Radiation Grafting Research Articles

Functionalization of graphene oxide by radiation grafting polyhedral oligomeric silsesquioxane with improved thermal stability and hydrophilicity

Functionalization of graphene oxide (GO) with octavinyl polyhedral oligomeric silsesquioxane (OvPOSS) is achieved by gamma-ray radiation-induced grafting under mild conditions. The grafting yield of OvPOSS-grafted GO (GOP), calculated by the content of silicon in GOP using X-ray photoelectron spectroscopy, increases gradually with the increase in the absorbed dose. The grafting of OvPOSS onto GO not only improves its thermal stability, but also increases its distance between the adjacent graphitic layers which could improve the reactivity of GO. In contrary to the hydrophobic GOP prepared via the traditional chemical method, it dramatically becomes more hydrophilic with the increase in the absorbed dose due to the introduction of nitrogen-containing group under irradiation, and the surface of GOP becomes super-hydrophilic at an absorbed dose of 50 kGy. Furthermore, GOP still has excellent electrical insulation property due to the grafting of insulated OvPOSS. Consequently, this work paves a feasible and green way for the functionalization of GO with improved performances.

Amine modifications of polypropylene films by gamma radiation to be applied in cell cultures

Abstract

A facile strategy for fabrication of HKUST-1 on a flexible polyethylene nonwoven fabric with a high MOF loading

Abstract Fabrication of metal-organic frameworks (MOFs) on polymer substrates has significant potential in the fields of adsorption, separation and catalysis. However, the loading of MOF and the stability of polymer/MOF composites require effective improvement, which remains a great challenge. In this work, a copper benzene-1,3,5-tricarboxylate MOF HKUST-1 (HK) is fabricated on a flexible polyethylene (PE) nonwoven fabric (NWF) with a high loading of 66 wt%. The synthesis of polyethylene-g-poly(acrylic acid)/HK (PE-g-PAA/HK) NWF including radiation grafting of acrylic acid (AA), adsorption of copper(II) (Cu2+) ions, and solvothermal growth process. Scanning electron microscopy images confirm that the surface of the grafted PE NWF substrate is completely covered by the HK crystals. Moreover, the loaded HK crystals present well-controlled morphology and uniform crystal size distribution. Owing to the porous structures of HK, the fabricated PE-g-PAA/HK NWF maintains a high Brunauer-Emmett-Teller (BET) surface area of 758.1 m2 g−1 and exhibits a good CO2 adsorption capacity of 2.23 mmol g−1 (101 kPa, 25 °C). The proposed radiation grafting combined activation process can be viewed as a facile strategy for fabrication of MOFs on flexible polymer substrates with a high MOF loading.

Preparation and characterization of proton exchange membrane by UV photografting technique

Ultraviolet (UV)-induced graft copolymerization of glycidyl methacrylate GMA onto poly(ethylene terephthalate) (PET) films and the subsequent sulfonation on the monomer units in the grafting chain using sulfuric acid were carried out to prepare proton exchange membranes (PEMs) for fuel cells. A maximum grafting value of 23.5% was found for 15 vol% GMA after 4-h radiation time. Optimum concentration of sulfuric acid was selected for the sulfonation reaction to be 1 mol/L based on the degree of sulfonation and the tensile strength studies of the membrane. The radiation grafting and the sulfonation have been confirmed by titrimetric and gravimetric analysis as well as FTIR spectroscopy. The maximum ion exchange capacity (IEC) of 2.085 meq g−1 was found at 46.99% degree of sulfonation and the maximum proton conductivity was found to be 60.35 mS cm−1 at 30 °C and relative humidity of 100%. The various physical and chemical properties of the PEMs such as water uptake, mechanical strength, thermal durability, free-volume content, and methanol permeability were also studied as function of sulfuric acid concentration. To investigate the suitability of the prepared membrane for fuel cell applications, its properties were compared with those of Nafion 112 as standard membrane.

The First Durable Imidazolium-Based Radiation Grafted Anion Exchange Membranes for Alkaline Fuel Cells: The Impact of Water Management

Recently, Radiation grafted anion exchange membranes (AEM) gained increasing interest for alkaline fuel cell applications due to their high performance such as the highest power density ever reported for alkaline fuel cells (>2W/cm2). 1 However, their durability under operating fuel cell conditions still the biggest challenge.2 In our group, several radiation grafted AEMs, having several imidizalium-based graft-polymers consisting of N-vinyl (NVIm), 2-methyl-1-vinyl- (NVMIm), 2-methyl-4-vinyl- (4VMIm), and 2-(4-ethenylphenyl)-imidazolium (2StIm) graft-polymers, have been developed.3,4 In this work, the durability of the membrane-electrode-assembly (MEA) consisting imidazolium based radiation grafting AEMs under the supply of H2 and O2 at 60 °C was investigated in comparison to the MAE with common benzyl trimethylammonium (BTMA) based membranes. The core of this study is to investigate the effect of water management and specifically the dew point of the flow gas at anode and cathode sides on the performance and durability of imidazolium based membranes. For example, by tuning the due points for NVMIm-AEM the maximum power density increased from 115 to 200 mW/cm2. On the other hand, In spite of the low durability of 4VMIm membranes under in-situ alkaline durability in solution,5 the 4VMIm retained 75 % of the initial voltage after 240 h under fuel cell conditions, that was more durable than BTMA-based MEA (Figure 1). This study reveals the main role of water management of AEMs not only on the performance but also on the membrane durability. The study discloses an alternative durable AEMs for the new generation of alkaline fuel cells and other energy applications.

Combination immunotherapy and radiotherapy causes an abscopal treatment response in a mouse model of castration resistant prostate cancer

BackgroundProstate cancer is poorly responsive to immune checkpoint inhibition, yet a combination with radiotherapy may enhance the immune response. In this study, we combined radiotherapy with immune checkpoint inhibition (iRT) in a castration-resistant prostate cancer (CRPC) preclinical model.MethodsTwo Myc-CaP tumor grafts were established in each castrated FVB mouse. Anti-PD-1 or anti-PD-L1 antibodies were given and one graft was irradiated 20 Gy in 2 fractions.ResultsIn CRPC, a significant increase in survival was found for radiation treatment combined with either anti-PD-1 or anti-PD-L1 compared to monotherapy. The median survival for anti-PD-L1 alone was 13 days compared to 30 days for iRT (p = 0.0003), and for anti-PD-1 alone was 21 days compared to 36 days for iRT (p = 0.0009). Additional treatment with anti-CD8 antibody blocked the survival effect. An abscopal treatment effect was observed for iRT in which the unirradiated graft responded similarly to the irradiated graft in the same mouse. At 21 days, the mean graft volume for anti-PD-1 alone was 2094 mm3 compared to iRT irradiated grafts 726 mm3 (p = 0.04) and unirradiated grafts 343 mm3 (p = 0.0066). At 17 days, the mean graft volume for anti-PD-L1 alone was 1754 mm3 compared to iRT irradiated grafts 284 mm3 (p = 0.04) and unirradiated grafts 556 mm3 (p = 0.21). Flow cytometry and immunohistochemistry identified CD8+ immune cell populations altered by combination treatment in grafts harvested at the peak effect of immunotherapy, 2–3 weeks after starting treatment.ConclusionsThese data provide preclinical evidence for the use of iRT targeting PD-1 and PD-L1 in the treatment of CRPC. Immune checkpoint inhibition combined with radiotherapy treats CPRC with significant increases in median survival compared to drug alone: 70% longer for anti-PD-1 and 130% for anti-PD-L1, and with an abscopal treatment effect.PrecisCastration-resistant prostate cancer in a wild-type mouse model is successfully treated by X-ray radiotherapy combined with PD-1 or PD-L1 immune checkpoint inhibition, demonstrating significantly increased median overall survival and robust local and abscopal treatment responses, in part mediated by CD8 T-cells.

Enhancement the properties of high and low-density polyethylene membranes by radiation grafting process

Enhancement the properties of high and low-density polyethylene membranes by radiation grafting process

Rational design of modified fluororubber-based quasi-solid-state electrolyte for flexible supercapacitors with enhanced performance

The poly(vinylidene fluoride-co-hexafluoropropylene) rubber (FKM) is a perfect matrix of organic quasi-solid-state polymer electrolyte (oQPE) due to its outstanding chemical stability, excellent elasticity, and non-flammability. However, the poor adhesion to electrodes limits its practical application. Herein, the porous FKM grafted poly(butyl acrylate) membranes (pFKM-g-PBA), prepared through a template pore-forming and γ-ray radiation grafting method, is reported. The corresponding oQPE (pFKM-g-PBA/Et4NBF4-AN) shows superior stretchability (the retention of 96.3% after 1000 stretching cycles at 100% strain), high ionic conductivity (8.1 × 10−3 S cm−1), and good flame resistance. Benefit from the considerable increase in adhesiveness, the pFKM-g-PBA/Et4NBF4-AN oQPE adhere firmly to the carboxylated multiwall carbon nanotubes-supported poly(1,5-diaminoanthraquinone) (cMWCNT@PDAA) flexible electrodes. The as-assembled flexible supercapacitor (cMWCNT@PDAA//pFKM-g-PBA/Et4NBF4-AN//cMWCNT@PDAA) delivers a high energy density of 65.2 Wh kg−1 at a power density of 0.67 kW kg−1 and retains specific capacitance of 87% after 10,000 charge-discharge cycles which is better than that of the raw FKM-based device (75%).

Surface Modification of Polypropylene with Primary Amines by Acrylamide Radiation Grafting and Hofmann's Transposition Reaction

AbstractPolypropylene (PP) film surface is modified with primary amines by means of gamma radiation to graft acrylamide (AAm) using the pre‐irradiation oxidative method at a dose of 50 kGy, a monomer concentration of 13%, and a temperature of 60 °C for 6 h, followed by Hofmann rearrangement to reduce the primary amide groups of the grafted polymer (PP‐g‐AAm) to obtain vinylamine (VAm) groups (PP‐g‐VAm). The films are characterized using infrared spectroscopy before and after the reduction reaction; the hydrophilicity is studied using the contact angle; the thermal stability of the films are observed using TGA and DSC; and the surface morphology is determined using SEM. The presence of primary amines and the corresponding decrease in C=O and O=C‐NH2 groups due to reduction reaction, are confirmed using X‐ray photoelectron spectroscopy. In addition, the surface primary amines are quantified using a colorimetric method that calculated the amount as 1.9+0.1 nmol/mm2.

Bis[2-(methacryloyloxy)ethyl] phosphate radiografted into track-etched PVDF for uranium (VI) determination by means of cathodic stripping voltammetry

We report the radiation grafting of bis[2-(methacryloyloxy)ethyl] phosphate (B2MP) through electron-beam onto PVDF films and through swift heavy ions (SHI) irradiations into the pores of track-etched PVDF membranes. Radiolytically produced radicals were studied using EPR. To adapt the radiation grafting protocol inside the nanopores of track-etched membranes, the electron-beam irradiated films at varying monomer concentrations, doses and solvent mixtures were first studied. It was found that track-etched membranes, even after 1 h of chemical treatment, do not require a post-etching irradiation to initiate free-radical polymerization of B2MP from remaining radiationinduced radicals. The presence of functional groups inside the nanopores of the membrane were examined using FTIR and XPS. After exposure of B2MP-g-PVDF membranes to a uranyl solution, XPS was also exploited to evidence of O2UO22+ trapping inside the membrane nanoporosity by tracking the presence of U 4f peak. The B2MP-g-PVDF membranes were converted into electrodes by depositing 35 nm of gold on each side through a mask. Detection of ppb concentrations (from 20 to 100 ppb) of uranyl by B2MP-g-PVDF membrane electrodes was demonstrated by means of square wave cathodic stripping voltammetry (SW-CSV). The limit of detection (LOD) was estimated to be 17 ppb (3σ−/ slope).

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.

Influence of monomer reactivity on radiation grafting of phosphorus flame retardants on flax fabrics

Flax fabrics were modified by radiation grafting method to improve their flame retardancy. Several phosphonated monomers with different carbon-carbon double bond reactivity were grafted. According to 1H NMR carried out on irradiated monomers solubilized in water, the reactivity is the highest for (acryloyloxy)methyl phosphonic acid (hPAAPC1), and the lowest for allyl phosphonic acid (APA). Nevertheless, grafting yield on flax, assessed by X-ray fluorescence and scanning electron microscopy showed a different tendency. Especially (methacryloyloxy)methyl phosphonic acid (hPMAPC1) and vinyl phosphonic acid (VPA) appear to be highly grafted. In all cases, diffusion of the molecules into the flax elementary fibers bulk was observed. The choice of the solvent in washing step after the irradiation step showed to be effective to control the final phosphorus content in flax fabrics. The effect of phosphorus grafting on thermal properties and fire behavior was studied using thermogravimetric analysis, pyrolysis combustion flow calorimetry and a preliminary fire test. According to the latter, self-extinguishing and non-flammable fabrics were obtained for phosphorus content of 0.5 wt% and 1.2 wt% respectively. Correlations with flammability at microscale were pointed out. Additional cone calorimeter tests highlight the influence of flame retardant treatment on flammability under forced flaming conditions.

Chemical and radiation grafted chitosan for the mitigation of arsenic from contaminated water

The removal of As (V) from aqueous solution was investigated with the grafted polymeric adsorbent (chitosan-g-HEMA) synthesized by using high energy 60Co gamma radiation as well as by conventional chemical method. The swelling behavior of grafted polymer at different pH conditions and their kinetic studies were investigated. Fourier Transform Infrared Spectroscopy (FTIR) was used to characterize the grafted polymer and the morphological structure was analyzed by Scanning Electron Microscope (SEM). As (V) ions uptake capacity of the adsorbent was evaluated in the light of varying pH, contact time, temperature, adsorbent dose, and different arsenate ion concentration. The adsorption data was fitted well in the Langmuir model and various static parameters were calculated. The removal of toxic As (V) ions was carried out by batch method using grafted sorbents synthesized by both gamma radiation and chemical grafting methods and it was observed that the adsorbent synthesized by the use of gamma radiation shows higher adsorption capacity as compared to the chemically grafted polymer.

Facile Preparation of EVOH-Based Amphoteric Ion Exchange Membrane Using Radiation Grafting Technique: A Preliminary Investigation on Its Application for Vanadium Redox Flow Battery.

A novel amphoteric ion exchange membrane (AIEM) was successfully prepared by one-step radiation grafting of sodium styrene sulfonate (SSS) and dimethylaminoethyl methacrylate (DMAEMA) onto ethylene-vinylalcohol copolymer (EVOH) powder and sequent transferring into film by casting method. Fourier transform infrared spectrometry (FT-IR), thermal gravimetric analyzer (TGA) and elemental analysis testified SSS and DMAEMA were successfully grafted onto EVOH. The ion exchange capacity, water uptake and proton conductivity of the resulting AIEM increased with grafting yield (GY). At the GY of 40.9%, the permeability of vanadium ions of AIEM was 3.98 × 10−7 cm2 min−1, which was better than Nafion117 membrane. Furthermore, the cost of this AIEM is much lower than that of Nafion117 membrane. This work provided a low cost and simple method for fabrication of the ion exchange membrane for vanadium redox flow battery (VRFB). Meanwhile, it also provided a new direction for the application of EVOH.

Facile Fabrication of N-Methyl-D-Glucamine Grafted HDPE Particle as Adsorbent for Boron Removal from Aqueous Solution

Glycidyl methacrylate (GMA) was grafted onto the surface of HDPE particles by radiation grafting and emulsion graft copolymerization. And subsequent ring-opening reaction of expoxy groups in poly-GMA graft chains with N-methylglucamine (NMG) was conducted to synthesis the boron adsorbent. The synthesis condition (radiation dose and NMG concentration) was optimized and characterized by IR and SEM. Adsorption behaviors of the boron adsorbent for boron removal presented that adsorption kinetics was well described by pseudo-second-order kinetic mode. The adsorption isothermal was well fitted with both Langmuir and Freundlich isotherm models. The adsorption capacity for boron reached 15.63 mg/g at optimal pH 8. Dynamic experiment revealed that boron could be efficiently adsorbed by the boron adsorbent and fully desorbed using 13 BV of 1 mol/L HCl.

(Invited) Low Ionic Resistance Radiation-Grafted Cation- and Anion-Exchange Membranes for Reverse Electrodialysis (salinity gradient power) Application: Cross-Linking Is Essential for High Permselectivities.

Reverse electrodialysis (RED) cells are a form of salinity gradient power technology where electrical energy can be recovered from the mixing of waters of differing salinities. RED cells require both cation- and anion-exchange membranes (CEM and AEM, respectively) in order to operate. This presentation details the development of radiation-grafted (RG) CEMs and AEMs, which were evaluated for ex situ resistances (conductivities) and permselectivities. Trends between ex situ properties will be discussed (e.g. room temperature Na+ conductivities (in water) are higher with RG-CEMs that possess higher gravimetric water uptakes, see Figure). It is clear that RG-CEMs and RG-AEMs are desirably low resistance. However, non-crosslinked RG-CEMs and RG-AEMs have permselectivities that are too low for application in RED cells. However, the addition of crosslinking (either via the addition of divinyl-monomers, such as BVPE, or through the use of difunctional amination agents, such as N,N,N',N'-tetramethylhexane-1,6-diamine) leads to higher permselectivity types. Therefore, we conclude that cross-linking is essential for the production of RG-ion-exchange membranes with high permselectivities for such application. Figure 1

Small-Angle Scattering from Weakly Correlated Nanoscale Mass Fractal Aggregates.

Formation of fractal aggregates is generally an undesired effect which may lead to end products with worse properties as compared to those of the individual components, especially in nanocomposite materials. Although several methods exist to overcome this issue, such as inclusion of additives, irradiation grafting or sonication, their effectiveness relies on a detailed knowledge of the structural properties of the aggregates. Here, small-angle scattering (SAS) technique is used and a theoretical model based on a unified Guinier–Porod approach with weak correlations is developed for investigating the structural properties of nanoscale fractal aggregates. It is shown how one can extract information concerning the correlation length/degree between aggregates, their fractal dimension and the overall size. These parameters can be used for development of various types of novel nanomaterials with pre-determined properties and functions.

Reconstructive Challenges of Proximal Ulnar Bone Tumors: Our Experience with Biological Osteoarticular Reconstruction Using Extracorporeal Irradiation and Reimplantation.

Introduction Limb salvage surgery following proximal ulna resection poses a challenge in reconstruction of the complex elbow anatomy. Various reconstruction methods described offer inadequate restoration of function and stability. Following resection of proximal ulna tumors, we aimed to restore the joint using the resected osteochondral segment of proximal ulna treated with extracorporeal irradiation and reimplantation. Questions/Purposes (1) Does irradiated osteoarticular autograft reconstruction for proximal ulna allow anatomical joint restoration and what are the oncological and functional outcomes? (2) Is there evidence of graft-related complications or osteoarthritis at a minimum of 2 years follow-up with irradiated osteoarticular autografts for the proximal ulna? (3) How does our method of reconstruction fare as compared to reported reconstruction options in the literature? Materials and Methods. 3 patients with primary bone tumors involving the proximal ulna underwent limb salvage surgery with en bloc resection and reconstruction using the resected bone after treating it with extracorporeal irradiation of 50 Gy. Minimum follow-up of 2 years was considered for assessment of final outcomes. Radiographs were assessed for bony recurrence, union across osteotomy junction, and signs of joint arthritis. Functional outcome measures included range of movement, muscle power testing, and functional and disability scores. Results 2 complete and 1 partial olecranon involving proximal ulnar resections were performed for three cases of Ewing's sarcoma in 2 males and 1 female. Follow-up ranged from 28 to 42 months, and all patients continue to remain disease free. All 3 patients have achieved full range of flexion-extension and pronosupination movement in comparison to the contralateral side. Muscle power for flexion and extension was 5/5. MSTS score: 100% (30/30); MEPS score: 100; and DASH score: zero were achieved for all patients. Union across osteotomy junctions at median follow-up of 8 months without need for intervention/bone grafting was achieved. No complications related to joint laxity/subluxation, infection, graft fracture, or implant failure was noted. None of the patients have clinical or radiological signs of joint arthritis across the irradiated articulation. Conclusion Biological restoration of elbow anatomy using osteoarticular irradiated graft for proximal ulna reconstruction offers great joint stability and functional outcomes. Although the potential risks of infection and graft failure need to be considered, reconstruction with the size-matched radiated autograft eliminates donor site morbidity, offers a low-cost alternative to endoprosthesis, and provides outcomes superior to any other methods of reconstruction as analyzed from the literature.

Extracorporeal Irradiation and Reimplantation of Tumor-bearing Bone Segments Following Diaphyseal Sarcoma Resection at the Tibia.

Reconstruction of diaphyseal tibial sarcomas with extracorporeal irradiated autograft is a rarely applied technique and is analyzed in this study. Eight patients with malignant sarcomas received local treatment by means of a wide resection and reimplantation of an extracorporeally-irradiated autograft. The graft was combined with an ipsilateral vascularized fibula when a full-thickness segment of the tibia had to be resected and no cortex could be preserved (n=5). Oncological and functional results were recorded. All patients had clear margins after resection, and with no local recurrence 72 months after treatment. Full weight-bearing was allowed at the time of radiological consolidation of the irradiated grafts (after a median of five months). The functional results were good and excellent in 7 of 8 patients, respectively. Extracorporeal irradiation grafting is a suitable method for the treatment of localised and resectable tibial sarcomas.

Assessment of olive pomace wastes as flame retardants

ABSTRACTOlive pomace (OP) is a lignocellulosic waste from olive oil industry. In order to valorize these wastes as flame retardant (FR) fillers into polymers, OP residues are milled and screened into three different fractions. Two strategies are then investigated. The first one is to modify OP particles by phosphorus molecules using radiation grafting as already done successfully with flax. Nevertheless, pyrolysis combustion flow calorimetry analyses show that the introduction of phosphorus does not promote charring of OP and flame retardancy is not significantly improved whichever the considered fraction. The second strategy is to replace pentaerythritol by OP as char source into well‐known FR systems based on ammonium polyphosphate. The incorporation of such system into ethylene‐vinyl acetate copolymer leads to satisfying FR performances according to cone calorimeter tests. Moreover, the presence of high amount of extractives into OP such as oleic acid does not appear detrimental. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 47715.