Reactive and Functional Polymers (v.63, #1)

The article describes the synthesis and extraction properties of new alkylnitrile and alkylbenzonitrile substituted calix[4]arene based polymers. These compounds have been synthesized via nucleophilic substitution reactions involving 5,11,17,23-tetra-tert-butyl-25,27-bis-(cyanomethoxy)-26,28-dihydroxycalix[4]arene (2a), 5,11,17,23-tetra-tert-butyl-25-(2-cyanobenzyloxy)-26,27,28-trihydroxycalix[4]arene (3a), or 5,11,17,23-tetra-tert-butyl-25,27-bis-(2-cyanobenzyloxy)-26,28-dihydroxycalix[4]arene (4a), with Merrifield’s resin (0.8 mM Cl/1.0 g resin). The two-phase extraction properties of ligands 2a–4a along with their polymers 2b–4b toward the selected metal cations and dichromate ( HCr 2 O 7 - / Cr 2 O 7 2 - ) anions are reported. Extraction studies with monomer 2a show selectivity for Hg2+, where as monomers 3a and 4a are selective for Cd2+ and Hg2+ cations. Nevertheless, due to the higher oxidative stability of nitrile groups, polymers 2b–4b have been developed as good extractants for transferring the selected metal cations and dichromate ( HCr 2 O 7 - / Cr 2 O 7 2 - ) anions from an aqueous into a dichloromethane phase.
Keywords: Calixarenes; Solvent extraction; Metal cations; Dichromate anions; Cone conformation;

Superabsorbent copolymers (SAPs) based on acrylamide (AAM) and sodium methacrylate (NMA) were prepared by simultaneous free radical polymerization in aqueous solution using ammonium persulfate (APS) and N,N,N′,N′-tetramethylethylenediamine (TMEDA) as initiating systems at room temperature. Eight different copolymers were prepared by varying NMA with a fixed concentration of acrylamide and 1,4-butanediol diacrylate (BDDA) or ethyleneglycol dimethacrylate (EGDMA) as crosslinkers. The acrylamide–sodium methacrylate (AAM–NMA) SAP formation was confirmed by IR spectroscopy. The percentage of swelling, swelling and diffusion kinetic parameters (i.e., initial swelling network constant, swelling rate constant, maximum swelling equilibrium, network structure constant and type of diffusion, etc.) were investigated for all the SAPs at 25 °C. The swelling behaviour was also studied at different temperatures ranging from 10 to 50 °C. The effect of different reaction parameters, such as, crosslinker, initiator and activator concentrations on the swelling capacity was investigated. The effect of variation of crosslinker concentration on the copolymer network structure was studied by SEM analysis. Further the saline sensitivity of the copolymers was investigated at different saline concentrations. The effect of pH and de-swelling behaviour for AAM–NMA SAPs prepared at optimum reaction conditions was studied.
Keywords: Superabsorbent copolymer; Simultaneous free radical polymerization; Swelling ratio; Activator; Crosslinked network structure;

Acid–base properties of ion exchangers. III. Anion exchangers on the basis of polyacrylonitrile fiber by A.A. Shunkevich; Z.I. Akulich; G.V. Mediak; V.S. Soldatov (27-34).
The anion exchange fibers on the basis of industrially produced polyacrylonitrile fiber NITRON with different strong and weak base groups have been described in the paper. Their acid–base properties were characterized by the acidity parameters calculated from the potentiometric titration curves. The method of computer analysis of the titration curves described elsewhere was used. It was established that the ion exchange fibers are polyfunctional and contain at least four types of functional groups. Their capacities and the acidity parameters have been calculated. The fibers have full ion exchange capacity about 3.5 meq/g. The capacity according to the strong base quaternary aminogroups (pK  ≅ 2) is usually about 2.5 meq/g. The water uptake, stability in hydrogen peroxide solutions, strong acids and alkalis of different concentrations at the ambient temperature and 100 °C have been studied. The fibers do not loose significantly their anion exchange capacities and mechanical properties except for the most extreme regimes of their treatment. At the same time they accumulate carboxylic acid groups in their structure due to hydrolysis of the residual nitrile groups in the fiber.
Keywords: Ion exchangers; Ion exchange fibers; Fibrous ion exchangers; Potentiometric titration;

An optical CO2 sensor based on the overlay of the CO2 induced absorbance change of pH indicator dye α-naphtholphthalein in poly(trimethylsiliypropyne) (poly(TMSP))layer with the fluorescence of tetraphenylporphyrin (TPP) in polystyrene layer is developed. The observed luminescence intensity from TPP at 655 nm increased with increasing the CO2 concentration. The ratio I 100/I 0 value of the sensing film, where I 0 and I 100 represent the detected luminescence intensities from a layer exposed to 100% argon and 100% CO2, respectively, that the sensitivity of the sensor, is estimated to be 10.3. The response and recovery times of the sensing film are less than 3.0 s for switching from argon to CO2, and for switching from CO2 to argon. The signal changes are fully reversible and no hysteresis is observed during the measurements. The highly sensitive and fast responsible optical CO2 sensor based on fluorescence intensity changes of TPP due to the absorption change of α-naphtholphthalein with CO2 is achieved using poly(TMSP) film.
Keywords: Optical CO2 sensor; pH indicator; α-Naphtholphthalein; Colorimetric change; Poly(trimethylsiliypropyne);

Hydrophobic porous polymer resins based on DVB and methyl acrylate (MA) could be prepared as water-wettable or swellable materials by using purified divinylbenzene (DVB, 98.8%). Consequently, the interior surface of the MA/DVB resins thus obtained, without prior wetting of the resins with a water-miscible organic solvent, is accessible to water, and hence, to solute present in an aqueous solution. The adsorption behavior of the MA/DVB resins was therefore investigated by focusing on the comparison between the resins with and without prewetted, using caffeine and phenol as model adsorbates. The adsorption behavior of the MA/DVB resins without prewetted in an aqueous solution was found to correlate well with the wetting ability of the resins in water, and thus was affected by the MA/DVB ratio, or the DVB and MA contents of the resins. The results suggest that a well water-wettable porous MA/DVB resin could be applied, in a dry state, to the adsorption from water by direct contact with the aqueous solution, without diminishing the ability of the resin to adsorb the solutes.
Keywords: Divinylbenzene–methyl acrylate resins; Hydrophobicity; Water-wetting ability; Adsorption behavior;

Structures and properties of cholesteric liquid crystalline elastomers by Ying-Gang Jia; Bao-Yan Zhang; Mei Tian; Ke-Qi Wei (55-61).
The synthesis of new side-chain cholesteric liquid crystalline elastomers containing mesomorphic crosslinking agent M-1 and cholesteric monomer M-2 was described by a one-step hydrosilylation reaction. The chemical structures of the obtained network polymers were confirmed by FT-IR spectroscopy. The mesogenic properties and phase behavior were investigated by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction measurements. The mesomorphic crosslinking agent was adopted to diminish the disturbance of the non-mesogenic crosslinking agent on liquid crystalline elastomers. The influence of the crosslinking units on the phase behavior was discussed. The liquid crystalline elastomers P-2–P-6 containing less than 10.8 mol% crosslinking agent showed elasticity, reversible phase transition, and cholesteric grandjean texture. The experimental results demonstrated that the glass transition temperatures and the isotropization temperatures of the networks polymers decreased a little with increasing concentration of crosslinking units but the cholesteric phase was not disturbed.
Keywords: Liquid crystalline; Cholesteric; Elastomers; Crosslinking; Polysiloxane;

Cobalt phthalocyanine sheet polymer showed very high-thermal stability with a maximum polymer decomposition temperature of 500 °C in air, and 860 °C in nitrogen, with char yield of 85% at 800 °C in a nitrogen atmosphere. MS and GC–MS studies of the cobalt phthalocyanine sheet polymer were conducted at high temperatures ranging from 500 to 1000 °C. Tentative mechanisms are proposed for its modes of fragmentations and the most probable degradation products were identified by GC–MS.
Keywords: Cobalt phthalocyanine sheet polymer; Thermal stability; Degradation mechanism; GC–MS;

2-(α-Hydroxymethyl)benzimidazole (Hhmbmz) has been covalently anchored to chloromethylated polystyrene cross-linked with 5% divinylbenzene. This chelating resin reacts with cupric acetate, vanadyl sulphate and [MoO2(acac)2] (Hacac = acetylacetone) in presence of Hhmbmz to give complexes PS-[Cu(hmbmz)2], PS-[VO(hmbmz)2] and PS-[MoO2(hmbmz)2] (where, PS-hmbmz = deprotonated 2-(α-hydroxymethyl) benzimidazole covalently linked with polymer), respectively. These complexes were characterized by elemental analyses, FT-IR, EPR and electronic spectra, SEM and TGA-DTA methods. EPR results indicate that complexes are well dispersed in the polymeric support. Complexes PS-[Cu(hmbmz)2] and PS-[VO(hmbmz)2] have been used as catalysts for the oxidation of styrene and ethyl benzene while PS-[VO(hmbmz)2] and PS-[MoO2(hmbmz)2] for the oxidative bromination of salicylaldehyde. Oxidation of styrene gives three major products, styrene oxide, benzaldehyde and benzoic acid while ethyl benzene gives acetophenone as the major product. Oxidative bromination of salicylaldehyde using H2O2/KBr gives 5-bromosalicylaldehyde selectively in quantitative yield. EPR spectra of both freshly prepared and recovered catalysts are identical, which indicate that the metal-Schiff base moiety is intact and the coordination environments are not altered during the reaction.
Keywords: Polymer anchored-complexes; Oxidation of styrene and ethyl benzene; Oxidative bromination of salicylaldehyde; 2-(α-hydroxymethyl)benzimidazole;

Bio-catalytic nanoparticles with urease immobilized in multilayer assembled through layer-by-layer technique by Zhenpeng Liang; Chaoyang Wang; Zhen Tong; Weihua Ye; Shiqu Ye (85-94).
A novel core-shell colloid with multilayer for biocatalysis was elaborated by the layer-by-layer assembly technique. Urease was adsorbed in alternation with the oppositely charged polyelectrolytes onto polystyrene (PS) colloid nanoparticles as either polycation or polyanion switched by the solution pH. Microelectrophoresis, transmission electron microscopy (TEM) and UV–vis spectrum absorbance were employed to monitor the regular and stepwise growth of the multilayer films with the enzyme and counterpart polyelectrolytes. The colloid nanoparticles coated with negatively charged urease were found to be more stable than those coated with positively charged urease. The catalytic activity of the urease immobilized on the PS nanoparticles, having higher storage stability, was 23.67% of that for the free urease in aqueous solution. Addition of 0.05 M NaCl increased the activity of the immobilized urease by 65%. Coverage of synthetic polyelectrolyte layers on the urease layer reduced the activity of the immobilized urease. Therefore, by adding salts or covering with polyelectrolytes, we have achieved an enhancement or restraint of the bioactivity of immobilized enzyme, indicating a novel method for biotechnology.
Keywords: Nanoreactor; Self-assembly; Immobilized urease;