Adsorption of urokinase by polypropylene films with various amine groups

Polypropylene films with various amine groups were prepared by radiation‐induced grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) films and the subsequent amination of poly‐GMA graft chains were examined. The physical and chemical properties of the GMA‐grafted PP film and the aminated PP film were investigated by IR, SEM, XPS, and TGA. The adsorption of urokinase for the PP films modified with various amine groups was examined under various conditions of different amine group contents and pH values. The adsorption of urokinase increased by increasing the amine group content. In the range of amine group content from 1.0 to 2.7 mmol/g, the adsorption of urokinase by the PP films modified with six kinds of amines was in the following order: trimethylamine > diethylenetriamine > triethylenetetraamine > ethylenediamine > dimethylamine > diethyleneamine. The adsorption amounts of urokinase by the PP film with the trimethylamine and triethylenetetraamine groups at pH 7.4 were higher than those at pH 9. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2851–2858, 2001     

Photografting of N‐isopropylacrylamide and glycidyl methacrylate binary monomers on polyethylene film: Effect of mixed solvent consisting of water and organic solvent

Photografting (λ > 300 nm) of N‐isopropylacrylamide (NIPAAm) and glycidyl methacrylate (GMA) binary monomers (NIPAAm/GMA) on low‐density polyethylene film (thickness = 30 μm) was investigated at 60°C using mixed solvent consisting of water and an organic solvent such as acetone. Xanthone was used as a photoinitiator by coating it on the film surfaces. A maximum percentage of grafting was observed at a certain concentration of acetone in the mixed solvent, which was commonly observed for both ratios of NIPAAm/GMA, 8/2 and 7/3. Based on the photografting of NIPAAm/GMA on xanthone‐coated film, monomer reactivity ratios of NIPAAm (r₁) and GMA (r₂) were calculated using the Fineman–Ross method. The values were 0.31 ± 0.1 and 4.8 ± 0.2 for the water solvent system, while they were 0.96 ± 0.1 and 4.9 ± 0.1 for the mixed solvent system. NIPAAm/GMA‐grafted films with a homogeneous distribution of grafted chains were formed by photografting using water and mixed solvents. The NIPAAm/GMA‐grafted films exhibited temperature‐responsive characters, whereas the grafted films showed a reversible change in the degree of swelling between 0 and 50°C, respectively. Epoxy groups in the grafted poly(NIPAAm/GMA) chains could be aminated with ethylenediamine in N,N′‐dimethylformamide at 70°C for 3 h. Complexes of the aminated NIPAAm/GMA‐grafted chains with cupric ion exhibited catalytic activity for the decomposition of hydrogen peroxide at 20 to 50°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2469–2475, 2005     

Surface modification of polypropylene film by radiation‐induced grafting and its blood compatibility

To endow blood‐compatible properties onto polypropylene (PP) film, we grafted 2,3‐epoxypropyl methacrylate (EPMA) to PP film with a preirradiation grafting technique and then introduced various functional groups onto the grafted PP film. The EPMA grafting extent was dependent on the absorbed dose, reaction time, and temperature. The reactions of hydroxylation, iminodiacetation, sulfonation, phosphonation, and amination were performed under various conditions to introduce functional groups into the epoxy group of EPMA‐grafted PP films, respectively. We also immobilized heparin on aminated PP film to compare blood compatibility with various functionalized samples. The grafting, functionalization, and heparinization reaction were confirmed by Fourier transform infrared spectroscopy in the attenuated total reflectance mode and electron spectroscopy for chemical analysis. The blood compatibility of various functional groups and heparin‐introduced samples as well as control samples was examined by the determination of platelet adsorption and thrombus formation. For the examination of the blood compatibility of functionalized PP samples, acid citrate dextrose human whole blood and platelet‐rich plasma were used. The amount of the formed thrombus and the adherent platelets on functionalized PP sample surfaces were evaluated by an in vitro method following Imai and Nose's technique and by scanning electron microscopy, respectively. The blood compatibility of various functional‐group‐introduced PP films after grafting was better than that of the PP control. Phosphoric‐acid‐group‐ and heparin‐introduced PP films had especially good blood compatibility. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1726–1736, 2003     

Amination of glycidyl methacrylate-grafted polystyrene particles and their adsorption capacity for Nd3+ and Cd2+

A new chelating adsorbent was prepared by grafting glycidyl methacrylate (GMA) onto polystyrene (PS) particles using simultaneous radiation technique and amination of graft copolymers by reacting with diethylenetriamine. The effects of various parameters such as, irradiation doses, inhibitor concentrations, amination temperature, and reaction time were investigated. The grafting yield increased with irradiation dose to reach its maximum value at 15 kGy. The accelerative effect of solvent medium on the grafting yield was higher in THF than DMF. The addition of 0.001 % (wt) inhibitor to the reaction medium led to a sharp increase of grafting yield. The best conversion ratio was obtained at 115 °C during 24 h. By using a column separation technique, the adsorption behaviors of the adsorbent toward Cd²⁺ and Nd³⁺ in aqueous solution were examined. The adsorption amount of both Cd²⁺ and Nd³⁺ increased with initial ions concentration. The maximum equilibrium of Cd²⁺ and Nd³⁺ adsorbed ions were 18.1 and 17.58 mg/g, respectively. It was observed that the functionalized GMA-g-PS was reusable by desorbing with 0.1 M nitric acid almost without losing their adsorption capacity. FTIR test indicates that epoxide and amine groups were introduced onto GMA-g-PS and aminated GMA-g-PS, respectively. The T _g of graft copolymer slightly decreased, and that of aminated GMA-g-PS was higher than graft copolymer.     

Radiation‐induced grafting of glycidyl methacrylate onto high‐density polyethylene (HDPE) and radiation lamination of HDPE

Radiation‐induced grafting of glycidyl meth‐acrylate (GMA) onto high‐density polyethylene (HDPE) and the radiation lamination of HDPE by bulk grafting of GMA were reported. The effects of irradiation dose, monomer concentration, and atmosphere on grafting were investigated. The extent of grafting initially increased with irradiation dose and then remained almost constant. The extent of grafting was higher in 2M GMA than in 1M GMA at the same irradiation dose. The extent of grafting in nitrogen was higher than that in air. The grafted samples were characterized with FTIR spectrometry and thermogravimetric (TG) analysis. A carbonyl group was found on grafted HDPE samples, and the carbonyl index increased with the extent of grafting. TG analyses proved the existence of grafted materials on HDPE and the grafted GMA thermally decomposes at a temperature lower than that of HDPE. Strong adhesion could be obtained with radiation lamination of HDPE by bulk grafting of GMA. Benzophenone facilitates the grafting in a proper concentration range. The adhesion mechanism of the laminated samples was the entanglement of the grafted chains. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 772–779, 2005     

Reactivity of glycidyl-methacrylate-grafted cellulose prepared by means of photografting

Photografting was applied to functionalize cellulose, that is, epoxy groups were introduced into the cellulose substrate by photografting of glycidyl methacrylate (GMA) using hydrogen peroxide as a photoinitiator. Dissolving pulp from softwoods was used as the cellulose sample. The GMA-grafted cellulose (G-Cell) was subjected to the following examinations in comparision with epoxy-activated cellulose (E-Cell) prepared by reaction with epichlorohydrin: (1) reactivity of G-Cell towards amines such as ethylenediamine, tetramethylenediamine, hexamethylenediamine, diethylenetriamine, and triethylenetetramine; (2) ability of the aminated celluloses obtained by examination (1) to adsorb cupric ion; and (3) catalytic activity of the aminated cellulose–cupric ion complexes prepared by examination (2) for decomposition of hydrogen peroxide. The amount of amine residue introduced into the substrate was higher for E-Cell than G-Cell, showing the existence of epoxy groups in G-Cell which cannot contribute to the reaction. The ability of the aminated celluloses to adsorb cupric ion was nearly equal for G-Cell and E-Cell though tetramethylenediamine and hexamethylenediamine-introduced samples did not show the ability. It was found that all complexes prepared by reaction of the aminated cellulose with cupric ion exhibited catalytic activity for decomposition of hydrogen peroxide. © 1995 John Wiley & Sons, Inc.     

Fuel Cell Membranes Based on Grafted and Post‐Sulfonated Glycidyl Methacrylate (GMA)

Glycidyl methacrylate (GMA) was pre‐irradiation grafted into ETFE base film of 25 μm thickness up to graft levels of 300%. The grafted films were sulfonated using a mixture of sulfite and bisulfite. FTIR and SEM–EDX analysis of the synthesized films and membranes was performed to confirm the grafting and the sulfonation. A pronounced front mechanism for grafting of GMA into ETFE was found. Regarding ex situ fuel cell relevant properties, conductivities of up to 0.25 S cm^–1 were attained. For the first time, fuel cell testing of this type of membrane is reported. These grafted membranes performed comparable to a commercial benchmark membrane (Nafion® 212) and better than a styrene‐based grafted membrane with similar conductivity. Post‐test FTIR analysis showed that a fraction of the grafted chains was lost during the test under constant current conditions, yet the membrane still exhibited superior durability compared to a styrene‐based grafted membrane. Hydrolysis of the methacrylate groups was shown not to be the principle cause of the loss of sulfonic acid groups.     

Graft copolymerization of polyethylene glycol methacrylate onto polyethylene film and its blood compatibility

In an attempt to produce surfaces that show low levels of adsorption of protein and adhesion of platelets, different molecular weights of polyethylene glycol methacrylate (PEG‐MA) were grafted onto polyethylene film by a preirradiation grafting process. The extent of grafting was found to be dependent on the storage condition of the irradiated polyethylene film, the preirradiated dose, reaction time and temperature, molecular weight of PEG‐MA, and the type of solvent. The grafting yield was found to decrease rapidly with storage time for irradiated polyethylene film stored at room temperature. On the other hand, the grafting yield in the irradiated polyethylene stored at −130°C remained nearly constant up to 20 days after irradiation. The grafting yield decreased with an increased PEG‐MA molecular weight. Human plasma protein was adsorbed onto control and PEG‐MA‐grafted polyethylene film surfaces, and the relative adsorbed amount of proteins on the surfaces was evaluated by electron spectroscopy for chemical analysis. The adsorbed protein and platelet adhesion on the polyethylene film surface decreased rapidly with the grafting yield. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 631–641, 1999     

Dialysis membranes from polyethylene films grafted with acrylic acid

Low‐density polyethylene‐g‐poly(acrylic acid) membranes were prepared by the direct radiation grafting of aqueous acrylic acid solutions (containing Mohr's salt) onto low‐density polyethylene films and were irradiated at two different irradiation doses (2 and 3 Mrad) at a dose rate of 0.02 Mrad/h. Two series of polyethylene‐g‐poly(acrylic acid) membranes with 100 and 150% grafting were obtained. The free carboxylic acid groups in the grafted films were converted into the corresponding acrylates by reactions with different metal salts. The swelling (water uptake) and dialysis permeability of glucose and urea through the grafted membranes in different metal‐ion forms were investigated. The prepared membranes showed good permeability to both solutes, which increased as the hydrophilicity of the membrane increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 10–14, 2004     

Effect of ultrasonic irradiation on ceric‐salt‐initiated grafting of methyl methacrylate onto regenerated cellulose film

Effect of ultrasonic irradiation on ceric salt (Ce⁴⁺)‐initiated grafting of methyl methacrylate (MMA) on regenerated cellulose film (thickness = 20 μm) was investigated under an air atmosphere in water solvent at 60°C. The grafting system with the ultrasonic irradiation was characterized by higher percentage of grafting and graft efficiency than the system without the irradiation. Reaction of cellulose with Ce⁴⁺ was also accelerated by the ultrasonic irradiation. No accelerating effect of grafting due to the ultrasonic irradiation was observed for the system under reduced pressure of 5 torr. The effect of the ultrasonic irradiation on the average molecular weight of MMA‐grafted chains was also studied. Moreover, the surface layer of the resulting grafted films was examined by attenuated total reflection–infrared (ATR–IR) measurement and scanning electron microscopy (SEM) observation. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 251–258, 1999     

Radiation‐induced graft polymerization of glycidyl methacrylate onto PE/PP nonwoven fabric and its modification toward enhanced amidoximation

A nonwoven fabric made of polypropylene coated by polyethylene was used as the trunk polymer in the preparation of a highly efficient new adsorbent. Metal ion uptake capacity has been aimed to be increased by introducing double amidoxime groups per repeating unit of the chains grafted to trunk polymer. The base polymer was irradiated by electron beams with a dose of 200 kGy under N₂ atmosphere and glycidyl methacrylate (GMA) was grafted onto irradiated nonwoven fabric. Grafting conditions were optimized, and GMA‐grafted polymer was modified with 3,3′‐iminodipropionitrile in ethanol at 80°C. GMA grafting (150%) was determined to be the optimum degree given that higher extent of grafting rendered the materials brittle. Pendant nitrile groups were then amidoximated by using 6% hydroxylamine in methanol–water mixture (1 : 1). The all‐polymeric structures were characterized by using FTIR, SEM, and thermal analysis methods, confirming the grafting, modification, and amidoximation stages gravimetrically, spectroscopically, and visually. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Grafting of glycidyl methacrylate onto high‐density polyethylene with reaction time in the batch mixer

The melt grafting of glycidyl methacrylate (GMA) onto high‐density polyethylene (HDPE) in the presence of free radical initiators was investigated in the batch mixer. The graft content was determined with the titration and FTIR spectroscopy. The graft content increased with the increase of peroxide and initially introduced GMA concentration. Increase of the grafted GMA content resulted in decrease of the melt index. Interestingly, there was a sudden drop of GMA grafting content with the reaction time. It is assumed that depolymerization of GMA have taken place over the ceiling temperature. The crystallinity of the prepared glycidyl methacrylate grafted high density polyethylene (HDPE‐g‐GMA) was determined by the measurement of the heat of fusion. GMA grafted site acted as defect and crystallinity of the HDPE‐g‐GMA decreased with the increase of grafting reaction. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

SEM study of the morphologic change of high‐density polyethylene surface grafted with glycidyl methacrylate

Scanning electron microscopy (SEM) study of the morphologic change of high‐density polyethylene (HDPE) surface grafted with glycidyl methacrylate (GMA) was reported. Radiation‐induced grafting of GMA onto HDPE was carried out in acetone and dichloromethane solution, respectively. The effects of irradiation dose, atmosphere, and swelling time on grafting were investigated. Generally, the extent of grafting increased with irradiation dose, but for the grafting carried out in acetone solution, the extent of grafting initially increased with irradiation dose and then remained almost constant. The extent of grafting was higher in acetone solution than in dichloromethane solution at the same irradiation dose. The extent of grafting in nitrogen was higher than that in air. The successful grafting of GMA onto HDPE was confirmed by weighing and FTIR analysis. SEM investigations showed that the morphologies of the PE samples grafted in acetone solution were quite different to those grafted in dichloromethane. The grafting of GMA carried out in acetone was mainly on HDPE surface and that carried out in dichloromethane was mainly in the bulk of HDPE. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effect of hydroquinone on location of methacrylic acid-grafted chains introduced into polyethylene film by photografting

Effect of hydroquinone (HQ) on photografting of methacrylic acid (MAA) on low-density polyethylene film (thickness = 30 μm) sensitized with xanthone was investigated at 60°C in water medium. Both the formation of grafted polymer and homopolymer were retarded by HQ. The contact angle of water on the MAA-grafted polyethylene films (sample with HQ) prepared in the system with HQ was larger than that of the grafted films (sample without HQ) prepared in the system without HQ. Based on electron probe microanalysis of the grafted films, it was found that distribution of grafted chains in the direction of film thickness is different between the both grafted films. Namely, the grafted chains of the sample with HQ distributed in the inside of the film compared with those of the sample without HQ. The difference in the distribution of grafted chains between the grafting systems with and without HQ was discussed in terms of effect of HQ on the photodecomposition of MAA-grafted chains and the subsequent initiation of polymerization by radicals due to the photodecomposition.     

Styrene‐assisted melt free radical grafting of glycidyl methacrylate onto an ethylene and propylene rubber

This article deals with the efficiency of using styrene (St) as a comonomer to promote the melt free radical grafting of glycidyl methacrylate (GMA) onto an ethylene and propylene rubber (EPR) in a batch mixer and a corotating self‐wiping twin screw extruder. The addition of St to an EPR/GMA/peroxide system increases not only GMA's grafting yield but also its grafting rate. The time required for the EPR/GMA/peroxide system without St to reach a given amount of grafted GMA is at least 10 times that needed for the same system in the presence of an equimolar amount of St. For example, about 60 min are required for the EPR/GMA/dicumyl peroxide (composition: 100/3.0/0.3 by weight) to reach 1.5 phr (parts per hundred resin) GMA (i.e., 1.5 g grafted GMA per 100 g EPR). The same amount of grafted GMA is reached in < 3 min when 3.0 phr St is charged to the system. This significant reduction of reaction time is crucial for a successful free radical grafting of GMA on EPR in a corotating twin screw extruder, because the residence time in such a machine is typically on the order of 0.5–5 min. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 125–133, 1999     

Characteristics of methacrylic acid‐grafted polyethylene films prepared by photografting in the presence of polyfunctional monomers

Photografting of methacrylic acid (MAA) on low‐density polyethylene film (thickness = 30 μm), on which xanthone photoinitiator was coated earlier, in the presence of polyfunctional monomers such as N,N′‐methylenebisacrylamide, ethylene glycol dimethacrylate, and trimethylol propane triacrylate was examined at 60°C in water/acetone (3:1 v/v) mixture solvent. The photografting was retarded at the earlier stage of polymerization, and then accelerated when small amounts of the polyfunctional monomers (1–3 mol % of MAA monomer used) were added to the system. Addition of the polyfunctional monomers did not affect distribution of the grafted chains in the cross section of the resultant MAA‐grafted PE film, which was measured by electron probe microanalysis. The MAA‐grafted samples were subjected to adsorption of cupric ions at 25°C for 24 h in the system of pH = 5. The adsorption was considerably suppressed for the grafted samples prepared at the earlier stage of polymerization in the system with the polyfunctional monomers. The phenomenon was discussed in terms of the formation of crosslinked and branched structures in the MAA‐grafted chains depending on the polymerization stage in the system with polyfunctional monomers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1262–1268, 2006     

Determination methods of the grafting yield in glycidyl methacrylate‐grafted ethylene/propylene/diene rubber (EPDM‐g‐GMA): Correlation between FTIR and 1H‐NMR analysis

A normalized and universally applicable calibration function for the Fourier‐transformed infrared (FTIR) quantification of the glycidyl methacrylate (GMA) grafting yield in polymers of known compositions having ethylene block sequences was established. The ¹H nuclear magnetic resonance (¹H‐NMR) spectroscopy results achieved on different GMA‐grafted ethylene/propylene/diene rubber (EPDM‐g‐GMA) and ethylene/GMA copolymers were correlated to their FTIR data to calibrate the relative determination of the FTIR method. Both direct and indirect standardization approaches were followed and evaluated. The calibration deduced was used to investigate the free radical grafting reaction of GMA on EPDM rubber in the melt phase. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2616–2624, 1999     

Polyethylenimine‐grafted and HSA‐immobilized poly(GMA–MMA) affinity adsorbents for bilirubin removal

The epoxy‐group‐containing microspheres from cross‐linked glycidyl methacrylate and methyl methacrylate, poly(GMA–MMA), were prepared by suspension polymerisation. The epoxy groups of the poly(GMA–MMA) microspheres were used for grafting with an anionic polymer polyethylenimine (PEI) to prepare non‐specific affinity adsorbents (poly(GMA–MMA)–PEI) for bilirubin removal. The specificity of the poly(GMA–MMA)–PEI adsorbent to bilirubin was further increased by immobilization of human serum albumin (HSA) via adsorption onto PEI‐grafted poly(GMA–MMA) adsorbent. Various amounts of HSA were immobilized on the poly(GMA–MMA)–PEI adsorbent by changing the medium pH and initial HSA concentration. The maximum HSA content was obtained at 68.3 mg g^?1 microspheres. The effects of pH, ionic strength, temperature and initial bilirubin concentration on the adsorption capacity of both adsorbents were investigated in a batch system. Separation of bilirubin from human serum was also investigated in a continuous‐flow system. The bilirubin adsorption on the poly(GMA–MMA)–PEI and poly(GMA–MMA)–PEI–HSA was not well described by the Langmuir model, but obeyed the Freundlich isotherm model. The poly(GMA–MMA)–PEI affinity microspheres are stable when subjected to sanitization with sodium hydroxide after repeated adsorption–desorption cycles. Copyright © 2004 Society of Chemical Industry     

Thermal properties of proton-conducting radiation-grafted membranes

Proton-exchange membranes are required to exhibit chemical, mechanical, and thermal stability for fuel cell applications. The present investigation has been carried out to explore the thermal behavior of poly(ethylene-alt-tetrafluoroethylene) (ETFE)-based proton-conducting membranes, both uncrosslinked and crosslinked, prepared by radiation grafting and subsequent sulfonation. The influence of preparation steps (irradiation, grafting, sulfonation, crosslinking) on the thermal degradation, crystallinity, and melting behavior of membranes with varying degree of grafting was examined. ETFE base film and grafted films were studied as the reference materials. Furthermore, poly(tetrafluoroethylene-co-hexafluoropropylene)-based grafted films and membranes were investigated as well for comparison. Membrane preparation steps, degree of grafting, crosslinking, type of base polymer have considerable influence on the thermal properties of membranes. The crystallinity of the films decreases slightly by grafting, while a significant decrease was observed after sulfonation. For instance, crystallinity decreased from 37% (pristine ETFE) to 36% (uncrosslinked grafted film) and 23% (uncrosslinked ETFE-based membrane). On the other hand, the melting temperature of the base polymer was almost unaffected by irradiation and grafting. The crosslinked ETFE-based membranes exhibit a slightly higher melting temperature (262.5°C) than their corresponding grafted films (261.3°C) and the base film (260.6°C). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Study of compatibilization of HDPE–PET blends by adding grafted or statistical copolymers

The reactive compatibilization of blends of HDPE–PET [high‐density polyethylene–poly(ethylene terephthalate)] was investigated in this study. The compatibilizers used were two grafted copolymers prepared by reactive extrusion containing 1.20–2.30 wt % GMA such as HDPE‐g‐GMA and one statistical copolymer containing 1 wt % GMA such as Lotader AX8920. HDPE was successfully functionalized using a melt free‐radical grafting technique. Grafting was initiated in two ways: adding an initiator in the polymer–monomer mixture or activation by ozone of polymer. Ozonization of HDPE by the introduction of a peroxide lead to a better grafting yield and to better grafting efficiency of the samples. The effects of the three compatibilizers were evaluated by studying the morphology and the thermal and mechanical properties of HDPE–PET (70/30 wt %) blends. Significant improvements were observed, especially in morphology, elongation at break, and Charpy impact strength of the compatibilized blends. A more pronounced compatibilizing effect was obtained with the statistical copolymer, for which the elongation at break and the impact strength were increased by 100%, while the uncompatibilized blends showed a 60% decrease in the Young's modulus and the strength at break. We also were able to show that the grafting yield increase of 1.20–2.30 wt % of GMA did not affect the properties of the blends because the grafted copolymers possess very similar chemical structures. However, compatibilization of blends with grafted copolymers is an interesting method, particularly for recycled blends, because the synthesis of these compatibilizers is easy and cheap in comparison to statistical copolymer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2377–2386, 2001