Reactive and Functional Polymers (v.66, #12)

The curing reactions of ethynyl-functional benzoxazine by Jianxiang Huang; Jian Zhang; Fan Wang; Farong Huang; Lei Du (1395-1403).
The model compounds 3-(3-ethynyl-phenyl)-6-methyl-3,4-dihydro-2H-benzoxazine (EPMB) and 6-methyl-3-phenyl-3,4-dihydro-2H-benzoxazine (PMB) were synthesized and the influence of ethynyl group on the thermal cure reaction of benzoxazine compound was investigated. The bond parameters of benzoxazine ring calculated at the level of B3LYP/6-31G(d) showed that the variations of benzoxazine structures due to the introduction of ethynyl were negligible. The cure reaction of EPMB and PMB was studied by DSC and kinetic parameters were determined by an autocatalytic model. The results revealed that the apparent activation energy for cure reaction of EPMB was 103.90 kJ/mol which was lower than that of PMB (124.14 kJ/mol). The kinetic parameters of cure reactions of PMB and EPMB obtained by the Kissinger and Ozawa methods agreed well with the results by the autocatalytic model. The structures of the cured EPMB were characterized by 1H NMR and solid-state 13C NMR. The results showed there are polyene structures and hydrogen bonds in the cured EPMB.
Keywords: Benzoxazine; Ethynyl-functional benzoxazine; Cure reaction; Kinetics;

A carbazole-based photorefractive polyphosphazene prepared via post-azo-coupling reaction by Li Zhang; Maomao Huang; Zhiwei Jiang; Zheng Yang; Zhijian Chen; Qihuang Gong; Shaokui Cao (1404-1410).
A carbazole-based photorefractive polyphosphazene was prepared via post-azo-coupling reaction. The polymer shows a low glass transition temperature of 50 °C, and has an excellent solubility in common organic solvents, which can easily be fabricated into an optically transparent film with long-term stability. The nonlinear optical effects, including two-beam-coupling and four-wave-mixing, were studied at 633 nm under room temperature. A gain coefficient of 79 cm−1 and a diffraction efficiency of 18% were observed at zero external electric field without any added plasticizer or sensitizer.
Keywords: Polyphosphazene; Post-azo-coupling; Carbazole; Photorefractive;

A series of predominantly syndiotactic poly(R,S)3-hydroxybutyrates (PHB) which were in widely different molecular weights (from 16,000 to 380,000 Da) were prepared by ring-opening polymerization of (R,S)β-butyrolactone(β-BL) initiated with cyclic tin alkoxide, using high vacuum technique in order to create and maintain the impurity-free conditions. Copolyesters poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)) have also been synthesized from copolymerizations of β-BL with either γ-butyrolactone (γ-BL) or (R,S)β-valerolactone (β-VL) with cyclic tin alkoxide. The resulting polymers were characterized by GPC, DSC, 1H, 13C NMR. Molecular weight of the polymer is largely dependent on an amount of initiator and inversely proportional to that. The glass-transition temperature of the PHB is 5 ± 2 °C, being independent of molecular weight of the samples. 13C NMR spectroscopy resolved stereosequences in synthetic PHB at the diad level for the carbonyl carbon and at the triad level for the methylene carbon. Analysis of diad sequence distributions at various polymerization temperatures for the cyclic tin alkoxide investigated showed an activation energy (ΔE  =  E s  −  E i ) of ca. −10.8 kJ/mol for syndiotactic versus isotactic diad formation. These analyses show that the cyclic tin alkoxide is a stereoselective initiator for ring-opening polymerization of β-BL and gives predominantly syndiotactic PHB (syndiotactic diad fraction from 0.59 to 0.79). Triad stereosequence distributions of PHB samples agree well with the Bernoullian statistical model of chain-end control.
Keywords: β-Butyrolactone; Poly-3-hydroxybutyrate; Cyclic tin alkoxide;

Immobilization of GOD on electrochemically synthesized Ppy–PVS composite film by cross-linking via glutaraldehyde for determination of glucose by V.K. Gade; D.J. Shirale; P.D. Gaikwad; P.A. Savale; K.P. Kakde; H.J. Kharat; M.D. Shirsat (1420-1426).
The Ppy–PVS-GOD biosensor for determination of glucose has been described. The enzyme, glucose oxidase (GOD) was immobilised by cross-linking via glutaraldehyde on a polypyrrole–polyvinyl sulphonate (Ppy–PVS) composite film. The Ppy–PVS film was electrochemically synthesized on indium–tin-oxide (ITO)-coated glass plate. We have synthesized Ppy–PVS film with 0.1 M pyrrole, 0.025 M PVS at 3.0 pH and 1 mA/cm2 current density. The immobilization was done by cross-linking 2 mg/ml GOD via 0.1% glutaraldehyde at 0.1 M phosphate buffer with 7.0 pH. The synthesized composite films were characterized using galvanostatic electrochemical technique, electrical conductivity, UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The cross-linking of enzyme and porous morphology of the polymer film leads to high enzyme loading and an increase in lifetime, stability and fast response time of the enzyme electrode. Amperometric response was measured as a function of different concentration of glucose. It was observed that current increases with increasing glucose concentration in the range 1–50 mM.
Keywords: Immobilization; Composite film; Glucose-oxidase; Cross-linking; Biosensor;

This paper reports the synthesis of a series of six new polystyrene anchored metal complexes of Co(II), Fe(III), Ni(II), Cu(II), Zn(II), and dioxouanium(VI) using the polystyrene anchored Schiff base of 2-nitrobenzaldehyde and the corresponding metal salts. The metal salts used were anhydrous FeCl3, CoCl2  · 6H2O, Ni(CH3COO)2  · 4H2O, Cu(CH3COO)2  · H2O, Zn(CH3COO)2  · 2H2O, and UO2(CH3COO) · 2H2O. Physico chemical characterizations have been made from diffuse reflectance and vibrational spectra, elemental analysis, magnetic measurements, and TG studies. The elemental analysis suggest a 1:2 metal:ligand ratio when the complexation has carried out at 70 °C for about 12 h reflux. The ligand is monodentate and coordinates through the azomethine nitrogen. The Fe(III), Co(II), Ni(II), and Cu(II) complexes are all paramagnetic whereas Zn(II) and U(VI) are diamagnetic. Zn(II) is assigned a tetrahedral structure, Cu(II) and Co(II) are assigned a square planar structure and Fe(III), Ni(II), and U(VI) are all assigned an octahedral structure. The polystyrene anchored ligand has been developed as an excellent reagent for the removal of Cu(II). Optimum conditions have been developed for the removal of metal ion from solutions by studying the effect of change of concentration of metal ion, ligand, effect of pH, time of reflux, and interference effect of other ions. It was found that within a span of 20 min it is possible to remove 90% of the metal ion from a 30 ppm metal ion solution in the pH range 4–5.5.
Keywords: Polymeric Schiff base complex; 2-Nitrobenzaldehyde; Cu(II) removal; Optimum condition;

A review: Non-cross-linked polystyrene bound reagents, catalysts and syntheses by Jianian Chen; Guichun Yang; Haiqing Zhang; Zuxing Chen (1434-1451).
Non-cross-linked polystyrene (NCPS), as a type of soluble polymer having remarkable properties, has attracted more and more attention. Many organic synthetic applications based on NCPS have been shown great success. NCPS is easily functionalized and can be used as supports in organic synthesis. Comparing to classical liquid-phase synthesis, their advantages involve simplified isolation, cycling procedures and increasing stereoselectivity. This review reported the recent developments using NCPS bound reagents focusing on three aspects: (1) NCPS-bound reagents, (2) NCPS-bound catalysts and (3) NCPS-bound syntheses.
Keywords: Non-cross-linked polystyrene; NCPS-bound reagent; NCPS-bound catalyst; NCPS-bound Synthesis;

Polymer based ion-sensor for the selective recognition of UO 2 2 + and Th4+ ions by M. Akhila Maheswari; M.S. Subramanian (1452-1461).
A polymer based ion-sensor, selective for concentrating UO 2 2 + and Th4+ ions is developed based on the use of a novel multi-donor ionophore, termed EHCOP (4,4-Bis-[bis-(2-ethyl-hexyl)-carbamoyl]-2-oxo-butyl}-phosphinic acid). The fabrication involves the stepwise chemical grafting of Amberlite XAD-16 resin beads with phosphinic acid and branched long alkyl chain amide moiety, to the desired EHCOP ligand. The grafted polymer exhibits phenomenal behavior in sensing both Th4+ and UO 2 2 + from acidic and neutral conditions, with greater decontamination factor values. Moreover, in this sensor the only possible co-extractable lanthanides ions can also be selectively eliminated with 2 M HCl. The concentrated ions can be sequentially recovered by gradient elution, by first stripping off Th4+ ions with 2 M HCl–NaCl mixture, followed by 0.5 M (NH4)2CO3 for pure UO 2 2 + fraction. The polymer’s lowest sensing limit for UO 2 2 + was 5 μg L−1 and 10 μg L−1 for Th4+. As the EHCOP moiety exhibits dual extraction property, it was successful in recovering uranium from seawater samples, with an RSD value of >3.9%. Based on the metal sorption capacity studies, the sensor material can be utilized both as an analytical and preparative column depending on the application. The response time involved for trace ion targeting was statically observed to be within 10 min and by dynamic mode with a flow rate of 14–16 mL min−1. The resin can be recycled as much as 15 cycles without any significant change in their sorption capacity. The chemical grafting was characterized by 13C CPMAS NMR, FT-NIR-FIR, and CHNP analyzer and the metal ion sensing was estimated by UV–vis and fluorescence spectroscopy.
Keywords: Grafted polymer; Ion-sensor; Preconcentration and uranium recovery;

Hydroxylated hyperbranched polyesters as crosslinking agents for polyurethane networks: Partial modification of the OH chain ends by Damien Thomasson; Fernande Boisson; Emmanuel Girard-Reydet; Françoise Méchin (1462-1481).
A 4th generation commercial hyperbranched polyester (HBP) based on bis(hydroxymethyl) propionic acid, bis(MPA), was used as an original crosslinker for polyurethane networks. However a partial modification of the numerous hydroxyl groups was necessary to obtain complete miscibility between the three polyurethane precursors, i.e. macrodiol, diisocyanate and hyperbranched, HB, crosslinking agent. A monofunctional aromatic isocyanate, para-tolylisocyanate, pTI, was used for that purpose. The pristine hyperbranched polyester was at first quite fully characterized, especially concerning the initial distribution of hydroxyl groups between linear, L, and terminal, T, bis(MPA) units. 1H and 13C NMR (both for urethane formation and hydroxyl consumption) and chemical titration were then used and compared for the determination of OH conversion. It appeared that a small part of the modifier was systematically lost in a side reaction with moisture, even though the reactive species had been thoroughly dried. All the remaining pTI molecules produced exclusively urethane end groups. NMR also demonstrated that the hydroxyls born by linear units had a lower reactivity as compared to T-type OH groups. Therefore their relative proportion increases with the modification degree, and more and more modified crosslinkers become less and less reactive.Calorimetric studies performed on pristine and partially modified HB polyesters revealed that hydrogen bonds played an important role as far as thermal behavior was concerned. With increasing modification, T g increases but also ordered domains resulting from strong interactions between hydroxyl groups are progressively replaced by new structures created by self-assembling aromatic urethanes. The latter are responsible for a high-temperature pseudo-melting for highly modified samples. However most of these interactions seem to remain intramolecular since the newtonian behavior of pristine HBP is maintained up to about 110–120 °C for pTI-modified oligomers; but annealing at higher temperature can result in even more ordering and in a final loss of the newtonian behavior.
Keywords: Hyperbranched polyesters; Chemical modification; Modification degree; Urethane; Hydrogen bonds;

Semi-IPNs of starch and poly(acrylamide-co-sodium methacrylate): Preparation, swelling and diffusion characteristics evaluation by P.S. Keshava Murthy; Y. Murali Mohan; J. Sreeramulu; K. Mohana Raju (1482-1493).
Semi-interpenetrating polymer network (IPN) hydrogels composed of starch and random copolymer of poly(acrylamide-co-sodium methacrylate) [poly(AAm-co-NMA)] were prepared by polymerizing an aqueous solution of acrylamide (AAm), sodium methacrylate (NMA) using ammonium persulphate (APS)/N,N,N 1,N 1-tetramethylethylenediamine (TMEDA) as redox initiating system in presence of a crosslinker and starch solution. IR spectroscopy was used to identify the presence of different repeating units in the IPN networks. The swelling and diffusion characteristics, such as initial swelling rate (r i), swelling rate constant (k s), equilibrium swelling ratio (S eq), diffusion constant (n) and diffusion coefficients (D) were evaluated for different semi-IPN hydrogels prepared under various formulations. For better understanding of network structure formation of these semi-IPNs, three different crosslinkers namely, N,N-methylenebisacrylamide (MBA), 1,4-butanediol diacrylate (BDDA) and diallyl phthalate (DP) were employed. Further, the swelling pattern of semi-IPN hydrogels was studied in different physiological, pH and ionic/salt solutions and showed great responsiveness due to their ionic character. The morphological features of these IPNs were observed using scanning electron microscopy (SEM).
Keywords: Interpenetrating polymer network; Hydrogel; Superabsorbent polymer; Crosslinker; Swelling ratio;

Recovery of benzaldehyde from aqueous streams using extractant impregnated resins by Katarina Babić; Louis van der Ham; André de Haan (1494-1505).
The performance of Extractant Impregnated Resin (EIR) technology for extraction of aldehydes from aqueous solutions has been investigated. The extraction capabilities of several different aliphatic and aromatic primary amines towards aldehydes were tested and compared. Aliphatic amines showed high affinity. The most promising extractant, Primene® JM-T, was immobilized in a porous particle. As a solid support three different macroporous adsorbents were tested, XAD-16, MPP and Stamypor. Their capacities for the removal of aldehydes were compared with the non-impregnated resin and the resin impregnated with the non-reactive solvent. It was shown that the addition of a reactive extractant can increase the adsorption capacity of an otherwise poor adsorbent for several orders of magnitude. The capacity for the removal of aldehydes was increased with the increase of amine loading on the particle. Temperature influence on the sorption of benzaldehyde on fully impregnated MPP was studied. It was shown that with temperature increase, sorption capacity is increased. The stability of EIRs regarding the loss of the extractant due to the leakage in water was also studied. It was shown that immobilization reduces the extractant’s solubility in water. Sorption kinetics was investigated for fully impregnated XAD-16 and MPP. The modified shrinking core model was used to determine the rate controlling step and it was shown that this sorption is most likely controlled by both chemical reaction and diffusion in the particle.
Keywords: Extractant impregnated resins; Aldehydes; Amines; Reactive extraction; Adsorption;

Poly{[9-(4-hexyloxyphenyl)-9-methoxyfluorene-2,7-diyl]-alt-co-[1,4-(2,5-bisdodecyloxy)phenylenevinylene]} [P(PV-FOMe)] was synthesized and its optical property changes upon exposure to various Lewis acids were studied. The fluorescence emission of the polymer solution was completely quenched by Lewis acid such as BF3OEt2, AlCl3, SiCl4, TiCl4, and SnCl4. The fluorescence emission was recovered when methanol was added. The PL on/off switching behavior could be repeatedly observed by alternatively adding Lewis acid and methanol in sequence. The fluorescence quenching behavior followed the Stern–Volmer relationship with a K sv value of 1.2 × 104  M−1 for a quencher BF3OEt2. From the 1H NMR study on a model compound, we found that the PL on/off switching behavior of P(PV-FOMe) is related to the reversible bonding and cleavage of the methoxy group to/from the fluorene unit. While the morphology of a spin-coated P(PV-FOMe)-only film has some defects, defect-free coating was obtained by blending the polymer with host PVK at a level of the P(PV-FOMe) composition below 40 wt%. Among the LEDs composed of P(PV-FOMe):PVK emissive layer, the EL performance was optimal for a blend where P(PV-FOMe)-composition was 10 wt%. The maximum power efficiency and brightness were 1.33 cd/A and 1200 cd/m2 in the device configuration of ITO/[P(PV-FOMe):PVK = 10/90]/Alq3/Al.
Keywords: Fluorene–phenylenevinylene alternating copolymer; Chemosensor; Fluorescence quenching; Lewis acid; Light-emitting diode;

Batch adsorption performance of methyl methacrylate/styrene copolymer membranes by Hsin-Chieh Chiu; Jun-Jie Huang; Chia-Hung Liu; Shing-Yi Suen (1515-1524).
Methyl methacrylate (MMA)/styrene copolymer membranes with different feed molar ratios of monomers are reported. The copolymer structure and properties were examined by contact angle measurements, FT-IR and 1H-NMR spectroscopy. Membranes were fabricated by casting a liquid film of 15–20 wt% copolymer in 1-methyl-2-pyrrolidinone that was exposed to air of 90% relative humidity for 3 min and then immersed into a 25 °C deionized water bath. A sponge-like morphology was observed for the copolymer membranes. The specific surface area and water content increased with increasing MMA/styrene ratio. In addition, the batch adsorption performance for various molecules (quercetin, proteins, α-tocopherol, and flavonoid glycosides in Ginkgo biloba L. extract) was investigated. The higher was the MMA/styrene molar ratio, the greater the related adsorption capacity was. In three cycles of batch adsorption/desorption operation, the content of flavonoid glycosides could be raised from 3.1 wt% to 14 wt%.
Keywords: Methyl methacrylate; Styrene; Copolymer membrane; Adsorption; Quercetin; Protein; α-Tocopherol; Flavonoid glycosides;

A novel water-soluble poly[N-(2-hydroxypropyl)methacrylamide] copolymers containing thiazolidine-2-thione reactive groups in the side chains suitable for preparation of polymer-modified biologically active compounds and water-soluble targeted polymeric anticancer drugs were synthesized and characterized. Copolymers containing thiazolidine-2-thione reactive groups were prepared by radical copolymerization in dimethyl sulfoxide. Molecular weight of the copolymers can be easily controlled by monomer and initiator concentrations and polymerization temperature. The copolymers containing thiazolidine-2-thione reactive groups showed low susceptibility to hydrolysis and high rate of aminolysis in aqueous solutions. The advantages of using TT copolymers for the synthesis of polymeric drugs are demonstrated on the synthesis of the polymer superoxide dismutase, polymer-doxorubicin and human immunoglobulin-targeted polymer-doxorubicin conjugates performed in aqueous solution in one-step procedure.
Keywords: Poly[N-(2-hydroxypropyl)methacrylamide]; Thiazolidine-2-thione reactive groups; Reactive polymers; Polymeric drugs; Drug delivery; Targeting;

To obtain a selective chelating resin for separation and preconcentration of Fe(III) ions in various water samples, amberlite XAD-4 was functionalized with 2,3-dihydroxy benzoic acid by coupling it through an –N=N– spacer. The resulting resin, characterized by thermogravimetric analysis and infrared (IR) spectroscopy, was packed in a minicolumn to be used as a sorbent. It was shown that Fe3+ ions could be sorbed at a pH of 3.5 in the minicolumn and that they could be then eluted using 0.5 mol dm−3 H3PO4. The released amount of Fe3+ was determined by flame atomic absorption spectrometry with a recovery of more than 98%. A linear calibration graph was obtained in the range of 5.0 × 10−8–1.5 × 10−6  mol dm−3 in treatment with aliquots of 500 ml of the solutions in which the experimental preconcentration factor was 100. By using the blank and 2.0 × 10−7  mol dm−3 solutions (n  = 7), the DL and RSD were found to be 6.0 × 10−9  mol dm−3 and 2.1%, respectively. None of the metal ions that are naturally present in water samples interfered in this analysis, even when the concentrations were in excess of two orders of magnitude. The resin is durable with >35 cycles resulting in no major change in its quantitative metal uptake nature. The practical applicability of the method was examined using various real water samples. The recoveries obtained for the spiked trace amount of Fe(III) ions were >95%, which confirmed the reliability of the method.
Keywords: Chelating resin; 2,3-Dihydroxybezoic acid; Fe(III) determination; FAAS;

Poly(dimer acid-co-alkyl polyamine) particles were activated by using various chemicals such as carbodiimide (CDI), ethylene diamine (EDA), and hexamethylene diamine (HMDA) and studied as support materials for covalent immobilization of α-amylase. The activities of the immobilized enzymes on these activated particles were investigated. The highest activity of free enzyme was obtained at pH 7.5 while this value was shifted to pH 6.5 for CDI and EDA activated systems and to pH 8.0 for HMDA activated system. The highest activities of immobilized enzymes were obtained at higher temperature (55 °C) than that of the free enzyme (40 °C). Kinetic parameters were calculated as 2.51, 3.13, 3.47 and 3.17 g dm−3 for K m and 1.67 × 10−3, 6.16 × 10−4, 7.34 × 10−4 and 3.30 × 10−4  g dm−3  min−1 for V max for the free enzyme, and CDI, EDA and HMDA activated immobilized systems, respectively. Enzyme activities were found to be about 75.0%, 62.5% and 95.0% of the original, for CDI, EDA and HMDA activated systems, respectively, after one month of storage while free enzyme lost its activity completely in 20 days. In repeated batch experiments, after 40 uses in 3 days; 91.3%, 77.6% and 99.1% of the original enzyme activities were retained by CDI, EDA and HMDA activated systems, respectively. Among the systems prepared, HMDA activated poly(dimer acid-co-alkyl polyamine) particles demonstrated the highest stability and efficient reusability for the immobilized α-amylase.
Keywords: Enzyme immobilization; α-Amylase; Poly(dimer acid-co-alkyl polyamine); Ethylene diamine; Hexamethylene diamine;

In situ preparation of magnetic chitosan/Fe3O4 composite nanoparticles in tiny pools of water-in-oil microemulsion by Jia Zhi; Yujun Wang; Yangcheng Lu; Jingyu Ma; Guangsheng Luo (1552-1558).
Chitosan nanoparticles with magnetic properties can be potentially used as drug delivery carrier, separation materials. Different from the two-step preparation method of suspension cross-linking, a new method was proposed to in situ prepare magnetic chitosan/Fe3O4 composite nanoparticles with tiny water pools of water-in-oil microemulsion containing chitosan and ferrous salt as microreactors by adding the basic precipitant of NaOH into the microemulsion. The images of transmission electron microscope showed that the cubic-shape magnetic iron oxide particles were encapsulated by the spherical chitosan nanoparticles. The chitosan particle size varied from 10 nm to 80 nm with different molecular weight of chitosan. The saturated magnetization of pure Fe3O4 nanoparticles was as high as 120 emu/g, and the saturated magnetization of composite nanoparticles could reach 11.15 emu/g. Meanwhile, the nanoparticles showed the characteristics of superparamagnetism. We may adjust the magnetization of composite particles by changing the weight ratio of chitosan and Fe3O4. After stirring in water for 48 h the composite nanoparticles showed the same magnetization as the original ones, indicating high stability of the composite nanoparticles.
Keywords: Chitosan; Nanoparticles; Microemulsion; Magnetization;

Electrospun poly(vinyl alcohol)/glucose oxidase biocomposite membranes for biosensor applications by Guanglei Ren; Xinhua Xu; Qiang Liu; Juan Cheng; Xiaoyan Yuan; Lili Wu; Yizao Wan (1559-1564).
A novel technique for enzyme immobilization on the surface of the Au electrode for designing amperometric biosensor by electrospinning poly(vinyl alcohol) (PVA) and glucose oxidase (GOD) is presented in this paper. The immobilized GOD remained active inside the electrospun PVA fibrous membranes. The membranes are promising candidates for immobilization of enzymes because of their high specific surface area and porous structure. The infrared spectrum, the UV–Vis spectrum, and the scanning electronic microscope of the membranes showed that the enzyme had been immobilized inside the PVA membranes. Chronoamperometric measurements demonstrated that electrospun fibrous enzymatic electrodes exhibited a rapid response (1 s) and a higher response current (μA level) to glucose in the normal and diabetic level. The linear response range (from 1 to 10 mM) and the lower detection limit (0.05 mM) of the sensor are satisfying. The electrospun method makes it convenient and efficient to prepare the enzymatic electrode for biosensors.
Keywords: Electrospinning; Glucose oxidase; Poly(vinyl alcohol); Immobilization;

In the present work, multilayered beads, prepared by complex coacervation of calcium alginate and chitosan, followed by sequential coating with chitosan and calcium alginate have been studied for the release of model drug vitamin B2 in the media of varying pH at 37 °C. It has been observed that the beads demonstrated nearly 54 ± 4% drug release in first 3 h in the artificial gastric fluid (pH 1.0) while remaining drug is released in the simulating intestinal fluid of pH 7.4 in 6 h. The stability of the beads and their drug releasing capacity has been studied as a function of composition of outermost alginate layer and its extent of crosslinking. Finally, to incorporate in vivo gastrointestinal (GI) conditions in the study, the release study was also carried out by ‘flow through diffusion cell (FTDC) method’. The beads demonstrated slower release in FTDC as compared to the tradition dissolution test. The nature of filler particles also affected the release profiles in FTDC method. The various diffusion coefficients have also been evaluated.
Keywords: Calcium alginate; Chitosan; Multilayered; Vitamin B2;

Electric field induced stress moduli in polythiophene/polyisoprene elastomer blends by Toemphong Puvanatvattana; Datchanee Chotpattananont; Piyanoot Hiamtup; Sumonman Niamlang; Anuvat Sirivat; Alexander M. Jamieson (1575-1588).
Electrorheological properties of polyisoprene and polythiophene/polyisoprene blends were investigated for electroactive actuator applications. Experiments were carried out under the oscillatory shear mode and with an applied electric field strength varying from 0 to 2 kV/mm. The dynamic moduli, G′ and G″, of the pure polyisoprene were measured in terms of the crosslinking ratio and electric field strength. In the absence of an electric field, the storage modulus (G″) increased but the loss loss modulus (G″) decreased with increasing crosslinking ratio. In the uncrosslinked polyisoprene fluid, the storage modulus (G′) exhibited no change in value with increasing electric field strength. For polyisoprene with crosslinking ratios of 2, 3, 5, and 7, the storage modulus sensitivity increased with electric field strength and attained maximum values of 10%, 60%, 25%, and 30%, respectively, at an electric field strength of 2 kV/mm. The dynamic moduli, G′ and G″, of blends of polythiophene with undoped particle concentrations of 5%, 10%, 20%, and 30% vol% were generally higher than those of crosslinked polyisoprene. The storage modulus sensitivity of these blends increased with electric field strength and attained maximum values of 50%, 35%, 110% ,and 45%, respectively, at an electric field strength of 2 kV/min.
Keywords: Electrorheological properties; Polyisoprene; Polythiophene; Dynamic moduli;

A versatile strategy has been developed in the preparation of well-defined and site specific protein–glycopolymer bioconjugates via controlled free radical polymerization. The first step involved the preparation of a biotinylated poly(ethylene oxide) atom transfer radical polymerization macroinitiator. Atom transfer radical polymerization (ATRP) was then carried out to generate well-defined biotinylated glycopolymers (M w/M n  < 1.35). Protein bioconjugation was then achieved using both wild type and mutated streptavidin protein. The resulting bioconjugates have been assessed by fluorescence, gel permeation chromatography and SDS–PAGE and the data obtained were consistent indicating that higher molecular weights biotinylated glycopolymer bind streptavidin protein at a slower rate as compared to free biotin. It was further noted that higher molecular weight and well-defined biotinylated glycopolymer (M n  = 24 kDa) could on average bind to only two binding pockets on streptavidin protein while sterically blocking the other two binding sites.
Keywords: Bioconjugates; Carbohydrate polymers; Atom transfer free radical polymerization;

New vinyl ester resins based on rosin for coating applications by Ayman M. Atta; Shymaa M. El-Saeed; Reem K. Farag (1596-1608).
Vinyl ester resins based on rosin were prepared from rosin adducts using rosin acid as diene and maleic anhydride (MA) or acrylic acid (AA) as dienophile. The produced adducts, maleopimaric (MPA) and acrylopimaric (APA), were used to prepare vinyl ester resins. MPA and APA were reacted with EG followed by reaction with epichlorohydrine in the presence of NaOH as a catalyst to produce epoxy resins. The terminal epoxy groups were reacted with acrylic and methacrylic acid in the presence of triphenyl phosphite as a catalyst to produce divinyl ester resins. The chemical structures of the resulting vinyl ester resins were confirmed by 1H NMR analysis. The curing exotherm vinyl ester resins and styrene was evaluated at temperatures from 35 to 55 °C using free radical initiator and accelerator. The curing behaviors of cured VE resins with styrene were evaluated by DSC measurements. The prepared VE curable resins were evaluated in the field of steel coating by measuring their mechanical properties and chemical resistance.
Keywords: Vinyl ester resins; Styrene; Coating; Rosin adducts; Epoxy resins;

The terpolymers containing oxadiazole pendant groups, obtained from chemical modification of a commercial polymer, present great interest due to their novelty and possible interesting properties. The synthesis of amidoxime-nitrile-3-hydroxyphenyl-1,2,4-oxadiazole (ANHOT) of different conversion times was prepared by chemical modification of polyacrylonitrile (PAN) as starting material. The first step of ANHOT synthesis was the well-known nitrile conversion into amidoxime groups. Afterwards, the 3,5-disubstituted 1,2,4-oxadiazolic ring was obtained by treatment of amidoxime-groups with an acyl chloride. The molecular structures were confirmed by IR, UV–Vis, 13C and 1H NMR spectroscopies. Conversion yields were calculated from elemental analysis. Thermal properties were studied by DSC and TGA techniques. All ANHOT series are completely soluble in very polar solvents. The dependency of viscosity with the conversion degree was analyzed with a control rate (CR) viscosimeter. Viscoelastic behavior was analyzed by rheometric measurements. The highest viscosity and elastic behavior were obtained with ANHOT of an hour conversion time; in this way it is the most attractive polymer among the ANHOT series.
Keywords: Amidoxime-nitrile-3-hydroxyphenyl-1,2,4-oxadiazole terpolymer; Polyacrylonitrile; High viscosity;

Studies on N-methylene phosphonic chitosan/poly(vinyl alcohol) composite proton-exchange membrane by V.V. Binsu; R.K. Nagarale; Vinod K. Shahi; P.K. Ghosh (1619-1629).
This study describes the modification of chitosan by introducing phosphonic acid group, which was confirmed by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) and preparation of its composite membranes with poly(vinyl alcohol) of different compositions. These membranes were extensively characterized for their morphology by scanning electron microscopy (SEM), thermal, mechanical and dimensional stability by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and water uptake measurements at different temperatures. Different electrochemical properties such as ion-exchange capacity, proton transport number, proton conductivity, activation energy needed for the proton transfer, and methanol permeabilities of these membranes were also measured and compared with those Nafion 117 membrane. All these membranes exhibited comparable proton transport number and conductivity with Nafion 117 membrane, but quite lower methanol permeability compared to Nafion 117 renders their applications to direct methanol fuel cells (DMFC). Furthermore, selectivity parameters for DMFC of all the synthesized membranes are much higher in comparison to Nafion 117 membrane.
Keywords: Proton-exchange membrane; Composite membrane; N-methylene phosphonic chitosan; Membrane conductivity; Methanol permeability;

Novel amphiphilic graft polyphosphazenes (PNIPAm/EtGly-PPPs) bearing poly (N-isopropylacrylamide) (PNIPAm) as a hydrophilic segment and ethyl glycinate (EtGly) as a hydrophobic group were synthesized via ring-opening polymerization and subsequent substitution reaction. The lower critical solution temperature (LCST) of copolymers was investigated by turbidity method using UV–Vis spectroscopy. Copolymers show their LCSTs in the range of 18.5–33 °C, depending on the mole ratio of the substituents. The self-assembly characteristics of copolymers in aqueous solution was studied by using fluorescence technique, dynamic light scattering (DLS), and TEM. The critical association concentration (CAC) of copolymers varied from 0.112 to 0.0309 g/L, was related with the mole ratio of PNIPAm to EtGly. The TEM images showed self-assembled nanoparticles with a spherical shape at about 30 °C, while network-like aggregates were observed for copolymer with high PNIPAm content at relatively low temperature. The particle size of nanoparticles, depending on copolymer compositions, was in the range of 80–900 nm at 25 °C. These copolymers may be used as injectable drug carriers for the delivery of hydrophobic compounds.
Keywords: Amphiphilic copolymers; Polyphosphazenes; Self-assembly; Nanoparticles; Drug carriers;

Adsorption of phenol on clustered micro-sphere porous beads made of cross-linked poly-4-vinylpyridine by Nariyoshi Kawabata; Yuya Tsuchida; Yutaka Nakamori; Mitsunobu Kitamura (1641-1648).
Clustered micro-sphere porous beads made of cross-linked poly-4-vinylpyridine were proposed as a new style polymeric adsorbent useful for separation technology. In batch adsorption experiments, rate of adsorption of phenol on the clustered porous beads was much faster than that with conventional porous beads having a similar BET surface area. In adsorption experiments studied by a continuous flow column method, the clustered micro-sphere porous beads exhibited much sharper breakthrough curve and elution curve when compared with those obtained with the conventional porous beads. These marked differences in adsorptions were explained in terms of much smaller size of the micro-sphere porous beads.
Keywords: Adsorption; Functional polymer; High performance polymer; Cross-linked polyvinylpyridine; Radical copolymerization; Separation techniques;

Polyaniline Sn(IV) phosphate, an ‘organic–inorganic’ composite material, was synthesized via sol–gel mixing of an electrically conducting organic polymer polyaniline into the matrices of inorganic precipitate of Sn(IV) phosphate. This material was used as a cation-exchanger. The physico-chemical properties of the material were determined using AAS, CHN elemental analysis, ICP-MS, UV–VIS spectrophotometry, FTIR, TGA–DTA, XRD, and SEM studies. Ion-exchange capacity, chemical stability, thermal stability and distribution behavior were also carried out to understand the cation-exchange behavior of the material. On the basis of distribution studies, the material was found to be highly selective for Pb(II). Its selectivity was examined by achieving some important binary separations like Pb(II)–Mg(II), Pb(II)–Sr(II), Pb(II)–Zn(II), and Pb(II)–Fe(III) on its column. This material possessed DC electrical conductivity in the semi-conducting range, i.e. 10−5–10−3  S cm−1. The stability in terms of DC electrical conductivity retention was also studied in an oxidative environment by two slightly different techniques viz. isothermal and cyclic techniques. The DC electrical conductivity of composite material was found stable upto 110 °C under ambient conditions.
Keywords: Organic–inorganic composite material; Cation-exchanger; Electrical conductivity; Stability in terms of DC electrical conductivity retention; Polyaniline Sn(IV) phosphate;

Novel fluorescent copolymers of styrene with benzazole chromophores by M.R. Becker; V. Stefani; M.M.C. Forte (1664-1669).
Novel green fluorescent copolymers of styrene and 2-[(5′-N-acryloyl)-2′-hydroxyphenyl]benzoxazole or 2-[(5′-N-acryloyl)-2′-hydroxyphenyl]benzothiazole were synthesized by radical polymerization. The copolymers were characterized by size exclusion chromatography, thermal analyses (DSC, TGA), UV–Vis and fluorescence spectrophotometry. The glass transition temperatures of the fluorescent copolymers were similar to that of the parent polystyrene and the average molecular weight was lower due to the chain transfer effect of the benzazole dyes. The maximum fluorescence emission wavelength of the copolymers in the solid state or in chloroform solution accessed by fluorescence spectrophotometry was also similar. The Stokes shift of the styrene–benzoxazole or –benzothiazole copolymers was similar to those presented by fluorochromes that exhibit an excited state intramolecular proton transfer mechanism.
Keywords: Fluorescence; ESIPT; Benzazole; Fluorescent copolymer;

Electrochemical oxidative polymerization of sodium 4-amino-3-hydroxynaphthalene-1-sulfonate and structural characterization of polymeric products by G. Ćirić-Marjanović; M. Trchová; P. Matějka; P. Holler; B. Marjanović; I. Juranić (1670-1683).
The new semiconducting, electroactive, water-soluble polymeric material has been synthesized by the electrochemical polymerization of sodium 4-amino-3-hydroxynaphthalene-1-sulfonate (AHNSA–Na salt), from its aqueous solution. The polymeric products were characterized by gel permeation chromatography (GPC), conductivity measurements, cyclic voltammetry, and UV–visible, FTIR, Raman, NMR (1H and 13C) and electron spin resonance (ESR) spectroscopic techniques. GPC profile evidenced chains of molecular weights up to ∼6300, and revealed oligomers (8-mer to 12-mer) as predominant species. FTIR spectroscopy findings of newly formed substitution patterns on naphthalene rings in the poly(AHNSA–Na salt) are well correlated with main coupling modes theoretically predicted by MNDO-PM3 semi-empirical quantum mechanical calculations. Based on these studies, it has been found that the poly(AHNSA–Na salt) consists mainly of dimer units formed via N–C6 and N–C8 coupling reactions. The paramagnetic nature of the poly(AHNSA–Na salt) has been proved by ESR spectroscopy, and its redox activity was confirmed by cyclic voltammetry. Intensity ratio of two new bands in the UV–visible spectrum assigned to the poly(AHNSA–Na salt) polaronic and bipolaronic forms, and the presence of naphthoiminoquinonoid and benzenoid segments detected by FTIR and Raman spectroscopy, indicate prevalence of partly and fully oxidized bipolaronic forms of the poly(AHNSA–Na salt).
Keywords: Electrochemical polymerization; Poly(sodium 4-amino-3-hydroxynaphthalene-1-sulfonate); Coupling mode; Redox form;

2,3-Branching benzyl ether dendrimers for the enhancement of dental composites by Noel M. Paul; Scott J. Bader; Scott R. Schricker; Jon R. Parquette (1684-1695).
The globular and highly branching nature of the 2,3-dihydroxybenzyl motif was utilized in the development of novel dental composite additives. Dental composites were formulated with varying percentages of multi-methacrylated dendritic additives and evaluated for the corresponding influence on material properties. The flexural strength of composites containing only 0.5% of multi-methacrylate dendritic additive improved 21–35%, compared with control. Addition of higher molecular weight (Mw) dendrimers resulted in composites with greater flexural strength. Higher concentrations of additive afforded no additional benefit to the composite strength. The degree of polymerization as a function of increasing additive Mw or concentration indicates a strong dependency on the diffusion coefficient of the dendrimer. Low concentrations of dendritic additive effected up to an 85% decrease in acetone-extractable material from the cured composite matrix. These studies demonstrate the ability of highly globular, highly cross-linking additives to improve composite properties even at very low concentrations.
Keywords: Dendrimers; Hyperbranched polymer; Polybenzyl ether; Flexural strength; Degree of polymerization; BisEMA; HDMA; Dental composite restorative;

Ring-opening polymerization of ε-caprolactone using a proton exchanged montmorillonite clay as initiator is reported. Effect of reaction temperature, solvent, weight ratio of initiator/monomer and reaction time on the conversion of monomer and the molecular weight are investigated .The kinetics indicated that the polymerization rate is first order with respect to monomer concentration and initiator concentration,respectively. Rate constants of bulk and in solution polymerizations are determinated at 80 °C. Mechanism studies showed that monomer inserted into the growing chains with the acyl–oxygen bond scission rather than the break of alkyl–oxygen bond.
Keywords: Montmorillonite; Ring-opening polymerization; ε-Caprolactone; Poly(ε-caprolactone);

Polyaniline incorporating cobalt ions from CoCl2 solutions by Magdalena Hasik; Izabela Kurkowska; Andrzej Bernasik (1703-1710).
The incorporation of cobalt ions from various CoCl2 solutions into polyaniline (PANI) has been investigated. PANI powders containing cobalt ions were obtained by suspending PANI in the following CoCl2 solutions: in H2O, in aqueous HCl, in aqueous LiCl and in acetonitrile. Thin films were prepared from a solution of PANI and CoCl2 in N-methylpyrrolidone by evaporating the solvent. Both the powders and thin films were investigated using various experimental techniques including UV/Vis, IR and XPS spectroscopies. The optimum conditions for preparation of PANI/Co powders were established and the chemical reactions taking place during the powder preparation examined. These results can be explained by consideration of the cobalt(II) species present in the reaction media.
Keywords: Polyaniline; Cobalt ions; Spectroscopic studies;

Preparation and characterization of crosslinked polysucrose microspheres by Xin Hou; Jing Yang; Jincheng Tang; Xiaomin Chen; Xiukui Wang; Kangde Yao (1711-1717).
A series of novel crosslinked polysucrose (PS) microspheres were prepared by a two-stage polymerization. A soluble (linear and/or comb) polysucrose was firstly synthesized by solution polymerization of sucrose and epichlorohydrin (EP); then the crosslinked polysucrose microspheres were prepared by reversed suspension polymerization of soluble PS with EP in chlorobenzene containing Span 80. The characterization by OM and SEM indicates that these spherical beads in diameters with the range from 250 to 450 μm have smooth surface. The hydrated and dry densities, equilibrium water contents, and hydroxyl loadings of PS microspheres were investigated. The equilibrium water content values of these microspheres changed from 79.6% to 94.1%, and the hydroxyl contents were 15.5–19.0 m mol/g dependent on the crosslinking degrees.
Keywords: Polysucrose; Microspheres; Reversed suspension polymerization; Epichlorohydrin;

A set of poly(triazinylstyrene)s containing ethylenediamine (PEd1 and PEd2) and pyridine (PAp2) moieties was prepared by the radical polymerization, in which PEd1 and PEd2 were synthesized at the lower temperature to avoid the gel formation. PEd2 having two hydrophilic ethylenediamine side chains could selectively bind copper(II) ion from an aqueous buffer solution containing individual metal(II) sulfate; on the other hand, PEd1 and PAp2 showed a poor chelating ability. Polymer catalysts prepared from copper(II) nitrate were subjected to the oxidation reaction of p-hydroquinone to analyze whether the complex bearing ethylenediamine moiety showed a higher catalytic activity. The activity of the catalyst improved with increasing pH of the reaction media, especially in the catalyst prepared from PEd2.
Keywords: Radical polymerization; Polymer ligand; Metal ion adsorption; Heterogeneous catalyst;

Molecularly imprinted polymer (MIP) shells are presented which have been synthesised by co-polymerising a functional monomer and a cross-linker around amino-functionalised silica particles with template molecules immobilised on their surfaces. In a subsequent step, the silica cores together with the template molecules have been dissolved by treatment with hydrofluoric acid. Due to the use of a transition state analogue of a hydrolysis reaction as template, the resulting polymer shells equipped with molecular imprints on their inner surfaces offer catalytic activity regarding the selected hydrolysis reaction. Furthermore, the molecular imprints, i.e., the catalytically active binding sites, have been provided with steric information, since an immobilised chiral phosphonate has been used as template. The findings presented here, can be considered as a new starting point with respect to the generation of enantioselective MIP-catalysts.
Keywords: Molecular imprinting; Polymer; Chiral template; Immobilised; Catalysis; Enantioselective; Hydrolysis;

Selective separation of quercetin by molecular imprinting using chitosan beads as functional matrix by Yong-qing Xia; Tian-ying Guo; Mou-dao Song; Bang-hua Zhang; Bao-long Zhang (1734-1740).
A molecularly imprinted polymer (MIP) material was prepared using quercetin as the imprinted molecule, methacrylic acid as functional monomer and macroporous chitosan beads as functional matrix. The obtained molecularly imprinted polymer materials were evaluated by liquid chromatograph using acetonitrile–methanol as mobile phase, with respect to their selective recognition properties for quercetin. The MIP exhibited a higher selectivity for quercetin in a mixture of flavonoids than the non-imprinted polymer (NIP). The Langmuir and Freundlich adsorption models were also applied to describe the equilibrium isotherms.
Keywords: Chitosan beads; Molecular imprinting; Quercetin;

A novel polyaniline–maleicacid–dodecylhydrogensulfate salt: Soluble polyaniline powder by Srinivasan Palaniappan; Chellachamy Anbalagan Amarnath (1741-1748).
A novel soluble polyaniline powder, polyaniline–maleicacid–dodecylhydrogensulfate salt was synthesized directly via emulsion polymerization pathway using benzoyl peroxide oxidant, sodium dodecyl sulfate surfactant and maleic acid as effective dopant. Dry polyaniline powder is soluble in polar solvents like DMF, NMP, DMSO and maximum solubility was found to be 6% w/v. In this emulsion polymerization pathway, both acid group (maleic acid – 0.21 U per aniline group) and surfactant molecule (dodecylhydrogensulfate – 0.25 U per aniline group) were incorporated as dopant in the polyaniline chain. Long and nonpolar chain dopant present in the polyaniline chain may provide space for the polyaniline backbone and allows the penetration of solvent molecules inside the chain and induces solubility of polymer in polar solvents. Polyaniline salt showed nano sphere morphology with average diameter of 200 nm size. The influence of synthetic conditions such as the duration of the reaction, concentration of the reactants and solvent medium on the properties of polyaniline was investigated to determine the optimum conditions for the synthesis of polyaniline salt. The conductivity of polyaniline salt was found to be 10−1  S/cm.
Keywords: Soluble polyaniline salt; Polar solvents; Dodecylhydrogensulfate; Maleic acid;

Thermodynamics of interphase equilibrium in system ion exchanger-solution of low molecular weight electrolyte by N.B. Ferapontov; V.I. Gorshkov; L.R. Parbuzina; N.L. Strusovskaya; A.N. Gagarin (1749-1756).
This work deals with thermodynamic description of equilibrium between an ion exchange resin and the solution of low molecular weight electrolyte. The suggested approach allows calculating thermodynamic constant of ion exchange equilibrium.In order to calculate the activity of ion exchange groups in the resin having monoionic form we used published reference data assuming that the activity of resin exchange sites and that of corresponding monomer are equal in the solutions with equal concentrations. For ion exchange resin in mixed form in equilibrium with the mixed solution of corresponding low molecular weight electrolytes the method of calculating each of ionic forms was also suggested. These activities were used to determine the constant of ion exchange equilibrium.
Keywords: Ion-exchange resin; Equilibrium; Theory;

Plasma polymerized acrylic acid (PPAA) coatings were deposited on PE films, in a 70 kHz low pressure plasma reactor, at various plasma powers. The COOH retention of PPAA coatings and its stability to washing in water were investigated by XPS, WCA (water contact angle), FTIR, ellipsometry and SEM analyses. The results have shown that the use of higher powers leads to an increase of the stability of the coating due to a high degree of cross-linking. Under optimized conditions, it is possible to obtain stable PPAA coatings which resist to washing with a COOH retention rate of 15% on PE, which is much higher than the coating deposited in a 13.56 MHz discharge. This high stability of the coatings observed in the low frequency discharge, which is somewhat similar to DC glow discharges, is probably due to the ions which play an important role in the cross linking process of the coatings. Optical emission spectroscopy measurements (OES) have shown good correlation between the CO density in the gas phase and the carboxylic content of PPAA coating.
Keywords: Water stability; Plasma polymerization; Acrylic acid; Carboxylic groups;