Radiation-induced Graft Polymerization Research Articles

Breaking of Supercooling of Water Using Silver Iodide Immobilized on Fiber Prepared by Radiation-induced Graft Polymerization

Breaking of Supercooling of Water Using Silver Iodide Immobilized on Fiber Prepared by Radiation-induced Graft Polymerization

PE/PP fibrous adsorbents with bifunctional groups of tertiary amine and phosphate prepared by electron beam induced co-grafting for heavy metal adsorption of both cationic and anionic forms in acidic conditions.

A novel fabric adsorbent having bifunctional groups of tertiary amine and phosphate was prepared by co-graft polymerization of 2-diethylaminoethyl methacrylate (NMA) and 2-hydroxyethyl methacrylate phosphate (PMA) onto a polyethylene/polypropylene nonwoven fabric (PE/PP NF) under low-energy electron beam acceleration. The process involved pre-irradiating the fabric and immersing it in the comonomer solution for grafting. The kinetics of radiation-induced graft polymerization at a total dose of 100 kGy was investigated. For pre-irradiation at 100 kGy, the optimum condition offering highest degree of grafting was at 12 wt% of NMA, 8 wt% of PMA and 4 h of reaction time. The adsorption of anions using hydrogen chromate (HCrO4−) or Cr(VI) and cations using lead (Pb(II)), cadmium (Cd(II)) and copper (Cu(II)) in aqueous solution was carried out. The results demonstrated that the bifunctional adsorbent was able to adsorb both heavy metal anionic and cationic ions from water. The co-grafted adsorbents with tertiary amine and phosphate were able to adsorb 85% Cr(VI) anion and 29% Pb(II) cations from mixed Cr(VI) and Pb(II) solution at pH 3.0 and 71% Pb(II), 13% Cd(II) and 31 % Cu(II) from mixed Pb(II), Cd(II) and Cu(II) solution at pH 5.0. The unique achievement of this study is its hypothesis that a bifunctional adsorbent can be prepared from radiation-induced graft polymerization of two different monomers onto NF, along with proof that the prepared bifunctional adsorbent can actually absorb both cationic or anionic heavy metals forms. Additionally, the adsorbent's preparation offers a rapid and straightforward one-step grafting technique. Therefore, the new bifunctional adsorbents can remove heavy metal ions in aqueous solution, either in the cation or anion form, thus offering highly promising applications in industrial wastewater treatment.

Gamma radiation induced optimized synthesis of amine functionalised poly-glycidyl methacrylate grafted poly-propylene non-woven fabric and its adsorption behaviour towards aqueous Pb(II)

Comprehensive optimization of the functionalization of polypropylene (PP) non-woven fabric through gamma irradiation-induced graft polymerization of glycidyl methacrylate (GMA), results in a material having high grafting yield. The technique, utilizing a mutual irradiation method, produced poly-GMA (PGMA) grafted PP fabric with a remarkable grafting yield of 125 % in a 1:1 acetone–water mixture, subjected to 25 kGy of total dose at a dose rate of 5 kGyh−1. The enhancement of the amination process utilizing PGMA-grafted PP was investigated with polyamines. Under the optimized conditions, the diethylene triamine (DETA) functionalized variant was identified as an effective adsorbent for aqueous Pb2+ ions. The optimized adsorbent exhibited a high saturation capacity of approximately 230 mgg−1 for Pb2+ ions, demonstrating rapid kinetics at near-neutral pH and 25 °C. This low cost innovative material holds significant promise for effective lead removal from drinking water and industrial wastewater, offering a sustainable economical solution for environmental remediation.

Effect of radiation-induced graft polymerization onto pineapple nonwoven fabric reinforced polymer composite

Natural fiber-reinforced polymer composites are gaining attention for their environmental benefits, such as biodegradability and reduced carbon footprint, as well as the potential of the natural fibers to replace or partially substitute synthetic fibers in various applications. However, challenges, such as poor interfacial adhesion and moisture absorption, limit the effectiveness of natural fibers, such as pineapple nonwoven fabric (PNWF) as reinforcement materials in polymer composites. To address these challenges, this study aims to enhance the properties of PNWF through glycidyl methacrylate grafting via radiation-induced graft polymerization. A 22 factorial design was employed to assess the effects of absorbed dosage and monomer concentration on the properties of the grafted PNWF. Infrared spectroscopy and electron microscopy analyses confirmed successful grafting. The grafted PNWF exhibited improved thermal stability and mechanical properties. The resulting composites showed significant enhancements in tensile and flexural strength, specifically, with tensile strength increase ranging from 23.32 to 34.49 MPa and flexural strength from 39.14 to 54.59 MPa. Additionally, the tensile modulus ranged from 0.77 to 1.29 GPa, while the flexural modulus varied from 1.17 to 2.06 GPa. These findings highlight the potential of PNWF grafted with polyglycidyl methacrylate (PNWF-g-PGMA) as an effective reinforcement material for various applications.

Engineered loose nanofiltration membrane for efficient dye/salt separation by starting from poly(ether sulfone) powder modification

Loose nanofiltration (LNF) is increasingly considered as the powerful technique for dye desalination due to its clear advantages at energy efficiency, selectivity and low pollution. But the membrane materials for loose nanofiltration process still suffer from the low permeance, unsatisfactory selectivity, membrane fouling and high cost. Herein, we propose a new three-step route to fabricate efficient poly(ether sulfone) (PES) LNF membrane, which starts from PES powder modification via mutual radiation-induced grafting polymerization and ensues immersion precipitation phase inversion and amination processes. The obtained PES-based LNF membrane possessed a thinner skin layer and an unusual irregular vesicular pore structure in sublayer instead of the finger-like macrovoids of conventional PES membrane. Thus, it achieved larger filtration permeance (35.5 L m–2 h−1 bar−1), high dye rejection (93.7 % to Congo Red) but low salt rejection (2.9 % to NaCl) during the filtration process of Congo red-containing saline water. It also showed excellent separation stability at high operation pressure and tolerance to acidic, alkaline and chlorine-oxidative conditions. Therefore, such a three-step strategy could endow the PES membrane with both loose and thinner skin layer in a reliable and scalable way, enlightening the development of high-performance LNF membrane for wastewater treatment and resource recovery.

Porous Microspheres as Pathogen Traps for Sepsis Therapy: Capturing Active Pathogens and Alleviating Inflammatory Reactions.

Sepsis is a systemic inflammatory response syndrome caused by pathogen infection, while the current antibiotics mainly utilized in clinical practice to combat infection result in the release of pathogen-associated molecular patterns (PAMPs) in the body. Herein, we provide an innovative strategy for controlling sepsis, namely, capturing active pathogens by means of extracorporeal blood purification. Carbon nanotubes (CNTs) were modified with dimethyldiallylammonium chloride (DDA) through γ-ray irradiation-induced graft polymerization to confer a positive charge. Then, CNT-DDAs are blended with polyurethane (PU) to prepare porous microspheres using the electro-spraying method. The obtained microspheres with a pore diameter of 2 μm served as pathogen traps and are termed as PU-CNT-DDA microspheres. Even at a high flow rate of 50 mL·min-1, the capture efficiencies of the PU-CNT-DDAs for Escherichia coli and Staphylococcus aureus remained 94.7% and 98.8%, respectively. This approach circumvents pathogen lysis and mortality, significantly curtails the release of PAMPs, and hampers the production of pro-inflammatory cytokines. Therefore, hemoperfusion using porous PU-CNT-DDAs as pathogen traps to capture active pathogens and alleviate inflammation opens a new route for sepsis therapy.

Preparation of xyloglucan-grafted poly(N-hydroxyethyl acrylamide) copolymer by free-radical polymerization for in vitro evaluation of human dermal fibroblasts

Xyloglucan is a rigid polysaccharide that belongs to the carbohydrate family. This hemicellulose compound has been widely used in biomedical research because of its pseudoplastic, mucoadhesive, mucomimetic, and biocompatibility properties. Xyloglucan is a polyose with no amino groups in its structure, which also limits its range of applications. It is still unknown whether grafting hydrophilic monomers onto xyloglucan can produce derivatives that overcome these shortcomings. This work aimed to prepare the first copolymers in which N-hydroxyethyl acrylamide is grafted onto tamarind xyloglucan by free-radical polymerization. The biocompatibility of these structures in vitro was evaluated using human dermal fibroblasts. Gamma radiation-induced graft polymerization was employed as an initiator by varying the radiation dose from 5–25 kGy. The structure of the graft copolymer, Xy-g-poly(N-hydroxyethyl acrylamide), was verified by thermal analysis, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. The findings indicate that the degree of grafting and the cytotoxicity/viability of the xyloglucan-based copolymer were independent of dose. Notably, the grafted galactoxyloglucan exhibited efficient support for human dermal fibroblasts, showing heightened proliferative capacity and superior migration capabilities compared to the unmodified polymer. This copolymer might have the potential to be used in skin tissue engineering.

Radiation grafting mediated tailoring of a mercury (Hg(II)) selective adsorbent “RAdMer”: Mechanistic insights, uptake performance and reusability evaluation in artificially contaminated groundwater

The presence of mercury (Hg(II)) in water bodies poses a pressing threat not only to aquatic life forms but also human health. This work proposes the fabrication of a novel thiol (-SH), amine (–NH–) and carboxylic (-COOH) group containing trifunctional adsorbent based on a radiolytically surface engineered biodegradable platform for selective sequestration of Hg(II) from aqueous media. Polyacrylonitrile (PAN) was gamma radiolytically incorporated onto cotton fabric via Radiation Induced Graft Polymerization (RIGP) process, followed by chemical conversion of the nitrile groups using dl-Cysteine as the trifunctional agent. The developed adsorbent RAdMer was characterized by FTIR, TGA, SEM-EDX, EDXRF, XRD, CHNS, 13C NMR and XPS techniques, and tested for Hg(II) removal in batch and continuous flow adsorption modes. Adsorption kinetics and equilibrium characteristics were validated using various theoretical models as well column adsorption models. Density Functional Theory (DFT) calculations performed to determine the complexation mechanism revealed the binding to be occurring predominantly in a 1:2 metal to ligand ratio with calculated binding affinity of −19.63 kcal.mol−1. RAdMer demonstrated fast uptake kinetics with over 60 % of total Hg(II) adsorption occurring within the first 30 min, while peak adsorption capacity was calculated at 174.3 mg.g−1. Moreover, RAdMer could be reused for >5 iterative cycles using an optimized HCl-Thiourea eluent system. Acting upon the UNOs SDG6 principle of providing “clean water and sanitation for all”, RAdMer efficiency was demonstrated with Hg(II) spiked ground water samples to successfully achieve the WHO permissible limit of <1.0 μg.L−1, and can therefore be potentially upscaled as an efficient methodology for remediation of Hg(II) ions in contaminated water.

Lignocellulosic Membranes Grafted with N-Vinylcaprolactam Using Radiation Chemistry: Load and Release Capacity of Vancomycin.

Radiation chemistry presents a unique avenue for developing innovative polymeric materials with desirable properties, eliminating the need for chemical initiators, which can be potentially detrimental, especially in sensitive sectors like medicine. In this investigation, we employed a radiation-induced graft polymerization process with N-vinylcaprolactam (NVCL) to modify lignocellulosic membranes derived from Agave salmiana, commonly known as maguey. The membranes underwent thorough characterization employing diverse techniques, including contact angle measurement, degree of swelling, scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier-transform infrared-attenuated total reflectance spectroscopy (FTIR-ATR), nuclear magnetic resonance (CP-MAS 13C-NMR), X-ray photoelectron spectroscopy (XPS), and uniaxial tensile mechanical tests. The membranes' ability to load and release an antimicrobial glycopeptide drug was assessed, revealing significant enhancements in both drug loading and sustained release. The grafting of PNVCL contributed to prolonged sustained release by decreasing the drug release rate at temperatures above the LCST. The release profiles were analyzed using the Higuchi, Peppas-Sahlin, and Korsmeyer-Peppas models, suggesting a Fickian transport mechanism as indicated by the Korsmeyer-Peppas model.

Drug delivery in thermo-responsive silicone catheters by grafting of N-vinylcaprolactam using gamma radiation

Radiation-induced graft polymerization of poly(N-vinylcaprolactam) onto silicone catheters by direct irradiation method was studied. The effects of the irradiation dose, as well as the monomer concentration, on the grafting efficiency were studied. The conditions for achieving maximum grafting yield were observed at 30% of monomer concentration in toluene at 50 kGy. The graft polymerization was examined by different characterization methods, including measurements such as thermogravimetric analysis, infrared, water contact angle, and swelling. The temperature-responsive behavior of smart grafted copolymer was studied by swelling at different temperatures. Differently from pristine silicone catheter, the N-vinylcaprolactam-grafted catheters were able to load vancomycin and sustain the release for 30 h.Graphical abstract

GFN-xTB-Based Computations Provide Comprehensive Insights into Emulsion Radiation-Induced Graft Polymerization.

Invited for this month's cover are the collaborating groups of Dr. Ryohei Kakuchi and Ms. Kiho Matsubara at Gunma University, Japan, Prof. Kei Takahashi at Fukuoka Institute of Technology and The Institute of Statistical Mathematics, Japan, Prof. Takeshi Matsuda at Hannan University, Japan, Dr. Noriaki Seko and Dr. Yuji Ueki at National Institutes for Quantum Science and Technology, Japan. The cover picture shows the machine learning-based optimization and interpretation of radiation-induced graft polymerizations under emulsion conditions based on realistic information for monomers calculated by the state-of-the-art semiempirical method. More information can be found in the Research Article by Kiho Matsubara, Kei Takahashi, Ryohei Kakuchi, and co-workers.

Modified abaca fiber prepared by radiation-induced graft polymerization as a reinforcement for unsaturated polyester resin composites

Modified abaca fiber prepared by radiation-induced graft polymerization as a reinforcement for unsaturated polyester resin composites

Synthesis, Characterization, and Adsorptive Characteristics of Radiation-Grafted Glycidyl Methacrylate Bamboo Fiber Composites.

In the present study, a biosorbent was prepared through the radiation-induced graft polymerization (RIGP) technique by using a glycidyl methacrylate (GMA) monomer. Functionalized bamboo materials were used for grafting. The grafting percentage (G %) of GMA on bamboo fibers was assessed based on the optimization of the absorbed dose and concentration of the monomer. The chemical modification of the polymerized product into the sulfonated form of the grafted biopolymer was carried out by using sodium sulfite solution. The modification of the biopolymer at various stages was analyzed by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques. By performing scanning electron microscopy (SEM), the morphological changes of the prepared biopolymer were analyzed. The temperature stability of the synthesized material was assessed by the thermogravimetric analysis (TGA) technique. The prepared sulfonated biosorbent was used in the batch adsorption study for the uptake of copper. We examined a variety of variables, including pH, adsorbent dosage, and time. The adsorption kinetics were studied using pseudo-first-order (PFO) and pseudo-second-order (PSO) models. Adsorption isotherms and thermodynamic parameters were also applied to study the adsorption capacity of the biosorbent. The maximum copper adsorption capacity was found to be 198 mg g-1 from the Langmuir isotherm. Copper adsorption followed PSO kinetics (R2 = 0.999). This inexpensive and eco-friendly biosorbent removed 96% of copper ions from the solution.

Radiation-induced graft polymerization acrylamide on PVDF membrane for cation dye removal

A preliminary study of the use of radiation-induced admicellar polymerization to modify PVDF film surfaces was conducted using gamma irradiation at 30 kGy and 0.5–1.5 M of acrylamide. The surface properties were studied in detail and characterized using FESEM, the water contact angle, surface tension, and mercury porosity. Furthermore, the point of zero charges of the grafted PVDF were determined before and after graft admicellar polymerization. The degree of polyacrylamide increased with increments of its concentration at 30 kGy. Increments in the degree of grafting created dense surfaces, as proven by the FESEM morphology. The porosity of the PVDF after grafting reduced slightly, leading to decreased water contact angles. The surface tension also increased due to the high density of the grafted polyacrylamide on the PVDF surfaces. The dye absorption showed that a higher amount of polyacrylamide removed more dye. This work indicates that radiation-induced admicellar polymerization is a suitable method for changing the PVDF surface and it could also be used for other monomers.

Direct observation of radiation-induced graft polymerization on a polyethylene film

Radiation-induced graft polymerization is widely used in the synthesis of polymeric materials with various functionalities; however, the details of the reaction mechanism are still unresolved. Herein, the initial stage of the graft polymerization reaction was investigated through atomic force microscopy (AFM). We used glycidyl methacrylate (GMA) in methanol (monomer solution) and a high-density polyethylene (HDPE) film with a well-ordered lamellar structure as the substrate. Using polymer film surfaces with a maximum grafting degree of 0.5%, AFM can distinguish between crystalline and amorphous polyethylene (PE) phases as well as a grafted polymer GMA (PGMA) phase. The graft polymerization reaction started from the interface between the crystalline and amorphous PE phases. As the reaction proceeded, the PGMA covered the crystalline PE phase: i.e., the entire surface of the PE film were covered by the PGMA. Further, the crystalline lamellae of the PE film eventually became a scaffold for the formation of aggregates comprising grafted polymer chains alone. The graft polymerization reaction mechanism was explained by comparing the solubility parameters of the monomer solution, substrate, and grafted polymer chains. Understanding the reaction mechanism at a low grafting degree obtained in this study may contribute to enhancing the efficiency of the graft polymerization reaction on any polymeric material.

Radiation induced graft polymerization of fluorinated monomers onto flax fabrics for the control of hydrophobic and oleophobic properties

Functional textiles have been one of the most studied topics in recent decades. Due to toxicity concerns, the treatment of fabrics for non-wettable properties with fluorinated molecules is nowadays limited to short fluoroalkyl chains. In this work, several fluorinated (meth)acrylic monomers such as 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, 2-(perfluorobutyl)ethyl methacrylate, 1H,1H,2H,2H-perfluorooctyl methacrylate, 1H,1H,2H,2H-perfluorooctyl acrylate and 1H,1H,2H,2H-perfluorodecyl methacrylate (denoted as M2, M4, M6, AC6 and M8, respectively) were grafted onto flax fabrics to improve their hydrophobic and oleophobic properties by radiografting using a pre-irradiation procedure. The effects of the length of the fluoroalkyl group of the monomer, the irradiation dose and the reaction time on the grafting rate were studied. The functionalization of flax fabrics by these five monomers was confirmed by FTIR spectroscopy analysis. The morphology of the fibers before and after treatment was studied by scanning electron microscopy (SEM). The location of fluorine element in the flax elementary fibers was assessed by SEM-EDX. The hydro- and oleophobic properties were determined by contact angle measurement using water and diiodomethane as solvents, respectively. The sliding angle was also measured to assess the water repellency of hydrophobic fabrics. Significant fluorine contents were obtained for flax fibers irradiated and treated with 10 wt% solutions of monomer. Hydro- and oleophobic fabrics were obtained for flax irradiated even at a low dose of 5 kGy and treated with M4, with water and diiodomethane contact angles (CAs) of about 139° and 120°, respectively. Superhydrophobic fabrics (CA = 150°) were also achieved for samples irradiated at 20, 50 and 100 kGy and treated with 10 wt% of M8. For this monomer, SEM analysis showed the formation of spherical microparticles of fluoropolymer covering the surface of elementary fibers. The formation of these particles is assumed to result from a dispersion polymerization mechanism. This is due to the fewer affinity of M8 with methanol and to the incompatibility of the formed polymer chains with this solvent used for the grafting reaction.

A highly efficient laccase-immobilized bioreactor prepared by radiation induced graft polymerization for removal of persistent pollutants

Radiation induced graft polymerization (RIGP) is an excellent tool for functionalization of polymers, allowing the preparation of high density polymer brushes suitable for enzyme immobilization. Herein, we report on a hollow fiber membrane bioreactor prepared using RIGP to host laccase which is an efficient enzyme for removal of phenolic compounds. Polymer brushes were functionalized with aldehyde moieties to allow covalent bonds in between the polymer and the enzyme for immobilization. Moisture retention was also greatly improved after functionalization. As a result, after optimization of immobilization and reaction conditions, the bioreactor showed high stability in organic media and efficient biodegradation of an organic phenolic pollutant (bisphenol A).

High atom utility of robust Ca-Co bimetallic catalyst for efficient Fenton-like catalysis in advanced oxidation processes

A durable catalyst composed of Ca-Co bimetallic complex structures on a large-scale substrate was fabricated for efficient activation of peroxymonosulfate (PMS) in organic pollutant degradation. Specifically, amidoxime groups were introduced onto the polymer substrate via radiation-induced graft polymerization (RIGP), followed by selective adsorption of Ca2+ and Co2+ ions. The catalyst demonstrated high effectiveness and stability in degrading 10 mg/L of tetracycline hydrochloride within 8 min by activating PMS under a broad pH range of 3–9. Structural characterization and density functional theory (DFT) calculations confirmed the precise doping of Ca2+, which regulated the energy level and enhanced the dispersion of Co2+. The combination of bulk substrates and fine structural control in catalytic process provided new ideas for the design of similar catalysts.

Effects of source correction on positron annihilation lifetime spectroscopic analysis of graft-type polymer electrolyte membranes

Introduction: Recently, the free-volume hole features of poly(styrene sulfonic acid) (PSSA)-grafted poly(ethylene-co-tetrafluoroethylene) polymer electrolyte membranes (ETFE-PEMs) have been studied using positron annihilation lifetime spectroscopy (PALS) to determine the relationship between gas crossover through a PEM and a fuel cell. As one such series, this work investigates the source correction in PAL spectroscopic analysis for ETFE-PEM. Method: ETFE-PEM was prepared by radiation-induced graft polymerization and subsequent sulfonation. The free-volume hole characteristics of ETFE-PEM with a grafting degree (GD) of 106% were determined using PALS with and without source correction. Results: After source correction, the original-ETFE and ETFE-PEM strains exhibited increases in r3 (smaller radius of free-volume holes in the lamellar amorphous regions, the PSSA grafts, and the interface zones inside the lamellae) and r4 (larger radius of free-volume holes in the mobile amorphous layers and the PSSA grafts outside of the lamellae). In addition, the full width at half maximum (FWHM) of r3 is much greater than that of r4 due to the rearrangement in the mobile amorphous region and the polystyrene layers outside the lamellar structure. Conclusion: Source correction causes a significant change in the distribution curves of r3 for the original-ETFE and ETFE-PEM. Thus, source correction of positron annihilation lifetime spectroscopic analyses is an important issue for determining the o-Ps lifetime of polymers, which is near the lifetime of positrons in source materials.

Silver nanoparticles-immobilized-radiation grafted polypropylene fabric as breathable, antibacterial wound dressing

In this work, a simplistic approach for developing an antibacterial and hydrophilic non-woven polypropylene (NWPP) fabric with excellent breathability has been presented via a two-step process. In the first step, acrylic acid was introduced onto NWPP fabric using simultaneous irradiation graft polymerization and pre-irradiation graft polymerization methods. Different grafting parameters, e.g., absorbed dose, monomer concentration, homopolymer inhibitor, reaction time, etc., were studied to optimize the grafting process. Subsequently, the acrylic acid grafted NWPP (NWPP-g-AA) fabric was immobilized with silver nanoparticles (Ag NPs), prepared from silver nitrate using trisodium citrate as reducing agent. After optimizing the grafting parameters, the NWPP-g-AA and Ag NPs-(NWPP-g-AA) samples were thoroughly characterized by grafting yield, FTIR, SEM, TEM, water contact angle, water vapor transmission rate (WVTR) and mechanical properties. The Ag NP-(NWPP-g-AA) fabric samples exhibited desired hydrophilicity, breathability and mechanical strength. Ag NP-(NWPP-g-AA) fabric samples were tested for antibacterial activity using plate count method after serial dilution, and exhibited excellent antibacterial efficacy against S.aureus (gram positive) and E.coli (gram negative) bacteria. This strategy demonstrated that a hydrophilic NWPP fabric having long-lasting antimicrobial activity was developed by gamma radiation-induced graft polymerization, which offers an ideal material for antibacterial wound dressing applications.