The branching orders of a quasi-ordinary projection

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Preparation of a reflective‐type electrochromic device based on monodisperse,micrometer‐size‐range polymeric microspheres and viologen pendants

A reflective electrochromic device (ECD) based on polymeric microspheres was proposed, and its feasibility for a display was investigated. The viologen moiety was introduced onto the surface of chloro‐functionalized polymeric microspheres via refluxing in toluene. The existence of the viologen pendants was confirmed with X‐ray photoelectron spectroscopy, and their redox reactions were examined with cyclic voltammetry. The ECD had an inherent white background without an applied potential because the micrometer size range of the substrate particles scattered the light, whereas a deep violet color appeared when 3.0 V was applied to the cell. This color change could have been caused by the reduction of viologen pendants on the surface of the polymeric microspheres. The reflectance values of the ECD were observed with a spectrophotometer, and the response times and cyclic stability of the ECD, depending on the potential, were also examined. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6562–6572, 2005     

Synthesis of poly(2‐vinyl pyridine)‐b‐poly(n‐hexyl isocyanate) amphiphilic coil‐rod block copolymer by anionic polymerization

A well‐defined amphiphilic coil‐rod block copolymer, poly(2‐vinyl pyridine)‐b‐poly(n‐hexyl isocyanate) (P2VP‐b‐PHIC), was synthesized with quantitative yields by anionic polymerization. A low reactive one‐directional initiator, potassium diphenyl methane (DPM‐K), was very effective in polymerizing 2‐vinyl pyridine (2VP) without side reactions, leading to perfect control over molecular weight and molecular weight distribution over a broad range of initiator and monomer concentration. Copolymerization of 2VP with n‐hexyl isocyanate (HIC) was carried out in the presence of sodium tetraphenyl borate (NaBPh₄) to prevent backbiting reactions during isocyanate polymerization. Terminating the living end with a suitable end‐capping agent resulted in a P2VP‐b‐PHIC coil‐rod block copolymer with controlled molecular weight and narrow molecular weight distribution. Cast film from a chloroform solution of P2VP‐b‐PHIC displayed microphase separation, characteristic of coil‐rod block copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 607–615, 2005     

Mössbauer analysis on the magnetic properties of Fe–Co nanoparticles synthesized by chemical vapor condensation process

The magnetic properties of Fe–Co nanoparticles synthesized by chemical vapor condensation (CVC) process were investigated. Effect of CVC processing variables on the magnetic properties was analyzed in detail, using Mössbauer spectroscopy, XRD, BET and HRTEM. The synthesized particles were nearly spherical, and their surfaces were identified to be -FeOOH, γ-FeOOH and Fe₃O₄, but not -Fe₂O₃. The magnetic properties were strongly influenced by CVC processing parameters. The increase of cobalt content had changed the magnetic property of the sample. However, when the decomposition temperature and the oxygen content in the carrier gas (Ar) were increased, the magnetic property reduced with decreasing the average particle size. Increasing the vacuum pressure in the chamber resulted in that the magnetic field reinforced with the increase of average particle size.     

Living polymerization of styrene initiated by mercaptan/ε‐caprolactam

The bulk polymerization of styrene initiated by ?‐caprolactam (CL) and n‐dodecyl mercaptan (RSH) has been explored. This novel polymerization system shows living characteristics. For example, the molecular weight of the resulting polymers increases with conversion, and the system has the ability to form diblock copolymers and so forth. The polymer chain end contains thiol and lactam structures, which we have investigated with Fourier transform infrared, ¹H NMR, and ¹³C NMR techniques. Electron spin resonance spectra and theoretical calculations by the Hartree–Fock methods have been used to examine the mechanism. The results reveal that the initial polymerization starts from thiol via a chain‐transfer reaction, and the propagation proceeds by the insertion of a monomer between the terminal group and the intermediate structure of lactam. Finally, the polymerization kinetics have been examined. The polymerization rate varies linearly with the concentration of CL and RSH, and this confirms the mechanism. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4976–4993, 2004     

Generation of highly stable amidate anion in anionic polymerization of 3‐(triethylsilyl)propyl isocyanate

To study living anionic polymerization, 3‐(triethylsilyl)propyl isocyanate (TEtSPI) monomer was synthesized by hydrosilylation of allylamine with triethylsilane and treatment of the resulting amine with triphosgene. The polymerization of TEtSPI was performed with sodium naphthalenide (Na‐Naph) as an initiator and in the absence and presence of sodium tetraphenylborate (NaBPh₄) as an additive in tetrahydrofuran (THF) at ?78 and at ?98 °C. A highly stabilized amidate anion for living polymerization of isocyanates was generated for the first time with the combined effect of the bulky substituent and the shielding action of the additive NaBPh₄, extending the living character at least up to 120 min at ?98 °C. Even the anion could exist at ?78 °C for 10 min. A block copolymer, poly(n‐hexyl isocyanate)‐b‐poly[(3‐triethylsilyl)propyl isocyanate]‐b‐poly(n‐hexyl isocyanate), was synthesized with quantitative yields and controlled molecular weights via living anionic polymerization in THF at ?78 °C for TEtSPI and ?98 °C for n‐hexyl isocyanate, respectively, with Na‐Naph with three times of NaBPh₄ as a common ion salt. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 933–940, 2004     

The representation of quadratic forms by almost universal forms of higher rank

 In this article, we prove that there are only finitely many positive definite integral quadratic forms of rank n+3(n≥2) that represent all positive definite integral quadratic forms of rank n but finitely many exceptions. Furthermore we determine all diagonal quadratic forms having such property and its exceptions remaining four as candidates. Received: 29 November 2000 ; in final form: 8 August 2002 / Published online: 1 April 2003 Mathematics Subject Classification (2000): 11E12, 11E20.     

Optical and structural properties of Sr-Nb-phosphate glasses

This research studied optical and structural properties of SrO-Nb₂O₅-P₂O₅ glasses containing 0 ~ 25 mol% Nb₂O₅ and 35 ~ 60 mol% SrO using spectra of UV-Vis, FTIR and XPS. Our aim was to work new moldable glasses which are colorless with high refractive index and transmittance, and their correlation with glass structure. Nb₂O₅ plays the role as an intermediate of glass formation, and transforms the role to network-former or glass-modifier depending on composition. Refractive index increases monotonically with Nb₂O₅ content at the expense of transmittance, and specific coloring which occurs in ternary compositions with the ratio P₂O₅/SrO > 1. This effect arises from much increased [Nb³⁺ and Nb⁴⁺] fraction, as quantitatively deconvoluted in Nb3d XPS spectra, in the ligand [NbO₆]_octahedral which is supported by FTIR and O1s XPS spectra. As the ratio P₂O₅/SrO ≤ 1, Nb₂O₅ is more of a network former and [NbO₆]_octahedral structure turns into [NbO₄]_tetrahedron with partial Nb-O…(Sr) bonding turns into (Nb-O-Nb)_tetrahedron, coloring disappears.     

Synthesis and characterization of Al-modified SBA-15 for Fischer–Tropsch synthesis (FTS) reaction

Research on Chemical Intermediates - In this work, we synthesized a Co-based catalyst supported on modified SBA-15 to obtain the uniform particle size of active metal and selective products with...