic polymer. Polymer Preprints, Japan 2009, 58, 4640.

Reversing the Common Sense, Thermoplastic Epoxy Resin
Yutaka TSUJIMURA
Nagase ChemteX Corporation
We have developed a new polymerization process using epoxy resins and phenols. In general, the epoxy resin is a conventional thermosetting resin due to generating cross-linking during polymerization. In our new process, an epoxy resin and a phenol are polymerized linearly by a consecutive reaction. As a result, it was found that a (no cross-linking) thermoplastic polymer was formed, because the polymer showed the second moldability and solubility in organic solvents. These features generally derive from the specific structure of thermoplastics. In addition, the polymer has some excellent properties such as flexural strength (130 MPa), fracture toughness (K1c) (2.0 MPa･ｍ1/2) and Izod impact strength (1100 J/m). We assume that the strong fracture toughness and impact strength arises from the intermolecular forces along the linear long molecular structures. It is expected that the thermoplastic epoxy resin is suitable for reuse, recycling and high strength materials. Polymer Preprints, Japan 2009, 58, 5505.

16-nm-periodic Nanohole Array through Block Copolymer Templating
Ryoko WATANABE1, Kaori ITO2, and Tomokazu IYODA2
1RIKEN (The Institute of Physical and Chemical Research), 2Division of Integrated Molecular Engineering, Chem. Res. Lab., Tokyo Inst. of Tech.
Surface patterning techniques are required to provide the nanometer resolution to realize nanodevices and high density recording storage. Block copolymer (BC) is a powerful candidate for the patterning down to the nanometer scale because of its self-assembled microphase- separated structures, i.e., periodic nanopatterns with unique chemical contrasts called nanotemplates. Amphiphilic BC consisting of poly(ethylene oxide) and liquid crystalline poly(methacrylate), PEO-b-PMA(Az), offers perpendicularly oriented PEO cylinders in its thin films, which serve as molecule- or ion-transport channels for permeable membranes. This thin film acted as a mask for selective etching of substrate surfaces to give hexagonally arranged nanoholes with the same nanopattern as the PEO cylinders. We fabricated 16-nm-periodic nanohole arrays on a silicon wafer through wet processes under ambient conditions within several hours. Polymer Preprints, Japan 2009, 58, 4399.

Non Humidified Fuel Cell Operation Using Sulfonated Polyimide/Protic Ionic Liquid Composite Membranes
Tomohiro YASUDA1, Seung-Yul LEE, Shin-ichiro NAKAMURA, and Masayoshi WATANABE2
Department of Chemistry and Biotechnology, Yokohama National University
Composite membranes were fabricated from a protic ionic liquid (diethylmethylammonium trifluoromethane sulfonate [dema][TfO]) and sulfonated polyimides by a solution casting method as electrolyte membranes for non-humidified fuel cells. The resulting composite membranes are flexible and mechanically reliable, and show good thermal stability (Td > 260℃). A composite membrane containing 75 wt% [dema][TfO] exhibits high ionic conductivity with a value of higher than 10-3 S cm-1 at above 40℃. In fuel cell operation using a composite membrane under non-humidified conditions, current densities of 600 mA cm-2, 250 mA cm-1 and 100 mA cm-2 were achieved at 30℃, 120℃ and 140℃, respectively. Further, the cell was stable for 230 h in the OCV durability test at 120℃. Polymer Preprints, Japan 2009, 58, 5688.