Graft Copolymerization Of Acrylic Acid Research Articles

Study of carboxymethyl chitosan based polyampholyte superabsorbent polymer I: Optimization of synthesis conditions and pH sensitive property study of carboxymethyl chitosan-g-poly(acrylic acid-co-dimethyldiallylammonium chloride) superabsorbent polymer

A novel polyampholyte superabsorbent polymer-carboxymethyl chitosan-g-poly(acrylic acid-co-dimethyldiallylammonium chloride) (CMCTS-g-(PAA-co-PDMDAAC)) has been prepared through the graft copolymerization of acrylic acid (AA) and dimethyldiallylammonium chloride (DMDAAC) onto the chain of carboxymethyl chitosan. The optimal conditions for synthesizing the polymer with the highest swelling ratio has been identified by studying the water absorption of the polymer prepared under different conditions. The swelling ratio of the prepared polyampholytic polymer was found to be pH dependent, and in particular, the prepared polymer showed peaks in swelling capacity at both acidic condition (pH 3.5) and basic condition (pH 9.5). The effects of the interactions between the charged groups on the polymer backbone as well as the counter ion screening on the non-freezable water content have also been studied by measuring the DSC curve of the swollen hydrogel at different pH values.

Polysaccharides Coatings on Medical-Grade PVC: A Probe into Surface Characteristics and the Extent of Bacterial Adhesion

Medical-grade polyvinyl chloride was coated by polysaccharides through a novel physicochemical approach. An initial surface activation was performed foremost via diffuse coplanar surface barrier discharge plasma in air at ambient temperature and pressure. Then, radical graft copolymerization of acrylic acid through grafting-from pathway was directed to render a well-defined brush of high density, and finally a chitosan monolayer and chitosan/pectin alternating multilayer were bound onto the functionalized surfaces. Surface characteristics were systematically investigated using several probe techniques. In vitro bacterial adhesion and biofilm formation assays indicated that a single chitosan layer was incapable of hindering the adhesion of a Staphylococcus aureus bacterial strain, while up to 30% reduction was achieved by the chitosan/pectin layered assembly. On the other hand, chitosan and chitosan/pectin multilayer could retard Escherichia coli adhesion by 50% and 20%, respectively. Furthermore, plasma treated and graft copolymerized samples were also found effective to diminish the degree of adherence of Escherichia coli.

An in vitro bacterial adhesion assessment of surface-modified medical-grade PVC

Medical-grade polyvinyl chloride was surface modified by a multistep physicochemical approach to improve bacterial adhesion prevention properties. This was fulfilled via surface activation by diffuse coplanar surface barrier discharge plasma followed by radical graft copolymerization of acrylic acid through surface-initiated pathway to render a structured high density brush. Three known antibacterial agents, bronopol, benzalkonium chloride, and chlorhexidine, were then individually coated onto functionalized surface to induce biological properties. Various modern surface probe techniques were employed to explore the effects of the modification steps. In vitro bacterial adhesion and biofilm formation assay was performed. Escherichia coli strain was found to be more susceptible to modifications rather than Staphylococcus aureus as up to 85% reduction in adherence degree of the former was observed upon treating with above antibacterial agents, while only chlorhexidine could retard the adhesion of the latter by 50%. Also, plasma treated and graft copolymerized samples were remarkably effective to diminish the adherence of E. coli.

Adsorption and Separation of Mercury: Sorption-Desorption of Hg2+ with Cross-Linked Graft Copolymer of Acrylic Acid and its Application in the Metal Ion Separation Process

A selective and reliable method has been developed for the extraction and separation of mercuric ion with cross-linked graft copolymer of acrylic acid based on sorption-desorption studies. The graft copolymer acts as an ion exchanger. The physico-chemical properties of the exchanger, and optimum pH, time, and temperature for Hg2+ adsorption were determined. Metal ion adsorption kinetics, isotherms, and thermodynamics have been studied. A plausible mechanism for mercury ion extraction has been suggested. Mercuric ion has been separated quantitatively from various synthetic mixtures containing metal ions (Ni2+, Cd2+, Pb2+, and Zn2+).

A novel multi-responsive polyampholyte composite hydrogel with excellent mechanical strength and rapid shrinking rate

Series of hydrophilic core–shell microgels with cross-linked poly(N-isopropylacrylamide) (PNIPAAm) as core and poly(vinyl amine) (PVAm) as shell are synthesized via surfactant-free emulsion polymerization. Then, the microgels are treated with a small amount of potassium persulfate (KPS) to generate free radicals on the amine nitrogens of PVAm, which subsequently initiate the graft copolymerization of acrylic acid (AA), acryloyloxyethyl trimethyl ammonium chloride (DAC), and acrylamide (AAm) onto microgels to prepare multi-responsive composite hydrogels. The composite hydrogels consist of cross-linked ungrafted polyampholyte chains as the first network and microgels with grafted polyampholyte chains as graft point and second network and show surprising mechanical strength and rapid response rate. The investigation shows the compress strength of composite hydrogels is up to 17–30 MPa, which is 60–100 times higher than that of the hydrogel matrix. The composite hydrogel shows reversible switch of transmittance when traveling the lowest critical temperature (LCST) of microgels. When the composite hydrogel swollen in pH 2.86 solution at ambient condition is immersed into the pH 7.00 solution at 45 °C, a rapid dynamic shrinking can be observed. And the character time ( τ) of shrinking dynamic of composite hydrogel is 251.9 min, which is less than that of hydrogel matrix ( τ = 2273.7 min).

Studies on Hg(II) ion retention properties of cross-linked graft copolymer of acrylic acid and its analytical application

The effects of different parameters such as time, concentration, pH and temperature, on metal ion retention properties of the polymer have been investigated. Metal ion adsorption kinetics, isotherms and thermodynamics have been studied. A plausible mechanism for mercury ion retention has been suggested. Mercuric ion has been isolated quantitatively from various synthetic mixture containing metal ions (Ni2+, Cd2+, Pb2+ and Zn2+).

Characterization and modification of commercial acrylic fibers grafted with acrylic acid

AbstractThe graft copolymerization of acrylic acid (AA) onto commercial acrylic fibers (PAN) has been studied using Azobis(isobutyro)nitrile (AIBN) as an initiator. AA grafting initiated by radicals formed from thermal decomposition of AIBN. In this study, the effects of monomer and initiator concentration, time and temperature reaction on the grafting yield have been investigated. The optimum conditions for this grafting reaction were obtained with an AA concentration of 1.67 M, an AIBN concentration of 0.0097 M, a reaction temperature of T=85 °C and with reaction time of 60 minutes.The fiber structure has been investigated by different experimental techniques of characterization such as Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), water absorption and also in this study has been investigated the mechanical property. The thermal analysis data showed that increasing in grafting yield, decreases the thermal stability of fiber. Grafting also affected slightly the fiber morphology. The experimental data of mechanical properties show clearly that by increasing of grafting yield, max extension will decrease. Grafting of poly AA improved water absorption.

Synthesis of cross-linked graft copolymer from acrylic acid, poly(vinyl alcohol), and glutaraldhyde for extraction of lead ion from aqueous solution

A novel graft copolymer of acrylic acid onto poly(vinyl alcohol) has been synthesized and it is cross-linked by glutaraldehyde for the investigation of its efficiency in removing lead ion from aqueous solution. The chemical nature of the ion exchange resin has been elucidated with the help of chemical, spectral, and thermal analysis. Particle size, surface area, ion exchange capacity, optimum pH, time, and temperature for Pb(II) adsorption were determined. Metal ion adsorption kinetics, isotherms, and thermodynamics have been studied. A plausible mechanism for lead ion exchange has been suggested.

Thermo- and pH-responsive polypropylene microporous membrane prepared by the photoinduced RAFT-mediated graft copolymerization

Thermo- and pH-responsive polypropylene microporous membrane prepared by photoinduced reversible addition–fragmentation chain transfer (RAFT) graft copolymerization of acrylic acid and N-isopropyl acrylamide by using dibenzyltrithiocarbonate as a RAFT agent. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR/FT-IR), X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FE-SEM) were used to characterize the structural and morphological changes on the membrane surface. Results of ATR/FT-IR and XPS clearly indicated that poly(acrylic acid) (PAAc) and poly(N-isopropyl acrylamide) (PNIPAAm) were successfully grafted onto the membrane surface. The grafting chain length of PAAc on the membrane surface increased with the increase of UV irradiation time, and decreased with the increase of the concentration of chain transfer agent. The PAAc grafted membranes containing macro-chain transfer agents, or the living membrane surfaces were further functionalized via surface-initiated block copolymerization with N-isopropyl acrylamide in the presence of free radical initiator, 2,2′-azobisisobutyronitrile. It was found that PNIPAAm can be grafted onto the PAAc grafted membrane surface. The results demonstrated that polymerization of AAc and NIPAAm by the RAFT method could be accomplished under UV irradiation and the process possessing the living character. The PPMMs with PAAc and PNIPAAm grafting chains exhibited both pH- and temperature-dependent permeability to aqueous media.

Novel Hybrid Materials Obtained During the Crystalline Growth of Layered Double Hydroxides Using Grafted Chitosan as a Template

To overcome some limitations of layered double hydroxides (LDH)-type materials in efficient development of composites with biopolymers, a templating method was employed based on graft copolymerization of acrylic acid onto CTS and successive impregnation of the LDH into the interstices of the grafted CTS matrix. The results indicated that, with gradual increase in the stirring speed, grafted CTS experienced evolutions from formless bulky agglomerations to well-dispersed spheroids and then to a well-ordered matrix of a copolymer network. In the subsequent templating synthesis, an LDH-type phase was formed and an LDH replica was obtained either by dissolution of the grafted CTS or by a calcination-reconstruction process. It was found that the copolymer network showed superiority over spheroids on adsorption of metal ions and efficient combination with the LDH that was generated in situ. The growth of LDH crystallites was templated and inhibited by the grafted copolymer, thereby filling the template voids of the matrix network in the form of a club at the nanometer scale with a load content up to 38.7 wt%. This type of novel hybrid biomaterial exhibited potential use in infrared camouflage by achieving a minimum emissivity value of 0.351 due to regular and ordered inorganic–organic combinations with large synergistic interfaces at molecular level.

PH‐induced on–off switching of polycarbonate track‐etched membranes by plasma‐induced surface grafting

AbstractSurface functionalization of the plasma‐pretreated polycarbonate (PC) track‐etched membranes via plasma‐induced thermally graft copolymerization of acrylic acid (AAc) was carried out. The resulting PC membranes with grafted AAc side chains were characterized by X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric (TG) analysis. The morphology of the PC membranes was studied by scanning electron microscopy (SEM). The results showed that the grafted PAAc polymers were formed uniformly inside the pores throughout the entire membrane thickness. With increase in the pore‐filling ratio, the pore diameters of PAAc‐grafted membranes became smaller. The PC‐g‐PAAc membranes exhibit rapid and reversible response of the flux to the environmental pH as pH is switched between 3 and 9. Between pH 3.5 and 5.5, the membranes demonstrate a pH‐valve function as the carboxyl group changes from neutral to charged with a corresponding variation in chain configuration. Copyright © 2009 John Wiley & Sons, Ltd.

Synthesis of Graft Copolymer of Poly(acrylic acid) and Poly(vinyl alcohol) in the Presence of Methylene Bisacrylamide Crosslinker and Investigation of its Efficiency in Removing Lead Ion from Aqueous Solution

A novel graft copolymer of acrylic acid onto poly(vinyl alcohol) has been synthesized and it is crosslinked by methylene bisacrylamide for the investigation of its efficiency in removing lead ion from aqueous solution. The chemical nature of the ion exchange resin has been elucidated with the help of chemical test, FTIR, TGA and DSC. Particle size (0.20 mm), surface area (85.6 m2/g), ion exchange capacity (5.3 meq H+/g), optimum pH (4.5), time (60 min) and temperature (40°C) for Pb(II) adsorption were determined. Metal ion adsorption kinetics, isotherms and thermodynamics have been studied. A plausible mechanism for lead ion exchange has been suggested.

Studies on interaction of molybdenum(VI) with modified lignocellulosics using a novel spectrophotometric method

A new adsorbent (PGPEP-COOH) bearing carboxylate functional group was prepared through graft co-polymerization of acrylic acid onto pulverized Phyllanthus emblica planks using ferrous sulphate/H 2 O 2 redox initiator system. The adsorbent obtained was tested for the uptake of molybdenum(VI) from aqueous solutions. The efficiency of the PGPEP-COOH to remove Mo VI ions at different time of contact, initial adsorbate concentration, adsorbent dose, pH, ionic strength and temperature was studied by batch experiments. The amount of molybdeitum(VI) in aqueous system was determined using a very simple and sensitive method of estimation using potassium hexacyanoferrate(II). Reddish brown solution of the molybdenum complex at pH 3.2 shows absorption maximum at 390 nm. To establish the most appropriate correlation for adsorption equilibrium, isotherm studies were performed using Langmuir, Freundlich and Redlich-Peterson models. The suitability of isotherm models was compared using linear least square fitting. Experimental kinetic data were described using a diffusion controlled first order reversible model and diffusion coefficient was evaluated at different temperatures. Applying Eyring equation thermodynamic parameters were calculated. PGPEP-COOH adsorbed 99.2% Mo VI from a solution of 10 μmol dm -3 concentration at 303 K. Desorption and regeneration studies of the adsorbent under different conditions were also studied.

Graft copolymerization of acrylic acid onto cocoyam starch by ceric ion in the presence of N,N′‐dimethylacetamide

AbstractGrafting of acrylic acid onto cocoyam starch, Xanthosoma sagittitolium was initiated by ceric ion—N,N′‐dimethylacetamide redox pair in aqueous media. The reaction was characterized by high graft yields of up to 676%, and infrared spectroscopy affirmed the presence of grafted polymer. Graft yield was enhanced by N,N′‐dimethylacetamide (DMAc) in the concentration range, 9.0–36.0 × 10−4M but lower concentrations were more favorable with the ratio of percentage graft, Pg/Pg0, in the presence and absence of DMAc respectively, of up to 1.34 at 9.0 × 10−4M of the latter. Ceric ion was nonterminating of the graft reaction and a 10‐fold increase in its concentration of 4.16 × 10−3M resulted in high efficiency of graft of 50.2% in monomer conversion to grafted polymer. Enhanced homopolymer formation and low efficiency of graft were observed at monomer concentration greater than 0.69M. Long reaction time, greater than 30 min, was unfavorable to the graft reaction and the latter showed negative dependence on temperature in the range, 30–50°C. At 30‐min reaction time, the graft yield at 50°C was not more than 70% of the corresponding value at 30°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Radiation Synthesis of Polyampholytic and Reversible pH-Responsive Hydrogel and Its Application as Drug Delivery System

Graft copolymerization of acrylic acid (AA) and acrylamide (AAm) onto chitosan (CS) was carried out using gamma irradiation. Their swelling behavior was investigated. The hydrogels before and after alkaline hydrolysis were confirmed by FTIR spectroscopic studies. The hydrogels show ampholytic and reversible pH-responsiveness characteristics. The swelling variations were explained according to swelling theory based on the hydrogel chemical structure. The ability of the prepared copolymer to be used as gastric antibiotic delivery system was estimated using amoxicillin trihydrate as a model drug. Release of amoxicillin trihydrate from these investigated hydrogels was studied. For non-ionized drugs, such as amoxicilin trihydrate, the electrostatic polymer/ polymer interactions take place between the cationic groups from CS and the anionic ones from PAA resulting in entrapping the drug into the mesh space of the hydrogel. The non-ionized amoxicillin release was controlled by the swelling/eroding ratio.

Synthesis and properties of starch‐graft‐acrylic acid/Na‐montmorillonite superabsorbent nanocomposite hydrogels

AbstractThe graft copolymerization of acrylic acid (AA) onto starch was carried out with monomer/starch weight ratio = 1.5. Cerium ammonium nitrate (CAN) and N,N′‐methylenebis acrylamide (NMBA) were used as initiator and crosslink agent, respectively. Na‐montmorillonite was used as nanoparticles. Starch‐graft‐acrylic acid/Na‐MMT (S‐g‐AA/MMT) nanocomposite hydrogels were characterized by X‐ray diffraction (XRD) and FTIR analysis. The effect of Na‐MMT content in nanocomposite hydrogels on the swelling behavior was investigated. Increasing the Na‐MMT/monomers ratio up to 1% causes an increment in water absorbency, which indicates that Na‐MMT can improve the ability of water absorbency but further increase of Na‐MMT causes a decrease in water absorbency. In addition, we describe the removal of safranine T from aqueous solutions using S‐g‐AA/MMT nanocomposite hydrogels. Effects of various parameters such as treatment time, initial dye concentration, and amount of the Na‐MMT were investigated. The Freundlich equations were used to fit the equilibrium isotherms. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Synthesis and characterization of stimuli-responsive poly(acrylic acid) grafted silicananoparticles

Silica-poly(acrylic acid) (PAAc) core–shell nanoparticles (NPs) were successfully preparedvia graft copolymerization of acrylic acid (AAc) onto vinyl-bond-modified silica NPs.Transmission electron microscopy (TEM) results indicated that the obtained microphereshave a core–shell morphology. Fourier transform infrared (FTIR) analysis and x-rayphotoelectron spectroscopy (XPS) measurements confirmed that the surface of thenanoparticles was polymer-rich, consistent with the core–shell morphology. The influence ofthe synthetic conditions, such as reaction time and AAc concentration on thegraft yield of PAAc grafted on the silica NPs was investigated. Dynamic lightscattering (DLS) analysis showed that the silica-PAAc core–shell nanoparticlespossessed excellent response to pH and ion strength. Because of their pH-responsivebehavior and small feature size, nanostructure devices designed from the smartsilica nanoparticles have potential applications including sensors and membranes.

Preparation of thermosensitive membranes by radiation grafting of acrylic acid/ N-isopropyl acrylamide binary mixture on PET fabric

Thermosensitive membranes were prepared by radiation-induced graft copolymerization of monomers on PET fabrics. A binary mixture of N-isopropyl acrylamide (NIPAAm) and acrylic acid (AA) was grafted on polyester fabric as a base material to introduce thermosensitive poly( N-isopropyl acrylamide) pendant chains having LCST slightly higher than 37 °C in the membrane. The influence of ferrous sulfate, radiation dose and monomer composition on the degree of grafting was studied. The structure of the grafted fabric was characterized by thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy. The thermosensitive nature of the fabric was monitored by swelling at different temperatures. The graft copolymerization of AA with NIPAAm enhanced the LCST of the resultant membrane to ∼37 °C. The moisture vapor transmission rate (MVTR) and air permeability of the fabric decreased slightly, may be due to the slight blocking of the fabric pores. The immobilization of tetracycline hydrochloride as the model drug and its release characteristics at different temperatures were monitored.

Synthesis, Characterization and Swelling Behavior of Gelatin-g-poly(sodium acrylate)/Kaolin Superabsorbent Hydrogel Composites

In the present paper, a novel superabsorbent hydrogel composite based on gelatin have been prepared via graft copolymerization of acrylic acid (AA) in the presence of kaolin powder using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. Certain variables of the graft copolymerization (i.e., the monomer, the initiator, and the crosslinker concentration as well as kaolin/gelatin weight ratio) affected on the ultimate water-swelling capacity were optimized. The composite structure was confirmed using Fourier transform infrared (FTIR) spectroscopy. A new absorption band at 1728 cm—1 in the composite spectrum confirmed kaolin—organic polymer linkage. The effect of kaolin amount and MBA concentration showed that with increase of these parameters, the water absorbency of the superabsorbent composite was decreased. The swelling measurements of the hydrogels were conducted in aqueous salt solutions. Results indicated that the swelling ratios decreased with an increase in the ionic strength of the salt solutions. This behavior can be attributed to `charge screening effect' for monovalent cations, as well as `ionic crosslinking' for multivalent cations. The effect of solutions with different pHs on the swelling of the superabsorbent was also studied and the hydrogels exhibited pH responsiveness, so a swelling—deswelling pulsatile behavior was recorded at pHs 2 and 8. Finally, the swelling kinetics of the synthesized composite with various particle sizes was preliminarily investigated as well.

Effects of Synthesis Conditions on Chemically Initiated Oil-swellable Suspension Graft Copolymerization of Acrylic Acid and Acrylamide onto Solid-state Chlorinated Polyethylene

Graft polymerization of acrylic acid (AA) and acryl amide (AM) onto solid-state chlorinated polyethylene (CPE) has been carried in oil-swellable suspension using benzoyl peroxide (BPO) as an initiator and ethyl acetate (EA) as a sweller. The effects of polymerization conditions on graft degree (GD) and graft efficiency (GE), including volume of sweller, monomer amount, volume of water and reaction time, have been investigated. The graft polymers have been characterized by means of IR. The results show that EA as a sweller, can improve GD obviously, GD of CPE-g-AA is more than 77% when V(EA)/ V(H 2O) = 7/50, GD of CPE-g-AM is more than 96% when V(EA)/V(H2O) = 8/50. With the increase of monomer amount, GE decreases but GD increases, and GD of mixed monomer is more than that of pure AA or AM monomer.