Radiation-induced Graft Polymerization Research Articles

Preparation of permeability-controlled track membranes on the basis of ‘smart’ polymers

The modification of polymer track membranes from polyethylene terephtalate (PET) and polypropylene (PP) was performed by radiation-induced graft polymerization of thermosensitive poly- N -isopropylacrylamide (poly-NIPAAM). The opening and closing of the pores was controlled by temperature and studied by the electric conductivity and water flow methods. The structure of the grafted membranes was investigated by scanning electron and atomic force microscopy.

Radiation-induced graft polymerization of acrylic acid onto poly(tetrafluoroethylene-perfluorovinyl ether) copolymer films: complexation with some transition metals and biological activity

The radiation-induced grafting of acrylic acid onto poly(tetrafluoroethylene-perfluorovinyl ether) copolymer film was carried out to synthesize graft copolymer membranes of complexing ability with some selected transition metal ions such as Cr III, Mn II, Cu II, Ag I and Cd II. The complex formation of these graft copolymer–metal complexes was studied by atomic absorption spectroscopy, X-ray fluorescence, IR, UV and electron spin resonance spectrometry. The overall results suggest octahedral geometry for both Cr III and Mn II but square planar for Cu II. The results revealed the high stability of the obtained ligand–metal complexes. The biological activity of the grafted film and its complexes with various metal ions was investigated under the same conditions. Silver (I) complexed membrane had a strong biocidal effect for all tested bacteria. The biological activity for Cr III complex has been effected on E. coli and S. aureus, whereas the Cd II complex has its effect on E. coli, B. anthrax and B. cereus. The Cu II complex has only antifungal activity. No biological effect has appeared for both the grafted film or Mn II complexed one on either bacteria or fungi.

High-speed recovery of germanium in a convection-aided mode using functional porous hollow-fiber membranes

A porous hollow-fiber membrane capable of recovery of germanium from a liquid stream was prepared by radiation-induced graft polymerization of an epoxy-group-containing vinyl monomer, glycidyl methacrylate, and subsequent functionalization with 2,2′-iminodiethanol, di-2-propanolamine, N-methylglucamine, and 3-amino-1,2-propanediol. The functional group density was as high as 1.4 mol per kg of the resultant hollow fiber. The polymer chains containing functional groups surrounding the pores enabled a high-speed recovery of germanium during permeation of a germanium oxide (GeO 2) solution through the pores of the hollow fiber. Because of a negligible diffusional mass-transfer resistance, germanium concentration changes with the effluent volume, i.e., breakthrough curves, overlapped irrespective of the residence time of the solution, which ranged from 0.37 to 3.7 s across the hollow fiber. After repeated use of adsorption and elution, the adsorption capacity did not deteriorate.

Comparison of Amidoxime Adsorbents Prepared by Cografting Methacrylic Acid and 2-Hydroxyethyl Methacrylate with Acrylonitrile onto Polyethylene

Methacrylic acid (MAA) and 2-hydroxyethyl methacrylate (HEMA) were cografted with acrylonitrile (AN) onto polyethylene fiber by radiation-induced graft polymerization. The cyano groups produced were converted to amidoxime groups (−C(NOH)NH2) by reaction with hydroxylamine (NH2OH) to recover uranium in seawater. Various weight ratios of AN/MAA or AN/HEMA in the monomer mixture for cografting generated MAA- and HEMA-cografted amidoxime (AO) fibers with various hydrophilicities. The amidoxime group density and water content were balanced to enhance the uranium adsorption from seawater. MAA-cografted AO fibers exhibited a higher adsorption rate than HEMA-cografted AO fibers. The optimum value of the weight ratio of AN/MAA = 60/40 in the monomer mixture was observed both in a submerged mode at an ocean site and in a flow-through mode in the laboratory. The amount of uranium adsorbed was 0.90 g/kg of the MAA-cografted AO fiber at 293−298 K after 20 days of contact at the ocean site.

Multilayer binding of proteins to polymer chains grafted onto porous hollow-fiber membranes containing different anion-exchange groups.

Various anion-exchange groups were introduced into the polymer chains grafted onto a porous hollow-fiber membrane for protein recovery by radiation-induced graft polymerization and subsequent functionalization of a monomer containing an epoxy group. The graft chains extended from the pore surface toward the pore interior, resulting in the multilayer binding of proteins to the graft chains. Combinations of three anion-exchange groups, namely, amino (AM), ethylamino (EA), and diethylamino (DEA) groups, and three proteins, namely, beta-lactoglobulin, bovine serum albumin, and urease, were examined to evaluate the degree of multilayer binding of protein to the graft chains in the permeation mode. Multilayer binding was observed for hollow-fiber membranes containing EA and DEA groups, with conversions of epoxy groups to EA or DEA groups of higher than 80%. The amount of adsorbed protein remained constant irrespective of the conversion for the hollow-fiber membrane containing an AM group. The dependence of the flux on the conversion was consistent with that of the degree of multilayer binding to the graft chains.

Properties of polymer track membranes modified by grafting with poly(2-methyl-5-vinylpyridine) and poly(N-isopropylacrylamide)

The properties of track membranes (TM) based on poly(ethylene terephthalate) (PETP) and polypropylene (PP) and modified by radiation-induced graft polymerization of 2-methyl-5-vinylpyridine (MVP) andN-isopropylacrylamide (NIPAA) were studied. The rate of grafting and the limiting degree of grafting increase linearly as the pore diameter of TM increases. The gasdynamic and hydrodynamic pore diameters of modified TM were determined. The dependence of water permeability of TM modified by grafting with poly(2-methyl-5-vinylpyridine) (PMVP) on the degree of grafting passes through a maximum, which, according to the data of wetting angle measurements, corresponds to the maximum hydrophilicity. The negative χ-potential of TM changes sign after modification by grafting with PMVP. Thermosensitive TM based on PETP and PP were prepared by radiation-induced graft polymerization of NIPAA. The structure of modified TM was studied by electron microscopy and atomic force microscopy.

Radiation grafting of N,N-dimethylaminoethylmethacrylate onto poly(ethylene terephthalate)

Radiation-induced graft polymerization of N,N-dimethylaminoethylmethacrylate (DMAEMA) from 50% solution in chloroform onto poly(ethylene terephthalate) (PET) was carried out by means of mutual γ-irradiation of polymer in presence of liquid or vapor phase monomer solutions (direct method), or by grafting of monomer from this liquid solution onto polymer preirradiated in air. It has been shown higher effectiveness of grafting by the direct method from vapor phase of monomer or by the preirradiation method as compared with direct grafting from liquid monomer solution. Grafting did not affect crystallinity, transparency and durability of the starting PET.

Study the effect of gamma irradiation on optical and morphological properties of grafted low density polyethylene

Radiation-induced graft polymerization of acrylamide (AAm) onto low density polyethylene (LDPE) samples has been investigated. The appropriate reaction conditions at which the grafting process occurred were enhanced significantly by using dioxane as solvent. The optical absorption as a function of grafted ratio from 1.4% to 24.2% and γ irradiation dose for low-density polyethylene (LDPE) is presented. The optical absorption spectra were measured in the wavelength range from 200 to 1100 nm at integrated γ-doses from 1 to 20 Mrad. The calculated absorption coefficients and the determined values of energy gaps (E0pt and ΔE) were found to be γ-irradiation dependent. The results indicated that, for LDPE, the validity of the Urbach rule depends on the grafting and the irradiation dose. The morphological stability of grafted LDPE is investigated. Moreover, effect of γ-radiation on the stability of these morphologies, is examined. The results show that the morphology affect by low grafting is cracking, buckling and pock marking and for high grafting the contrast between faces was improved. After radiation, the carbon black aggregates are smaller than before and the pock marking and cracking more obvious.

Radiation-induced graft polymerization and sulfonation of glycidyl methacrylate on to porous hollow-fiber membranes with different pore sizes

Abstract An epoxy group containing monomer, glycidyl methacrylate, was grafted on to a porous hollow-fiber membrane, made of polyethylene, whose different pore sizes ranged from 0.2 to 0.5 μm. The resulting epoxy group was converted into a sulfonic acid group as a cation-exchange group to capture metal ions. The porous network was retained after grafting and subsequent sulfonation because the poly-GMA chains invaded the polymer matrix. An increase in the SO3H group density of the graft chain decreased the permeability of pure water because the graft chains expanded toward the pore interior due to their mutual electrostatic repulsion. The ion-exchange adsorption of Pb ions during the permeation of a Pb(NO3)2 solution through the pores edged by the cation-exchange graft chains was observed with a negligible diffusional mass-transfer resistance.

Graft polymerization of N,N-dimethylaminoethylmethacrylate onto polycarbonates by the preirradiation method

Radiation-induced graft polymerization of N,N-dimethylaminoethylmethacrylate (DMAEMA) from solutions in carbon tetrachloride or in chloroform onto bisphenol A-derived polycarbonate (PC-1) and allyl diglycol carbonate (PC-2), respectively, was carried out by method of preirradiation in air. It has been found essential difference in transparency and durability of the modified PC-1 and PC-2. Effects of preirradiation dose as well as temperature and time of graft polymerization on effectiveness of DMAEMA grafting onto PC-2 were investigated, the optimal values of dose and temperature are 500 kGy and 55°C, respectively.

Novel heterocyclic synthesis and investigation on radiation-grafted low-density polyethylene with 2-N-vinylpyrrolidone

Radiation-induced graft polymerization of low-density polyethylene with N-vinylpyrrolidone, LDPE-g-PNVP, was used as a starting material for the synthesis of polyfunctionally substituted heterocyclic products. Thus, LDPE-g-PNVP reacts with ylidenemalononitrile derivatives to give the Michael addition products. In multistep reaction, LDPE-g-PNVP reacts with N,N-dimethylformamide dimethyl acetal (DMFDMA), hydrazine hydrate and malononitrile, respectively, to give a hydropyrrolopyridazine derivative. The latter could also be prepared via the reaction of LDPE-g-PNVP with DMFDMA, followed by treating with cyanoacetohydrazide. Also, LDPE-g-PNVP reacts with malononitrile to give an adduct product, dimer malononitrile derivative 13. The latter reacts with sulfur element to afford the thiophene derivative. Furthermore, this adduct reacts with hydrazine hydrate to isolate the original starting material, LDPE-g-PNVP, and aminopyridine derivative. The resulted films were characterized by infrared (IR) spectroscopy, 1H nuclear magnetic resonance (1H-NMR) mass spectroscopy, elemental analysis, swelling behavior, and electron scanning microscope. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2963–2970, 1999

Ionic crosslinking of SO 3H-group-containing graft chains helps to capture lysozyme in a permeation mode

SO 3H-group-containing polymer chains were grafted onto a porous hollow-fiber membrane uniformly across the thickness of the membrane (about 0.9 mm) by radiation-induced graft polymerization of glycidyl methacrylate and subsequent reaction with sodium sulfite. The graft chains extended from the pore surface due to their mutual electrostatic repulsion, and were crosslinked with bivalent ions such as Mg 2+ and Ca 2+, resulting in an increase in permeation rate of the liquid through the pores. Lysozyme was bound in multilayers to the SO 3H-group-containing graft chains, which had been previously crosslinked with Mg ions, and the permeation rate was increased with the progression of lysozyme binding based on the ion-exchange interaction with Mg ions.

Radiation grafting of styrene and acrylonitrile to cellulose and polyethylene

Abstract Radiation induced graft polymerization is one of the best methods for obtaining material with new properties. In this work, radiation grafting of styrene, mixture of styrene and acrylonitrile to cellulose and polyethylene in the presence of methanol as a solvent by mutual method is discussed. At a low dose rate, high grafting yields were obtained from the two systems used, due to lesser termination of free radicals with the polymer growing radicals and recombination of primary radicals, resulting in a longer chain length of the grafted copolymer. In the system of styrene and acrylonitrile, comonomer technique was used and the styrene controlled the homopolymer formation during graft polymerization. Water uptake of cellulose decreased by increasing the grafting yields. Grafted cellulose can be molded to some extent and in a high percent of grafting, a new transparent material was obtained. By radiation grafting of styrene–acrylonitrile to low density polyethylene a high degree of crosslinking was observed.

Preparation of silver-ion-loaded nonwoven fabric by radiation-induced graft polymerization

Sulfonic acid (SO 3H) groups were appended to three nonwoven fabrics made of polyethylene (PE), polypropylene (PP), and a hybrid of PP and PE by radiation-induced graft polymerization of glycidyl methacrylate (GMA) and subsequent ring-opening with sodium sulfite. Silver ion was loaded onto the resultant SO 3H-type cation-exchange nonwoven fabric at a density of 2.0 mmol g −1, where the molar ratio of Ag ions to SO 3H groups was unity.

Modification of poly(vinyltrimethylsilane) by radiation-induced graft polymerization

The modification of polyvinyltrimethylsilane (PVTMS) has been carried out using the radiation-induced graft polymerization. PVTMS is applied as a basis for gas-separating membranes. Acrylonitrile, acrolein, ethyl acrylate, acrylic acid and acrylamide were used as monomers. The grafting was performed both from vapour and liquid phase of monomers and their solutions by the direct radiation method. Some kinetic regularities of radiation graft polymerization of monomers and the character of distribution of grafted polymers along the thickness of PVTMS films were studied. It was shown that grafting improves the chemical resistance, the selective permeability of gases and some mechanical properties of PVTMS films.

The use of radiation-induced graft polymerization for modification of polymer track membranes

Track membranes (TM) made of poly(ethylene terephtalate) (PET) and polypropylene (PP) films have a number of peculiarities as compared with other ones. They have high mechanical strength at a low thickness, narrow pore size distribution, low content of extractables. However, TM have some disadvantages such as low chemical resistance in alkaline media (PET TM), the low water flow rate due to the hydrophobic nature of their surface. The use of radiation-induced graft polymerization makes it possible to improve the basic characteristics of TM. In this communication our results on the modification of PET and PP TM are presented. The modified membranes were prepared by radiation-induced graft polymerization from the liquid phase. Three methods of grafting were used: (a) the direct method in argon atmosphere; (b) the pre-irradiation of TM in air followed by grafting in argon atmosphere; (c) pre-irradiation in vacuum followed by grafting in vacuum without contacting oxygen. The aim of the work was to investigate some properties of TM modified by grafted poly(methylvinyl pyridine) (PMVP) and poly(N-isopropylacrylamide) (PNIPAAM). It was shown that the modification of TM with hydrophilic polymer results in the growth of the water flow rate. In the past few years many works have been devoted to the synthesis of new polymers – the so-called “intelligent” materials – such as PNIPAAM. However, it is very difficult to make thin membranes of this polymer. Recently, it has been proposed to manufacture composite membranes by grafting stimulus-responsive polymers onto TM. Following this principle, we prepared thermosensitive membranes by the radiation-induced graft polymerization of N-isopropylacrylamide (NIPAAM) onto PET TM. PET TM with the pore size of about 1 μm and pore density of 10 6 cm −2 were first inserted into a solution of NIPAAM containing inhibitor of homopolymerization (CuCl 2) and then exposed to the γ-rays from a 60Co source. The transport properties of the grafted TM were investigated. The permeation of water through the TM was controlled by temperature. The grafted TM exhibited almost the same transition temperature (about 33°C) as that of PNIPAAM.

Adsorption of CO2+ by stylene-g-polyethylene membrane bearing sulfonic acid groups modified by radiation-induced graft copolymerization

Cation-exchange hollow fiber membrane was prepared by radiation-induced grafting polymerization of styrene onto polyethylene hollow fiber membrane and its sulfonation. Adsorption characteristics for the cation-exchange membranes are examined when the solution of Co 2+ permeates across the cation-exchange fiber membrane. The maximum grafting peak was obtained from 70% styrene concentration at 50°C. The degree of grafting (%) was enhanced with additives such as H 2 SO 4 and divinylbenzene. The content of -SO 3 H groups ranged from 2 to 5 mmol g -1 with chlorosulfonic acid (ClSO 3 H) in dichloroethane, from 0.5 to 6 mmol g -1 with ClSO 3 H in H 2 SO 4 , respectively. The adsorption of Co 2 by the cation-exchange membranes increased with increasing -SO 3 H content.

Chemical reactive filter paper prepared by radiation-induced graft polymerization—I

Abstract Chelating filter papers with chemically bonded amidoxime groups were synthesized by radiation-induced grafting of acrylonitrile onto filter paper (W3) followed by chemical treatment with hydroxylamine. The effect of grafting conditions such as absorbed dose, dose rate, monomer concentration and filter paper thickness on the grafting yield was studied. It was found that the degree of grafting increases with increasing absorbed dose and dose rate, and then tends to level off at high doses. The order of the dependence of the initial grafting rate on the dose is found to be of 0.33. An increasing monomer concentration was accompanied by a significant increase in grafting. At high monomer concentration the initial rate of grafting is fast followed by a slow rate. The rate of grafting is controlled by the filter paper thickness and the diffusion of monomer into the interior of the filter paper. Mechanical properties of the prepared filter paper were improved over the ungrafted paper. The amidoxime filter papers were examined for adsorption of uranium concentration ranging between 10–100 ppm.

Radiation-induced graft polymerization is the key to develop high-performance functional materials for protein purification

We have described a preparation scheme for immobilizing polymer chains at a uniformly high density onto a microfiltration membrane. Highly efficient protein recovery was demonstrated by the results of the determination of breakthrough and elution curves. The three requirements of high rate, high capacity, and repeated use for the protein recovery were satisfied by ensuring the occurrence of convection, multilayer binding, and hydrophilization, respectively. In addition, easy scale-up to fabrication of a membrane module was verified on a small scale.

High resolution of DL-tryptophan at high flow rates using a bovine serum albumin-multilayered porous hollow-fiber membrane.

We describe a bovine serum albumin (BSA)-multilayer-adsorbed porous hollow-fiber membrane as a stationary phase that enables chiral separations at a high resolution and high rate. Epoxy-group-containing graft chains were uniformly immobilized on the surface of pores throughout a porous hollow-fiber membrane by radiation-induced graft polymerization. Subsequently, a diethylamino group as an anion-exchange moiety was introduced to the graft chains, which caused the chains to expand toward the interior of the pores due to mutual electrostatic repulsion. The expanding polymer chains provided multilayer binding sites for BSA as a chiral selector. BSA with a degree of multilayer binding of 4 specifically recognized L-tryptophan with a separation factor of 6.6 during permeation by a mobile phase (Tris-HC1 buffer) injected with a racemic solution of DL-tryptophan through the BSA-multilayered porous membrane. In addition, the separation factor was constant irrespective of flow rates of the mobile phase because of negligible diffusional mass-transfer resistance of tryptophan to BSA multilayered by the graft chains.