Reactive and Functional Polymers (v.55, #1)

Polyacrylamide was grafted from N-chlorosulfonamide groups onto crosslinked polystyrene beads using copper-mediated atom transfer radical polymerization (ATRP) methodology. A beaded polymer with a polyacrylamide surface shell was prepared in four steps, starting from styrene–divinylbenzene (10%) copolymer beads of 210–420 μm particle size: chlorosulfonation; sulfamidation with propylamine; N-chlorination with aqueous hypochloride; and grafting using a concentrated aqueous acrylamide solution with a CuBr–tetramethylethylenediamine complex (1:2). The resulting polymer resin with 84 wt% grafted polyacrylamide has been demonstrated to be an efficient mercury-specific sorbent, able to remove Hg(II) from solutions at ppm levels. No interference arises from common metal ions such as Cd(II), Fe(III), Zn(II), and Pb(II). The sorbed mercury can be eluted by repeated treatment with hot acetic acid without hydrolysis of the amide groups.
Keywords: Mercury extraction; Mercury-specific polystyrene sorbent; Grafting by ATRP; Polyacrylamide graft;

Polyacrylates in aqueous solution. The dependence of protonation on molecular weight, ionic medium and ionic strength by Concetta De Stefano; Antonio Gianguzza; Daniela Piazzese; Silvio Sammartano (9-20).
The protonation constants of polyacrylates with different molecular weights (W=2000–750 000 Da) were determined in different ionic media (alkali metal chlorides and nitrates, tetraalkylammonium chlorides), at 25 °C, by potentiometric measurements (H+–glass electrode). Literature data were also considered. Different models used to analyse protonation data were compared: the first was the modified Henderson–Hasselbalch two-parameter equation, and the second was the three-parameter equation proposed by Högfeldt. The dependence on the ionic strength of the different supporting electrolytes and all the protonation parameters involved in the two models showed the trend Et4N+≫Li+>Na+≥K+, in accordance with the tendencies of these cations to interact with polycarboxylates. The dependence on molecular weight shows a slightly increasing effect with N (number of monomer units in the polyelectrolyte). Empirical relationships were found for the dependence of the protonation parameters on both ionic strength (I/mol l−1) and N. The use of protonation data was considered for polyacrylates in speciation studies, and specific interaction parameters were calculated according to the SIT (Specific Ion Interaction Theory) model.
Keywords: Polyacrylates; Acid–base properties; Medium effects; Dependence on molecular weight; Predictive relationships; Specific interaction parameters;

Nanostructure and molecular accessibility of gel-type resins for supported bio-catalysis by Manola Turacchio; Giovanna Di Nino; Angelo A. D’Archivio; Karel Jerábek; Silvano Lora; Giovanni Antonini; Benedetto Corain (21-26).
Hydroxyethylmethacrylate (HEMA), hydroxypropylmethacrylate (HPMA) and trimethylolpropanetrymethacrylate (TMPTM) are copolymerised by γ-irradiation to give five potentially amphiphilic gel-type resins. The molar fraction of TMPTM (the cross-linker) is constant (4 mol%) while the five resins are featured by different HEMA/HPMA molar ratios (96/0, 68/28, 48/48, 28/68 and 0/96, respectively). The swollen state morphology of the five materials is investigated by means of inverse steric exclusion chromatography (ISEC) and electron spin resonance (ESR) spectroscopy based on the spin-probe TEMPONE (2,2,6,6-tetramethyl-4-oxo-1-oxyl-piperidine) both in water and tetrahydrofuran (THF). In THF, swelling and accessibility of the polymer network increase with the increase in HPMA content. In contrast, the five materials are poorly swollen by water and no apparent dependence of swelling on HPMA/HEMA ratio is detected.
Keywords: Amphiphiles; Resins; Swelling; Morphology; ESR;

Polymer supported iminodipropylene glycol functions for removal of boron by Bahire Filiz Senkal; Niyazi Bicak (27-33).
Polymer supported iminodipropylene glycol functions have been shown to be efficient in chelation with boric acid and can be used for removal of boric acid at ppm levels. Glycidyl methacrylate (GMA)–methyl methacrylate (MMA)–DVB (divinyl benzene) terpolymer beads have been prepared and used as support. The polymer support with 3.4 mmol g−1 oxirane content can be readily modified by reacting with an excess of ethylene diamine, in high conversion yields (99.1%). Reaction of the latter with glycidol gives corresponding resin with aminopropylene glycol functions. The resulting resin has been demonstrated to be an efficient sorbent for removal of boron. The resin has 3 mmol g−1 of boron loading capacity and shows reasonably rapid sorption ability so that boron in 10 ml of H3BO3 solution (50 ppm) can be removed almost completely in less than 12 min of contact time by 0.5 g of polymer sample. Splitting of sorbed boron can be achieved by simple acid leaching (4 M HCl) and regenerated by NaOH solution (0.1 M).
Keywords: Boron specific resin; Boron removal; Polyglycidyl methacrylate; Iminopropylene glycol functions;

Preparation and characterization of CdS quantum dots chitosan biocomposite by Zhan Li; Yumin Du; Zhiling Zhang; Daiwen Pang (35-43).
In this paper biopolymer chitosan was used as a matrix to fabricate cadmium sulfide (CdS) quantum dots (QDs) with a narrow size distribution under mild conditions, resulting in a novel QDs biocomposite. The CdS QDs, whose size can be controlled by varying the reaction time and precursor concentration, were characterized by TEM and XRD. The limitation on CdS particle growth and agglomeration by chitosan was suggested by UV–vis spectrum and TEM results. FTIR-attenuated total reflectance (ATR) revealed strong hydrogen bonding between the CdS QDs and chitosan via N2 and O3 groups. This interaction was also reflected in AFM, XRD and swelling study results. The chitosan-capped CdS QDs exhibited improved aqueous solubility and stability. On the other hand, in the presence of CdS QDs, the thermal decomposition of chitosan was shifted toward a higher temperature by about 50 °C.
Keywords: Chitosan; CdS QDs; Biocomposite; Interaction;

The aim of this study was to explore in detail the performance of polyamide hollow fibers to which Cibacron Blue F3GA was attached for adsorption of proteins. Model proteins were glucose oxidase, as a flavo-enzyme and contains two tightly bound flavine adenine dinucleotide cofactor, and catalase as a heme-containing metallo-enzyme. The hollow fiber structure was characterized by scanning electron microscopy. These dye-carrying hollow-fibers (35.8 μmol/g) were used in the glucose oxidase and catalase adsorption–elution studies. The non-specific adsorption values were 1.25 mg/g for glucose oxidase and 1.97 mg/g for catalase. Cibacron Blue F3GA attachment increased the adsorption capacity up to 248 mg/g. Langmuir adsorption model was found to be applicable in interpreting glucose oxidase and catalase adsorption by Cibacron Blue F3GA-attached hollow fibers. Significant amount of the adsorbed proteins (up to 97%) was eluted in 1 h in the elution medium containing 1.0 M NaSCN at pH 8.0. In order to determine the effects of adsorption and elution conditions on possible conformational changes of studied protein structures, fluorescence spectrophotometry was employed. It was concluded that polyamide dye-affinity hollow-fibers can be applied for glucose oxidase and catalase adsorption without causing any significant conformational changes. Repeated adsorption/elution processes showed that these dye-attached hollow-fibers are suitable for glucose oxidase and catalase separation.
Keywords: Hollow-fibers; Cibacron Blue F3GA; Glucose oxidase; Catalase; Dye affinity adsorbents; Polyamide;

Interpenetrating polymer network (IPN) hydrogels composed of poly(vinyl alcohol) (PVA) and chitosan were prepared by UV irradiation. The characteristics of IPN hydrogels were investigated by swelling experiments, Fourier transform infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC). IPN hydrogels exhibited a relatively high swelling ratio in the range of 210–350% at 35 °C. The swelling ratio of PVA/chitosan IPN hydrogels depended on pH and temperature. DSC was used for the quantitative determination of the amounts of freezing and non-freezing water. Free water contents in IPN1, IPN2 and IPN3 were 62.0, 69.6 and 72.3% in pure water, respectively.
Keywords: Interpenetrating polymer network; Poly(vinyl alcohol); Chitosan; Swelling;

Interpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) (PVA) and poly(N-isopropylacrylamide) (PNIPAAm) were prepared by the sequential-IPN method. The characterizations of IPN hydrogels were investigated by swelling experiment, Fourier transform infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC). IPN hydrogels exhibited a relatively high swelling ratio in the range 180–300% at 35 °C. The swelling ratio of hydrogels depended on pH and temperature. DSC was used for the quantitative determination of the amounts of freezing and non-freezing water. Free water contents in the hydrogels IPN1, IPN2 and IPN3 were 45.8, 37.9 and 33.1% in pure water, respectively.
Keywords: Interpenetrating polymer network; Poly(vinyl alcohol); Poly(N-isopropylacrylamide); Hydrogel;

Interpenetrating polymer network (IPN) hydrogels based on poly(propylene glycol) (PPG) and poly(acrylic acid) (PAAc) were prepared by UV irradiation and equilibrium water uptake (EW) and diffusion coefficients were measured by dynamic vapor sorption system (DVS). The EW of IPN hydrogels increased with increasing the PAAc content in IPN hydrogels. With an increase in the hydrophilic content of the IPN hydrogels, the values of diffusion coefficients were found to increase due to greater penetration of water into the hydrogels. Diffusion coefficients of IPN hydrogels increased with increasing temperature and decreased with increasing content of PPG.
Keywords: Interpenetrating polymer network; Poly(acrylic acid); Poly(propylene glycol); Water sorption;

The donor–acceptor type norbornadiene (D–A NBD) carboxylic acids containing carbamoyl groups such as dipropylcarbamoyl, methylphenylcarbamoyl, propylcarbamoyl, and phenylcarbamoyl groups were synthesized in good yields. Benzyl esters of the D–A NBD carboxylic acids were also prepared by the reaction of D–A NBD carboxylic acids with benzyl bromide as reference compounds for the polymers. Polystyrenes with pendant D–A NBDs were prepared with 100% degree of substitution by the reaction of D–A NBD carboxylic acids and poly[(p-chloromethyl)styrene] at 70 °C for 6 h using 1,8-diazabicyclo[5.4.0]undecene-7 as a base in N-methylpyrrolidone. The photochemical valence isomerizations of the reference compounds and all the NBD polymers were examined upon UV-irradiation in THF solution or in the film state, and it was found that the polymer containing phenylcarbamoyl group had especially high photoreactivity. In addition, the rate of the photochemical reaction of the NBD polymers increased efficiently by the addition of 4,4′-bis(diethylamino)benzophenone as photosensitizer in the film state, and all the NBD groups of the polymers isomerized to the QC group in as little as only 20 s. The stored thermal energy of the irradiated polymers was also evaluated by DSC to be 32–52 kJ/mol.
Keywords: Donor–acceptor type norbornadiene; 1,8-Diazabicyclo[5.4.0]undecene-7; Photochemical valence isomerization; Photosensitizer; Quadricyclane; Stored energy;

Polyacrylonitrile-2-amino-2-thiazoline resin (PAN-ATAL) was synthesized from macroporous type crosslinked polyacrylonitrile and 2-amino-2-thiazoline. The functional group capacity and percentage conversion of functional group of PAN-ATAL prepared under the optimum condition were 2.002 mmol FG/g and 15.90%, respectively. The structure of PAN-ATAL was confirmed by elemental analysis and X-ray photoelectron spectroscopy (XPS). The sorption capacities of PAN-ATAL for Rh(III), Ru(IV), Ir(IV) and Pd(II) were 72.07, 137.6, 147.1 and 230.7 mg/g resin, respectively. PAN-ATAL resin has excellent sorption selectivity for Pd(II) and Rh(III) in the presence of common metal ions over a wide acidity range. The sorption rate constants of PAN-ATAL resin for Rh(III) and Ir(IV) were determined. The apparent sorption activation energy (E a) of PAN-ATAL for Ru(IV) and Ir(IV) was 58.8±0.6 kJ mol−1 and 65.9±0.9 kJ mol−1, respectively.
Keywords: PAN-ATAL resin; 2-Amino-2-thiazoline; Sorption; Rh, Ru, Pd, Ir; Sorption activation energy;

Since the discovery of the implication of aluminium in dialysis encephalopathy, much progress has been made in the preparation of dialysis water from which the metal is now virtually excluded. In this study, Alizarin Yellow-attached magnetic poly(2-hydroxyethyl methacrylate) (mPHEMA) beads were investigated as a specific adsorbent for aluminium removal from both drinking and dialysis water. Magnetic PHEMA beads in the size range of 80–120 μm were produced by a dispersion polymerization technique. Then Alizarin Yellow was covalently attached onto mPHEMA beads. Al(III) adsorption from aqueous solutions was examined in a batch system. Alizarin Yellow-attached mPHEMA beads were characterized by scanning electron microscopy (SEM) and elemental analysis. The mPHEMA beads have a spherical shape and porous structure. Alizarin Yellow loading was found to be 208 μmol/g polymer. Non-specific Al(III) adsorption was about 23 μmol/g polymer. Alizarin loading greatly improved the adsorption capacity (420 μmol/g polymer). The maximum Al(III) adsorption was observed at pH 5.0. Adsorption capacity of the Alizarin Yellow-attached beads from drinking and dialysis water for Al(III) ions was higher than that for other ions (i.e. Cu(II), Fe(III) and Zn(II)). More than 90% of the adsorbed Al(III) ions were desorbed successfully using 2.0 M HNO3 solution. It was possible to reuse these Alizarin Yellow-attached mPHEMA beads without significant losses in the Al(III) adsorption capacities.
Keywords: Aluminium; Dye-affinity adsorbents; Magnetic beads; Alizarin Yellow; PHEMA;