Properties of grafted polymer metal complexes as ion exchangers and its electrical conductivity

A polyelectrolyte has been prepared, as a potential proton exchange polymer, by grafting acrylic acid/acrylamide (AAc/AAm) and acrylic acid/acrylonitrile (AAc/AN) comonomers onto a low‐density polyethylene film via gamma irradiation. The developed polymers were characterized by evaluating their physico‐chemical properties such as ion exchange capacity (IEC) and electrical conductivity as functions of grafting yield. The grafted film at different compositions was characterized by Fourier transform infrared, thermogravimetric analysis, and scanning electron microscopy. IEC of the grafted film at grafting % 191 and monomer concentration ratio 50:50 for (LDPE‐g‐AAc/AAm) was found to be more than that for (LDPE‐g‐AAc/AN). The electrical conductivity was found to be greatly affected by the comonomer composition, were it increased as the degree of grafting increased for all grafted films. After alkaline treatment with 3% KOH (3% potassium hydroxide), the electrical conductivity of the grafted films found to be increased. The presence of potassium as counter ion maximized the electrical conductivity of the grafted films. The electrical conductivity of Cu‐membrane complexes was higher than that of both Co (cobalt) and Ni (Nickel) complexes. It has been indicated that, the electrical conductivity increased by increasing both Cu ion content and temperature. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers.     

Drug delivery system based on poly(ether‐block‐amide) and acrylic acid for controlled release of vancomycin

Poly(ether‐block‐amide) (PEBA) films were grafted with acrylic acid (AAc) by gamma radiation, using the oxidative pre‐irradiation technique. The effect of dose, monomer concentration, temperature, and reaction time on the graft percentage of AAc onto PEBA was studied. The modified material PEBA‐g‐AAc was characterized by Fourier infrared spectroscopy (FTIR), scanning electron microscopy, and water contact angle. It was found that PEBA films did not suffer degradation at low doses (<30 kGy) during the grafting process. Additionally, PEBA‐g‐AAc was proved as drug delivery system using vancomycin as drug model. The PEBA‐g‐AAc with 39 and 98% of AAc loaded 63 and 98 mg g^?1, respectively. The release profiles showed a sustained delivery by 48 h with a partial retention of drug, which depends of grafting percentage. The microbiological tests showed that PEBA‐g‐AAc was able to inhibit the growing of Staphylococcus aureus in three consecutive challenges. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45745.     

Uptake of Pb2+ Using N-Vinyl Imidazole Based Uniform Porous Hydrogels

The uniform porous and continuous phase lead (II) adsorbent hydrogel, was prepared by copolymerizing 2-hydroxyethyl methacrylate (HEMA), acrylic acid (AAc), and N,N′-methylenebisacrylamide (MBAAm), with n-vinyl imidazole (VIM). A series of hydrogels, including different ratios of VIM, were prepared by photopolymerization and characterized. The influence of the uptake conditions such as pH, functional monomer percent, contact time, initial feed concentration, and foreign metal ions on the metal ion binding capacity of hydrogel, were also tested. The selective chelation of heavy metal ions from synthetic wastewater was also studied. The affinity order on molar basis was observed as follows: Pb (II) > Zn (II) > Cd (II). Chelation behavior of heavy metal ions could be modelled using both the Langmuir and Freundlich isotherms and it was seen that the Langmuir isotherm model was the best fit for the adsorption of Pb (II) ions in P(VIM/AAc/HEMA) hydrogel. Moreover, the limits of detection and the quantification values were determined. Regeneration of the hydrogels was easily performed with 1 M HCl and the same hydrogel can be reused five times almost without any loss of adsorption capacity. All these features make P(VIM/AAc/HEMA) hydrogels potential candidate adsorbent for heavy metal removal.     

Graft polymerization of acrylic acid onto macroporous polyacrylamide gel (cryogel) initiated by potassium diperiodatocuprate

Potassium diperiodatocuprate-initiated graft polymerization was found to be an efficient and convenient method for grafting of acrylic acid (AAc) onto superporous polyacrylamide gels, so called cryogels (pAAm cryogels). It was possible to achieve grafting degrees as high as 70% with about 25% yield of grafted polymer with respect to the initial amount of monomer. The superporous structure of the cryogels promoted grafting by providing an ample surface of the gel for grafting, ensuring good mass transfer inside the gel sample and allowing to wash easily both homopolymer of AAc and insoluble by-products formed during the polymerization reaction. The grafted cryogels could be dried at 60 °C and re-swollen with retaining their properties. The adsorption of water vapours by dried pAAm cryogels was marginally dependent on the degree of grafting. The swelling of AAc-grafted pAAm cryogel increased pronouncedly with increasing pH. The adsorption of low-molecular weight ligand, Cu(II), by AAc-grafted pAAm cryogels increased linearly with the degree of grafting, while binding of high-molecular weight ligand, lysozyme, increased linearly till the degree of grafting of about 40% followed by a sharp, nearly three-fold increase in lysozyme binding when the degree of grafting increased from 60 to 70%. The results indicate that a ‘tentacle’-type binding of lysozyme to grafted polyAAc takes place after a certain degree of grafting has been reached.     

Metal complexes of natural and synthetic fabrics grafted with vinyl monomers by gamma irradiation

Graft copolymers of natural and synthetic fabrics with acrylic acid (AAc) prepared by gamma irradiation were transformed into metal complexes of the divalent metal ions of cobalt, nickel, and copper. The factors that affect the grafting process without affecting the physical properties of fabrics and homogeneous grafting were studied. These factors involved inhibitor (FeCl₂) concentration, solvent composition, AAc concentration, and irradiation dose. The results showed that the appropriate irradiation dose in all cases was 20 kGy, whereas the inhibitor concentration was 0.1 wt% in the case of cotton and 0.2 wt% in the case of cotton/polyester blend and polyester fabrics. The suitable solvent composition was H₂O (90%)/MeOH(10%) in the case of cotton and H₂O (90%)/MeOH(10%) in the cotton/polyester blend and polyester fabrics. On the other hand, the suitable AAc concentration was 30% in the case of cotton and 50% in the cotton/polyester blend and polyester fabrics. The homogenous grafting and subsequent distribution of metal complexation was illustrated by a method based on the measurement of color parameters. Moreover, the effect of radiation grafting and metal complexation on the water absorption and mechanical properties of fabrics was investigated. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers     

Functionalizing of polyurethane surfaces by photografting with hydrophilic monomers

Poly(ester urethane) (PU) with functional groups (amide, hydroxyl, carboxyl) on surfaces were prepared by grafting monomers such as acrylamide (AAm), hydroxyethyl acrylate (HEA), and methacrylic acid (MAA) onto the PU membranes. Grafting copolymerization was carried out by the combined use of photooxidization and UV irradiation grafting. The PU membrane was photooxidized in hydrogen peroxide solution under UV light to yield hydroperoxide groups on the surface and then irradiation grafting with monomer in water. The ATR‐FTIR spectrum, X‐ray photoelectron spectroscopy characterized the grafted copolymers and verified the occurrence of grafting copolymerization. The results showed that the content of hydroperoxide groups yielded was dependent on the photooxidization time and reached maximum at about 8 h. Grafting copolymerization was enhanced when irradiating by UV light. The degree of grafting was increased with the increase of content of hydroperoxide groups, irradiation time, and monomer concentration. The grafting copolymerization was enhanced when an appropriate amount of ferrous ions was added. After grafting, the wettability of PU and the water absorption percentage increased with the degree of grafting. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2505–2512, 2000     

Preparation and characterization of teflon–FEP films grafted with acrylic acid by radiochemical method

In an attempt to prepare permselective membrane, grafting of acrylic acid (AAc) onto Teflon–fluorinated ethylene-propylene (FEP) film was studied in aqueous medium by the preirradiation method in air. Grafting was carried out by heating a mixture of AAc, water, and preirradiated Teflon–FEP film in air at 93°C for definite time periods. Percentage ofgrafting was determined as a function of total dose, monomer concentration, reaction time, and amount of water. Maximum percentage of grafting (60.17%) was obtained at a total dose of 4.8 Mrad using 0.07M [AAc]. Evidence of grafting was obtained from the physical appearance and swelling behavior of the grafted film in polar solvents. Infrared spectroscopic and thermal analysis of the grafted film provided additional evidence for grafting. A plausible mechanism for grafting of AAc onto preirradiated Teflon–FEP film in air has been proposed. © 1995 John Wiley & Sons, Inc.     

Pectin‐[(3‐acrylamidopropyl) trimethylammonium chloride‐co‐acrylic acid] hydrogel prepared by gamma radiation and selectively silver (Ag) metal adsorption

Pectin‐[(3‐acrylamidopropyl) trimethylammonium chloride‐co‐acrylic acid] hydrogel has been prepared from the aqueous blend solution of pectin, (3‐acrylamidopropyl) trimethylammonium chloride (APTAC), and acrylic acid (AAc) by applying gamma radiation of different doses (1–25 kGy) from ⁶⁰Co gamma source. The hydrogels were characterized by equilibrium swelling, Fourier transform infrared, differential scanning calorimetry, and scanning electron microscopy. The hydrogels were used in multielement adsorption and it was found that pectin‐(APTAC‐co‐AAc) gel is highly selective toward silver (I) ion among 27 metal ions. The data obtained from equilibrium adsorption studies were fitted in Langmuir and Freundlich adsorption isotherm models and model parameters evaluated. The maximum adsorption capacity of pectin‐(APTAC‐co‐AAc) gel was found to be 67.6413 mg/g of dry gel at sample volume of 25 mL. The kinetic data were tested using pseudo‐first order and pseudo‐second order kinetic models and different adsorption diffusion models such as film diffusion and intra‐particle diffusivity model. Thiourea solution was used for desorption of adsorbed metal ions from the hydrogel. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45906.     

Effects of polydimethylsiloxane grafting on the calcification,physical properties,and biocompatibility of polyurethane in a heart valve

Segmented polyurethane (PU) has proven to be the best biomaterial for artificial heart valves, but the calcification of polyurethane surfaces causes serious problems in long‐term implants. This work was undertaken to evaluate the effects of polydimethylsiloxane (PDMS) grafting on the calcification, biocompatibility, and blood compatibility of polyurethane. A grafted polyurethane film was compared with virgin polyurethane surfaces. Physical properties of the samples were examined using different techniques. The hydrophobicity of the polyurethane films increased as a result of silicone modification. The effects of surface modification of polyurethane films on their calcification and fibroblast cell (L 929) and platelet behavior were evaluated in vitro. Fourier transform infrared spectroscopy indicated the direct involvement of the polyether soft segments of the polymer in the calcification process. Scanning electron microscopy of films indicated that grafting of silicone rubber to the surface of polyurethane successfully prevented the calcification process. The morphology of fibroblast cells that adhered to the PU films and modified films was similar to that of controls and showed the same proliferation. On the other hand, grafting PDMS onto PU did not affect the amount of platelets that adhered to the polyurethane surfaces. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 758–766, 2005     

The polydopamine-assisted heparin anchor enhances the hydrophilicity,hemocompatibility, and biocompatibility of polyurethane

Surface heparinization is an effective solution to resolve low endothelialization, poor anticoagulation, and hemocompatibility of polyurethane (PU) used as materials of small-diameter vascular grafts. Here, the effects of polydopamine (PDA) and poly (acrylic acid) (PAA) as crosslinking agents on the surface heparinization were explored. The PU membranes grafted with heparin (Hep) via dopamine (PU/PDA-Hep) showed better hydrophilicity and stability, compared to heparinized PU membranes via acrylic acid (PU/PAA-Hep). The results of X-ray photoelectron spectroscopy demonstrated that heparin was successfully grafted onto the PU surface and the grafting efficiency was high when PDA as a cross-linking agent. The grafted heparin aggregated and formed nanoparticles, and increased the surface roughness of PU membranes. The heparinized membranes demonstrated good anti-adhesion of bovine serum albumin and fibrin protein. In addition, no activated platelets or educts on heparinized PU were found by platelet adhesion tests, implying that heparin-immobilized surfaces had good hemocompatibility. Moreover, the in vitro cytocompatibility assessment showed that the PU/PDA-Hep significantly improved the proliferation of L929 cells and was superior to PU/AA-Hep. These results demonstrated that PDA-assisted surface heparinization was an effective method to improve the anticoagulant and biocompatibility of PU small-diameter vascular materials and could be extended to other implantable materials.     

Investigation on selective adsorption of Hg(II) ions using 4‐vinyl pyridine grafted poly(ethylene terephthalate) fiber

In the work, poly(ethylene terephthalate) (PET) fibers were grafted with 4‐vinyl pyridine (4‐VP) monomer using benzoyl peroxide (Bz₂O₂) as initiator in aqueous media. The removal of Hg(II) ions from aqueous solution by the reactive fiber was examined by batch equilibration technique. Effects of various parameters such as pH, graft yield, adsorption time, initial ion concentration, and adsorption temperature on the adsorption amount of metal ions onto reactive fibers were investigated. The optimum pH of Hg(II) was found 3. The maximum adsorption capacity was found as 137.18 mg g^?1. Moreover such parameters as the adsorption kinetics, the adsorption isotherm, desorption time and the selectivity of the reactive fiber were studied. The adsorption kinetics is in better agreement with pseudo‐first order kinetics, and the adsorption data are good fit with Freundlich isotherms. The grafted fiber is more selective for Hg(II) ions in the mixed solution of Hg(II)‐Ni(II), Hg(II)‐Zn(II), and Hg(II)‐Ni(II)‐Zn(II) at pH 3. Adsorbed Hg(II) ions were easily desorbed by treating with 1M HNO₃ at room temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Determination of the competitive adsorption of heavy metal ions on poly(n‐vinyl‐2‐pyrrolidone/acrylic acid) hydrogels by differential pulse polarography

Poly(N‐vinyl‐2‐pyrrolidone) and poly(N‐vinyl‐2‐pyrrolidone/acrylic acid) hydrogels were prepared by gamma irradiation for the removal of heavy metal ions (i.e., lead, copper, zinc, and cadmium) from aqueous solutions containing different amounts of these ions (2.5–10 mg/L) and at different pH values (1–13). The observed affinity order in adsorption of these metal ions on the hydrogels was Zn(II) > Pb(II) > Cu(II) > Cd(II) under competitive conditions. The optimal pH range for the heavy metal ions was from 7 to 9. The adsorption of the heavy metal ions decreased with increasing temperature in both water and synthetic seawater conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2013–2018, 2003     

Application of recycled polyol and benzimidazole to the enhancement of antifungal activity of polyurethane

Recycled polyol and benzimidazole were both grafted onto polyurethane (PU) to enhance the surface hydrophilicity and antifungal activity, respectively. The two grafted groups affected the viscosity, crosslink density, soft segment glass transition, breaking stress, flexibility at freezing temperature, shape recovery at ?10 °C, surface hydrophilicity, and antifungal activity. The glass transition temperature increased from ?67.5 °C for plain PU up to ?60.8 °C after the grafting of polyol. The breaking stress and shape recovery of the grafted PU increased up to 425% and 200%, respectively, relative to plain PU because of the chemical linking by the grafted polyol. The hydrophilicity of PU, evaluated by the water contact angle and water swelling ratio, increased with increasing polyol content. A PU sample demonstrated excellent low‐temperature flexibility in comparison to plain PU and control sample. Finally, the PUs modified with grafted polyol and benzimidazole completely suppressed fungal growth. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46600.     

Graft copolymer–metal complexes obtained by radiation grafting on polyethylene film

Radiation induced grafting of acrylic acid onto polyethylene film was investigated. The grafted films rapidly adsorbed Cu²⁺, Cd²⁺, Th⁴⁺, and UO ions in high efficiency. The carboxylic acid groups on AAc‐grafted PE film acted as a chelating site for the selected metal ions. Complex formation of metal ions and carboxylic acid group on PE film were investigated by IR, UV/VIS and x‐ray photoelectrons spectroscopy (XPS). Electrical conductivity and thermal properties of the graft copolymer‐metal complexes onto PE film were also investigated. The application of such prepared graft copolymer‐metal complexes in the field of semiconductor may be interest. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 500–508, 2000     

Grafting of High α-Cellulose Pulp Extracted from Sunflower Stalks for Removal of Hg (II) from Aqueous Solution

Dissolving pulp containing 95.5% α-cellulose was extracted from sunflower stalks. The pulped sunflower stalks (PSFS) were used as starting material for grafting with acrylamide (Aam). All factors affecting the grafting reaction were examined. These factors include liquor ratio (LR), ceric ammonium nitrate (CAN) concentration as a catalyst, Aam concentration, as well as reaction time and temperature. The grafted PSFS (GPSFS) samples were characterized by estimation of nitrogen %. The GPSFS was utilized as adsorbent material to remove Hg (II) ions from aqueous solutions. All factors affecting adsorption process were examined. These factors include pH, adsorbent concentration, temperature, and agitation time. The adsorption data show that the maximum adsorption capacity, q_e, of Hg (II) onto GPSFS is 625 mg/g. The adsorption data also showed that the adsorption of Hg (II) onto GPSFS obeys Langmuir and Freundlich isotherms.     

Graft copolymer–lanthanide complexes obtained by radiation grafting on polyethylene film

Radiation‐induced grafting of acrylic acid (AAc) onto polyethylene (PE) film was investigated. The grafted films rapidly adsorbed Eu, Gd, Tb, and Dy ions at high efficiency. The carboxylic acid groups on the AAc‐grafted PE film acted as a chelating site for the selected lanthanide ions. Complex formation of lanthanide ions and the carboxylic acid group on PE film was investigated by IR, FT–Raman, and X‐ray photoelectron spectroscopy (XPS). Photoluminescence (PL) spectra and the thermal properties of the graft copolymer–lanthanide complexes onto PE film were also investigated. The application of such prepared graft copolymer–lanthanide complexes in the field of fluorescence emission displays (FEDs) may be interest. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 328–336, 2003     

The temperature-sensitive water vapor permeation control of polyurethane membrane using the graft-polymerized poly(N-isopropylacrylamide) and the impact on the tensile strength and shape recovery effect

Poly(N-isopropylacrylamide) (poly(NIPAM)) was grafted onto polyurethane (PU) using a graft-polymerization method to develop a thermo-responsive PU and to investigate the impact on cross-link density, solution viscosity, soft segment thermal transitions, tensile properties, shape memory effect, and water vapor permeation through PU membrane. The soft segment crystallization peak sharply decreased with the increase in NIPAM content, whereas the glass transition temperature (T_g) slightly increased with the increase of NIPAM content. The breaking tensile stress rapidly increased with the increase in NIPAM content due to the cross-linking effect between the grafted poly(NIPAM) chains, whereas the strain at break did not significantly decreased as the NIPAM content increased. The shape recovery at 10°C rapidly increased from 46.9% for plain PU to above 90% after the grafting of poly(NIPAM) onto PU, and the shape retention at ?25°C slightly decreased with the increase in NIPAM content. Finally, the grafting of poly(NIPAM) onto PU demonstrated the temperature-responsive control of water vapor permeation through PU film due to the conformational change of the grafted poly(NIPAM) with the increase of temperature and the potential applications of the resulting PUs are discussed.     

Preparation of amidoximated polyester fiber and competitive adsorption of some heavy metal ions from aqueous solution onto this fiber

In this study, a fibrous adsorbent containing amidoxime groups was prepared by graft copolymerization of acrylonitrile (AN) onto poly(ethylene terephthalate) (PET) fibers using benzoyl peroxide (Bz₂O₂) as initiator in aqueous solution, and subsequent chemical modification of cyano groups by reaction with hydroxylamine hydrochloride in methanol. The grafted and modified fibers were characterized by FTIR, TGA, SEM, and XRD analysis. The crystallinity increased, but thermal stability decreased with grafting and amidoximation. The removal of Cu(II), Ni(II), Co(II), Pb(II), and Cd(II) ions from aqueous solution onto chelating fibers were studied using batch adsorption method. These properties were investigated under competitive conditions. The effects of the pH, contact time, and initial ion concentration on the removal percentage of ions were studied. The results show that the adsorption rate of metal ions followed the given order Co(II) > Pb(II) > Cd(II) > Ni(II) > Cu(II). The percentage removal of ions increased with initial ion concentration, shaking time, and pH of the medium. Total metal ion removal capacity was 49.75 mg/g fiber on amidoximated fiber. It was observed that amidoximated fibers can be regenerated by acid without losing their activity, and it is more selective for Pb(II) ions in the mixed solution of Pb‐Cu‐Ni–Co‐Cd at pH 4. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Characterization of Polyurethane Grafted with Bis(2-hydroxyethyl) Terephthalate

Bis(2-hydroxyethyl) terephthalate (BHETPA) was grafted onto polyurethane (PU) to investigate the effects of BHETPA, which contains a rigid aromatic group and flexible hydroxyethyl groups, on the physical properties of PU. The cross-link density, viscosity, tensile strength, and shape recovery notably increased with an increase of BHETPA due to chemical cross-linking by BHETPA. A PU sample demonstrated excellent low-temperature flexibility compared with plain PU, showing complete recovery at approximately 0°C. Therefore, grafting BHETPA onto PU modified the thermal behavior and greatly improved the tensile stress, shape recovery, and low-temperature flexibility of PU compared to plain PU.     

Water-compatible,pH-sensitive,colour-changing polyurethane with low-temperature flexibility

A pH indicator (Bromocresol Green, Bromocresol Purple, or Thymol Blue) is grafted onto polyurethane (PU) using 2,2-dimethylolpropanoic acid (DMPA) to enhance water compatibility. The indicator-grafted, water-compatible PU is analysed for soft-segment thermal, tensile, and shape recovery properties, fast colour change depending on various pH conditions, and low-temperature flexibility. The PU surface becomes water compatible as DMPA content increases, and the characteristic UV-vis absorbance is observed for each grafted indicator. The PU series exhibits a sharp increase in tensile stress and crosslink density at low DMPA content, but a decrease with increased DMPA content. The glass transition temperature increases significantly with increased DMPA content. Shape recovery remains high, but shape retention sharply decreases after an indicator is grafted. The grafting of pH indicator onto PU improves the low-temperature flexibility and imparts an immediate colour change according to the solution pH and grafted indicator.