Cellulose Graft Copolymers Research Articles

Competitive removal of heavy metal ions by cellulose graft copolymers

AbstractThe effect of composition of graft chains of four types cellulose graft copolymers on the competitive removal of Pb2+, Cu2+, and Cd2+ ions from aqueous solution was investigated. The copolymers used were (1) cellulose‐g‐polyacrylic acid (cellulose‐g‐pAA) with grafting percentages of 7, 18, and 30%; (2) cellulose‐g‐p(AA–NMBA) prepared by grafting of AA onto cellulose in the presence of crosslinking agent of N,N′‐methylene bisacrylamide (NMBA); (3) cellulose‐g‐p(AA–AASO3H) prepared by grafting of a monomer mixture of acrylic acid (AA) and 2‐acrylamido‐2‐methyl propane sulphonic acid (AASO3H) containing 10% (in mole) AASO3H; and (4) cellulose‐g‐pAASO3H obtained by grafting of AASO3H onto cellulose. The concentrations of ions which were kept constant at 4 mmol/L in an aqueous solution of pH 4.5 were equal. Metal ion removal capacities and removal percentages of the copolymers was determined. Metal ion removal capacity of cellulose‐g‐pAA did not change with the increase in grafting percentages of the copolymer and determined to be 0.27 mmol metal ion/gcopolymer. Although the metal removal rate of cellulose‐g‐p(AA–NMBA) copolymer was lower than that of cellulose‐g‐pAA, removal capacities of both copolymers were the same which was equal to 0.24 mmol metal ion/gcopolymer. Cellulose did not remove any ion under the same conditions. In addition, cellulose‐g‐pAASO3H removed practically no ion from the aqueous solution (0.02 mmol metal ion/gcopolymer). The presence of AASO3H in the graft chains of cellulose‐g‐p(AA–AASO3H) created a synergistic effect with respect to metal removal and led to a slight increase in metal ion adsorption capability in comparison to that of cellulose‐g‐pAA. All types of cellulose copolymers were found to be selective for the removal of Pb2+ over Cu2+ and Cd2+. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2034–2039, 2003

Water‐soluble grafted polysaccharides containing sulfobetaine groups: Synthesis and characterization of graft copolymers of hydroxyethyl cellulose with 3‐dimethyl(methacryloyloxyethyl)ammonium propane sulfonate

AbstractNew water‐soluble grafted polysaccharides containing sulfobetaine groups were synthesized by the grafting of the sulfobetaine‐type zwitterionic monomer 3‐dimethyl‐(methacryloyloxyethyl)ammonium propane sulfonate (DMAPS) onto hydroxyethyl cellulose (HEC) in the presence of a ceric ammonium nitrate (CAN)/ethylenediaminetetraacetic acid (EDTA) initiation system. The effects of the concentrations of CAN, EDTA, DMAPS, and HEC, as well as the polymerization time and temperature, on the grafting reactions were investigated in terms of the grafting percentage (%GP) and grafting conversion (%GC) of the monomer. The %GP and %GC increased and then decreased with increasing concentrations of CAN, EDTA, and HEC. The %GP and %GC increased with increasing DMAPS concentration up to a certain value, beyond which the %GP did not significantly increase and the %GC decreased. The appropriate polymerization time and temperature were favorable for the grafting reactions. With infrared, thermogravimetric analysis, and viscosity measurements, the resulting grafted polysaccharides were characterized. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2755–2761, 2002; DOI 10.1002/app.10191

Synthesis of Cellulosic Graft Copolymers by Atom Transfer Radical Polymerization.

Atom transfer radical polymerization (ATRP) of styrene and methyl methacrylate (MMA) was carried out using chloroacetyl cellulose and cellulose acetate (CA) as an initiator in glyme. ATRP was also done using 2-chloropropionyl cellulose and CA. The cellulosic graft copolymers were prepared through the activation of initiators by the metal complex consisted of CuBr and pentamethyldiethylenetriamine (PMDATA). Increase in the degree of substitution (DS) of chloroacyl groups led to increase in grafting ratio. Grafting efficiency was over 80 % with both monomers. 2-chloropropionyl cellulose and CA revealed higher reactivity than chloroacetyl derivatives nevertheless their much lower DS of 2-chloropropionyl groups. Though styrene was not polymerized below 100°C by any initiators used, it became feasible to be polymerized at 80°C by mixing with MMA which was easily polymerized at this temperature. Copolymers of styrene and MMA was grafted in this case. CA-graft-PMMA copolymers having grafting ratio over 80 % were dissolved in acetone and dimethyl sulfoxide.

Fibre Chemisorbents Based on Modified Graft Copolymers of Cellulose and Polycaproamide

A general characterization of chemisorption fibres with complexing properties is given. The specific features of the effect of the polymer matrix of fibre chemisorbents manufactured by hydrazidation of graft copolymers of cellulose (or polycaproamide) and polyacrylonitrile on the sorption properties, selectivity of sorption of metal ions, and stability of the properties in conditions simulating the conditions of use are examined.

Direct pyrolysis mass spectrometry of acrylonitrile–cellulose graft copolymer prepared by radiation-induced graft polymerization in presence of styrene as homopolymer suppressor

Graft polymerization of acrylonitrile onto cellulosic filter paper competing with the homopolymerization by mutual irradiation technique was studied in the presence of homopolymer suppressors. Addition of FeCl 3 decreased both homopolymerization and graft polymerization, whereas inclusion of a low ratio of styrene monomer with acrylonitrile leads to successful grafting of acrylonitrile with little homopolymer formation. Chemical structure and thermal behavior of the produced graft copolymers were investigated by gradual heating in the solid probe of a mass spectrometer equipped with a GCMS data system. The resulting total ion current (TIC) showed that the degradation of graft copolymers follows two-step pyrolysis. The presence of a low ratio of styrene comonomer increased thermal stability of the prepared acrylonitrile–cellulose graft copolymer. The pyrolysis products have mass spectra characteristic of the copolymer composition; they contain the repeating unit of the oligomers. Total ion current and spectrum subtractions were used to separate and measure spectra of graft copolymers at distinctly different temperatures.

Polymers from renewable resources: sorption of Cu 2+ ions by cellulose graft copolymers

To investigate the potential of some cellulose graft copolymers, especially with respect to the structural aspects of graft copolymer chains as new membrane materials, sorption studies of Cu 2+ ions from aqueous solution of CuSO 4 have been studied. Grafting improves metal ion sorption behaviour of cellulose. A method of synthesis for grafting copolymers has a tremendous effect on sorption behaviour. For identical graft levels graft copolymers synthesized by gamma radiation initiation sorb three times more ions as compared to the graft copolymers initially synthesized with the persulphate redox system. Copolymers having binary monomer units grafted sorb less than those which have only poly (Sty) grafted. Some reasons have been put forth to account for the sorption behaviour of graft copolymers.

New amphoteric graft copolymers of sodium carboxymethyl cellulose with acrylamide and dimethylaminoethyl methacrylate: Aqueous solution properties

The solubility and viscosity properties of new amphoteric graft copolymers of sodium carboxymethyl cellulose with acrylamide and dimethylaminoethyl methacrylate in aqueous solutions were investigated by turbidimetry and viscometry experiments. The factors investigated include the pH of the medium, the composition of the graft copolymer, the concentration and type of added salt, temperature, aging time, and the addition of organic solvent. Unlike conventional copolymers, these graft copolymers have unique solution behavior due to the presence of both acidic and basic groups along the macromolecular backbone. In addition, their solution properties are closely related to their conformations and are partially controlled by the net electrical charge and the ionic strength. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 305–310, 2000

Biodegradation studies of cellulose and its vinylic graft copolymers by thermal analysis and mechanical spectroscopy

Cotton cellulose with different % NaOH treatments and graft copolymers of cellulose prepared with vinyl acetate (AV) and methyl acrylate (MA), and Ce(IV) ion as an initiator were submitted to biodegradation conditions. Cellulose is a biopolymer consisting solely of glucose units, and, consequently, is also easily biodegradable. Nevertheless, modified cellulose, for example, by graft copolymerization, shows an increased resistance to biodegradation. The aim of this work was to study by calorimetric and dynamic-mechanical analysis how the chemical modification of cellulose affects its biodegradability. From the obtained results some information has also been deduced about the composition and mechanical behavior of the vinylic grafted chains. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 326–335, 2000

New amphoteric graft copolymers of sodium carboxymethyl cellulose with acrylamide and dimethylaminoethyl methacrylate: Aqueous solution properties

The solubility and viscosity properties of new amphoteric graft copolymers of sodium carboxymethyl cellulose with acrylamide and dimethylaminoethyl methacrylate in aqueous solutions were investigated by turbidimetry and viscometry experiments. The factors investigated include the pH of the medium, the composition of the graft copolymer, the concentration and type of added salt, temperature, aging time, and the addition of organic solvent. Unlike conventional copolymers, these graft copolymers have unique solution behavior due to the presence of both acidic and basic groups along the macromolecular backbone. In addition, their solution properties are closely related to their conformations and are partially controlled by the net electrical charge and the ionic strength. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 305–310, 2000

Adsorption of chromium and zinc ions from aqueous solutions by cellulosic graft copolymers

Cellulosic graft copolymers were prepared by the reaction of bast fibers of the kenaf plant ( Hibiscus cannabinus) with acrylonitrile and methacrylonitrile monomers in aqueous media initiated by the ceric ion-toluene redox pair. The cellulose-polyacrylonitrile (Cell-PAN) and cellulose-polymethacrylonitrile (Cell-PMAN) graft copolymers were used for the removal of Zn(II) and Cr(III) ions from aqueous solutions at 30°C. Zn(II) ion was more sorbed than Cr(III) ion by both copolymers by an average factor of 1.80 ± 0.40. For each metal ion, the Cell-PAN graft copolymer was a more effective sorbent than the Cell-PMAN derivative. The amount of ion sorbed decreased with an increase in percentage graft and over the range 38–149% of the graft the amounts of Zn(II) and Cr(III) ions sorbed by Cell-PAN decreased by 44% and 56%, respectively.

Dependence of the dyeability of modified cotton on the substituents and the nature of the dye

Cotton cellulose was chemically modified by introducing acrylamide, acrylonitrile and carboxyalkyl moieties in the form of groups or polymers. In carbamylethylated, cyanoethylated and carboxymethylated cotton, these moieties are in monomeric groups, whereas, in graft copolymers of cotton cellulose with acrylamide, acrylonitrile or acrylic acid, the moieties are in polymeric forms. These substrates were dyed independently using direct, acid, basic or reactive dyes. Results showed that at roughly equal nitrogen content, polyacrylamide–cotton graft copolymer exhibited a much higher colour strength than carbamylethylated cotton when the two substrates were dyed using basic dye. The opposite is the case for direct and reactive dyes. The acid dye produced comparable colour strengths. Similar trends were observed when the other samples were dyed with these four dyes. The results were explained in terms of microstructural changes in the physical and chemical structure of cotton caused by the etherification and grafting reactions.

Fabrication and properties of antimicrobial cellulose materials based on polyelectrolyte complexes

The effect of the structure of the reacting compounds and reaction conditions on the composition of polyelectrolyte complexes formed in the reaction of polyanions — graft copolymer of cellulose and polyacrylic acid and polymethacrylic acid sodium salt (C-gr-PAa (PMAA)) and polyhexamethyleneguanidine hydrochloride (PHMG) and polyethylenimine (PEI) — and the kinetics of their formation were investigated. The conditions that ensure complete binding of the polycation were determined and the necessity of a significant excess of polycation and long duration of the reaction for formation of complexes of stoichiometric composition was demonstrated. In studying desorption of antimicrobial substances from the polyelectrolyte complex, the effect of the process production scheme and type of cation and the significant role of diffusion factors in this process on the stability of the complex was established.

Synthesis and characterization of new amphoteric graft copolymer of sodium carboxymethyl cellulose with acrylamide and dimethylaminoethyl methylacrylate

The graft copolymerization of sodium carboxymethylcellulose (NaCMC) with acrylamide (AM) and dimethylaminoethyl methylacrylate (DMAEMA) was conducted in an aqueous solution using ammonium persulfate (APS) and N,N,N′,N′-tetramethylethylene diamine (TMEDA) as the initiator. The effects of various factors on grafting, such as temperature, pH, initiator concentration, and concentrations of AM, DMAEMA, and NaCMC were studied. The composition and thermal stability of the graft copolymers were characterized by infrared, elemental, and thermogravimetric analysis, and degradation activation energy and kinetic order were calculated. The relationship between its reduced viscosity and pH in aqueous NaCl was also investigated. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 879–885, 1998

Interpolymer reaction between antimicrobial polycation and polyanions grafted to cellulose fibre

The characteristics and features of the interpolymer reaction (IPR) between a polymeric antimicrobial substance (AS) containing basic groups — poly-1,2-dimethyl-5-vinylpyridinium methylsulfate (PDMVPMS), and graft copolymers of cellulose of varying structure containing acid groups (C-gr-PAA-Na, C-gr-PMAA-Na, C-gr-PSSA-Na) were established. It was found that with a high bath modulus, IPR takes place for a long time; the structure of the polyanion chain grafted to the cellulose and the presence of “cross-links” in the graft chains affect the kinetics of IPR and the composition of the polyelectrolyte complexes (PEC) formed. It was shown that the characteristics of the IPR investigated differ significantly from the characteristics of IPR with the participation of polymethyldiallylammonium chloride (PDAC), another antimicrobial polycation containing a quaternary ammonium group, and the same graft polyanions.

Effect of the Molecular Chain Length of Cellulose Trunk Polymer on the Swelling Behavior of Cellulose Graft Copolymer.

The partially hydrolyzed graft copolymers of crosslinked polyacrylamide (PAM) on water-soluble hydro-xyethylcelluloses(HECs) with different molecular chain lengths were synthesized by using of the ceric ion in-itiation method in an aqueous medium, and the effect of the molecular chain length of the HEC trunk polymer on the swelling behavior of the graft copolymer (HEC-AM-Hyd) was investigated. The synthesized HEC-AM-Hyds were similar to one another in the proportion of the HEC trunk polymer and the grafted branch polymer and in the crosslinking density and content of carboxyl groups of the partially hydrolyzed PAM branch polymer. The absorbency of HEC-AM-Hyd increased with an increase in the molecular cahin length of the HEC trunk polymer. The HEC-AM-Hyd from the HEC with longer chain length had higher resistibility against the decrease in the absorbency with an increase in the NaCl concentration than that from the HEC with shorter chain length. It is con-sidered that the HEC molecule that has high rigidity and extends largely in water acts effectively in the swelling of HEC-AM-Hyd, and that the superior swelling properties of the HEC-AM-Hyd from the HEC with longer chain length are due to the larger extension of its trunk polymer.

Sorptive properties of anion-exchange fibrous sorbents based on graft copolymers of cellulose and polyacrylonitrile

Sorptive properties of anion-exchange fibrous sorbents based on graft copolymers of cellulose and polyacrylonitrile

Studies on the Solubility Vinyl Compound/Polysaccharide Graft Co polymers. (Part 3). Water Solubility of Gellulose Graft Copolymers Having Hydrophilic Vinyl Polymers as Graft.

Acrylonitrile (AN) and vinyl acetate (VAc), respectively, were grafted onto viscose rayon (MW=5.0×104) in vapor phase by using potassium persulphate as an initiator. Each graft product was refluxed in 10% aq NaOH for 2hr to yield the viscous solutions. The alkaline solution from the AN graft product was dialyzed for 100hr against running water by the use of cellophane tube as semipermeable membrane to yield the transparent dialyzate solution. The solution from the VAc graft product was neutralized and then dialyzed under the same conditions to produce the transparent dialyzate solution. IR spectra of the solutes of the dialyzate showed characteristic absorptions of both cellulose molecule and the hydrolyzed graft chains. Huggins constant determined for the water-soluble dialyzate from the VAc graft product was about six times that of the PVA sample obtained by hydrolyzing the trunk cellulose molecules. From these results, it may be concluded that water-soluble cellulose graft copolymers could be obtained by grafting hydrophylic vinyl monomers onto cellulose.

Porous structure and rheological properties of hydrogels of highly water‐absorptive cellulose graft copolymers

AbstractThe porous structures of the highly swollen hydrogels of cellulose—acrylamide graft copolymers were studied by the solute exclusion technique. For these hydrogels, the cumulative volume of pores up to 560 Å in pore width was between 450 and 850 mL/g, and was between 20 and 30% of the total pore volume. With an increasing in the amount of crosslinker added in the grafting procedure, the cumulative pore volume up to 560 Å decreased. Furthermore, larger pores shrunk preferentially. In the range of concentration from 0.003 to 0.3%, the viscosity of the hydrogels increased remarkably with an increase in concentration. The concentration dependence of the viscosity showed a transition at about 0.03%, which corresponded to the reciprocal of the water retention values for each copolymer. At concentrations over 3%, fluidity of the hydrogels was lost and the water swollen copolymers became viscoelastic. This dynamic viscoelasticity remained essentially unchanged in the temperature range of 20 to 80°C. The dynamic viscoelasticity was dependent on the concentration, but the concentration dependence was smaller than that of the viscosity. The larger the amount of the crosslinker added, the larger the value of dynamic modulus became.

Studies on the Solubility of Vinyl Compound/Polysaccharide Graft Copolymers. Part 2. Detailed investigation on cellulose graft copolymers soluble in organic solvents.

Styrene (ST) and methyl methacrylate (MMA) were grafted onto cellulose gel, which had been prepared from cellulose solution in 85% phosphoric acid, by use of ceric ammonium nitrate as an initiator.The frequency of grafting for the ST/cellulose graft copolymer obtained as a toluene extract separated from the attendant unreacted cellulose was found to be unity. Intrinsic viscosities of the cellulose graft copolymers extracted from graft products with organic solvents implied that the copolymers were in a uniform molecular dispersion, forming monomolecular micell-like structures in the organic solvents. Cellulose crystallites were hardly found in the film prepared with the MMA/cellulose graft copolymer extracted from the MMA/cellulose graft product with 1, 2-dichloroethane.

Drag‐reduction efficiency, shear stability, and biodegradation resistance of carboxymethyl cellulose‐based and starch‐based graft copolymers

AbstractGraft copolymers of carboxymethyl cellulose and starch with polyacrylamide have been synthesized by grafting acrylamide onto carboxymethyl cellulose and starch, respectively, using a ceric‐ion‐initiated solution polymerization technique. These graft copolymers have been tested for their drag‐reduction effectiveness, shear stability, and biodegradability. It has been shown that grafting enhances the drag‐reduction effectiveness and shear stability and also that these factors are very much dependent on the length and number of grafts in the molecule. None of the graft copolymer solutions shows any microbial degradation up to 10 days.