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  • 1
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A new thermotropic side-chain liquid crystalline polymers based on poly (dipropargylamine) backbone were prepared by metathesis polymerization with transition metal catalysts. It was found that the MoCl5-EtAlCl2 catalyst system were very effective for the cyclopolymerization of presently investigated monomers. Resulting polymers were soluble in common organic solvents such as THF, chloroform, etc. The number-average molecular weight ( $$\left( {\overline {{\text{Mn}}} } \right)$$ ) values of the polymers were in the range of 6.49x103–11.6x103, relative to polystyrene standard by GPC. Thermal properties of the monomers and the polymers synthesized were examined by differential scanning calorimetry (DSC) and cross-polarized optical microscopy. Both monomer and polymer displayed enantiotropic liquid crystallinity showing the reversible phase transition.
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  • 2
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Different amphiphilic triblock copolymers of n-butyl methacrylate (BMA) and 2-methacryloyloxyethyltrimethyl ammonium iodide were prepared by the reaction of precursor polymer and iodomethane. The precursor polymers were obtained by Group-Transfer Polymerization (GTP) of BMA with 2-(dimethylamino)ethyl methacrylate (DMAEMA) using a difunctional initiator at room temperature. Their molecular weight and composition could be controlled by regulating the monomer to initiator ratio and the feed ratio of two monomers. From quantitative quaternization of poly(DMAEMA) segments of precusor polymers by iodomethane, the target polymers were prepared. These amphiphilic triblock copolymers exhibited excellent surface activity and lowered the surface tension of their aqueous solutions. The lowest surface tension (γ) value reached to 27.4 dyn/cm.
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  • 3
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Cyclopolymerization was carried out by various catalyst systems. MoCl5-based catalyst systems are more effective for the polymerization of 4,4-diphenoxy-1,6-heptadiyne than WCl6-based catalyst systems. Polymerization of 4,4-diphenoxy-1,6-heptadiyne leads to soluble, purple colored polymer with number average molecular weight (Mn) of 3.6x104-5.2x104.1H- and13C-MNR, IR,and UV-visible spectra of the resulting polymer indicated that poly(4,4-diphenoxy-1,6-hepatadiyne) possesses a polyene structure presumably with cyclic recurring units in the polymer backbone. Poly(4,4-diphenoxy-1,6-heptadiyne) had good thermal and oxidative stability, and good solubility in organic solvents. The electrical conductivity of iodine-doped polymer was 10−3-10−2 S/cm.
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  • 4
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Difference ABA triblock copolymers (1) of 2-trimethylsilyloxyethyl methacrylate (TMS-HEMA) and n-butyl methacrylate (BMA) were prepared by group transfer polymerization (GTP) with a difunctional initiator. The polydispersities of the block copolymers were in 1.16 to 1.43 range. From selective and quantitative hydrolysis of poly (TMS-HEMA) segments of 1, block copolymers (2) of 2-hydroxyethyl methacrylate (HEMA) and BMA could be prepared. 2 showed different solubilities depanding on their compositions. From transmission electron micrographs of films casted from dilute solution of the polymers, it was found that microphase separation of the hydrophilic and hydrophobic domains occurs in different geometries.
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  • 5
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A new polymer, poly {5-[[(6-N-carbazoylhexyl)oxy]methyl]-2-norbornene} [Poly (NCHN)], was synthesized by ring-opening metathesis polymerization (ROMP) with various transition metal catalyst systems. The structure of the poly (NCHN) was analyzed by NMR, IR, and UV-vis spectroscopy. The electrochemical properties of the poly (NCHN) were characterized by cyclic voltammetric technique. From the cyclic voltammetric results it was concluded that the carbazole units in side chain of the polymer were oxidized and coupled irreversibly to form dicarbazyls. The redox kinetics was mainly controlled by both electron transfer and ClO4 - diffusion processes preserving the electro-neutrality of the polymer.
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  • 6
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Poly(triethyldipropargylphosphonoacetate) (TDPA), poly[(tetraethyl dipropargylmethylenediphosphonate) (TDMDP) were prepared by metathesis polymerization using transition-metal catalysts. MoCl5-based catalyst systems were more effective for the polymerization of these monomers than WCl6-based catalyst systems. Resulting polymers exhibited good solubility in common organic solvents and could be easily cast on glass plates to give thin films. Third-harmonic Maker fringe technique was used to measure third-order nonlinear susceptibility,x (3), for thin film of poly(TDPA). Thex (3) was evaluated to be 3.4x10-11 esu at incident wavelength of 1.907μm.
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  • 7
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Novel side chain NLO organic/inorganic polymers were developed by sol-gel process of dye-contained triethoxysilane with tetraethoxysilane. A NLO moiety based on 4-[N, N-bis(2-hydroxyethyl)amino]-4′-nitrostilbene (diol-DANS) was covalently bounded to the triethoxysilane derivative. The sol-gel derived NLO polymers were analyzed by analytic techniques, including FT-IR, TGA, solid state 29Si-NMR, SEM, etc. The incorporation of the DANS dye into silicon oxide networks induces high dimensional stability of dipole alignment and the easy film fabrication. They exhibited a significant improvement in the thermal stability at high temperatures exceeding 270°C. The electro-optic coefficient at 1.3 μm is 4.3 pm/V for the copolymer containing 50 wt % of the dye-contained triethoxysilane system poled with corona discharge and is shown excellent long-term stability with 80% of initial value even after 3 hrs at 150°C.
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  • 8
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Novel liquid crystalline monomer, 4-methoxybiphenyloxy-(N,N′-dipropargyl)undecane amide, subjected to metathesis reaction with transition metal catalyst systems. It was found that the MoCl5-EtAlCl2 catalyst system was very effective for the cyclopolymerization of the monomer. Resulting polymers exhibited good solubility in common organic solvents such as THF, chloroform, etc. The number-average molecular weight (Mn) values of the polymers were in the range of 0.98x104–1.4x104, relative to polystyrene standard by GPC. Thermal properties of the monomer and the polymer synthesized were examined by differential scanning calorimetry (DSC) and cross-polarized optical microscopy. The polymer exhibited the enanfiotropic liquid crystallinity and smectic mesophase.
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  • 9
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary ABA type block copolymerization of N-phenylmaleimide (NPM), N-hexyl maleimide (NHM), methyl methacrylate (MMA), and butyl methacrylate (BMA) was investigated by group transfer polymerization (GTP) with [1,5-bis (trimethylsilyloxy)-1,5-dimethoxy-1,4-pentadiene] (1) as difunctional initiator. A novel block copolymers (2) of NPM and MMA (or BMA) could be prepared by sequential addition of NPM to the living PMMA (or PBMA) produced with 1. The reaction did not exhibit the characteristics of living polymerization when NPM was added. The resulting copolymers showed good thermal stability. On the other hand, gelation occurred in GTP of NHM.
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  • 10
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: SUMMARY: We utilized the first metathesis reaction to synthesize a new type of photorefractive polymers that contain both a carbazole moiety as a hole transporter and NLO chromophores. These polymers have a long tail band at above 700 nm, indicating the formation of intramolecular charge transfer complexes between the carbazole groups and the conjugated double bonds in the polymer backbone. Also, these polymers show two maximum values of photocurrent around 350 and 700 nm. The electro-optic coefficient (r 33) at the wavelength of 1.3 µm for polymer thin films poled around the 85°C were in the range of 1.6 ∼6.3 pm/V. The hyperpolarizabilities, 〈γ〉, of the resulting polymers were ca. 2.9 × 10−32 esu. at the incident wavelength of 1.907 µm.
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