Ionic-conductivity switching of vinyl malachite green leuconitrile copolymers based on photoinduced carrier generation

Copolymers of bis[4-(N,N-dimethylamino)phenyl]-4-vinylphenylmethanenitrile (vinyl Malachite Green leuconitrile) with methyl methacrylate or ω-methoxyoligo(oxyethylene) methacrylate have been synthesized, aiming at designing one-component-type organic polymers for photoswitchable ion-conducting films. The triphenylmethanenitrile copolymers with ω-methoxyoligo(oxyethylene) methacrylate were found to undergo ionic-conductivity switching by turning on and off UV light at ambient temperature, owing to their low glass transition temperature. © 1993 John Wiley & Sons, Inc.     

Synthesis and characterization of maleimide polymers with pendant pyrazole groups. IV. Copolymerization of pyrazole-modified maleimides with vinyl ethers

The synthesis of maleimides that have pyrazolic or bipyrazolic pendant groups is described. Their homopolymerization and their copolymerization with 2-chloroethyl vinyl ether (CEVE) is reported. The homopolymerizations of such maleimides were performed under various conditions and led to low molecular-weight polymers. However, alternating copolymers were obtained from CEVE as comonomers whatever the monomers feed compositions. A similar behavior was also observed for maleimides that do not exhibit any spacer, whereas for bulky vinyl ethers, random copolymers were produced. A comparison of the thermal behavior between these copolymers (glass transition temperatures, T_g, and decomposition temperatures) and other copolymers having different spacers between the nitrogenated cycles and the chain are related. Thus, an important decrease of T_g, was observed when C₃H₆CO₂CH₂ groups were used as the spacer instead of methylene groups. Moreover, the thermal weakness of these copolymers may come from the substituents of the vinyl ether and is discussed. © 1994 John Wiley & Sons, Inc.     

过氧化氢与N—甲基苯胺盐酸盐引发体系的研究

在水介质中,研究了新型的过氧化氢/N-甲基苯胺盐酸盐引发体系对 AM 与 PVA 的接枝共聚。产物经紫外光谱、红外光谱和 ~1H-核磁共振进行表征,并提出了引发机理。     

Hydrolytically stable, diaminocarboxylic acid-based membranes buffering in the pH range from 6 to 8.5 for isoelectric trapping separations

Diaminocarboxylic acid carrier ampholytes, such as L-histidine, 2,3-diaminopropionic acid, L-ornithine, and L-lysine, were reacted with glycerol-1,3-diglycidyl ether (GDGE) and poly(vinyl alcohol) (PVA) in the presence of sodium hydroxide to produce hydrolytically and mechanically stable hydrogels, supported on a PVA substrate, for use as buffering membranes in isoelectric trapping (IET) separations. The pH values of the DACAPVA membranes were determined with the help of small-molecule pI markers and proteins and were found to be in the 6 < pH < 8.5 range. The membranes were successfully used to isoelectrically trap small ampholytes, desalt ampholyte solutions in IET mode, and effect the binary separation of chicken egg white proteins.     

DABCO-catalyzed reactions of hydrazones with activated olefins

This paper describes several highly efficient DABCO-catalyzed aza-Michael addition reactions of hydrazones to activated olefins. In most cases, these aza-Michael addition reactions gave the corresponding products in high yields under mild conditions. The plausible reaction mechanism is discussed on the basis of deuterium labeling experiments. Upon treatment with HCl, the corresponding cyclized products can be obtained in high yields from the Michael addition products.     

Synthesis and properties of amphiphilic vinyl acetate triblock copolymers prepared by copper mediated living radical polymerisation

Polymerisation of vinyl acetate by conventional free radical polymerisation using a diazo initiator followed by copper mediated living radical polymerisation with a range of monomers was studied. This method led to the synthesis of triblock copolymers. We have thus successfully prepared several new ABA triblock copolymers where B is poly(vinyl acetate) and A is (dimethylamino)ethyl methacrylate (DMAEMA), (polyethylene glycol) methyl ether methacrylate (MeO(PEG)MA) or solketal methacrylate (SMA). The sequential conventional/living radical polymerisation approach provided an efficient route to synthesis of new block copolymers. The properties of these amphiphilic polymers have been subsequently investigated by ¹H NMR, fluorescence spectroscopy, tensiometry and dynamic light scattering to investigate their behaviour as potential surfactants.     

Synthesis of statistical glycidyl methacrylate‐n‐vinyl pyrrolidone copolymers and their reaction with naproxen

Free‐radical copolymerization of glycidyl methacrylate (GMA) with N‐vinylpyrrolidone (VPD) was carried out at 50 °C using 3.0 mol · L^?1 of N,N′‐dimethylformamide solution and 9.0 · 10^?3 mol · L^?1 of 2,2′‐azobisisobutyronitrile as an initiator. The modification reaction of GMA‐VPD copolymers with a model bioactive carboxylic acid, 6‐methoxy‐α‐methyl‐2‐naphthaleneacetic acid (naproxen), was studied in the homogeneous phase using basic catalysts. The influence of the type of catalyst and the GMA content was evaluated. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1192–1199, 2002     

Polyvinyl pyridines as flocculating agents

Summary High molecular weight poly 2- and 4-vinyl pyridines were synthesized by ionic polymerisation and their flocculation efficiency tested against kaolin and silica dispersions at pH 3. Low additions of the polymers, around 3 parts per 10₃ parts solid, destabilize the dispersions and clarify silica dispersions to a remarkable extent; however, over-addition of polymer leads to partial restabilization. The flocculation efficiency improves with increase of solids content, especially with clay dispersions. Flocculation efficiency increases with polymer molecular weight, especially over the lower part of the range covered, but is relatively independent of pH in the range 2–4. Quaternization of poly(4-vinyl pyridine) with bromobutane produces a good flocculant for aqueous silica dispersions in which the degree of restabilization on over-dosing depends on the KCI content. TheN-oxide derivatives of the vinyl pyridine polymers do not affect the colloidal stability of silica dispersions. The observations are interpreted in terms of bridging flocculation by the cationic polymer molecules between anionic surface sites on the solid particles.     

ξ-potential and surface dye-ability of poly(vinyl alcohol) fiber with different degree of formalization in a cationic dye solution

Summary The surface dyeability of the poly(vinyl alcohol) fiber with different degree of formalization was studied by measuring -potential of the fiber in alkaline aqueous solutions (pH 10) of a cationic dye Methylene Blue. With the increase in the dye concentration, the sign of the -potential of the fiber changed from negative to positive and thereafter the positive value approximated to saturated value, and the amount of dye adsorbed (expressed in mol/cm²-fiber) increased also. These results may possibly be attributed to the formation of the electrostatic bond between the fiber and the dye. The linear relations were found between and logC _d and its slope did not change with rise of temperature. The free energy of dyeing G (negative) calculated from the slope of the -logC _id curve, etc. increased with increasing the degree of formalization of the fiber. This fact corresponds to the increase in the surface dye adsorption with increasing the degree of formalization. With increasing the degree of formalization, the heat of dyeing H (negative) increased and the entropy of dyeing S (positive) decreased. The positive value of S for each fiber, suggests the formation of hydrophobic bond as a driving force to the dyeing of Methylene blue on the fiber surface in addition to the electrostatic bond.This paper is Part XXVII in a series on Studies on -potentials and Surface Dyeability of Natural and Synthetic Fibers in Dye Solution. Part XXVI: T. Suzawa andK. Kawakami, Nippon Kagaku Kaishi1975, No. 7,1134.     

Polymerizable benzophenone derivatives for labeling vinyl acetate‐butylacrylate latex particles

We describe the synthesis and characterization of three new polymerizable benzophenone derivatives [2‐acryloxy‐5‐methyl benzophenone ( 8 ), 4′‐dimethylamino‐2‐acryloxy‐5‐methyl benzophenone ( 9 ), and 4′‐dimethylamino‐2‐(β‐acryloxyethyl)oxy‐5‐methyl benzophenone ( 10 )]. We show that these monomers can successfully be incorporated into vinyl acetate (VAc) copolymer latex particles. These particles were prepared by semicontinuous emulsion polymerization and mini‐emulsion polymerization of VAc with butylacrylate (BA) for VAc/BA = 4/1 by weight. The two monomers 9 and 10 bearing the 4′‐dimethylamino group satisfy the important spectroscopic criteria required of a dye to serve as an acceptor chromophore for nonradiative energy transfer from phenanthrene (Phe) as the donor. Their UV absorption spectra suggest significant overlap with the emission spectrum of Phe, which can be incorporated into P(VAc‐co‐BA) latex through copolymerization with 9‐acryloxymethyl Phe ( 2 ). In addition, these chromophores provide a window in their absorption spectra for excitation of the Phe chromophore at 300 nm. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3001–3011, 2002