Radiation grafting of NIPAAm and acryloxysuccinimide onto PP films and sequent crosslinking with polylysine

N-isopropylacrylamide (NIPAAm) and N-acryloxysuccinimide (NAS) were grafted from their binary mixtures in tetrahydrofurane (THF) and toluene solutions onto polypropylene (PP) films by the pre-irradiation oxidative method in air. Effects of pre-irradiation dose, dose rate, and monomer concentrations (NAS/NIPAAm) were studied. The grafted copolymers exhibited the lower critical solution temperature (LCST) at around 31 °C. Based on its thermo-reversible behavior, this system has been used for immunoassay, drug delivery, separation processes and immobilization of enzymes. N-acryloxysuccinimide (NAS) has been used as an active ester to bind proteins through amide bond formation with lysine, and because of this property, the grafted copolymer has been crosslinked with polylysine. Techniques used to characterize the films included differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), infrared (FTIR-ATR) and elemental analysis. Results on thermo-sensitivity are presented. This new system could find applications in vesicle immobilizations.     

Radiation-induced grafting polymerization of MMA onto polybutadiene rubber latex

The grafting of methyl methacrylate (MMA) onto polybutadiene rubber latex by the direct radiation method was carried out. The effects of monomer concentration, absorbed dose and dose rate of gamma rays on the grafting yield were investigated. The graft copolymers were characterized by transmission electron microscopy (TEM), FTIR spectroscopy, and differential scanning calorimetry. TEM photographs revealed that the core–shell structures of latex particles are formed at low MMA content, and with the increasing of MMA content, the semi-IPN-like structure with core–shell could be developed due to the high gel fraction of polybutadiene (PBD) seed particles. In addition, infrared analysis confirmed that MMA could be grafted onto PBD molecular chains effectively under appropriate irradiation conditions. The interfacial adhesion between PBD rubber (core) and PMMA (shell) phases could be enhanced with the increase of MMA concentration.     

Radiation-induced grafting of diallyldimethylammonium chloride onto acrylic acid grafted polyethylene

Diallyldimethylammonium chloride (DADMAC) was grafted onto polyethylene (PE) films by a double grafting procedure. The PE film was initially modified by grafting acrylic acid (AA), through a mutual irradiation method. AA-g-PE film, thus obtained was subjected to subsequent radiation grafting reaction of DADMAC, to give a DADMAC-g-AA-g-PE film having a comb-type structure. The influence of different conditions, such as the extent of AA grafting, DADMAC concentration, absorbed dose and dose rate, on the grafting yield of DADMAC was investigated. A maximum DADMAC grafting of 30% was achieved. The equilibrium degree of swelling (EDS) of the grafted films were gravimetrically determined. TGA and FT-IR techniques were employed to characterize the grafted PE films.     

Radiation-induced grafting of perfluorinated vinyl ether into fluorinated polymer films

We report herein the first successful grafting of perfluorinated vinyl ether monomer into base polymer films by simultaneous radiation method. 2-Bromotetrafluoroethyl trifluorovinyl ether (BrTFF) could be grafted into poly(ethylene-co-tetrafluoroethylene) (ETFE) films by γ-rays irradiation at room temperature. The grafting yield increased linearly with an increase in the dose up to 1400 kGy. The required dose for a satisfactory grafting yield, such as 20%, was as high as ca. 400 kGy probably due to low polymerization reactivity of fluorinated monomers. However, the solvent and catalyst had no positive influence for improving the grafting yield. FTIR spectra and SEM-EDS testified that BrTFF was successfully grafted into ETFE films homogeneously in the perpendicular direction. The thermal analysis of the grafted films further indicated no phase separation between poly(BrTFF) grafts and ETFE films, probably owing to high compatibility of the fluorinated grafts and base polymers.     

Radiation-induced grafting of vinyl benzyl trimethyl ammonium chloride onto nylon-6 fabric

Vinyl benzyl trimethyl ammonium chloride (VBTAC) was grafted onto nylon-6 fabric in the presence of 2- hydroxy ethyl methacrylate (HEMA) by the simultaneous irradiation method in the presence of air with ⁶⁰Co γ-radiations. An increase in grafting was observed with increasing dose. Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) confirmed the grafting of VBTAC. Morphological changes after grafting were confirmed by scanning electron microscopy (SEM). The X-ray diffraction (XRD) pattern showed changes in crystallinity on grafting. The initial studies carried out with grafted nylon fabric showed behavioural changes in the burning properties.     

Radical grafting on lignin. Part I. Radiation-induced grafting of styrene onto hydrochloric acid lignin

By irradiation with gamma rays styrene was grafted onto hydrochloric acid lignin. When the graft polymers were subjected to nitrobenzene oxidation, the vanillin yields indicated two kinds of reaction occurring in the grafting. Polystyrene branches were separated from the graft polymers, and their M?_n were determined osmometrically. At grafting ratios of up to 100 the vanillin yields diminished proportionately with increasing grafting, and the M?_n of the branches, 5000, was unchanged. At grafting ratios of more than 100 the vanillin yields were constant, independent of the ratios, but the M?_n values of the branches increased with grafting. Paper chromatography of the aromatic acids obtained by oxidation of methylated lignin and the graft polymer indicated that isohemipic and metahemipic acids were more abundant in the acid fraction of the graft polymer than in the lignin itself. A qualitative mass analysis of the gaseous products evolving from the irradiated lignin showed the presence of hydrogen molecules only. Gamma-ray radiation brought about no change in the yields of vanillin. It was therefore concluded that radiation grafting on lignin at grafting ratios of less than 100 proceeded through the addition of the styrene polymer radicals to the aromatic nuclei of the lignin and that then branches propagated from the aliphatic part of the lignin, where C? H bond scission had been caused by the irradiation. The grafting sites of lignin would be C-5 and C-6 of the guaiacyl nucleus and, probably the β and γ carbon atoms of the aliphatic side chain of the lignin.     

Ring‐opening grafting polymerization of cyclic monomers onto human hair

Natural human hair was successfully modified by the graft polymerization of trimethylene carbonate, β‐propiolactone, ε‐caprolactone, glycidol, ε‐caprolactam, and 5,5‐dimethyl‐1,3‐dioxane‐2‐thione. In contrast, we could not modify natural human hair by the graft polymerization of oxetane under similar conditions. The model reaction suggested that the main initiating species in these polymerizations were the amino, thiol, and hydroxyl groups in hair, which could induce ring‐opening polymerization. Among the tested monomers, β‐propiolactone was most effective for hair modification with its graft polymer, whose concentration was as high as 0.5 g/g of hair though polymerization under mild conditions. The effects of the hair pretreatment and polymerization temperature on the weight ratio of the grafted polymers were also investigated. Hair modified by grafted polymers was characterized with scanning electron microscopy and Fourier transform infrared measurements. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 736–744, 2007     

Radiation induces grafting of styrene onto silicone sealant films

Grafting of styrene onto silicone sealant films was realized in different methanol solutions by gamma radiation, from a ⁶⁰Co source at room temperature. The styrene grafted onto silicone sealant films was synthesized by pre-irradiation oxidative method. Pre-irradiation method was optimized by tuning the γ-irradiation dose, reaction time, temperature, and monomer concentration. The characterization of silicone sealant films were examined by infrared, differential scanning calorimetry, and swelling behavior analysis. The silicone sealant films could be applied to radiation resistance materials or in separation process of low volatile organic compounds from aqueous solution.     

Radiation-induced graft polymerization of metal-containing monomers

Graft polymerization of acrylates and acrylamide complexes of Mn(II), Cr(III), Fe(III), Co(II), Ni(II), and Cu(II) from alcohol solutions onto a polyethylene powder preirradiated in air up to total doses of 10–300 kJ/kg was studied. Graft copolymers with a metal content of as high as 1.7 mass% were obtained. The addition of a σ- or a coordinate-bound metal atom to the monomer molecule (acrylic acid, acrylamide) was shown to decelerate the process of thermal homopolymerization by 4 to 8 times, significantly reduce the reaction order in respect with monomer concentration in solution, and in most cases produce no effect on the polymer chain termination mechanism. The grafting of metal-containing monomers was found not to alter the structure of the monomer unit, valent state, and coordination of the metal atom, either. The graft polymerization of the monomers from solution is distinguished by a weak effect of the radical reaction inhibitors. The effective activation energies for the grafting of the metal-containing monomers lie within 42–60 kJ/mol.     

Radiation-induced grafting of acrylamide onto guar gum in aqueous medium: Synthesis and characterization of grafted polymer guar-g-acrylamide

Mutual radiation grafting technique has been applied to carry out grafting of acrylamide (AAm) onto guar gum (GG) using high-energy Co⁶⁰ γ radiation to enhance its flocculating properties for industrial effluents. The grafted product was characterized using analytical probes like elemental analysis, thermal analysis, Fourier transformed infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). The grafting extent was observed to decrease with the dose rate and increase with the concentration of AAm. Thermo gravimetric analysis (TGA) of grafted and ungrafted samples indicated better stability of grafted product. γ and microwave radiation effect on grafted and virgin GG has also been reported.     

Radiation-induced grafting of sensitive polymers

Films of PP and PTFE were modified by gamma-radiation grafting of pH and thermo sensitive monomers (two step method) by using both the preirradiation and the direct methods. The effects of the absorbed dose, monomer concentration and reaction time were investigated. The surface chemistry of grafted samples was analyzed by FTIR-ATR spectroscopy, while their thermal properties were analyzed by TGA and DSC. The stimuli-responsive behavior was studied by swelling and contact angle in water, as well as by DSC. Sensitive films presented a critical pH and LCST.     

Study on grafting of different types of acrylic monomers onto natural rubber by γ-rays

 A comparative study of various acrylic monomers for grafting onto natural rubber was done. The stability of natural rubber latex (NRL) against coagulum with monomer, mechanical properties of grafted rubbers and percent of grafting were investigated. The NRL with monomers, methylacrylate (MA), ethylacrylate (EA) and n-butylacrylate (n-BA), is unstable but it is stable with methyl methacrylate (MMA), n-butyl methacrylate (BMA) and cyclohexyl methacrylate (CHMA). The mechanical properties and degree of grafting attained a maximum at a total radiation dose of 4 kGy. The values of tensile properties of MMA and CHMA grafted rubbers are almost similar, and higher than those of BMA grafted rubbers. On the other hand, the degree of grafting for CHMA is higher than those of MMA and BMA grafted rubbers. The infrared (IR) spectra of monomer grafted natural rubber were also studied.     

Radiation-induced grafting of N-isopropylacrylamide onto the brominated poly(2,6-dimethyl-1,4-phenylene oxide) membranes

A novel thermo-sensitive switching membrane has been prepared by radiation-induced simultaneous grafting N-isopropylacrylamide (NIPAAm) onto brominated poly(2,6-dimethyl-1,4-phenylene oxide) BPPO. In order to attain a high grafting degree, the effects of dose, dose rate, concentration of NIPAAm, concentration of inhibitor Cu²⁺, membrane thickness and solvents were investigated. The grafting process was characterized by FTIR spectroscopy and the highest grafting degree obtained was 7.87%. The thermo-sensitive property of the grafted membrane was measured by water flux (20–48 °C). The results showed that the grafted membrane could respond instantly to environmental temperature changes, and there was a sharp change around the lower critical solution temperature as it is normally seen in PNIPAAm hydrogel.     

Graft polymerization of acrylic monomers onto starch fractions. I. Effect of reaction time on grafting methyl methacrylate onto amylose

A study was made of the ceric-ammonium-nitrate-initiated graft polymerization of methyl methacrylate (MMA) onto a lineal fraction of starch (amylose). Grafting yields were determined by extraction with appropriate solvents: 1,2-dichloroethane for homo-PMM, and 0.5N NaOH for ungrafted amylose. Percent grafting was calculated by acid hydrolysis with 1N HCl. Molecular weights of PMMA side chains were determined by gel permeation-chromatography. Grafting efficiencies ranged from 72 to 83%, grafting, from 190 to 271%, and frequency of attachment of side chains, from 900–1250 glucose units per chain. The results observed are discussed.     

Some investigations on the post radiation grafting of acrylamide onto polyethylene films

A study has been made on the post radiation grafting of aqueous acrylamide onto low density polyethylene film. It was found that the addition of 0.05 wt % Mohr's salt reduced effectively the homopolymerization of acrylamide and the grafting process was successfully achieved. The dependence of the grafting rate on the preirradiation dose and monomer concentration was found to be of 1.43 and 1.4 order, respectively. The overall activation energy for the graft polymerization was found to be 13.5 and 1.95 Kcal/mol below and above 45°C, respectively. Some properties of the graft copolymer such as swelling behaviour, electrical conductivity, and reverse osmosis desalination of saline water (water flux and salt rejection), were also investigated and the possibility of its uses in the practical applications was discussed.     

Graft copolymers obtained by radiation grafting of methacrylic acid onto polypropylene films

Direct radiation grafting of methacrylic acid (MAA) onto polypropylene films (PP) was studied. The effect of different solvents such as benzene, distilled water, dimethyl formamide, isopropanol, isopropanol/water-mixture, on the swelling and the grafting process of MAA onto (PP) films was investigated. It was found that the grafting process was enhanced under vacuum irradiation in benzene as a diluent for MAA as compared with other solvents examined. The dependence of the grafting rate on such monomer concentrations was found to be 1.2 order. The relationship between the grafting rate and film thickness gave a negative first order dependence. This grafting system proceeded by a diffusion controlled process. Some selected properties of the grafted films such as mechanical and electrical properties, swelling behaviour, and gel determination, were also investigated.     

Grafting copolymerization of polyethylene glycol methacrylate (PEGMA) onto preirradiated PP films

Polyethylene glycol methacrylate (PEGMA) with different polyethylene oxide units were grafted onto polypropylene (PP) films by a preirradiation grafting method. The effect of co-solvent system on the degree of grafting and water contact angle were determined, respectively. The grafted sample films were verified by Fourier Transform Infrared (FTIR) spectroscopy in the attenuated total reflectance mode (ATR). The biocompatibility and blood compatibility of the grafted PP films were evaluated by the determination of protein adsorption, platelet adsorption and thrombus.