Radiation Graft Polymerization Research Articles

Recent Advances in Superabsorbent Hydrogels Derived from Agro Waste Materials for Sustainable Agriculture: A Review.

Superabsorbent hydrogels made from agro waste materials have the potential to promote sustainable agriculture and environmental sustainability. These hydrogels not only help reduce water consumption and increase crop yields but also contribute to minimizing waste and lowering greenhouse gas emissions. Recent research on superabsorbent hydrogels derived from agro wastes has focused on the preparation of hydrogels based on natural polymers isolated from agro wastes, such as cellulose, hemicellulose, and lignin. This review provides an in-depth examination of hydrogels developed from raw agro waste materials and natural polymers extracted from agro wastes, highlighting that these studies start with raw wastes as the main materials. The utilization strategies for specific types of agro wastes are comprehensively described. This review outlines different methods utilized in the production of these hydrogels, including physical cross-linking techniques such as dissolution-regeneration and freeze-thawing, as well as chemical cross-linking methods involving various cross-linking agents and graft polymerization techniques such as free radical polymerization, microwave-assisted polymerization, and γ radiation graft polymerization. Specifically, this review explores the applications of agro waste-based superabsorbent hydrogels in enhancing soil properties such as water retention and slow-release of fertilizers for sustainable agriculture.

Influence of phosphonic acid as a functional group on the adsorption behavior of radiation grafted polypropylene fabrics for Co(II) removal

The efficiency of new adsorbents, including polypropylene nonwoven fabrics by radiation grafting polymerization in the removal of cobalt (II) from aqueous solution, was in the batch experiments. The composition of the acrylonitrile and acrylic acid monomers was used in mutual irradiation grafting, and phosphonic acid was applied as a functional group. Factors affecting the grafting process as well as the adsorption percentage were studied, such as radiation dose (10–40 kGy), monomer concentration, adsorption time (2–24 h), solvent type (dioxane, and dimethylformamide), initial aqueous pH (0.5–6.5), temperature (25–65 °C), and adsorbent mass (0.01–0.1 g). Also, the synthesized adsorbent for the adsorption of various heavy metals such as nickel, cobalt, and zinc was studied. The outcomes revealed that the nonwoven fabrics could act as the excellent adsorbents of enough adsorption sites for cobalt ions or other heavy metals, mainly due to the high grafting percentage of 125.3% and adsorption percentage 99.78%. In this way, the synthesis adsorbents with high efficiency, protected, valuable and financial attributes could be novel potential materials applied in the heavy metal removal.

A comparative study of immobilizing ammonium molybdophosphate onto cellulose microsphere by radiation post-grafting and hybrid grafting for cesium removal.

Ammonium molybdophosphate (AMP) exhibits high selectivity towards Cs but it cannot be directly applied in column packing, so it is necessary to prepare AMP-based adsorbents into an available form to improve its practicality. This work provided two AMP immobilized cellulose microspheres (MCC@AMP and MCC-g-AMP) as adsorbents for Cs removal by radiation grafting technique. MCC-g-AMP was prepared by radiation graft polymerization of GMA on microcrystalline cellulose microspheres (MCC) followed by reaction with AMP suspension, and MCC@AMP was synthesized by radiation hybrid grafting of AMP and GMA onto MCC through one step. The different structures and morphologies of two adsorbents were characterized by FTIR and SEM. The adsorption properties of two adsorbents against Cs were investigated and compared in batch and column experiments under different conditions. Both adsorbents were better obeyed pseudo-second-order kinetic model and Langmuir model. MCC-g-AMP presented faster adsorption kinetic and more stable structure, whereas MCC@AMP presented more facile synthesis and higher adsorption capacity. MCC@AMP was pH independent in the range of pH 1-12 but MCC-g-AMP was sensitive to pH for Cs removal. The saturated column adsorption capacities of MCC@AMP and MCC-g-AMP were 5.4g-Cs/L-ad and 0.75g-Cs/L-ad in column adsorption experiments at SV 10 h-1. Both adsorbents exhibited very high radiation stability and can maintain an adsorption capacity of >85% even after 1000kGy γ-irradiation. On the basis, two AMP-loaded adsorbents possessed promising application in removal of Cs from actual contaminated groundwater. These findings provided two efficient adsorbents for treatment of Cs in radioactive waste disposal.

Fabrication of Cotton Linter-Based Adsorbents by Radiation Grafting Polymerization for Humic Acid Removal from Aqueous Solution.

Two kinds of cotton linter-based adsorbents were synthesized by grafting dimethylaminoethyl methacrylate (DMAEMA) on cotton linter via radiation grafting polymerization, followed by further quaternization (QCL) or protonation (PCL). The effect of radiation dose and monomer concentration on grafting yield was optimized. The synthesized adsorbents were characterized by Fourier transform infrared spectrometry (FT-IR), Thermogravimetric Analysis (TGA), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The adsorption behaviors of the two adsorbents toward humic acid (HA) were investigated and discussed. pH effect studies showed that QCL was pH-independent, whereas PCL was just suitable for HA adsorption with pH < 6. The adsorption kinetics of the PCL and QCL adsorbent for HA removal were better described by pseudo-second-order kinetic mode and reached equilibrium in 40 min. The adsorption isotherms of the PCL and QCL adsorbent were well fitted with both Langmuir and Freundlich isotherm models, for which adsorption capacity reached 250 mg/g and 333 mg/g at pH 6, respectively. XPS analysis revealed the ratio of two amino group species at different pH, suggesting that the interaction mechanism of the adsorbent and HA was electrostatic adsorption.

Development of Radiation Grafted Super Absorbent Polymers for Agricultural Applications

Super Absorbent Polymers (SAPs) were prepared by radiation grafting polymerization of neutralized Acrylic Acid (AA) on to two cellulose samples separately from bagasse, which were extracted from alkaline hydrogen peroxide and microwave assisted alkaline pretreatments in the presence of N.N-methylenebisacrylamide (MBA) as a cross linker using mutual grafting by applying gamma radiation under an environment of nitrogen gas. Characteristics of grafting, morphological and soil degradation of developed SAPs were identified by using Fourier Transform Infra-Red Spectrometer (FT-IR), Scanning Electronic Microscope (SEM) and soil burial method respectively. Additionally, water absorbency in distilled water and prepared fertilizer solutions were measured. Further, different agricultural practices implemented for survival of transplanted seedlings of Capsicum annuum, cultivation of Ipomoea aquatica and survival of cut Chrysanthemum instagram flowers were evaluated. The results indicated that developed SAPs had cross-linked cellulose-g-PAA(Na) and PAA(Na) with water absorbency ratios that were 236-325 in distilled water. Cross-linked cellulose-g-PAA(Na) had highly porous morphological structure, good degradability in soil compared to PAA(Na) and expected to be useful for survival of transplanted seedlings, cut flowers and cultivation of crops under limited supply of water.

Non-Fluorinated High Performance Pre-Irradiation Grafted Anion-Exchange Membranes

There have been a boom in the development of anion-exchange membranes (AEMs) for fuel cells (AEMFC) and water electrolyzers in recent years. These devices permit the use of a wider range of non-precious-metal electrocatalysts along with additional fuel flexibility (e.g. the use of N-containing fuels such as hydrazine). A significant tool for the production of AEMs is radiation induced graft polymerization. We have proved that a water-based, emulsion radiation graft polymerization of vinylbenzyl chloride (VBC) onto partially fluorinated ETFE film enhanced the degree of grafting compared to when an organic diluent was used. 1 A major challenge in handling ETFE-based radiation-grafted AEMs has always been their rather poor mechanical stability due to the radiation treatment. 2 Locally, fuel cell tests were not necessarily terminated due to chemical degradation but due to swelling stresses and membrane rupture. This study focuses on the emulsion-type radiation (peroxidation) grafting of VBC onto non-fluorinated LDPE films of 25 μm thickness using electron-beams (in air). VBC is an ideal grafting monomer as it contains both a polymerizable double bond and a reactive benzyl chloride group, the latter of which can be converted to positively charged anion-exchange groups on reaction with amines. ETFE with the same thickness, 25 μm, was grafted under identical conditions as the benchmark. An elevated electron-beam dose was required with the LDPE to obtain the desired grafting levels (cf. ETFE). The LDPE- and ETFE-based AEMs were characterized in terms of ion-exchange capacity (IEC), water uptakes and swelling, and in-plane conductivity. Raman microscopy of the AEM cross-sections was used to map the distribution of the graft component across the samples’ thicknesses (μm spacial resolution). The LDPE-AEMs exhibited enhanced mechanical stabilities (relative tensile stress–strain testing). A high-performance LDPE-AEM, with enhanced properties compared to the reference ETFE-AEM was evaluated in single H2/O2 fuel cell tests. The fuel cell performances were tested up to T = 80°C. The polarisation curves are presented in Fig. 1a. A significantly higher fuel cell performance was obtained with the LDPE-AEM. The enhancement is due to a combination of high anion conductivity and enhanced water management (facilitated water back transport from the anode to the cathode). Furthermore, the LDPE-AEM exhibited superior mechanical strength (cf. ETFE-AEM) even after alkali treatment (Fig. 1b). Figure 1. a) H2/O2 AEMFC performance at 80 °C (PtRu/C anodes and Pt/C cathodes, Pt loadings all 0.4±0.02 mg cm-2) and no gas back-pressurization. b) Tensile measurements on the LDPE- and ETFE-AEMs (before and after aqueous KOH (1 M) treatment at 80°C for 7 days). 1. L. Q. Wang, E. Magliocca, E. L. Cunningham, W. E. Mustain, S. D. Poynton, R. Escudero-Cid, M. M. Nasef, J. Ponce-González, R. Bance-Soualhi, R. C. T. Slade, D. K. Whelligan and J. R. Varcoe, Green Chemistry, 2017, 19, 831-843. 2. J. Huslage, T. Rager, B. Schnyder and A. Tsukada, Electrochim Acta, 2002, 48, 247-254. Figure 1

Increase the strength characteristics of polymer films by radiation graft polymerization

The possibility of increasing the strength characteristics of polymer films based on polyethylene and polyamide by radiation graft polymerization was investigated. Two methods of graft polymerization (direct method and the method of polymer mixtures cross-linking) on the PMMA films surface were studied. The possibility of increasing the strength and elasticity of polymeric films by radiation modification of polymethyl methacrylate was shown.

Fabrication of Unidirectional Diffusion Layer onto Polypropylene Mat for Oil Spill Cleanup

In this study, a cross-linking layer which performed as a unidirectional diffusion layer was fabricated onto a polypropylene (PP) mat through UV radiation graft polymerization. On the one hand, the introduction of acrylate monomers enhanced the hydrophobility of the sorbent, and the swelling of PP sorbent provided more spaces, which increased the sorption capacity. On the other hand, the diffusion channels were locked after saturation adsorption. Thus, the retention capacity was dramatically intensified. A reusability test revealed that the cross-linking layer also performed as a scaffold to sustain the inner fibrous structure, which improved the reusability. Also, the oil sorption and retention mechanism were systematically elucidated. The study proposed a potential method to fabricate fibrous sorbent and increase the oil sorption and retention capacity.

Development of hydrogels by radiation induced polymerization for use in slow drug delivery

In the present work, in order to improve the drug release profile of indinavir sulfate, a potent inhibitor of HIV protease, controlled drug delivery systems in the form of hydrogels have been designed by a radiation graft polymerization method. These hydrogels have been prepared by using dietary fiber psyllium and binary monomers mixture of acrylamide (AAm) and 2-acrylamido-2-methylpropanesulfonic acid (AMPSA). These polymers have been characterized with cryo-SEMs, FTIR, XRD and swelling studies. The swelling of hydrogels has been determined in solution of different pH, temperature and [NaCl]. in vitro release studies of model drug indinavir sulfate in different pH have been carried out to determine the drug release mechanism. The release of dug occurred through non-Fickian mechanism.

High fluence irradiation effect on the ion beam graft polymerization method

Radiation graft polymerization method has been applied to make many industrial product. Ion beam graft polymerization method has been developed by Betz and many researchers, and we have also developed the method with proton whose energy is below a few MeV. Using the method, the substrate, e.g. polyethylene film, is graft-polymerized and has the graft chains near the surface. To conduct the method for some times, the structure of graft chains near the surface can be formed. When we want to produce the graft chains inside of the substrate, the graft chains near the surface are unnecessary. One of our objectives is to produce a functional polymer with a structure in the film. When the sample is irradiated in sufficiently high fluence, the sample can’t be graft-polymerized in the next irradiation. Comparing the density of radicals and the number of double bond with the degree of grafting, the reason why formation of a part not grafted in high fluence irradiation was discussed. Because the number of the double bond and the allyl radicals in PE are increased for high fluence irradiation, the number of the alkyl radical as a grafting point is decreased. Moreover, the alkyl radical is not produced in following irradiation since existence of double bond and peroxy radical.

Grafting of a novel phosphorylcholine-containing vinyl monomer onto poly-carbonateurethane surfaces by ultraviolet radiation grafting polymerization

An original phosphorylcholine (PC) containing vinyl monomer (compound 1) was grafted onto the surface of polycarbonate urethane (PCU) films by ultraviolet (UV) initiated polymerization. The vinyl monomer was synthesized from 2-hydroxyethyl methacrylate (HEMA), hexamethylene diisocyanate (HDI) and L-α-glycerylphosphorylcholine (GPC) by two relative reactions through the coupling of the isocyanate groups in HDI with the hydroxyl groups in HEMA and GPC, respectively. The existence of phosphorylcholine groups on the surface of compound 1-grafted PCU films was verified by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and water contact angle measurements. The surfaces of the grafted PCU films showed lower water contact angles than did the surfaces of non-grafted PCU films. Furthermore, the surface morphology of a grafted PCU film was observed using scanning electrical microscopy (SEM), which showed that the grafted polymer film exhibits a rough and pinhole-free surface. In addition, the blood compatibility of the compound 1-grafted PCU films was evaluated by platelet adhesion studies using the non-grafted PCU film as a reference. It was found by SEM that fewer platelets adhered to the surfaces of the grafted PCU films compared to the reference. The high PC-grafted PCU film did not show any substantial platelet attachment on its surface. These results indicated that these compound 1-grafted polymers may have potential application as biomaterials for vascular grafts and some subcutaneously implanted devices. Open image in new window

Polytetrafluoroethylene modification by radiation grafting of vinylidene chloride and its dehydrochlorination

A process has been designed for manufacturing a new composite material consisting of a PTFE matrix with a carbon phase implanted in the surface layer of up to 30 μm thickness. The process involves radiation graft polymerization of vinilydene chloride (VDC) from the vapor phase onto the PTFE matrix followed by dehydrochlorination of implanted PVDC. The VDC grafting kinetics, the distribution of the grafted polymer and the carbon phase, and the mechanical characteristics of the composite material have been investigated. It has been shown that unlike initial PTFE, the composite possesses good adhesive bonding properties and a small contact angle.

Fabrication of a polymer with three-dimensional structure by the ion beam graft polymerization method

The graft polymerization method is one of the most effective techniques to produce a new polymer with unique function. To produce the polymer, we conducted experiments on radiation graft polymerization using ion beams of several hundred keV energy. A high density polyethylene (PE) film was irradiated with H + beams, then, graft polymerization with monomer solution such as acrylic acid or acrylonitrile was conducted. Radicals generated by the interaction between the beam ions and the PE molecules become the starting point of the graft polymerization. Since the range in PE depends on ion energy, the density distribution of the graft chain can be controlled by the ion energy. Using a mask which restricts the ion beam incidence, PE sheets containing graft chains only in the unmasked area were obtained. Multiple ion beam graft polymerization can produce a polymer which has some functional bases at specified position. We have demonstrated the production of a polymer film with a three-dimensional structure.

Study on Preparation and Application in Flocculants of Modified Lignin

The lignin sulfonate was modified with olefins monomer by the method of radiation graft polymerization, by which a new type of natural polymer flocculants can be made. And results of the flocculation and sedimentation are tested in the furfural wastewater treatment process. Furfural wastewater is a complex composition, whose COD is about 20000mg / L, is difficult to be treated by conventional methods. Our results showed that the kind of flocculants can remove 50 percent COD or more from furfural wastewater after aerating and adjusting pH value to 9.

Synthesis of fluorinated polymer electrolyte membranes by radiation grafting and atom transfer radical polymerization techniques

A novel polymer electrolyte membrane was synthesized by radiation-induced grafting and consequent atom transfer radical polymerization (ATRP). First, bromine-containing perfluorinated grafts were prepared by radiation grafting of 2-bromotetrafluoroethyl trifluorovinyl ether (BrTFF) into a poly(ethylene-co-tetrafluoroethylene) (ETFE) film. Then, the bromine atoms in the ETFE-g-PBrTFF grafted films were acted as initiators, and the films were treated with Cu(I)-based catalytic system of a CuBr and 2,2′-bipyridyl (bpy) for the ATRP. By adjusting the molar ratio of initiator/CuBr/bpy and the reaction temperature, branched poly(styrene) with a grafting yield of above 100% on the poly(BrTFF) main chains was constructed in ETFE-g-PBrTFF films. Thermal analysis revealed that the perfluorinated poly(BrTFF) main chains were miscible to ETFE, whereas the hydrocarbon poly(styrene) branches were phase-separated from the ETFE-g-PBrTFF film. Sulfonic groups could be further introduced into the poly(styrene) grafts of ETFE-g-PBrTFF-g-PS films with homogeneous distribution in a perpendicular direction to the membrane surface. The resulting membrane with a styrene grafting yield of 15% exhibited higher proton conductivity than commercial Nafion 117 membrane. Likewise, it had better chemical stability than ETFE-g-PSSA membrane prepared by conventional radiation-induced grafting.

Effect of heat and solvent treatment on radiation grafting of acrylic acid to poly(ethylene terpehthalate)

Direct radiation graft polymerization of acrylic acid onto oriented poly(ethylene terephthalate) films and fibers subjected to thermal treatment and treated with structure-active solvents, such as dichloroethane and dioxane, was studied. Based on the results of thermomechanical analysis, X-ray diffraction, sorption, and acrylic acid grafting, conclusions were drawn concerning the character of structural changes in poly(ethylene terephthalate) exposed to structure-active solvents. The physicochemical properties of the graft copolymers obtained were examined, including the resistance against γ-radiation.

Immobilization of streptavidin-horseradish peroxidase onto a biotinylated poly(acrylic acid) backbone that had been radiation-grafted to a PTFE film

Films of polytetrafluoroethylene (PTFE) were modified by radiation graft polymerization of acrylic acid (AAc). Optimal conditions for efficient AAc grafting were studied, including pre-irradiation dose in air, monomer concentration, temperature and time of the grafting process. Carboxylic groups of the grafted polyAAc were activated with carbodiimide (EDC) for biotinylation by reaction with 5-(biotinamido) pentylamine. Streptavidin-horseradish peroxidase (SA-HRP) was immobilized by affinity complexation of the SA with the biotin groups on the PTFE surface. The amount of active HRP immobilized on the PTFE films was determined as a function of the extent of polyAAc grafting. This study has demonstrated the utility of combining the processes of (a) radiation grafting of polymers with reactive groups onto inert polymers such as PTFE, (b) biotinylation of the graft polymer reactive groups, (c) immobilization of streptavidin on the biotinylated surface sites, followed by (d) immobilization of biotinylated, biologically active molecules via complexation of their conjugates with streptavidin. In this study, the last two steps were combined by immobilizing the complex of streptavidin and biotinylated HRP onto the biotinylated surface sites. The unique nature of this process is the ability to immobilize biotinylated molecules on an inert surface as PTFE.

Preparation of Polymer Membranes for Fuel Cells by Radiation Graft Polymerization

Publications on the use of radiation graft polymerization for the manufacture of polymer membranes for fuel cells are systematized and generalized. Data on the syntheses, structures, and physicochemical properties of the membranes are given. The areas of practical applications of the membranes are demonstrated. The review mainly surveys works published in the past decade.

Polypropylene Modification by the Radiation Graft Polymerization ofN-Vinylcaprolactam

The radiation graft polymerization of N-vinylcaprolactam onto polypropylene films was studied. The radiation graft polymerization was performed with preirradiation in air (peroxide method) or using a direct method in aqueous solutions and organic solvents. The effects of radiation dose, reaction time, monomer concentration, and homopolymerization inhibitor on the radiation graft polymerization were studied. It was found that the radiation graft polymerization from a monomer emulsion in water occurred at the highest rate. The IR spectra of grafted polymers were obtained. With the use of differential scanning calorimetry and equilibrium swelling in water, it was found that the modified polymers of polypropylene with grafted poly(N-vinylcaprolactam) chains exhibited thermoresponsive properties.

Modification of Polymers by Radiation Graft Polymerization (State of the Art and Trends)

The state of the art polymer modification by radiation graft polymerization is surveyed. The mainstream of research in this field is elucidated. Data published within the last five–ten years are summarized.