Kinetics and crystallization in pH‐sensitive free‐radical crosslinking polymerization of acrylic acid

Free‐radical crosslinking polymerization and crystallization of acrylic acid (AAc) were investigated by shear storage modulus (G′) measurements in pH 2, as well as in pH 6 and pH 10, by varying the molar ratio of crosslinking agent (N,N′‐methylene bis‐acrylamide; MBAAm) to AAc (0.583 × 10^?3, 1.169 × 10^?3, 1.753 × 10^?3, and 2.338 × 10^?3). Our results showed that the pre‐gelation time was the same at pH 2, regardless of the concentration of MBAAm. The propagation time was determined by the initial feed concentration of AAc, and the length of the linear curve in the propagation was proportional to the concentration of MBAAm. The Avrami exponent (n), as an indicative of growing pattern of an infinite molecule, in the crystallization was increased in proportional to the concentration of MBAAm, and generally low at pH 2. In the deceleration phase, n was observed near 1.0 throughout the all specimens. These results indicated that (1) the length of the pre‐gelation period was determined by the ionization of AAc (or pH), (2) the polymerization rate of AAc was not affected by the concentration of MBAAm, and (3) the inhomogeneity of hydrogel was determined by the growing pattern of infinite molecule in propagation phase. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42195.     

Particle number and size of polystyrene‐dependent micellar crosslinking polymerization of acrylic acid

The effect of the number and size of polystyrene particles and the concentration of ammonium persulfate used as the initiator on the micellar crosslinking polymerization of acrylic acid was studied by real‐time monitoring of the storage modulus (G ′), the damping factor (tanδ), and the ratio of the complex modulus (G*) to the maximum G* (G*_max) during 1 h of polymerization. The molar ratio (5.83 × 10^?4) of N,N′‐methylenebis‐acrylamide to acrylic acid was fixed. Polystyrene particles were prepared by emulsifier‐free emulsion polymerization. The diameter of the particles ranged from 233 to 696 nm. The results show that crosslinking polymerization was most effective when 1.31 × 10¹² particles were incorporated into the system, while crosslinking polymerization was less effective in the particle‐filled system than in the unfilled polymerization system if the particle number was 50% lower or higher. Crosslinking was also more effective with the use of uncrosslinked firmer and larger particles at the fixed particle number, except for the anomalous behavior observed with 696 nm polystyrene particles. Increasing the feed concentration of the initiator resulted in more efficient crosslinking up to a limiting concentration of 0.765 mg mL^?1 (the molar ratio of initiator to monomer was 8.52 × 10^?4). When this initiator concentration was doubled, the rate of increase of G ′ in the deceleration phase was slower after the network was formed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42851.     

Effects of solvent basicity on free radical polymerizations of N,N′‐bismaleimide‐4,4′‐diphenylmethane initiated by barbituric acid

The polymerizations of N,N′‐bismaleimide‐4,4′‐diphenylmethane (BMI) initiated by barbituric acid (BTA) carried out in a variety of solvents at 130°C were studied. The nitrogen‐containing cyclic solvents such as N‐methyl‐2‐pyrrolidinone acted as a catalyst to promote the formation of the three‐dimensional crosslinked network structure. By contrast, the polymerization in a cyclic solvent that did not contain nitrogen such as γ‐butyrolactone resulted in nil gel content. The higher the solvent basicity, the larger the amount of insoluble polymer species formed. The molar ratio of BTA to BMI also played an important role in the polymerizations. The resultant polymers, presumably having a hyper‐branched structure, exhibited much narrower molecular weight distributions than those prepared by conventional free radical polymerizations. The BMI polymerizations using BTA as the initiator could not be adequately described by conventional free radical polymerization mechanisms. A polymerization mechanism that took into account the generation of a ketone radical pair between BTA and BMI and the subsequent initiation, propagation and termination reactions was proposed. It was concluded that the nitrogen‐containing cyclic solvents were capable of participating in the ketone radical pair formation process, thereby increasing the extent of polymer crosslinking reactions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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

Grafting 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, P_g/P_g0, 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     

Photopolymerized pH‐sensitive semi‐IPN: Synthesis,water uptake analysis,and preliminary drug release study

A series of pH‐sensitive semi‐IPN hydrogels, composed of varying amounts of monomer acrylic acid(AAc), crosslinker N,N′ methylene bisacrylamide, polymer cellulose acetate (CA) were synthesized via photoinitiated polymerization in dimethyl formamide (DMF) medium. The CA/P (AAc) hydrogels were characterized by FTIR, and TG analysis. The equilibrium water uptake data was used to determine various network parameters. For all the samples synthesized, the swelling exponent “n,” initial diffusion coefficient D and average diffusion coefficient D_ave were found to be in the range of 0.51–0.72, 3.16 to 7.14 × 10^?6 cm² min^?1 and 94.16–120.56 cm² min^?1, respectively. The hydrogel demonstrated fair pH‐dependent swelling behavior, with nearly 20% swelling in the medium of pH 1.0 and 615% in the medium of pH 7.4 at 37°C, respectively. The gel showed excellent swelling–deswelling cycles which were interpreted quantitatively by first order kinetic swelling and deswelling models. Finally, the preliminary insulin release study, carried out in the media of varying pH, observed almost 16% release of entrapped drug in the simulating gastric fluid (SGF) of pH 1.0 in first 2 h and nearly 51% in next 6 h in simulating intestinal fluid(SIF) of pH 7.4 at 37°C. POLYM. ENG. SCI., 53:2129–2140, 2013. © 2013 Society of Plastics Engineers     

m‐Chloroaniline emulsion polymerization,macromolecular chain structure and electrochemical properties

Poly(m‐chloroaniline) (PmClAn) was synthesized by emulsion polymerization. The influences of reaction temperature and initiator concentration on polymerizations were studied. It was found that PmClAn with number‐average molecular weight of 1.85 × 10³ g mol^?1 was obtained by the following conditions: 80 °C, [monomer] = 0.187 × 10^?3 mol l^?1, [sodium lauryl sulfate] = 4.8 × 10^?2 mol l^?1, [potassium peroxydisulfate] = 5.6 × 10^?2 mol l^?1, reaction period = 2.0 h. ¹H NMR, FTIR, and transmission and scanning microscopy were used for structural characterization of PmClAn. It was shown that the ratio of benzoid to quinoid units in the macromolecular chain was respectively 3:2, and that PmClAn has a typical crystalline monoclinic form. A PmClAn molecular chain configuration was also proposed on the basis of crystallographic data. Cyclic voltammetry experiments revealed the PmClAn membrane electrode electroactivity. This electroactivity increased when the polymer was proton‐doped. When Pt particles were electrodeposited onto the polymer membrane electrode, they presented a preferred orientation. Isopropanol oxidation intensities with platinized PmClAn modified electrodes were larger than with a platinized Pt electrode. We also found that oxidation occurred mainly on the Pt particles deposited on the polymer, and that the anodic peak potential changed with polymer and its doping level. These results indicated that the Pt particles interacted with the polymer and that catalytic properties could be observed. © 2002 Society of Chemical Industry     

Effect of solvent proton affinity on the kinetics of michael addition polymerization of n,n′‐bismaleimide‐4,4′‐diphenylmethane with barbituric acid

The effect of solvent proton affinity on the kinetics of the Michael addition polymerizations of N,N′‐bismaleimide‐4,4′‐diphenylmethane (BMI) and barbituric acid (BTA) in different solvents [N‐methyl‐2‐pyrrolidone (NMP), N,N′‐dimethylacetamide (DMAC), and N,N′‐dimethylformamide (DMF)] were investigated. This was achieved by the complete suppression of the competitive free radical polymerization via the addition of a sufficient amount of hydroquinone (HQ). A mechanistic model was developed to adequately predict the polymerization kinetics before a critical conversion, at which point the diffusion‐controlled polymerization become the predominant factor during the latter stage of polymerization, was achieved. The activation energy (E_a) of the Michael addition polymerization of BMI with BTA in the presence of HQ in increasing order was: NMP < DMAC < DMF, which was correlated quite well with the solvent proton affinity (NMP > DMAC > DMF). By contrast, the frequency factor (A) in increasing order is: NMP < DMAC < DMF. As a result of the compensation effect between E_a and A, at constant temperature, the Michael addition rate constant decreased with increasing solvent proton affinity. POLYM. ENG. SCI., 54:559–568, 2014. © 2013 Society of Plastics Engineers     

Synthesis and characterization of a porous poly(hydroxyethylmethacrylate‐co‐ethylene glycol dimethacrylate)‐based hydrogel device for the implantable delivery of insulin

Poly(hydroxyethylmethacrylate‐co‐ethylene glycol dimethacrylate) [poly(HEMA‐co‐EGDMA)]‐based hydrogel devices were synthesized by a free‐radical polymerization reaction with 2‐hydroxyethylmethacrylate as the monomer, different concentrations of ethylene glycol dimethacrylate (EGDMA) as the crosslinking agent, and ammonium persulfate/N,N,N′,N′‐tetra‐methyl ethylenediamine as the free‐radical initiator. The porosity of the poly(HEMA‐co‐EGDMA) hydrogels was controlled with water as the porogen. The Fourier transform infrared spectrum of poly(HEMA‐co‐EGDMA) showed absorption bands associated with ? C?O stretching at 1714 cm^?1, C? O? C stretching vibrations at 1152 cm^?1, and a broad band at 3500–3800 cm^?1 corresponding to ? OH stretching. Atomic force microscopy studies showed that the hydrogel containing 67% water had pores in the range of 3500–9000 nm, whereas the hydrogel containing 7% water did not show measurable pores. The hydrogel synthesized with 1% EGDMA showed 50% thallium‐201 release within the first 30 min and about 80% release within 60 min. In vitro insulin‐release studies suggested that the hydrogel with 27% water showed sustained release up to 120 min, whereas the hydrogels with 47 and 67% water showed that nearly all of the insulin was released within 60 min. Hydrogel devices synthesized with 27% water and filled with insulin particles showed sustained release for up to 8 days, whereas the hydrogels synthesized with 47 and 67% water released insulin completely within 3 days of administration. Animal studies suggested that the hydrogel devices synthesized with 27% water and filled with insulin‐loaded particles (120 IU) were able to control blood glucose levels for up to 5 days after implantation. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Drug delivery system based on poly(ether‐block‐amide) and acrylic acid for controlled release of vancomycin

Poly(ether‐block‐amide) (PEBA) films were grafted with acrylic acid (AAc) by gamma radiation, using the oxidative pre‐irradiation technique. The effect of dose, monomer concentration, temperature, and reaction time on the graft percentage of AAc onto PEBA was studied. The modified material PEBA‐g‐AAc was characterized by Fourier infrared spectroscopy (FTIR), scanning electron microscopy, and water contact angle. It was found that PEBA films did not suffer degradation at low doses (<30 kGy) during the grafting process. Additionally, PEBA‐g‐AAc was proved as drug delivery system using vancomycin as drug model. The PEBA‐g‐AAc with 39 and 98% of AAc loaded 63 and 98 mg g^?1, respectively. The release profiles showed a sustained delivery by 48 h with a partial retention of drug, which depends of grafting percentage. The microbiological tests showed that PEBA‐g‐AAc was able to inhibit the growing of Staphylococcus aureus in three consecutive challenges. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45745.     

Synthesis and properties of radiation‐induced acrylamide–acrylic acid hydrogels

Acrylamide (AAm)/acrylic acid (AAc) hydrogels in the cylindirical form were prepared by γ‐irradiating binary systems of AAm/AAc with 2.6–20.0 kGy γ‐rays. The effect of the dose and relative amounts of AAc and pH on the swelling properties, diffusion behavior of water, diffusion coefficients, and network properties of hydrogel systems was investigated. The swelling capacities of AAm/AAc hydrogels were in the range of 1000–3000%, while poly(acrylamide) (PAAm) hydrogels swelled in the range of 450–700%. Water diffusion into hydrogels was found to be non‐Fickian‐type diffusion. Diffusion coefficients of AAm/AAc hydrogels were found between 0.79 × 10^?5 and 2.78 × 10^?5 cm² min^?1. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3570–3580, 2002     

Synthesis and characterization of chitosan‐g‐methacrylic acid and studies of its additional physicochemical properties,such as swelling,metal‐ion sorption,and flocculation behavior

The aim of this study was to examine the synthesis of a graft copolymer of chitosan and methacrylic acid (MAA) by free‐radical polymerization with a potassium peroxymonosulfate/cyclohexanone (CY) redox system in an inert atmosphere. The optimum reaction conditions affording maximum grafting ratio (%G), grafting efficiency (%E), add on (%A), and conversion (%C) were determined. The grafting parameters were found to increase with increasing concentration of MAA up to 24 × 10^?2 mol/dm³, but thereafter, these parameters decreased. With increasing concentration of peroxymonosulfate from 0.6 × 10^?2 to 1.2 × 10^?2 mol/dm³, %G, %A, and %E increased continuously. All of these grafting parameters increased with increasing concentration of CY up to 1.2 × 10^?2 mol/dm³, but beyond this concentration, the grafting parameters decreased. With various concentrations of chitosan from 0.6 to 1.4 g/dm³, the maximum %G, %A, and %E were obtained at 1.4 g/dm³. %G, %A, and %C decreased continuously with various concentrations of hydrogen ions from 2 × 10^?3 to 6 × 10^?3 mol/dm³. The grafting parameters increased with increasing temperature up to 35°C, but thereafter, these parameters decreased. With increasing time period of reaction from 60 to 180 min, %G, %A, and %E increased up to 120 min, but thereafter, these parameters decreased. The graft copolymer was characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Kinetic and structural studies of the polymerization of N,N′‐bismaleimide‐4,4′‐diphenylmethane with barbituric acid

Both the isothermal and non‐isothermal polymerizations of N,N′‐bismaleimide‐4,4′‐diphenylmethane (BMI) with barbituric acid (BTA) were investigated by the differential scanning calorimeter. The experimental results showed that the polymerizations of BMI with BTA were governed by the competitive Michael addition reaction and free radical polymerization mechanisms. Furthermore, the contribution of free radical polymerization becomes more important when the mole fraction of BTA decreases. ¹H NMR and ¹³C NMR measurements further support the coexistence of the Michael addition reaction and free radical polymerization mechanisms. A preliminary kinetic model that took into account the competitive Michael addition reaction and free radical polymerization mechanisms was developed. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Preparation and properties of a salt‐resistant superabsorbent polymer

Crosslinked sodium polyacrylate was prepared by solution polymerization with N,N‐methylene‐bisacrylamide (bisAM) as crosslinking agent; it was subsequently surface‐crosslinked by ethylene glycol diglycidyl ether (EGDE) and then was modified with inorganic salt to obtain a superabsorbent with water absorbency in 0.9 wt % NaCl aqueous solution at atmosphere and applied pressure (P ≈ 2 × 10³ Pa) of 55 and 20 g.g^?1, respectively. Moreover, it also had excellent hydrogel strength. The effects of reaction temperature, reaction time, neutralization degree (ND) of acrylic acid, amount of initiator, crosslinking agent, and surface‐crosslinking agent, mass ratio of inorganic salt to initial superabsorbent, molar ratio of sodium aluminate (NaAlO₂) to potassium dihydrogen hyphosphate (KH₂PO₄) on water absorbency (WA) in 0.9 wt % NaCl aqueous, and the hydrogel modulus were investigated and optimized. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2532–2541, 2004     

Synthesis and characterization of novel optically active poly(imide–urethane)s derived from N,N′‐(pyromellitoyl)‐bis‐(L‐leucine) diisocyanate and aromatic diols

N,N′‐(Pyromellitoyl)‐bis‐(L ‐leucine) diacid was reacted with ethyl chloroformate in the presence of triethylamine followed by reaction with activated sodium azide and gave N,N′‐(pyromellitoyl)‐bis‐(L ‐leucine) diacylazide in high yield. This diacylazide was heated in dry benzene and gave the unstable N,N′‐(pyromellitoyl)‐bis‐(L ‐leucine) diisocyanate ( 5 ) in quantitative yield. Thus, diisocyanate 5 was generated in situ and polycondensation reaction of this monomer with several aromatic diols, such as 4,4′‐dihydroxybiphenyl, 1,4‐hydroquinone, bisphenol A, phenolphthalein and 1,4‐dihydroxyanthraquinone, was performed in dry toluene under refluxing in the presence of 1,4‐diazabicyclo[2.2.2]octane (triethylenediamine) as a catalyst. The polymerization reactions proceeded within 48 h, producing a series of optically active poly(imide–urethane)s with good yield and moderate inherent viscosity in the range 0.18–0.28 dl g^?1. All of the above polymers were fully characterized by infrared spectra, elemental analyses and specific rotation. Some structural characterization and physical properties of these optically active poly(imide–urethane)s are reported Copyright © 2003 Society of Chemical Industry     

Free radical polymerization kinetics of monomers functionalized with ?AsO(OH)2 in aqueous media

The free radical polymerization kinetics of the isomer sodium salts of o‐ and p‐methacryloylaminophenylarsonate in aqueous solution have been studied using a dilatometric method. The polymerizations, initiated with potassium persulfate, were carried out at a constant monomer initial concentration of 0.50 mol/L and the initiator initial concentration was fixed at one of the following: 1.00, 2.00, 5.00, 8.00, or 10.00 (× 10^?3 mol/L). Another set of polymerizations were carried out at a constant initiator initial concentration of 2 × 10^?3 mol/L and the monomer initial concentration was fixed at one of the following: 0.20, 0.30, 0.50, 0.70, or 1.00 (mol/L). The polymerization reactions were conducted isothermally at 70°C. The order with respect to initiator was consistent with the classical kinetic rate equation, while the order with respect to monomer was greater that unity. The effects of temperature on the polymerization rate were also investigated and the activation energy gave values of 20.66, 22.68, and 23.22 kcal mol^?1 K^?1 over a temperature range of 50–70°C. For the case of o‐methacryloylaminophenylarsonic acid monomer, its kinetic study was carried out in DMF as solvent and AIBN initiator. p‐Methacryloylaminophenylarsonic acid was too insoluble in DMF to be studied. The polymers obtained were characterized by H‐NMR, IR, and viscosity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1662–1669, 2004     

Synthesis,characterization, conductivity,band gap,and kinetic of thermal degradation of poly‐4‐[(2‐mercaptophenyl) imino methyl] phenol

The oxidative polycondensation reaction conditions of 4‐[(2‐mercaptophenyl) imino methyl] phenol (2‐MPIMP) were studied in an aqueous acidic medium between 40 and 90°C by using oxidants such as air, H₂O₂, and NaOCl. The structures of the synthesized monomer and polymer were confirmed by FTIR, ¹H NMR, ¹³C NMR, and elemental analysis. The characterization was made by TGA‐DTA, size exclusion chromatography (SEC) and solubility tests. At the optimum reaction conditions, the yield of poly‐4‐[(2‐mercaptophenyl) imino methyl]phenol (P‐2‐MPIMP) was found to be 92% for NaOCl oxidant, 84% for H₂O₂ oxidant 54% for air oxidant. According to the SEC analysis, the number‐average molecular weight (M_n), weight‐average molecular weight (M_w), and polydispersity index values of P‐2‐MPIMP were found to be 1700 g mol^?1, 1900 g mol^?1, and 1.118, using H₂O₂; 3100 g mol^?1, 3400 g mol^?1, and 1.097, using air; and 6750 g mol^?1, 6900 g mol^?1, and 1.022, using NaOCl, respectively. According to TG analysis, the weight losses of 2‐MPIMP and P‐2‐MPIMP were found to be 95.93% and 76.41% at 1000°C, respectively. P‐2‐MPIMP showed higher stability against thermal decomposition. Also, electrical conductivity of the P‐2‐MPIMP was measured, showing that the polymer is a typical semiconductor. The highest occupied molecular orbital, the lowest unoccupied molecular orbital, and the electrochemical energy gaps (E′_g) of 2‐MPIMP and P‐2‐MPIMP were found to be ?6.13, ?6.09; ?2.65, ?2.67; and 3.48, 3.42 eV, respectively. Kinetic and thermodynamic parameters of these compounds investigated by MacCallum‐Tanner and van Krevelen methods. The values of the apparent activation energies of thermal decomposition (E_a), the reaction order (n), pre‐exponential factor (A), the entropy change (ΔS*), enthalpy change (ΔH*), and free energy change (ΔG*) were calculated from the TGA curves of compounds. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and properties of poly(sodium acrylate‐co‐2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid)/attapulgite as a salt‐resistant superabsorbent composite

A novel salt‐resistant superabsorbent composite was prepared by copolymerization of partially neutralized acrylic acid, 2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid (AMPS) and attapulgite (APT). To enhance the swelling rate (SR) of the copolymer, sodium bicarbonate was used as a foaming agent in the course of copolymerization. Furthermore, for improving the properties of swollen hydrogel, such as strength, resilience and dispersion, the copolymer was surface‐crosslinked with glycerine and sodium silicate, and then the surface‐crosslinked copolymer was blended with aluminum sulfate and sodium carbonate in post treatment process. The influences of some reaction conditions, such as amount of AMPS, APT, and initiator, and neutralization degree of acrylic acid on water absorbency in 0.9 wt% NaCl aqueous solution both under atmospheric pressure (WA) and load (WA_P, P ≈ 2 × 10³ Pa) were investigated. In addition, the effect of them on SR was also studied. The WA and WA_P of the superabsorbent composite prepared under optimal conditions in 0.9 wt% NaCl aqueous solution were 52 g·g^?1 and 8 g·g^?1, respectively. Besides, the SR was fast, and it could reach 0.393 mL·(g·s)^?1. Moreover, the swollen hydrogel possessed excellent salt resistance, hydrogel resilience and dispersion. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

Radiation synthesis and application of a hydrogel based on acrylic acid and 2‐mercaptobenzimidazole

A hydrogel based on gamma‐radiation polymerization of acrylic acid (AAc) in the presence of 2‐mercaptobenzimidazole (MBI) and a crosslinking agent was prepared. The properties of this AAc/MBI hydrogel were characterized in terms of gel content, swelling in different solvents, structure morphology, and IR spectroscopy. Moreover, the thermal decomposition behavior of the prepared hydrogel was investigated by thermogravimetric analysis (TGA). The TGA thermograms were also used to determine the different kinetic parameters such as order of reaction and activation energy. The sorption of some divalent metal ions such as Cu²⁺, Pb²⁺, Cd²⁺, and Hg²⁺ by the AAc/MBI hydrogel also was studied. The results showed that the AAc/MBI hydrogel has a higher tendency to swell in water and polar solvents than in nonpolar solvents. The highest metal uptake by the hydrogel was found for Hg²⁺ and Cd²⁺, whereas the lowest was for Cu²⁺ and Pb²⁺ ions. The ratios between the distribution coefficients of the different metals [separation factors (SF)] indicate that the hydrogel has a high selectivity for Hg²⁺ over Cu²⁺ (SF = 10.923) and Pb²⁺ (SF = 19.110). However, the hydrogel prefers Hg²⁺ over Cd²⁺ (SF = 1.356) and showed a high selectivity for Cd²⁺ over Cu²⁺ (SF = 7.822) and Pb²⁺ (SF = 7.240). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1607–1614, 2002     

Synthesis of acrylamide‐co‐(itaconic acid) superabsorbent polymers and associated silica superabsorbent polymer composites

Superabsorbent polymers (SAPs) were synthesized from acrylamide (AM) and itaconic acid (IA) via a crosslinking polymerization. SAP composites (SAPCs) were formed by the incorporation of silica with three particle sizes into the polymerization to increase the gel strength of SAPs. Effects of AM: IA molar ratios, silica types and concentrations on water absorbency, absorbency rate and absorbency under loadings (AUL) of the composites were investigated. The highest water absorbency of the SAP is 233 ± 8 g g^?1 at an AM: IA molar ratio of 97:3 with absorbency of 149 ± 2 g g^?1 within 15 min. The highest AUL of the SAPC with 0.5%–2.0% w w^?1 silica is 13 g g^?1 by 1.93 × 10³ Pa load. A pseudo‐second‐order kinetics for water absorbency was found in both SAPs and in situ SAPCs. In situ SAPCs and the mechanically mixed SAPCs in vertical and horizontal direction yielded similar water absorbency values. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

One pot synthesis of xanthan gum‐g‐N‐vinyl‐2‐pyrrolidone and study of their metal ion sorption behavior and water swelling property

In this article, graft copolymerization of N‐vinyl‐2‐pyrrolidone onto xanthan gum initiated by potassium peroxydiphosphate/Ag⁺ system in an aqueous medium has been studied under oxygen free nitrogen atmosphere. Grafting ratio, grafting efficiency, and add on increase on increasing the concentration of potassium peroxydiphosphate (2.0 × 10^?3 to 12 × 10^?3 mol dm^?3), Ag⁺(0.4 × 10^?3 to 2.8 × 10^?3 mol dm^?3), and hydrogen ion concentration from 2 × 10^?3 to 14.0 × 10^?3 mol dm^?3. Maximum grafting has been obtained when xanthan gum and monomer concentration were 0.4 g dm^?3 and 16 × 10^?2 mol dm^?3, respectively, at 35°C and 120 min. Water swelling capacity, swelling ratio, metal ion uptake, and metal retention capacity have also been studied, and it has been found that graft copolymer shows enhancement in these properties than pure xanthan gum. The graft copolymer has been characterized by FTIR and thermal analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009