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Chiral Polymers (chiral + polymer)
Selected AbstractsCatalytic Asymmetric Cycloaddition of Carbon Dioxide and Propylene Oxide Using Novel Chiral Polymers of BINOL-Salen- Cobalt(III) SaltsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Peng Yan Abstract Four new chiral polymers of BINOL-Salen-cobalt(III) salt complexes have been designed, synthesized and applied to the direct fabrication of chiral propylene carbonate from racemic propylene oxide. The (R/S)-polymer catalyst 2 and (S/R)-polymer catalyst 4 exhibit better enantioselectivity than the (R/R)-polymer catalyst 1 and the (S/S)-polymer catalyst 3 and have been recovered and reused more than ten times without loss of activity and enantioselectivity. [source] Chiral polymers for resolution of enantiomersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2009Yoshio Okamoto Abstract In 1979, the formation of one-handed helical poly(triphenylmethyl methacrylate) (PTrMA) was found through the helix-sense-selective polymerization of methacrylate using chiral anionic initiators, and the existence of a stable helical polymer without chiral side chains was proved. The chiral polymer exhibited unexpected high chiral recognition of various racemic compounds when used as the chiral packing material (CPM) for HPLC, which was commercialized in 1982 as the first chiral column based on an optically active polymer. This success encouraged us to develop further useful commercial chiral packing materials (CPMs) based on polysaccharides, cellulose, and amylose. By using these polysaccharide-based CPMs, particularly phenylcarbamate derivatives, nearly 90% of chiral compounds can be resolved not only analytically but also preparatively, and several chiral drugs have been produced using the CPMs. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1731,1739, 2009 [source] New design of actuator using shear piezoelectricity of a chiral polymer, and prototype devicePOLYMER INTERNATIONAL, Issue 3 2010Michiya Sawano Abstract Chiral polymers have been known to exhibit small shear piezoelectricity for about fifty years. However, recently, we reported that poly(L -lactic acid) treated with supercritical carbon dioxide (sc-PLLA), which is a type of chiral polymer, exhibits much higher shear piezoelectricity than other chiral polymers. On the other hand, we found an important difference between motion due to shear piezoelectricity and that due to tensile piezoelectricity in piezoelectric materials through computer simulations. On the basis of these results, we fabricated a new type of electrically controlled tweezers constructed from a pair of sc-PLLA sheets with shear piezoelectricity. In general, when conventional tweezers open to the left and right, the trajectory of their motion becomes fanlike at the center of the connection (one end of the tweezers). In the new tweezers, the two small sheets making up the tweezers open parallel to each other, without the motion of parts near the connection. Moreover, a prototype ,finger' system using sc-PLLA sheets to realize complex motion in which the finger curled upon stretching of the sc-PLLA sheets was manufactured as a trial device. Using the prototype finger system, we demonstrated the firm grasping of a sample, but the sample could not be removed from a vessel. Thus, sc-PLLA increases the likelihood of realizing a device with highly operational pick-up in a very small region by using the shear piezoelectricity of a chiral polymer. Copyright © 2010 Society of Chemical Industry [source] Recent progress in the use of soluble ionic polymers as pseudostationary phases for electrokinetic chromatographyELECTROPHORESIS, Issue 23-24 2004Christopher P. Palmer Abstract This review concerns the development, characterization, and application of soluble ionic polymeric materials as pseudostationary phases for electrokinetic chromatography since 2002. Cationic polymers, anionic siloxanes, polymerized surfactants (micelle polymers), and chiral polymers are considered. The use of stable suspensions of polymer nanoparticles in electrokinetic chromatography is also reviewed. [source] Catalytic Asymmetric Cycloaddition of Carbon Dioxide and Propylene Oxide Using Novel Chiral Polymers of BINOL-Salen- Cobalt(III) SaltsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Peng Yan Abstract Four new chiral polymers of BINOL-Salen-cobalt(III) salt complexes have been designed, synthesized and applied to the direct fabrication of chiral propylene carbonate from racemic propylene oxide. The (R/S)-polymer catalyst 2 and (S/R)-polymer catalyst 4 exhibit better enantioselectivity than the (R/R)-polymer catalyst 1 and the (S/S)-polymer catalyst 3 and have been recovered and reused more than ten times without loss of activity and enantioselectivity. [source] Enantioseparation of doubly functionalized polar norbornenes by HPLC and their ruthenium-catalyzed ring-opening metathesis polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2010Yasushi Nishihara Abstract Doubly fuctionalized polar norbornenes bearing the cyano and ester groups in 2,3-positions are synthesized and enantiomers are separated by high performance liquid chromatography (HPLC) with a chiral stationary phase. These optically active monomers are polymerized by ruthenium carbene catalysts, and high yields of the polymers were obtained. The chiral monomer bearing ethyl ester gave an optically active polymer of lower, but opposite sign of optical rotation (monomer [,]D = +61.0°, polymer [,]D = ,3.1°). The circular dichroism (CD) of the obtained chiral polymers gave a Cotton effect. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 485,491, 2010 [source] Synthesis and characterization of novel liquid-crystalline copolymers containing thermally stable photochromic groupsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2007Jui-Hsiang Liu Abstract To overcome the defects of the thermal instability of azobenzene, a series of novel photochromic, chiral, liquid-crystalline monomers and polymers were synthesized from (+)-camphor. The copolymerization of the photochromic monomers with comonomers was carried out. The synthesized monomers and polymers were identified with nuclear magnetic resonance, Fourier transform infrared, and elemental analysis. The composition of the copolymers was estimated with elemental analysis. The specific rotation of the chiral compounds and polymers was evaluated. The thermal stability and phases of the polymers during heating and cooling cycles were studied with differential scanning calorimetry and thermogravimetric analysis. The phases of the polymers were identified with polarized optical microscopy textures and X-ray diffraction analysis. The distance between the layers of smectic liquid crystals was estimated from the diffraction angles. Photoisomerization of the configurational E/Z structures was investigated with an ultraviolet,visible spectrophotometer with 300-nm ultraviolet irradiation. The thermal stability of the Z-structural segment in the polymers was confirmed through the heating of the polymer at 70 °C for over 10 h. The photoisomerization and thermal stability of the CC bond in the polymeric materials were demonstrated through a series of novel chiral polymers synthesized in this investigation. Both the polarity of the center part and the molecular length at the ends of the molecules were found to be necessary factors for the formation of liquid-crystalline molecules. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2026,2037, 2007 [source] Synthesis of Polyanilines Bearing Optically Active SubstituentsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 12 2006Hiromasa Goto Abstract Summary: Optically active polyanilines were prepared by an interfacial polymerization with (NH4)2S2O8 in a water/perchloric acid/chloroform system. The pristine polymer obtained in this way is in the oxidized (doped) form. The polymers display the mirror-image Cotton effect. The doping process in solution allows a change in the circular dichroism of the polymer. The procedure has great potential in the improved preparation of durable optoelectrical devices based on the good film-forming properties of chiral polymers. CD spectra of R - P2 (solid line) and S - P2 (dashed line) in 4.0,×,10,4M THF solution. [source] New design of actuator using shear piezoelectricity of a chiral polymer, and prototype devicePOLYMER INTERNATIONAL, Issue 3 2010Michiya Sawano Abstract Chiral polymers have been known to exhibit small shear piezoelectricity for about fifty years. However, recently, we reported that poly(L -lactic acid) treated with supercritical carbon dioxide (sc-PLLA), which is a type of chiral polymer, exhibits much higher shear piezoelectricity than other chiral polymers. On the other hand, we found an important difference between motion due to shear piezoelectricity and that due to tensile piezoelectricity in piezoelectric materials through computer simulations. On the basis of these results, we fabricated a new type of electrically controlled tweezers constructed from a pair of sc-PLLA sheets with shear piezoelectricity. In general, when conventional tweezers open to the left and right, the trajectory of their motion becomes fanlike at the center of the connection (one end of the tweezers). In the new tweezers, the two small sheets making up the tweezers open parallel to each other, without the motion of parts near the connection. Moreover, a prototype ,finger' system using sc-PLLA sheets to realize complex motion in which the finger curled upon stretching of the sc-PLLA sheets was manufactured as a trial device. Using the prototype finger system, we demonstrated the firm grasping of a sample, but the sample could not be removed from a vessel. Thus, sc-PLLA increases the likelihood of realizing a device with highly operational pick-up in a very small region by using the shear piezoelectricity of a chiral polymer. Copyright © 2010 Society of Chemical Industry [source] | ||||||||||