Grafting Of Acrylamide Research Articles

New method for the covalent immobilization of a xylanase by radical grafting of acrylamide on cellulose acetate membranes

This work deals with a new grafting method of acrylamide on cellulose acetate powder and flat membranes, followed by activation with glutaraldehyde in order to provide supports for the enzyme immobilization. The grafting of acrylamide was proved by FTIR and by determination of nitrogen content of the cellulose acetate material. The influence of some polymerization parameters on the grafting degrees was checked. The grafting degrees of acrylamide, on cellulose acetate flat membranes, increased almost linearly with the initiator/membrane ratio, polymerization time and monomer/membrane ratio, whereas the activation time had a more complex influence. The immobilization of xylanase was successfully occurred on the acrylamide grafted CA membranes. The bonded enzyme has shown biocatalytic activity in beechwood xylan solution, after subsequent incubations at 50 °C, lasting 7 h altogether. The immobilized enzyme was more resistant to inactivation by heat than the soluble enzyme.

Synthesis and Properties of Sepiolite/poly (acrylic acid-co-acrylamide) Nanocomposites

Novel hydrogel nanocomposites, based on sepiolite, acrylic acid (AA), acrylamide (AM), and N,N’-methylenebisacrylamide (MBA), were synthesized by solution copolymerization. The structure, morphology and liquid absorbency of these composites were investigated through FTIR, SEM and the like. The influences of sepiolite, crosslinker content, initiator dosage, neutralization degree of AA and molar ratio of AA/AM on the distilled water absorbency (Q w ), physiological saline solution absorbency (Q p ) were discussed in detail. Results showed that needleshaped sepiolite dispersed in nanoscale, and the grafting of AA and/or AM on the sepiolite surface occurred. Compared with the sepiolite-free hydrogel, sepiolite contributed to liquid absorbency, and at its weight content of 15.0%, Q w and Q p were enhanced as high as 11.6% and 14.5%, respectively.

Solvent-Free Vapor-Phase Photografting of Acrylamide onto Poly(ethylene terephthalate)

Poly(ethylene terphthalate) (PET) films were photografted under reduced pressure in a solvent-free vapor of acrylamide and a co-initiator, benzophenone. Characterization of grafted samples by ESCA and contact angles showed that the grafting increased with grafting time and temperature. The amide groups obtained by the acrylamide grafting were converted into amine groups by the Hofmann rearrangement to be used in coupling reactions. The amine groups were confirmed by reaction with pentafluorobenzoyl chloride, which provides a fluorine label for ESCA. Surface grafting of polymeric substrates in the vapor phase induced by plasma or high energy and UV irradiation is reviewed.

Graft Copolymerization of Acrylamide onto Oil Palm Empty Fruit Bunch (OPEFB) Fiber

Grafting of acrylamide (AAm) onto oil palm empty fruits bunch fiber using hydrogen peroxide as initiator and methyl acrylate as comonomer was investigated. The amount of comonomer needed to make grafting of acrylamide possible was determined. The percentage of poly(acrylamide) and the comonomer in the final graft copolymer was estimated by elemental analysis. Results obtained indicated that methyl acrylate facilitated the incorporation of acrylamide monomer onto OPEFB. The reactivity ratios for both monomers were determined by using Fineman–Ross plot. The effects of reaction temperature and period as well as amount of the initiator, solvent, monomer and comonomer on the percentage of grafting at fixed amount of comonomer (11 mmol) were studied. Maximum percentage of grafting was achieved when the amount of initiator and solvent 3.98×10−3 mol and 50 mL respectively. The optimum reaction temperature was 50 ○C and the reaction period was 90 min. Highest percentage of grafting was 232% when 25.6 mmol of acrylamide was used under these optimum conditions. The presence of functional group in the grafted polymer is characterized by infrared spectroscopy and the surface morphology is observed by scanning electron microscopy. Thermoanalytic investigation on OPEFB and OPEFB-g-PAAM were carried out to evaluate the thermal stability and respective activation energy of the materials.

Functionalization of LDPE and PP to Produce Grafted Membranes Used in Dialysis Processes. Part I

: Gamma radiation-induced grafting of acrylamide (AAm) monomer onto low-density polyethylene (LDPE) and polypropylene (PP) films was studied. The effect of monomer concentration, irradiation dose, and inhibitor concentration on the grafting percent was determined. The swelling behavior of the grafted membranes has been investigated, and it was shown that the modification of LDPE and PP films with hydrophilic monomers results in the growth of the water uptake percent. The permeability of high molecular weight materials, such as creatinine and urea, through AAm grafted membranes increased with increase in grafting percent. Thermal properties of the grafted membranes using thermo gravimetric analysis (TGA) were studied. The morphology of grafted membranes was investigated by using X-ray diffraction (XRD) and the scanning electron microscope (SEM). The mechanical properties of the grafted membranes have been studied, and their structures were elucidated by spectroscopic analysis as (FTIR).

Enzyme‐mediated grafting of acrylamide to ultrahigh molecular weight polyethylene fiber: A novel radical initiation system

AbstractThe enzyme‐mediated grafting of acrylamide (AM) to ultrahigh molecular weight polyethylene (UHMWPE) fibers using horseradish peroxidase (HRP) was demonstrated. To optimize the reaction condition, the concentrations of monomer, H2O2, the initiator, and time were varied. The grafting results were discussed and a reaction mechanism was proposed. Function groups and structural change of the graft copolymer were determined by FTIR spectroscopic and scanning electron microscopy micrographs for proof of grafting and the results were discussed. Results show that the surface of treated fiber becomes rougher than the untreated surface. Compared to unmodified fiber, modified fiber surface had significantly increased the interfacial shear strength, and carbonyl‐stretching regions in the IR spectra. The interfacial shear strength of the UHMWPE fiber increased, clearly indicating that enzymatic‐grafted acrylamide could significantly increase the hydrophilicity of the surfaces of UHMWPE fibers. Moreover, the hydrophilicity of treated fiber depends on the monomer concentration, the initiator concentration, and oxidizing agent concentration as well as the time of the reaction. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1011–1016, 2005

Enzymatic surface modification of Kevlar fibers

Horseradish peroxidase catalyzed grafting of acrylamide (AM) onto Kevlar fibers has been studied. The modified fiber has been characterized with scanning electron microscopy (SEM), elemental analysis and the grafting yield. From the SEM micrographs, the surface of the grafted Kevlar fiber is rougher than that of the untreated fiber, and the elemental analysis indicated that the nitrogen content of the treated fibers is higher than that of the untreated fiber. All the results suggested that AM must have been grafted onto the Kevlar surface through HRP-mediated radical initiated grafting reaction. The probably mechanism of HRP catalyzed grafting of AM onto Kevlar surface is proposed.

Enzyme-mediated radical initiation of AM graft onto the HDPE film

The mechanism of the enzymatic grafting of high-density polyethylene (HDPE) films with acrylamide compounds was studied. The potential for using horseradish peroxidase (HRP) to graft acrylamide onto the surface of HDPE films was examined. Several analytical approaches provided evidence that the chemical composition and morphology of HDPE surfaces were changed after grafting. Results show that the surface of treated films becomes rougher than the untreated surface. Compared to unmodified HDPE, modified HDPE surface had significantly increased absorbance in the UV-visible region, and the N–H and carbonyl-stretching regions in the IR spectra. The hydrophilicity of treated and untreated HDPE films was analyzed by staining and contact angle measurements. The decreased contact angle of the HDPE film with water and increased adsorption ability of the surface to a water-soluble dye clearly indicated that enzymatic grafted acrylamide could significantly increase the hydrophilicity of the surfaces of HDPE films. Moreover, the hydrophilicity of treated film depend upon the monomer concentration, the initiator concentration and oxidizing agent concentration as well as the time of the reaction, its optimum value appears when the monomer concentration, the initiator concentration, H2O2 concentration and the reaction time were 0.15M, 3.0×10−2M, 6.0×10−3M, and 300min, respectively.

Preparation of pH- and thermo-sensitive hydrogel by two-step grafting of acrylamide and acrylic acid onto preirradiated polyethylene film

Two-step grafting reaction of acrylamide (AAm) and acrylic acid (AAc) onto preirradiated polyethylene (PE) film were performed. The effects of irradiation dose, reaction temperature and reaction time on the grafting yield were studied. The effect of reaction time of the first step grafting on the yield of the second step grafting was also evaluated. The original and the irradiated PE films were tested by Fourier transform infrared (FTIR) spectroscopy in the attenuated total reflectance mode (ATR). The AAm and AAc grafted PE film appeared thermo- and pH-sensitive which are similar to the interpenetrating polymer network hydrogel.

1,2-propanediol-cellulose-acrylamide graft copolymers

1,2-Propanediol–cellulose–acrylamide graft copolymers (PCACs) were developed for enhanced oil recovery. They were prepared with acrylamide and 1,2-propanediol (PDO)–cellulose, which was formed through the addition of glycols to cellulose by the Shotten–Baumann reaction between 3-chloro-1,2-propanediol and cellulose. The graft copolymerization was initiated with a redox system between Ce4+ and glycols in cellulose. The infrared spectrum of PDO–cellulose had some characteristic absorption bands around 2960 (νCH) and 1050 cm−1 (νCO) that also appeared for the PDO group and pyranose ring of cellulose, respectively. The rate of Ce4+ consumption by PDO–cellulose was investigated through the calculation of the overall kinetic constant from the slopes of ln(D − DR) versus time (where D is the absorbance and DR is the absorbance of the original polysaccharide solution) The results showed that PDO–cellulose had high reactivity and that there were two mechanisms of oxidation by Ce4+ with PDO–cellulose. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3022–3029, 2004

Controlled grafting of N-isoproply acrylamide brushes onto self-standing isotactic polypropylene thin films: surface initiated atom transfer radical polymerization

Surface initiated atom transfer radical polymerization (ATRP) technique using CuBr/CuBr 2/bpy complex is employed to graft N-isopropyl acrylamide (NIPAA) brushes onto ‘self-standing’ isotactic polypropylene (iPP) film surface via iPP-Br macro-initiator. The successful accomplishment of surface grafting is understood from the UV–Vis, ATR-FTIR, XPS, SEM analysis and contact angle measurements of the modified samples. The ability to control the degree of grafting of NIPAA brushes reaffirms the elegance of the surface initiated ATRP technique to develop tailor-made polymer surfaces. The LCST nature of the NIPAA brushes would introduce stimuli responsive character onto the surface of the iPP films used for various specialty applications, especially for biomedical purposes.

An interesting grafting reactivity of EB preirradiated polypropylene film

An interesting grafting reactivity of electron beam preirradiated polypropylene (PP) film was found by grafting of acrylic acid (AAc) and acrylamide (AAm) repeatedly or intermittently. The preirradiated PP film could be grafted several times intermittently and the free radicals or peroxides on the samples could be determined after several times grafting reaction. The effects of storage time, reaction time and repeated reaction times on the degree of grafting were investigated. The trapped radicals, peroxy-radicals and peroxides on the preirradiated and reacted PP films were determined by using electron spin resonance (ESR) and 1,1-diphenyl-2-picryl hydrazyl (DPPH), respectively. An interpenetrating polymer networks (IPN) with both temperature and pH sensitive properties was obtained by two times grafting of AAm and AAc onto preirradiated PP film.

Release kinetics and diffusion coefficients of solid and liquid pesticides through interpenetrating polymer network beads of polyacrylamide-g-guar gum with sodium alginate

Grafting of acrylamide onto guar gum is achieved by Ce(IV) induced free-radical polymerization to prepare interpenetrating polymer network (IPN) beads of polyacrylamide-g-guar gum with sodium alginate by crosslinking with glutaraldehyde. Two widely used pesticides, solid chlorpyrifos and liquid fenvelarate, are loaded up to 60–70% efficiency in the IPN beads. The polymer and beads are characterized by Fourier transform IR spectroscopy to confirm grafting and to understand the possible interactions between the pesticides and the polymer matrix. Scanning electron microscopy is used to study the morphology of the beads. Equilibrium swelling experiments indicate that the swelling of the beads decreases with an increase in crosslinking, as well as an increase in pesticide loading. The in vitro release studies are performed under static conditions, and the release data are fitted to an empirical relationship to evaluate the transport parameters. Diffusion coefficients are calculated for the transport of pesticides through the polymeric beads using the initial and later time approximation methods. These values show a decrease with increasing crosslinking and increasing pesticide loading. Long-term diffusion coefficients as computed by Fick's equations are found to be smaller in magnitude when compared to the initial time diffusion coefficients. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 451–457, 2003

Preparation of ion-exchange membranes by hydrolysis of radiation-grafted polyethylene-g-polyacrylamide membranes

Polyethylene-g-polyacrylamide membranes were prepared by graft polymerization of acrylamide onto polyethylene films using a preirradiation method. The ion-exchange membranes were obtained by the hydrolysis of grafted films so as to transform amide groups into carboxyl groups. The fraction of amide groups transformed into carboxyl groups was limited to ∼0.5. The characterization and thermal behavior of membranes with different degrees of grafting were evaluated by FTIR, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) measurements. The heat of fusion and the crystallinity of polyethylene decreased considerably in the hydrolyzed membranes depending on the degree of grafting. It was found that the grafting of acrylamide led to the reduction in crystallinity due to disruption of the crystallites (crystal defects) and dilution of the inherent crystallinity (dilution effect). The contribution of the hydrolysis step to the crystallinity decrease was negligible. The thermal stability of the membranes as obtained from TGA showed considerable enhancement after hydrolysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 149–154, 2003

Effect of silane monomer on the improvement of mechanical and degradable properties of photografted jute yarn with acrylamide

AbstractUV radiation was used to graft acrylamide (AA) to jute yarn in order to improve the mechanical properties. The physicomechanical properties of the grafted jute yarn were investigated. A series of solutions of different AA concentrations in methanol along with photoinitiator (Irgacure‐907, 2%) were prepared. The jute yarns were soaked in the solution for 30 min before radiation. The effect of irradiation time, concentration of monomer on polymer loading, and tensile properties of the jute yarn were studied. The highest polymer loading (22%) and tensile strength (95%) of the yarn were observed when the yarn was treated in 30% AA in methanol with 60 min of UV radiation. The surfaces of both treated and untreated jute were characterized by X‐ray photospectrometry, infrared spectroscopy, and environmental scanning electron microscopy, and it was observed that the AA reacted or deposited on the jute surface. A minute amount (1%) of silane monomer [3‐(trimethoxysilyl)‐propyl methacrylate] was used as an additive in the AA solution to further improve the mechanical properties of jute yarn. Better improvement was achieved by using 1% silane monomer. Water uptake, simulating weathering, and soil degradation tests of untreated and treated yarns were also performed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3530–3538, 2003

Synthesis and characterization of modified chitosan microspheres: Effect of the grafting ratio on the controlled release of nifedipine through microspheres

AbstractThe grafting of acrylamide onto a chitosan backbone was carried out at three acrylamide concentrations (polymer/monomer ratio = 1:1, 1:2, and 1:3). The synthesis of the grafted polymer was achieved by K2S2O8‐induced free‐radical polymerization. Microspheres of polyacrylamide‐g‐chitosan crosslinked with glutaraldehyde were prepared to encapsulate nifedipine (NFD), a calcium channel blocker and an antihypertensive drug. The microspheres of polyacrylamide‐g‐chitosan were produced by a water‐in‐oil emulsion technique with three different concentrations of glutaraldehyde as the crosslinking agent. Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) were used to characterize the grafted copolymers, and the microspheres were prepared from them. FTIR and DSC were also used to analyze the extent of crosslinking. The microspheres were characterized by the particle size; the water transport into these microspheres, as well as the equilibrium water uptake, were studied. Scanning electron microscopy confirmed the spherical nature of the particles, which had a mean particle size of 450 μm. Individual particle dynamic swelling experiments suggested that with an increase in crosslinking, the transport became case II. The release of NFD depended on the crosslinking of the network and on the amount of drug loading. Calculating the drug diffusion coefficients with the initial time and later time approximation method further supported this. The drug release in all 27 formulations followed case II transport, and this suggested that the time dependence of the NFD release followed zero‐order kinetics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2940–2949, 2003

Effect of plasma treatment on the degree of AAm grafting for high-density polyethylene

The aim of this article was to determine a suitable method and optimal conditions for grafting of acrylamide (AAm) monomer onto the surface of high-density polyethylene (HDPE). We studied argon plasma treatment of HDPE (PHDPE) and AAm graft copolymerization (AAm-g–PHDPE) using thermal induction with or without adding an initiator, benzoyl peroxide (BPO) [AAm-g (BPO)–PHDPE]. The 1,1-diphenyl-2-picrvlhydrazyl (DPPH) method was adopted to estimate the concentration of peroxide, and consequently the appropriate plasma treatment conditions were determined according to its optimal concentration. ATR-FTIR spectroscopy and ESCA analysis were used to evaluate the degree of grafting copolymerization. The maximum degree of grafting was 0.55 and 2.41 as evaluated by total-reflectance Fourier-transform IR (ATR-FTIR) spectroscopy and electron spectroscopy for chemical analysis (ESCA), respectively. The degree of grafting shows similar trends by ATR-FTIR and ESCA analysis and the optimal grafting time is 4 h. The result also shows that the degree of grafting is also affected by the plasma treatment time. DPPH measurements showed that the maximum peroxide introduced onto HDPE sheets by plasma treatment at 40 W for 3 min and air exposure for 1 h is 5.2×10 −8 mol cm −2. In this investigation, the best graft copolymerization conditions for HDPE are plasma treatment at 40 W for 3 min and thermally induced grafting for 4 h with an initiator (2×10 −3 M).

Role of Amino Acids on In Situ Photografting of Jute Yarn with Acrylamide Using Ultraviolet Radiation

To improve the mechanical performance of jute yarn, grafting with acrylamide (AM) monomer has been performed on in situ UV radiation and optimized; the monomer concentration (30%) and irradiation time (60 min) attained 195% tensile strength with 22% polymer loading (PL). The effect of amino acids (1%) as additives in AM with photografted jute yarn at optimized system has been studied. The PL and tensile properties, such as tensile strength (TS) and elongation at break (Eb), of treated samples were enhanced by incorporation of amino acids, and the highest TS value (270%) and Eb value (300%) with 27% PL value were achieved by the sample treated with L‐arginine (Arg). Weak acid [3% acetic acid (Ace)] and strong acid [1% sulfuric acid (Sul)] were also incorporated in the optimized system of AM grafting to investigate their effect on the mechanical properties of photografted jute yarn. Water absorption and weathering resistance of treated untreated samples (TS0) were also studied.

Surface modification of poly-L-lactic acid (PLLA) membrane by grafting acrylamide: an effective way to improve cytocompatibility for chondrocytes

Poly-L-lactic acid (PLLA) membranes were photo-oxidized in hydrogen peroxide solution under ultraviolet light (UV) to introduce hydroperoxide groups onto the PLLA membrane surfaces. The photo-oxidized membranes were then immersed in acrylamide (AAm) solution containing Fe2+ to graft polyacrylamide (PAAm) onto the PLLA membrane surfaces. The density of the hydroperoxide groups introduced on the PLLA membrane surfaces varied with the temperature and the photooxidization time. The occurrence of grafting was verified by X-ray photoelectron spectroscopy (XPS). The degree of grafting increased with the monomer concentration and the polymerization time. Water contact angle measurements showed that the wettability of the modified PLLA membranes had improved. Chondrocytes proliferated more rapidly and were more spread out on the modified membrane than on the control PLLA membrane, indicating that the PAAm-grafted PLLA membrane has better cytocompatibility for chondrocytes.

Synthesis of Graft Copolymers of Acrylamide and Comonomers on to Cellulose: A Study of the Effect of Comonomer on Polymer Yields, Structure and Properties

Cellulose extracted from pine needles was graft copolymerized with acrylamide using benzoyl peroxide as initiator. Following a novel synthetic strategy and using the optimum reaction conditions evaluated for the grafting of acrylamide, some comonomers viz: glycidyl methacrylate, 2-hydroxyethyl methacrylate, acrylic acid and acrylonitrile have been grafted along with acrylamide using five different concentrations of the comonomers. SEM, FT-IR and thermal studies of graft copolymers were carried to obtain evidence of the incorporation of acrylamide and comonomers into cellulose. Reactivity of acrylamide in grafting reactions alone and in the presence of comonomers has been studied. The molar ratio of acrylamide and comonomers, and hence the structure of the graft chain remains independent of the comonomer concentration in the feed. It has also been observed that compared to acrylamide, less acrylonitrile was incorporated while far higher amount of the methacrylates were incorporated in the graft chain.