Synthesis,characterization and polychelatogenic properties of poly[(2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid)‐co‐(methacrylic acid)]

Poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid), poly(methacrylic acid), and five copolymers of poly[(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)‐co‐(methacrylic acid)] were synthesized by radical polymerization and obtained in yields >97%. The polymers were characterized by FT‐IR, [¹H]NMR, and [¹³C]NMR and studied by means of the Liquid‐phase Polymer‐based Retention (LPR) technique. The metal ion retention ability of the copolymers for Cu(II), Cd(II), Co(II), Hg(II), Ni(II), Zn(II), Cr(III) and Ag(I) was investigated at different pH values because of their environmental and analytical interest. The retention profiles of the copolymers were compared with those of the corresponding homopolymers and retention of metal ions was found to increase with increasing pH. © 2001 Society of Chemical Industry     

Effect of thermal aging on electrical conductivity of the 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid‐doped polyaniline fiber

The thermal characteristics of inherently conductive polyaniline (PANi) fiber have been studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Fibers show five major weight losses at ∼100°C, 165°C, 215°C, 315°C, and 465°C, which are associated with the removal of moisture, residual solvent, decompositions of the sulfonic acid and degradation of PANi fiber, respectively. The 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPSA) that dopes the PANi (in fiber form) performs two‐stage decompositions. The conductivity of the drawn fibers aged at 50°C, 100°C, 150°C, and 190°C under vacuum for various periods of time decreases, particularly at temperatures higher than 100°C. The reduction in conductivity of the fiber aged at temperatures lower than 100°C is mainly due to the evaporation of the residual solvent (15–20% in the as‐spun fiber). Further decrease in conductivity of the fiber aged at temperatures higher than 100°C is caused by the decomposition of the dopant AMPSA. The temperature‐dependent conductivity of the fiber was measured at 15 K (−258.5°C) to 295 K (21.5°C). The conductivity of both aged and un‐aged fibers is all temperature activated, however, the conductivity of the un‐aged fibers is higher than that of the aged fibers. Although a negative temperature coefficient was observed in the temperature range from 240 K (–24.5°C) to 270 K (–3.5°C) for the un‐aged fibers, it was disappeared when the fibers were thermal aged at 100°C for 24 h in vacuum oven. These results indicate that the residual solvent trapped inside the fiber enhanced the electrical conductivity of the fibers and its “metallic” electrical conductivity at temperatures ∼263 K (–10°C). © 2001 John Wiley & Sons, Inc. † J Appl Polym Sci 79: 2503–2508, 2001     

Electrical conductivity properties of poly[(maleic acid)‐co‐(vinyl pyrrolidone)] salts in aqueous solutions

The interaction of alkaline ions with an anionic dicarboxylic polyelectrolyte is studied by means of electrical conductivity measurements. The results show that lithium, sodium and potassium counter‐ions interact in a very different way with this polyelectrolyte. The Kohlrausch plots bend downwards in the high‐dilution zone. The limiting equivalent conductivities of these polymers were then determined according to Vink's method by a polynomial adjustment of specific conductivity data. Whereas the dissociation order follows the sequence Li⁺ > Na⁺ > K⁺, the trend in equivalent conductivity follows the reverse order, and apparently is mainly determined by the equivalent conductivity of the counter‐ions. The interaction parameter f was determined using the Manning theory for the limiting equivalent conductivity of the polyion species. From the values of the latter parameters, the average distance between charges agrees well with that calculated from simple geometrical calculations for a mesomeric configuration. An alternative method was used to obtain the relative interaction parameter f* as a function of polymer concentration. The results can be explained in terms of the hydration parameters and the limiting equivalent conductivities of the counter‐ions. © 2001 Society of Chemical Industry     

Magnetic and electrical properties of polypyrrole nanocomposites with iron nanoparticles attached to 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid

Polypyrrole (PPy) nanocomposites with iron nanoparticles attached to 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMP) were chemically prepared by varying the concentration of AMP using ammonium persulfate as an oxidant. The synthesized composites were characterized by using Fourier transform infrared (FTIR) spectroscopy, and their surface morphology and amended crystallinity were determined by using the transmission electron microscopy (TEM) and X‐ray diffraction (XRD), respectively. The electrical and magnetic properties of PPy–Fe–AMP composites were investigated at room temperature. The increase of AMP has brought out a significant increase of DC conductivity and magnetic saturation moment of the composites, which might have been caused by the increased mobility of charge carriers due to the hydrophilic AMP components. POLYM. COMPOS., 35:364–371, 2014. © 2013 Society of Plastics Engineers     

Entrapment of urease in poly(1‐vinyl imidazole)/poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) network

In this article, urease was immobilized in a conducting network via complexation of poly(1‐vinyl imidazole) (PVI) with poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) (PAMPS). The preparation method for the polymer network was adjusted by using Fourier transform infrared (FTIR) spectroscopy. A scanning electron microscope (SEM) study revealed that enzyme immobilization had a strong effect on film morphology. The proton conductivity of the PVI/PAMPS network was measured via impedance spectroscopy, under humidified conditions. The basic characteristics (Michealis‐Menten constants, pH_opt, pH_stability, T_opt, T_stability, reusability, and storage stability) of the immobilized urease were determined. The obtained results showed that the PAA/PVI polymer network was suitable for enzyme immobilization. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Proton conducting polymer blends from poly(2,5‐benzimidazole) and poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)

Proton conducting polymer electrolyte membranes were produced by blending of poly(2,5‐benzimidazole) (ABPBI) and poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) (PAMPS) at several stoichiometric ratios with respect to polymer repeating units. The membranes were characterized by using Fourier transform infrared spectroscopy for interpolymer interactions and scanning electron microscope for surface morphology. Thermal stability of the materials was investigated by thermogravimetric analysis. Glass transition temperatures of the samples were measured via differential scanning calorimetry. The spectroscopic measurements and water uptake studies indicate a complexation between ABPBI and PAMPS that inhibited polymer exclusion up on swelling in excess water. Proton conductivities of the anhydrous and humidified samples were measured using impedance spectroscopy. The proton conductivity of the humidified ABPBI:PAMPS (1 : 2) blend showed a proton conductivity of 0.1 S/cm, which is very close to Nafion 117, at 20°C at 50% relative humidity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Role of poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) in the modification of polysulfone membranes for ultrafiltration

In this study polysulfone membranes with antifouling and hydrophilic properties were synthesized using poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) (AMPS) as an additive for the first time. Different wt % of AMPS was used to prepare polysulfone membranes by phase inversion method. The role of AMPS on the porosity, pore size distribution, hydrophilicity, and antifouling nature was investigated and analyzed in detail. Characterization techniques like field emission scanning electron microscope, atomic force microscopy, and imageJ software were used to characterize the morphology of prepared membranes. There is positive effect of the additive addition on all the membrane parameters like Pure water flux [101.76 L/(m² h)] (MR0) to 464.06 L/(m² h) (MR4)], hydraulic permeability [0.65 (MR0) to 2.01 (MR4)], equilibrium water content [21.74 (MR0) to 71.45 (MR4)], and porosity [0.024 (MR0) to 0.58 (MR4)]. Response surface methodology was used for the optimization of bovine serum albumin (BSA) flux and rejection. The results of the morphological as well as permeation studies depicted that permeate flux and antifouling nature were increased with the amount of AMPS present in the membrane matrix. The antifouling study of the prepared membranes was undertaken by using BSA solution of 1000 mg/L. Positive results were seen with the increase in amount of AMPS, since, the total membrane resistance has been decreased from 0.95 (MR0) to 0.74 (MR4). Separation of humic acid from aqueous medium was also performed with the best performing membrane (MR4, having the highest amount of AMPS). Separation efficiency of 100% and 94% were obtained using 10 mg/L and 50 mg/L of HA, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45290.     

Hydrolyzed collagen‐grafted‐poly[(acrylic acid)‐co‐(methacrylic acid)] hydrogel for drug delivery

Hydrolyzed collagen‐grafted‐poly[(acrylic acid)‐co‐(methacrylic acid)] hydrogels were synthesized by solution polymerization and confirmed by infrared spectroscopy. From sequential univariate analysis, the optimal molar ratio of acrylic acid: methacrylic acid was 92:8 in the presence of N,N′‐methylenebisacrylamide, ammonium persulfate, and N,N,N′,N′‐tetramethylethylenediamine at 0.12, 0.015, and 0.2% mol of the monomers, respectively. The water absorbency of this hydrogel was both pH‐ and temperature‐dependent, but was higher in nonbuffered water than in boric acid/citric acid/phosphate buffer under the same conditions. The optimal hydrogel could swiftly swell and deswell in neutral and acid solutions, respectively. Its potential application in drug delivery was examined using insulin and methylene blue as model payload drugs. Loading in a 50% (v v^?1) ethanol solution gave a higher insulin loading level than in the buffer water. Insulin and methylene blue were both released at pH 6.8 but not at pH 1.2, but followed first order kinetics and the Higuchi equation, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45654.     

Spectroscopic and thermal studies of poly[(N‐vinylimidazole)‐co‐(maleic acid)] hydrogel and its quaternized form

BACKGROUND: In this study, poly[(N‐vinylimidazole)‐co‐(maleic acid)] (poly(VIm/MA)) hydrogels were prepared by γ‐irradiation of ternary mixtures of N‐vinylimidazole–maleic acid–water using a ⁶⁰Co γ‐source. Spectroscopic and thermal analyses of these hydrogels as a function of protonation showed that the results are consistent with the existence of an H‐bridged complex when the imidazole rings are partially protonated. Finally, the efficiency and binding trends of Cu²⁺, Co²⁺, Cd²⁺ and Pb²⁺ ions with both protonated and unprotonated poly(VIm/MA) hydrogels were determined. RESULTS: Gelation of 90% was reached at around 180 kGy dose at the end of irradiation. The poly(VIm/MA) hydrogels synthesized were further protonated in HCl solutions with different concentrations. Hydrogels originally showed 450% volumetric swelling; this ratio reached 1900% after protonation at pH = 5.0. Fourier transform infrared spectral changes in the ⁺N? H stretching region (3200–3600 and 1173 cm^?1) and the ring mode deformation at 915 cm^?1 are consistent with the formation of an H‐bridged complex between the protonated and unprotonated imidazole rings upon partial protonation. Similar changes were obtained from NMR spectra of both the protonated and unprotonated forms of the hydrogels. CONCLUSION: Protonated and unprotonated hydrogels have been used in heavy metal ion adsorption studies for environmental purposes. Adsorption decreased with decreasing pH value due to the protonation of the VIm ring. The adsorption of Me²⁺ ions decreased in the order Cu²⁺ > Co²⁺ > Cd²⁺ > Pb²⁺, which is related to the complexation stability as well as the ionic radius of the metal ions. These results show that P(VIm/MA) hydrogels can be used efficiently to remove heavy metal ions from aqueous solutions. However, the protonated form is a bad choice for heavy metal ion adsorption due to electrostatic repulsion forces; it can nevertheless be assumed to be a good choice for anion adsorption from environmental waste water systems. Copyright © 2007 Society of Chemical Industry     

Electrical actuation of ionic hydrogels based on polyvinyl alcohol grafted with poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid‐co‐acrylonitrile) chains

Novel electrically conducting composite materials consisting of poly(pyrrole) (PPy) nanoparticles dispersed in a poly(vinyl alcohol)‐g‐poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid‐co‐acrylonitrile) hydrogels were prepared within the polymer matrix by in situ polymerization of pyrrole. The conversion yield of pyrrole into PPy particles was determined gravimetrically while structural confirmation of the synthesized polymer was sought by Fourier Transform Infrared (FTIR) and UV‐visible spectroscopy. The morphology of PPy nanoparticles containing hydrogel matrix was investigated by Scanning Electron Microscopy (SEM) analysis. Electrical conductivity of nanocomposite hydrogels of different compositions was determined by LCR meter while electroactive behavior of nanocomposite hydrogels swollen in electrolyte solutions was investigated by effective bend angle measurements. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Synthesis and characterization of poly(thiophen‐3‐yl acetic acid 4‐pyrrol‐1‐yl phenyl ester‐co‐N‐methylpyrrole) and its application in an electrochromic device

Copolymer of thiophen‐3‐yl acetic acid 4‐pyrrol‐1‐yl phenyl ester (TAPE) with N‐methylpyrrole (NMPy) was synthesized by potentiostatic electrochemical polymerization in acetonitrile–tetrabutylammonium tetrafluoroborate solvent–electrolyte couple. The chemical structures were confirmed via Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), and UV–vis spectroscopy. Electrochromic and spectroelectrochemical properties of poly(TAPE‐co‐NMPy) [P(TAPE‐co‐NMPy)] were investigated. Results showed that the copolymer revealed color change between light yellow and green upon doping and dedoping of the copolymer, with a moderate switching time. Furthermore, as an application, dual‐type absorptive/transmissive polymer electrochromic device (ECD) based on poly(TAPE‐co‐NMPy) and poly(3,4‐ethylene dioxythiophene) (PEDOT) have been assembled, where spectroelectrochemistry, switching ability, stability, and optical memory of the ECD were investigated. Results showed that the device exhibited good optical memory and stability with moderate switching time. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1988–1994, 2006     

Surface‐active amphiphilic poly[(2‐acrylamido‐2‐methylpropanesulfonic acid)‐co‐(N‐isopropylacrylamide)] nanoparticles as stabilizer in aqueous emulsion polymerization

This work reports the effect of nanogel solid particles on the surface and interfacial tension of water/air and water/styrene interfaces. Moreover, the work aimed to use nanogels as a stabilizer for miniemulsion aqueous polymerization. A series of amphiphilic crosslinked N‐isopropylacrylamide (NIPAm) and 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) copolymer nanogels were synthesized based on an aqueous copolymerization batch method. Divinylbenzene and N,N‐methylene bisacrylamide were used as crosslinkers. The morphologies of the prepared nanogels were investigated using transmission and scanning electron microscopies. The lower critical transition temperatures were determined using differential scanning calorimetry. The surface tension of colloidal NIPAm/AMPS dispersions was measured as functions of surface age, temperature and the morphology of the NIPAm/AMPS nanogels. The NIPAm/AMPS nanogels reduced the surface tension of water to about 30.1 mN m^?1 at 298 K with a small increase at 313 K. Surface activities of these nanogels in water were determined by surface tension measurements. The NIPAm/AMPS dispersions had high surface activity and were used as a stabilizer to prepare a crosslinked poly(styrene‐co‐AMPS) microgel based on emulsion crosslinking polymerization. © 2013 Society of Chemical Industry     

Poly(acrylic acid‐co‐acrylamide‐co‐2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)‐grafted nanocellulose/poly(vinyl alcohol) composite for the in vitro gastrointestinal release of amoxicillin

Superabsorbent polymer composites (SAPCs) are very promising and versatile materials for biomedical applications. This study concentrates on the development of novel cellulose‐based SAPC, Poly(acrylic acid‐co‐acrylamide‐co?2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)‐grafted nanocellulose/poly(vinyl alcohol) composite, P(AA‐co‐AAm‐co‐AMPS)‐g‐NC/PVA, as a potential drug delivery vehicle. Amoxicillin was selected as a model drug, which is used for the treatment of Helicobacter pylori induced peptic and duodenal ulcers. P(AA‐co‐AAm‐co‐AMPS)‐g‐NC/PVA was synthesized by graft copolymerization reaction, and FTIR, XRD, SEM, and DLS analyses were performed for its characterization. Equilibrium swelling studies were conducted to evaluate the stimuli‐response behavior of the SAPC and found that equilibrium swelling was dependent on pH, contact time, temperature, ionic strength, concentration of crosslinker and PVA. Maximum drug encapsulation efficiency was found out by using different concentrations of amoxicillin. Drug release studies were carried out at simulated gastric and intestinal fluids and the release % was observed as maximum in intestinal fluids within 4 h. The drug release kinetics was investigated using Peppas' potential equation and follows non‐Fickian mechanism at pH 7.4. Thus, the drug release experiments indicate that P(AA‐co‐AAm‐co‐AMPS)‐g‐NC/PVA would be a fascinating vehicle for the in vitro administration of amoxicillin into the gastrointestinal tract. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40699.     

Designing of fullers‐earth‐containing poly(vinyl alcohol)‐g‐poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) nanocomposites: Swelling and deswelling behaviors

In this study, polymer–clay nanocomposites (PCNs) composed of poly(vinyl alcohol)s (PVAs), poly(2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid), and fullers earth were prepared by the effective dispersal of inorganic nanoclays in the organic PVA matrix via in situ free‐radical polymerization with potassium persulfate as an initiator and N,N‐methylene bisacrylamide as a crosslinker. The monomer, 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid, was grafted onto the PVA backbone, and at the same time, fullers earth layers were intercalated and exfoliated into the grafted copolymer, especially at a low or moderate loading of the fullers earth. The synthesized PCN materials were characterized by Fourier transform infrared spectroscopy and wide‐angle X‐ray diffraction techniques. The morphological features of the synthesized materials were studied by scanning electron microscopy; this revealed that the swelling ratio of this nanocomposite increased with increasing fullers earth content. The X‐ray diffraction results indicated that the fullers earth was exfoliated in the nanocomposite matrix, and its introduction into the polymer matrix enhanced the percentage crystallinity of the polymer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Poly(2‐acrylamido glycolic acid‐co‐2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid): Synthesis,characterization, and retention properties for environmentally impacting metal ions

Poly(2‐acrylamido glycolic acid‐co‐2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid) [P(AGA‐co‐APSA)] was synthesized by radical polymerization in an aqueous solution. The water‐soluble polymer, containing secondary amide, hydroxyl, carboxylic, and sulfonic acid groups, was investigated, in view of their metal‐ion‐binding properties, as a polychelatogen with the liquid‐phase polymer‐based retention technique under different experimental conditions. The investigated metal ions were Ag⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Pb²⁺, and Cr³⁺, and these were studied at pHs 3, 5, and 7. P(AGA‐co‐APSA) showed efficient retention of all metal ions at the pHs studied, with a minimum of 60% for Co(II) at pH 3 and a maximum close to 100% at pH 7 for all metal ions. The maximum retention capacity (n metal ion/n polymer) ranged from 0.22 for Cd²⁺ to 0.34 for Ag⁺. The antibacterial activity of Ag⁺, Cu²⁺, Zn²⁺, and Cd²⁺ polymer–metal complexes was studied, and P(AGA‐co‐APSA)–Cd²⁺ presented selective antibacterial activity for Staphylococcus aureus with a minimum inhibitory concentration of 2 μg/mL. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and antitumor activity of poly(3,4‐dihydro‐2H‐pyran‐co‐maleic anhydride‐co‐vinyl acetate)

The radical‐initiated terpolymerization of 3,4‐dihydro‐2H‐pyran (DHP), maleic anhydride (MA), and vinyl acetate (VA), which were used as a donor–acceptor–donor system, was carried out in methyl ethyl ketone in the presence of 2,2′‐azobisisobutyronitrile as an initiator at 65°C in a nitrogen atmosphere. The synthesis and characterization of binary and ternary copolymers, some kinetic parameters of terpolymerization, the terpolymer‐composition/thermal‐behavior relationship, and the antitumor activity of the synthesized polymers were examined. The polymerization of the DHP–MA–VA monomer system predominantly proceeded by the alternating terpolymerization mechanism. The in vitro cytotoxicities of poly(3,4‐dihydro‐2H‐pyran‐alt‐maleic anhydride) [poly(DHP‐alt‐MA)] and poly(3,4‐dihydro‐2H‐pyran‐co‐maleic anhydride‐co‐vinyl acetate) [poly(DHP‐co‐MA‐co‐VA)] were evaluated with Raji cells (human Burkitt lymphoma cell line). The antitumor activity of the prepared anion‐active poly(DHP‐alt‐MA) and poly(DHP‐co‐MA‐co‐VA) polymers were studied with methyl–thiazol–tetrazolium testing, and the 50% cytotoxic dose was calculated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2352–2359, 2005     

Study on swelling behavior of poly(sodium acrylate‐co‐2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid)/attapulgite macroporous superabsorbent composite

A fast swelling sulfonic acid macroporous superabsorbent composite is prepared by copolymerization of partially neutralized acrylic acid, 2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid, and attapulgite. The effects of pH values, ions, and their concentration on swelling behavior of sample are investigated. The results show that the swelling behavior of sample is affected by pH value. The supercase Π diffusion is observed in all NaCl solutions with different pH value. An overshooting effect appears in all solutions containing multivalent cations. This phenomenon may be attributed to the reorganization of the gel structure due to the formation of complex compound between cation and polymer network. A quantitative kinetics model proposed by Díez‐Peña is used to interprete it and the theoretical curves are in good agreement with the experimental data. For anions, it shows little effect on swelling process, and supercase Π diffusion is also observed no matter which kind of anion exists in swelling medium. POLYM. ENG. SCI., 55:681–687, 2015. © 2014 Society of Plastics Engineers     

Encapsulation of diclofenac sodium with acidic copolymer hydrogels based on PEG/poly(N‐isopropylacrylamide‐co‐2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) semi‐interpenetrating network using in situ loading technique

A pH‐ and temperature‐responsive semi‐interpenetrating copolymer PEG6000/poly(NIPA‐co‐AMPS) (PEG/AMPS‐co‐NIPA SIPN), for short PEG SIPN, was made by ammonium persulfate‐initiated suspension copolymerization of N‐isopropylacrylamide, 2‐acrylamido‐2‐methylpropanesulphonic acid, and N,N′‐methylene‐bis‐acrylamide (MBAA; crosslinker) in the presence of PEG6000. The PEG SIPN copolymer matrices containing nanostructures made in the high‐temperature copolymerization resulted in channels for PEG and facile migration of drugs. In drug encapsulation or drug‐loading process, one can easily ignore or pay less attention to the interaction between a drug and its encapsulation materials; however, the ignored interactions may induce problems in drug properties or the release behavior in use. Sodium diclofenac (DFNa) precipitates as the carboxylic acid form in an acidic environment, and it is challenging to encapsulate sodium diclofenac in such an acidic matrix without precipitation of the sparingly soluble acid form of DFNa on the surface of the polymer substrate. To avoid bulky precipitation in drug loading, an in situ loading technique was developed for producing gel spheres with DFNa uniformly distributed in the polymer matrix. The technique is based on fast polymerization of spherical droplets of a pregel solution in which the drug is dissolved. Diffusion‐loading prodrugs were made in comparison with in situ loading prodrugs in thermal, release kinetics, and release behavior. Drug release profiles (in pH 7.4 phosphate buffer) show that the new drug loading technique gives controlled release during a period of about 7 days at 37°C. By contrast, gel spheres loaded with sodium diclofenac using the conventional diffusion technique produced almost total release of the drug within about 24 h. The thermal stability of sodium diclofenac, the PEG/AMPS‐co‐NIPA SIPN, and the prodrugs made with the SIPN and sodium diclofenac was studied. A near zero‐order release kinetics was found in the in vitro release of sodium diclofenac with in situ loading PEG SIPN prodrug. We have, for the first time, studied sodium diclofenac release behavior from the PEG SIPN hydrogel systems. © 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     

Graft copolymerization of 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid onto carboxymethylcellulose (sodium salt) by H2O2/Fe+2 redox pair

The effect of the reaction conditions on the grafting parameters during grafting of 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid onto sodium carboxymethylcellulose using H₂O₂/Fe⁺² redox pair are studied at 30°C. The grafting ratio, add on, and conversion initially increase with the H₂O₂ concentration in the range of (10.0–15.0) × 10^?2 mol dm^?3. Thereafter, these parameters decrease with the H₂O₂ concentration. The grafting ratio, add on, and conversion increase when increasing the ferrous ion concentration from (0.5 to 4.0) × 10^?2 mol dm^?3 and decrease with a further increase in the concentration. It is observed that the grafting ratio and add on increase with the monomer concentration, whereas the conversion decrease. The hydrogen ions seem to be facilitating the grafting reaction up to a certain concentration and after this concentration seem to be retarding the process. The grafting ratio, add on, and conversion decrease with the sodium carboxymethylcellulose concentration. When increasing the time period from 60 to 90 min, the grafting parameters increase but decrease thereafter. Similarly, when increasing the temperature from 25 to 30°C, the grafting parameters increase and decrease thereafter. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4819–4825, 2006