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Volume 64, Issue 8
Displaying 1-6 of 6 articles from this issue
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Comprehensive Papers
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Yuji SHIBASAKI2007 Volume 64 Issue 8 Pages 475-485
Published: 2007
Released on J-STAGE: October 01, 2007
JOURNAL FREE ACCESSA mesoporous silica, SBA-15, was modified with a diamine having a silan-couling group, followed by the coordination of CuCl for the oxidative coupling polymerization of phenol derivatives. The prepared catalyst was characterized by XRD, N2 absorption-desorption analysis, elemental analysis, and ICP analysis; the copper ion was found to be dispersed homogeneously inside the channel. The mesoporous-supported copper-amine catalyst (SBA-15-Cu) was then applied to the polymerization of 2,6-dimethylphenol in order to investigate the ability of the catalyst. The corresponding poly(2,6-dimethyl-1,4-phenylene ether) was obtained in good yield with the number average molecular weight of 19000, which was lower than the conventional homogeneous catalyst. The durability of the SBA-15-Cu catalyst was proved for at least five repetitions the polymerization. The catalyst was then applied to the 2,5-dimethylphenol and o-cresol polymerization, where the coupling selectivity was further improved compared to the conventional homogeneous catalyst, indicating the usefulness of the mesoporous supported catalyst. The properties of the resulting polymers were also discussed.
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Yoshihiko MURAKAMI2007 Volume 64 Issue 8 Pages 486-497
Published: 2007
Released on J-STAGE: October 01, 2007
JOURNAL FREE ACCESSNovel functional hydrogels can be synthesized by the use of functional crosslink structures. Hydrogels were synthesited that contain crosslink structures that can recognize molecules, adhere to tissue surface and release drugs in a sustained manner. The hydrogels containing ‘rationally designed ssDNA’ as the crosslinker were capable of shrinking or swelling in response to ssDNA, and could recognize a single base difference in the samples. The hydrogels containing a ‘reactive polymeric self-assembled structure’ as the crosslinker was capable of strongly adhering to tissue surfaces and releasing drugs in a regulated and sustained manner. This comprehensive paper describes the methodology to design these novel functional hydrogels and their applications as biomaterials.
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Ken KOJIO2007 Volume 64 Issue 8 Pages 498-503
Published: 2007
Released on J-STAGE: October 01, 2007
JOURNAL FREE ACCESSI investigated the specific chain structure of polyurethane (PU) films, which possess strong polar groups in the main chains and multiblock structure under confinement. The PU was synthesized from poly(oxytetramethylene) glycol (PTMG), 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD) by a prepolymer method. The hard segment contents were 20, 34 and 45 wt%. The ultrathin PU films were prepared onto a silicon wafer from a PU tetrahydrofuran solution by spin coating. The PU films exhibited microphase-separated structures, which are composed of hard segment domains surrounded by a soft segment matrix. For thicker films (~200 nm), interdomain spacing almost corresponded to bulk value. On the other hand, it dramatically decreased for film thickness below 7 nm. This effect seems to be directly related to the decreasing film thickness. This is the first report, in which the phase-separated domain size of multiblock copolymers decrease with decreasing film thickness.
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Akinori TAKASU2007 Volume 64 Issue 8 Pages 504-515
Published: 2007
Released on J-STAGE: October 01, 2007
JOURNAL FREE ACCESSLow-temperature polycondensation of methylsuccinic acid (MSA) (at 35°C), bromosuccinic acid (BSA), 2-bromoadipic acid (BAA) (at 40°C), and citraconic acid (CA) (at 60°C) with diols containing 1,3-propanediol (1,3-PD) and 1,4-butanediol (1,4-BD) were performed under reduced pressure (0.3—30 mmHg) using scandium trifluoromethanesulfonate [Sc(OTf)3], scandium trifluoromethanesulfonimide [Sc(NTf2)3], and polymer-supported scandium trifluoromethanesulfonate (PS-Sc) to give poly(alkylene succinate)s with Mn=0.67×104-1.41×104 without transesterification (Mw/Mn=1.4—2.1). The catalysts are recovered quantitatively and reused. Room-temperature polycondensation made it possible to use thermally unstable monomers containing carbon-carbon double bond and bromo functionalities, and α,ω-dihydroxyl polyesters as monomers. Also room-temperature polycondensation enabled us to combine polycondensation with atom-transfer radical polymerization (ATRP) via both “grafting from” and “grafting through” techniques, to hybridize with vinyl polymers. Furthermore, chemoselective dehydration polycondensation of dicarboxylic acids and diols having pendent hydroxyl group was attained.
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Hiroshi MORITA2007 Volume 64 Issue 8 Pages 516-524
Published: 2007
Released on J-STAGE: October 01, 2007
JOURNAL FREE ACCESSAdhesion between two polymer films consisting of end grafted polymers has been studied by coarse-grained molecular dynamics simulations. The grafting density of the polymer film and the topology of the grafting polymer (one-end grafted polymer; the straight polymer) and the two-end grafted polymer (the loop polymer) is varied. Using these grafting films, I studied the debonding behavior by varying the temperature. I could find three types of separation patterns; fibril, cavity and brittle separation. The series of simulations shows that the glass transition temperature of the film is one of the important parameters to distinguish between the fibril or the brittle and the cavity separation.
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Hiroki UEHARA2007 Volume 64 Issue 8 Pages 525-538
Published: 2007
Released on J-STAGE: October 01, 2007
JOURNAL FREE ACCESSPolymeric materials give different morphologies, depending on the processing conditions, even with the same molecular architectures. If such morphological formation becomes fully controllable, the ultimate properties of molecular chains can be achieved in the bulk state. Therefore, the varieties in structure and properties are expectable even for conventional polymers having the simple chemical structure. Molecular anisotropy and entanglement, which a priori originate from their chain architectures, are key factors for structural and property development mechanisms on processing. Recent methodological improvement reveals the changes in such molecular characteristics during processing. In this research, the melt-drawing technique is applied to induce the molecular anisotropy by disentanglement formation. Also, in-situ structural analyses during such melt-drawing processes and their industrial applications are discussed.
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