Water‐dispersible microgel modified with methacryloyl groups by ionic bonding on the surface and the photopolymer microgel

A novel water‐dispersible reactive microgel, which had a diameter of 40–90 nm, was synthesized for photopolymer materials. The microgels have segments with substituted ammonium groups, to provide water solubility, in their polymer networked structure. It has unsaturated groups connected to the quaternary nitrogens by ionic bonding (I‐type microgel). The I‐type microgel was compared with one that has methacryloyl groups connected with the quaternary nitrogens of the microgel by covalent bonding (C‐type microgel). The I‐type microgels were able to separately control the modified amount of quaternary nitrogen and methacryloyl group. In the presence of 2,4‐diethylthioxantone as a photoinitiator and pentaerthritol triacrylate as a crosslinker, the photopolymer containing the C‐type or I‐type microgels had sensitivity high enough for practical use. Not only the amount of the methacryloyl group of the microgel but the amount of the quaternary nitrogen affected the sensitivity and the rate of polymerization of the water‐dispersible photopolymer containing the I‐type microgels. Copyright © 2000 John Wiley & Sons, Ltd.     

Rectilinear distance to a facility in the presence of a square barrier

This paper derives analytical expressions for the rectilinear distance to a facility in the presence of a square barrier. The distribution of the barrier distance is derived for two regular patterns of facilities: square and diamond lattices. This distribution, which provides all the information about the barrier distance, will be useful for facility location problems with barriers and reliability analysis of facility location. The distribution of the barrier distance demonstrates how the location and the size of the barrier affect the barrier distance. A?numerical example shows that the total barrier distance increases as the barrier gets closer to a facility, whereas the maximum barrier distance increases as the barrier becomes greater in size.     

The Reaction K¯ d → π Σn in the Λ(1405) Resonance Region

Calculations of K¯ d → π Σn in the Λ(1405) resonance region are presented taking into account single scattering and two-step processes. The influence of some common approximations in the kinematics on the predicted lineshape for the resonance are discussed.     

Viscoelastic properties of poly(methyl methacrylate) with high glass transition temperature by lithium salt addition

The effect of ion‐dipole interaction between lithium cations and oxygen atoms in poly(methyl methacrylate) (PMMA), which leads to the great enhancement of glass transition temperature (T_g), on the linear viscoelastic properties is studied using binary blends of PMMA and lithium trifluoromethanesulfonate (LiCF₃SO₃). The strong interaction at low temperature leads to the high modulus in the glassy region even near T_g. The interaction becomes weak as increasing the temperature. Consequently, the rheological terminal region is clearly detected without a marked enhancement of steady‐state compliance, although the zero‐shear viscosity increases by the LiCF₃SO₃ addition. The result indicates that the crosslinking due to the ion‐dipole interaction has a lifetime that decides the longest relaxation time. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2388–2394     

Continuous location model of a rectangular barrier facility

This paper develops a bi-objective model for determining the location, size, and shape of a finite-size facility. The objectives are to minimize both the closest and barrier distances. The closest distance represents the accessibility of customers, whereas the barrier distance represents the interference to travelers. The distributions of the closest and barrier distances are derived for a rectangular facility in a rectangular city where the distance is measured as the rectilinear distance. The analytical expressions for the distributions demonstrate how the location, size, and shape of the facility affect the closest and barrier distances. A numerical example shows that there exists a trade-off between the closest and barrier distances.     

A Five‐layer π‐Aromatic Structure Formed through Self‐assembly of a Porphyrin Trimer and Two Aromatic Guests

In this study we synthesized two‐ and four‐armed porphyrins – bearing two carboxyl and four 2‐aminoquinolino functionalities, respectively, at their meso positions – as a complementary hydrogen bonding pair for the self‐assembly of a D₂‐symmetric porphyrin trimer host. Two units of the two‐armed porphyrin and one unit of the four‐armed porphyrin self‐assembled quantitatively into the D₂‐symmetric porphyrin trimer, stabilized through ammidinium‐carboxylate salt bridge formation, in CH₂Cl₂ and CHCl₃. The porphyrin trimer host gradually bound two units of 1,3,5‐trinitrobenzene between the pair of porphyrin units, forming a five‐layer aromatic structure. At temperatures below ?40 °C, the rates of association and dissociation of the complexes were slow on the NMR spectroscopic time scale, allowing the 1 : 1 and 1 : 2 complexes of the trimer host and trinitrobenzene guest(s) to be detected independently when using less than 2 eq of trinitrobenzene. Vis titration experiments revealed the values of K₁ (2.1±0.4×10⁵ M^?1) and K₂ (2.2±0.06×10⁴ M^?1) in CHCl₃ at room temperature.     

Preparation and Thermal Decomposition of Cyclic Azoamidinium Salts as Water-Soluble Radical Initiators for Polymerization over A Wide Temperature Range

Abstract

A series of cyclic azoamidinium chlorides as water-soluble initiators were prepared by reactions of the iminoether derived from 2,2′-azobisisobutyronitrile with substituted alkylene diamines. The first-order rate constants for the decomposition of the azoamidinium salts varied from 0.59 × 10^?5 to 14.1 × 10^?5 s^?1 with the ring size and the alkyl substitution of the ring. Decomposition of 2,2′-azobis[2-(imidazoline-2-yl)propane] dihydrochloride was found to be accelerated by alkyl substitution on the imidazolinium ring. However, the azoamidinium compounds having larger rings, 2,2′-azobis[2-(3,4,5-trihydropyrimi-dine-2-yl)propane] dihydrochloride and 2,2′-azobis[2-(4,5,6,7-tetra-hydro-1H-1,3-diazepine-2-yl)propane] dihydrochloride, decomposed at a slower rate than the unsubstituted azobis[2-(imidazoline-2-yl)-propane] dihydrochloride. These new initiators were found to be capable of initiating radical polymerizations of acrylamide and vinyl acetate.     

Photosensitive fluorinated polyimides with a low dielectric constant based on reaction development patterning

The fluorinated polyimide PI(6FDA/HFBAPP) was prepared by the reaction of 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) with 2,2‐bis[4‐(4‐aminophenoxy)phenyl]hexafluoropropane (HFBAPP) in 1‐methyl‐2‐pyrrolidone/toluene. A multiblock copolyimide with both fluorinated and rigid‐rod segments, PI(6FDA/HFBAPP)(BPDA/2‐DMB), was prepared by the addition of a second dianhydride, 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), and a second diamine, 2,2′‐dimethylbenzidine (2‐DMB), to the polyimide main chain. The potential lithographic performance of photosensitive polyimides composed of nonphotosensitive fluorine‐containing polyimides and photosensitive diazonaphthoquinone (DNQ) was studied on the basis of a new imaging principle recently proposed by our laboratory, that is, reaction development patterning. Neat PI(6FDA/HFBAPP) showed a low dielectric constant (?) of 2.41 and a low dissipation factor (tan δ) of 0.0027 at 20 GHz, and a 10‐μm resolution of the fluorinated polyimide/DNQ system was demonstrated with reactive development with a solution including ethanolamine after ultraviolet exposure. Although slight changes in the dielectric properties were observed in the presence of DNQ residues, these values (? = 2.63 and tan δ = 0.0033 at 20 GHz) were low enough for use in microelectronic applications. However, PI(6FDA/HFBAPP)(BPDA/2‐DMB), having a lower coefficient of thermal expansion (CTE; 33 ppm/°C) than PI(6FDA/HFBAPP) (49 ppm/°C), exhibited good positive photosensitivity, whereas the relatively low‐CTE multiblock copolyimide displayed a much higher ? value (3.48 at 1 MHz) than the highly fluorinated polyimide (2.88 at 1 MHz). A film consisting of PI(6FDA/HFBAPP)(BPDA/2‐DMB) and the remaining DNQ derivatives showed a CTE value comparable to that of the neat polyimide film. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 861–871, 2003     

Photo‐alignment material with azobenzene‐functionalized polymer linked in film

Application of a new azo‐polymer as a photo‐alignment material for liquid crystals (LCs) was demonstrated. 4‐(Vinyloxyethyloxy)azobenzene (VAZO), which has thermally reactive vinyl ether groups, reacted with the ? OH groups of poly(4‐hydroxystyrene) (PHS) during the baking process. The azo‐attached polymer (PHS‐VAZO) film showed anisotropic spectra after exposure to 365‐nm linear polarized light (LPL) unlike the VAZO‐doped poly(methylmethacrylate) (PMMA) film. The anisotropy of the film was small at high concentration of the azo‐chromophore because of thermal randomization of the polarized state. In the evaluation of photo‐alignment of the LC, the LC hybrid cell using the PHS‐VAZO film achieved high LC alignment. The azo‐attached polymer using the thermal reaction of vinyl ethers is useful for a photo‐alignment material. Copyright © 2002 John Wiley & Sons, Ltd.