Hot Topics

Vol. 60, No. 2, Februay (2011)

Disordered Phase Formation in Plasticized Poly(L-lactic acid)
Takahiko KAWAI
Department of Production Science and Technology, Graduate school of Engineering, Gunma University

Crystallization of poly(L-lactic acid)(PLLA) is a matter of concern for industry since the crystallization rate is extremely low compared to the other semicrystalline polymers. Aiming to control the crystallization of PLLA, the effect of plasticizer has been investigated. In addition to the great enhancement in crystallization rate, it was also found that the crystalline form of PLLA changes with plasticizer concentration as well as the crystallization temperatures (Tcs). At concentrations higher than 14% and at Tcs lower than 40oC, peculiar WAXD patterns with single broad diffraction at q=11.6 nm-1 were observed, indicating more disordered phase formation compared to the other crystalline forms (α and α' form)
Polymer Preprints, Japan 2010, 59, 698.

Precise Regulation of Sequential Structure Provides Novel Bio-Based Polymers with High Performance and Specific Function
Hideki ABE
Bioplastic Research Team, RIKEN Biomass Engineering Program
Many types of biopolymers display specific properties or functions by constituting the uniform molecular linking or defined molecular arrangements. Following such a ﾒregulation systemﾓ of biopolymers, we have made progress in the synthesis of novel copolymers with defined periodic sequence structure from bio-based chemicals. The high thermal-resistant bio-based copolymers have been successfully obtained from linear aliphatic diacids, diols, and diamines by regulating their sequential structure of the monomeric units. We also succeeded in producing new functional periodic copolymers consisting of 3-hydroxybutyrate and aspartate units. They allow to control the starting point of biodegradation for the copolymers by changing the pH as outer stimulus. Thus, the precise regulation of sequential structure provides high performance and specific functional bio-based polymer materials.
Polymer Preprints, Japan 2010, 59, 2169.

High Carrier Mobility in Organic Field Effect Transistor Using Polydiacetylene in the Active Layer
Hiroyuki SASABE
Chitose Institute of Science and Technology
High hole mobility of ca. 0.8 cm2/ Vs was obtained in the organic field effect transistor (OFET) prepared by a dry process (vacuum deposition) under the morphological control of polydiacetylene film in the active layer. The dewetting (wet process) is applicable to form fiber- or plate-like crystals easily on the comb-type-electrodes (a bottom type contact). This technique is a simpler and more economical way to form an active layer than the dry process. By controlling the concentration of 10, 12- pentacosadiynoic acid (PDA)/ chloroform solution, followed by a UV irradiation to polymerize PDA, the similar high value of 1.3x10-2 cm2/Vs was obtained at 35 mg/ml.
Adv. Mater. 2006, 18, 3120.
Polymer Preprints, Japan 2010, 59, 3902.

Potentials of Conjugated Polymer Backbones: Intrinsic Charge Carrier Mobility along Conjugated Molecular Backbones
Shu SEKI1,2
1Department of Applied Chemistry, Osaka University 2JST-PRESTO "Photons on Soft Materials"
Are electrodes indispensable to catch the motions of electrons? The electromagnetic waves certainly interact with the electrons in matter, and the interactions have been often used in many devices in our world. We would like to know how mobile the electrons in one conjugated polymer chain are, which were finely designed and synthesized, many methodologies to "touch (making contacts)" one single conjugated chain have been developed recently. The measurement of direct current (DC) of electrons in a single chain, however, requires ultra-high technologies of electrode patterning and contacting the molecules. Unlike the DC techniques, an alternating-current (AC) method of time-resolved microwave conductivity (TRMC) is probing the non-translational motion of charge carriers on conjugated molecules without contacts (electrode-less). This has been applied to elucidate the intrinsic value of mobility free from the above mentioned "disturbing" processes, because the translational motion of charge carriers on the molecular materials is limited within the nm-scaled spatial area. We have discussed comprehensively the mechanisms of charge carrier transports in the conjugated macromolecules in view of what the determining processes are in the macroscopic properties in the charge carrier transport processes.
Polymer Preprints, Japan 2010, 59, 2190.
Self-Repairing Behavior of a Weak Gel Containing a lot of Dangling Chains
Masayuki YAMAGUCHI
School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST)
A weak gel having a lot of dangling chains, whose one end is not connected to the network, shows various interesting properties because of the entanglement couplings associated with dangling chains. In particular, it should be noted that a gel near the critical point shows autonomic self-repairing behavior. Mobility of the dangling chains, which is confirmed by a high level of tan d above the glass transition temperature, is responsible for the repairing nature, whereas the permanent network prohibits the macroscopic flow or deformation. Further, a tear experiment reveals that approximately 80% of the tear strength is recovered for the sample having longer dangling chains. The material design is available to any polymer species and thus will be employed in various applications.
Polymer Preprints, Japan 2010, 59, 2181.

Syntheses of Novel Fluorinated Polymers -Facile Carbon-Carbon Bond Formation Reaction by the Aid of Fluorine Substituents-
Tadashi NARITA
Saitama Institute of Technology
Anionic addition polymerization of polyfluorinated vinyl monomers such as CH2=C(CF3)COORf, CF2=CF-C6H5 and CF2=CF-CF=CF2, which show poor radical homopolymerization reactivity, has successfully been developed. Anionic polyaddition has been achieved by the double Michael addition of CH2=C(CF3)COO-C6H4-OCOC(CF3)=CH2 to active methylene compounds such as NCCH2COOC2H5 and CH3COCH2COCH3 catalyzed by C2H5ONa. Radical addition of fluorinated vinyl monomers such as CF2=C(CF3)OCOC6H5 and CH2=C(CF3)COORf with many organic compounds possessing carbon-hydrogen bonds has been accomplished. Radical polyaddition of CF2=C(CF3)OCO-C6H4-COOC(CF3)=CF2 has been achieved with a wide variety of organic compounds which have never been supposed to be starting materials in polymer syntheses. The facile carbon-carbon bond formation is accomplished by the aid of fluorine substituents.
Polymer Preprints, Japan 2010, 59, 4707.
J. Fluorine Chem. 2010, 131, 812.
J. Polym. Sci. A 2004, 42, 4101.
Kobunshi 2004, 53, 583.
Macromol. Rapid Commun. 2000, 21, 613.
Prog. Polym. Sci. 1999, 24, 1095.