Kobunshi - Vol. 59, No. 2 (Feburary, 2010)

Hot Topics

Vol. 59, No. 2, February (2010)

Lipophilic Polyelectrolytes
Kazuki SADA
Department of Applied Chemistry, Kyushu University

Polyelectrolytes are defined as polymers with ionizable groups that can dissociate into leaving charges on polymer chains and releasing counter ions into solution. Their impressive solution behaviors, for example the extended conformations, have been widely known in water, but not in nonpolar media, because polymer scientists believe that no ion pairs can dissociate into ions in them. We developed the first example of ﾒlipophilicﾓ polyelectrolytes active in the nonpolar organic solvents, such as chloroform, THF and dichloromethane. The key for the lipophilic polyelectrolytes is the use of tetraalkylammonium tetraphenylborate as the ionizable groups in the poly(octadecyl-acrylate) backbone. These cross-linked polyelectrolytes swell to a large extent, and swelling degrees rise up to several hundreds time as large as their dried weights. They act as super-absorbent polymers for organic solvents. Polymer Preprints, Japan 2009, 58, 4510.

Precise Chemical Recycling of Commodity Plastics
Takashi SAWAGUCHI
Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University
Recent chemistry and technologies for the precise chemical recycling of commodity plastics such as polyethylene, polypropylene and polystyrene into monomers and novel oligomers are reviewed. The novel oligomers such as monochelics having one end-functional group and telechelics having both end-functional groups could be selectively produced by controlling the conditions of thermal degradation, catalytic degradation and oxidative degradation. Moreover, preparation methods of chemically recyclable polyolefin are introduced.Polymer Preprints, Japan 2009, 58, 5374.

Constructing a Real-World Cellular Model
Kenichi YOSHIKAWA
Department of Physics, Kyoto University
A powerful method was developed to construct cell-sized phospholipid vesicles entrapping desired amounts of bio-macromolecules together with substrates. It can be shown that even at the same solution composition containing polyamine with physiological concentration, DNA molecules exhibit markedly different conformations between the bulk solution and the cell-sized space; a compact folded structure in the former whereas an unfolded compact state attaching to the membrane surface in the latter. It was also found that actin tends to form a mesh-structure on the membrane surface at magnesium ion concentrations, where actin shows gradual transition from dispersed fibrous state into thick bundle. Further extension of the physico-chemical studies to unveil the characteristic effects on the structure and function of biomacromolecues in cell-sized environments is on the way. Polymer Preprints, Japan 2009, 58, 5187.

Correlation between the Function of Polymer Materials and the Structure of Vicinal Water
Hiromi KITANO
Department of Applied Chemistry, University of Toyama
The O-H stretching band in infrared spectra for water molecules incorporated in the films of zwitterionic copolymers and that of poly(2-methoxyethylacrylate) (PMEA) were not largely different from that for bulk water (Figure 1). Furthermore both the adsorption of plasma proteins and the adhesion of platelets to these polymer films were very small. Based on these experimental data, it is strongly suggested that these polymers do not significantly disturb the hydrogen bonding between water molecules in the vicinity of these polymers, resulting in their excellent bio- and blood- compatibilities. Polymer Preprints, Japan 2009, 58, 5021.

Biomass Carbon Ratio of Bioplastics Measured by Accelerator Mass Spectrometry
Masao KUNIOKA
National Institute of Advanced Industrial Science and Technology
The biomass carbon ratio of raw materials such as starches, sugar, chitin, or bioplastics related wood powders and bioplastics itself were measured using Accelerator Mass Spectrometry (AMS) based on ASTM D6866. AMS measures the isotope carbon ratio of 14C to 12C and 13C in graphite derived from sample powders. The biomass carbon ratios of starches, sugar or chitin were almost 100% which means that they are fully biobased. The biomass carbon ratios of the wood powders were over 140% due to the effect of the post 1950s 14C injection due to nuclear testing. Bioplastics such as poly(e-caprolactone) (PCL) and poly(butylenes succinate) (PBS) poly(lactic acid) (PLA) composite samples were prepared for AMS measurements. Standard deviation for the International Standard (ISO) was measured by AMS for the blends of PLA and PBS. Polymer Preprints, Japan 2009, 58, 5414.

Synthesis and Functionalities of Silicon-Bridged p-Conjugated Polymers
Joji OHSHITA
Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University
Organic field-effect-transistors (FETs) are of considerable interest, and several compounds and polymers composed of expanded p-conjugated systems have been investigated as FET-active materials. However, much less is known for the FET-activity of s-p conjugated systems. Recently, we found that star-shaped oligothiophene derivatives with an organosilicon core could be used as high-performance p-type semiconductors in FETs in the form of their vapor-deposited films. We also demonstrated that dithienosilole with a silole ring fused to a bithiophene unit showed extended conjugation, because of the planar structure and the bonding interaction between the silicon s* and bithiophene p* orbital lowering the LUMO energy level. Poly(dithienosilolediyl) was prepared and its application to organic light emitting diodes was explored. Polymer Preprints, Japan 2009, 58, 2828.

Precise Syntheses and Functions of Helical Macromolecules Using Transition Metal Complexes
Kiyotaka ONITSUKA
Department of Macromolecular Science, Graduate School of Science, Osaka University
Helical polyisocyanides possessing functional molecules in the side chain were precisely synthesized by the living polymerization method using Pd-Pt m-ethynediyl complex as an initiator. Porphyrin pendants were arrayed around the stiff helical backbone of polyisocyanides, and their strong Cotton effect with exciton coupling was successfully applied for determination of the helical sense of polyisocyanides. Helical conformation of the main chain was reversibly controlled with electrochemical stimuli in polyisocyanides having ferrocenyl pendants. Helical macromolecular ligands were prepared by random copolymerization between achiral isocyanide with a bipyridylmethyl group and chiral monomers, and used for Cu-catalyzed asymmetric Diels-Alder reaction and Zn-catalyzed asymmetric 1,3-dipolar addition. Polymer Preprints, Japan 2009, 58, 2620.

Two-Dimensional Patterning by Using Block Copolymer Lithography
Toru YAMAGUCHI and Hiroshi YAMAGUCHI
NTT Basic Research Laboratories, NTT Corporation
Flexibly designable two-dimensional patterning is demonstrated by taking full advantage of the bottom-up self-assembly of block copolymers and the top-down fabrication of the alignment guide by using high-precision electron-beam lithography. The combination of the neutralization of the substrate surface and the use of hydrogen silsesquioxane resist patterns with a hydrophilic surface as an alignment guide enables the graphoepitaxy of the vertical lamellar domains of the symmetric diblock copolymer PS-b-PMMA in an intentionally designed confinement between the alignment guides. Both bent lamellae and concentric cylinders are formed and successfully transferred onto a semiconductor substrate with a 16-nm half-pitch resolution. Our method enhances the applicability of block copolymer lithography to nanodevice fabrication, as the size scale of nanodevices is beyond the reach of the top-down technology. Polymer Preprints, Japan 2009, 58, 4401.

Angle-Independent Structural Color in Colloidal Amorphous Arrays
Yukikazu TAKEOKA
Department of Molecular Design & Engineering, Nagoya University
We have demonstrated for the first time that an amorphous state of condensed gel particle suspension displays structural color without angle-dependence. This finding is in contrast to the common understanding that a periodic dielectric structure is fundamental to Photonic Band Gap (PBG) production, and it validates the theory that a ﾒtight bonding modelﾓ that is applicable to semiconductor systems can be also applied to photonic systems. More practically, this structural colored suspension represents a promising new material for the manufacture of reflective full-color displays with a wide viewing angle and non-fading color materials. This liquid system shows promise as a display material because electronic equipment used for display systems can easily be filled with the liquid in the same way that liquid crystals are currently used. Polymer Preprints, Japan 2009, 58, 4331. ACS Applied Materials & Interfaces 2009, 1, 982.