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Showing papers on "Polymer nanocomposite published in 1997"


Journal ArticleDOI
TL;DR: In this paper, a multilayer ultrathin films composed of titanium dioxide nanosized particles and ionic polystyrene molecules have been fabricated on single-crystal silicon, quartz, and glass substrates by a novel molecular self-assembly process.
Abstract: Multilayer ultrathin films composed of titanium dioxide nanosized particles and ionic polystyrene molecules have been fabricated on single-crystal silicon, quartz, and glass substrates by a novel molecular self-assembly process. X-ray photoelectron spectroscopy (XPS) indicates that the formed cationic TiO2 particles adsorb only on negatively charged and not on positively charged surfaces. Contact angle measurements demonstrate that the water contact angle oscillates regularly in accordance with which molecules form the outermost layer of the films. A molecular-level ordered transparent film, up to 120 layers (60 bilayers) in thickness, has been obtained and characterized by UV−vis spectroscopy. It is also demonstrated that film transmission in the UV light range decreases progressively with an increasing number of the bilayers and negligible attenuation in the visible range.

189 citations


Journal ArticleDOI
TL;DR: In this paper, molecular dynamics simulations of the thermal degradation of polymer nanocomposites were performed in an attempt to explain the reduction in the flammability of these materials, as compared to the pure polymer, that has been observed in experimental measurements.

51 citations


Patent
24 Oct 1997
TL;DR: In this paper, a method for the production of polymer microparticles in the absence of organic solvent is described. But the method is carried out in the presence of an organic solvent, and consists in the steps of combining first and second polymers, heating the combination obtained in step (a) so as to melt the first polymers; shaking the melted polymers obtained in stage (b) under conditions effective to produce a biphasic system.
Abstract: The present invention relates to a new method for the production of polymer microparticles The method is carried out in the absence of organic solvent, and consists in the steps of (a) combining first and second polymers, the first and second polymers being incompatible or immiscible, (b) heating the combination obtained in step (a) so as to melt the first and second polymers; (c) shaking the melted polymers obtained in step (b) under conditions effective to produce a biphasic system, the biphasic system comprising a dispersed phase and a matrix continuous phase, the dispersed phase consisting of a dispersion of the first polymer, the matrix continuous phase comprising the second polymer, the dispersed phase containing microparticles of the first polymer dispersed in the matrix continuous phase; (d) solidifying the biphasic system obtained in step (c) so as to keep the microparticles of the first polymer dispersed in the matrix continuous phase; and (e) separating and isolating the microparticles of the first polymer from the matrix continuous phase, wherein the first polymer in said dispersed phase is water-insoluble, while the second polymer forming the continuous phase is water-soluble

13 citations


Patent
12 Aug 1997
TL;DR: A polymer dispersed liquid crystal material comprising a polymer matrix, a liquid crystal and a diffusing agent was used in this article for the first time in the 1990s. But it was not used in the first half of the 2000s.
Abstract: A polymer dispersed liquid crystal material comprising a polymer matrix, a liquid crystal and a diffusing agent.

12 citations


Patent
29 Jul 1997
TL;DR: A polymeric solid electrolyte comprising a polymer matrix, a polymerization initiator, an inorganic salt and a petertoddsolvent, and a lithium secondary cell adopting the same are provided in this article.
Abstract: A polymeric solid electrolyte comprising a polymer matrix, a polymerization initiator, an inorganic salt and a solvent, and a lithium secondary cell adopting the same are provided. The polymer matrix is composed of a copolymer of a vinyl monomer having an amide group at a side chain and a polymer with an oxyethylene repeating unit. The polymeric solid electrolyte has excellent conductivity and can easily be processed due to its good mechanical property.

5 citations


Journal ArticleDOI
TL;DR: In this article, the authors measured the cross-relaxation rate in the polymer dispersed 4-pentyl4-cyanobiphenyl (5CB) droplets by the selective magnetization inversion NMR technique.
Abstract: Measurements of the proton cross-relaxation rate in the polymer dispersed 4-pentyl4-cyanobiphenyl (5CB) droplets were performed by the selective magnetization inversion NMR technique. This method makes possible direct determination of the magnitude of the fast cross-relaxation rate in theMHz regime where the standard spin-lattice relaxation measurements only indicate its presence. In the isotropic phase, the cross-relaxation rate is found to be more than ten times larger in the droplets of pure 5CB than that reported earlier for the liquid crystal mixture E7 in the same polymer. The difference is discussed in terms of dynamic processes in the surface layer.

4 citations



Journal ArticleDOI
TL;DR: In this article, preliminary rheological characterizations of aluminum nitride (AIN) nanoparticle suspensions in nonaqueous Newtonian fluid media, NMP and NMP/poly(amic acid) solutions, reveal marked differences in viscoelastic behavior, at relatively low dispersed phase volume fractions.
Abstract: Preliminary rheological characterizations of aluminum nitride (AIN) nanoparticle suspensions in nonaqueous Newtonian fluid media, NMP and NMP/poly(amic acid) solutions, reveal marked differences in viscoelastic behavior, at relatively low dispersed phase volume fractions. Dynamic mechanical and steady shear measurements provide experimental evidence of the effective interparticle and polymer/particle interactions in a dispersion process of nonoxide nanoparticles for ceramic/polymer nanocomposites. The rheological nature of the nanoparticle suspensions corresponds to interparticle physicochemical interactions that have been previously concluded and discussed.

Journal ArticleDOI
TL;DR: In this article, the surface chemical species of a GaN nanosized powder by diffuse reflectance infrared Fourier transform spectrometry was characterized using the first atomic layer of the GaN nanoparticles.
Abstract: The use of GaN/polymer nanocomposites in optoelectronics requires a perfect control of the GaN dispersion in the polymer matrix. This cannot be achieved without a good knowledge of the first atomic layer of the GaN nanoparticles. This paper reports the characterization of the surface chemical species of a GaN nanosized powder by diffuse reflectance infrared Fourier transform spectrometry.

Patent
30 Dec 1997
TL;DR: In this paper, a polymer having dispersed therein at least one layered clay material which has been cation exchanged with an organic cation salts represented by Formula (I) wherein M represents either nitrogen or phosphorous; X represents an anion selected from the group consisting of halogen, hydroxide, or acetate anions, preferably chloride and bromide; R1 is selected from a group of straight and branched alkyl groups having at least 8 carbon atoms.
Abstract: The present invention relates to a composition comprising a polymer having dispersed therein at least one layered clay material which has been cation exchanged with an organic cation salts represented by Formula (I) wherein M represents either nitrogen or phosphorous; X represents an anion selected from the group consisting of halogen, hydroxide, or acetate anions, preferably chloride and bromide; R1 is selected from the group consisting of straight and branched alkyl groups having at least 8 carbon atoms; R2, R3, and R4 are independently selected from straight or branched alkyl groups having 1 to four carbon atoms; and at least one expanding agent which is compatible with said polymer. Preferred polymers include polyesters. The compositions of the present invention show vastly improved platelet separation as evidenced by higher than previously reported basal spacing.