Poly Acrylic Acid

In this study, a simple method was developed to use water soluble polymer, polyacrylic acid, for the separation and pre-concentration of trace Cd, Cu and Zn prior to their analysis by flame atomic absorption spectrometry. For this purpose, the sample and poly-acrylic acid were mixed and the metal-bound polymer was precipitated by the addition of acetone. The precipitate was separated and dissolved in a minimum amount of water and aspirated into a flame AAS. The method was compared with traditional water insoluble sorbents in all aspects. The technique described is fast, simple, precise and inexpensive. Blank values were low and recoveries were 96.5% for Cd, 99.7% for Cu and Ž. y1 y1 y1 98.0% for Zn. Detection limits 3 were 1.8 g l for Cd, 2.5 g l for Cu, and 2.2 g l for Zn.

The aim of the present study was to investigate the effect of poly(acrylic acid)-cysteine (PAA-cysteine) exhibiting a molecular mass of 100 and 250 kDa and reduced glutathione (GSH) on the absorption of the P-glycoprotein (P-gp) and cytochrome P450 (CYP450) substrate paclitaxel in vitro and in vivo. In vitro transport studies were performed with Caco-2 monolayers. Furthermore, the delivery system based on PAA-cysteine, GSH and paclitaxel was evaluated in vivo in rats. In vitro, the formulation comprising 0.5% (m/v) PAA-cysteine (100 kDa)/0.5% (m/v) GSH improved the transport of paclitaxel 6.7-fold (P app ¼ 8.7 AE 1.3 Â 10 À6 cm/s) in comparison to paclitaxel itself serving as buffer only control (P app ¼ 1.3 AE 0.4 Â 10 À6 cm/s). Moreover, in the presence of the formulation containing 0.5% (m/v) PAAcysteine (250 kDa)/0.5% (m/v) GSH paclitaxel absorption was even 7.4-fold (P app ¼ 9.7 AE 0.3 Â 10 À6 cm/s) improved in comparison to the buffer only control. In vivo, the oral administration of formulations containing 1 mg of paclitaxel, 1 mg of GSH and 8 mg of PAA-cysteine (100 kDa or 250 kDa) resulted in an improved paclitaxel plasma concentration and bioavailability. The area under the plasma concentrationtime curve (AUC 0e8) of paclitaxel was 4.7-fold and 5.7-fold improved in comparison to the oral formulation containing paclitaxel alone, respectively. Moreover, c max was improved by 6.3-fold and even 7.3fold in comparison to the oral formulation containing paclitaxel alone, respectively. Thus, according to the achieved results it is suggested that PAA-cysteine in combination with GSH would be a potentially valuable tool for improving the oral bioavailability of P-gp and CYP450 substrates such as paclitaxel.

Hydrophilic hydrogels based on poly(acrylic acid) as synthetic polymer and sodium alginates as natural polymer (AG) were prepared by gamma irradiation. The AAc/AG hydrogels were characterized by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The effect of temperature and pH on the degree of swelling in water was studied. In addition, the metal sorption affinity of the prepared hydrogels for Cu +2 , Co +2 and Ni +2 was investigated. The XRD spectroscopic analysis indicates the formation of interpenetrating polymer networks. The TGA study showed that the hydrogels based on AAc/AG hydrogels at different ratios displayed lower thermal stability than PAAc hydrogel. The kinetic study of swelling in water showed that PAAc and AAc/AG hydrogels reached the equilibrium swelling state after five hours. However, AAc/AG hydrogels showed degree of swelling in water greater than PAAc hydrogel. The degree of swelling of AAc/AG hydrogels was affected by temperature, it increases within the temperature range 25-40°C and displayed pH sensitivity within the range 5.5-9 depending on composition. The metal sorption study showed that PAAc hydrogel possessed higher affinity for Cu +2 ions than AAc/AG hydrogels, whereas AAc/AG hydrogels showed higher affinity for Co +2 and Ni +2 ions than PAAc hydrogel.

The cloud point curve, tie-lines and interfacial tensions were measured for solutions of 50 mol-Yo neutralized (counter-ion Na@) poly(ary1ic acid) (mass-average molar mass M , = 9700 g/mol; polydispersity index a,/M, = 2,O) in the mixed solvent water/2-propanol at 30 "C.

Glass polyalkenoate cements (GPCs) have been used in dentistry for over 40 years. These novel bioactive materials are the result of a reaction between a finely ground glass (base) and a polymer (acid), usually poly(acrylic acid) (PAA), in the presence of water. This article reviews the types of PAA used as reagents (including how they vary by molar mass, molecular weight, concentration, polydispersity and content) and the way that they control the properties of the conventional GPCs (CGPCs) formulated from them. The article also considers the effect of PAA on the clinical performance of CGPCs, including biocompatibility, rheological and mechanical properties, adhesion, ion release, acid erosion and clinical durability. The review has critically evaluated the literature and clarified the role that the polyacid component of CGPCs plays in setting and maturation. This review will lead to an improved understanding of the chemistry and properties of the PAA phase which will lead to further innovation in the glass-based cements field.

Carbon nanotubes have been shown to be easily dispersed within an acidic aqueous solution of poly(acrylic acid) but precipitate when the pH is increased. Transmission electron microscopy showed that the nanotubes were more exfoliated under the acidic condition but highly aggregated under the basic condition. Carbon K-edge NEXAFS spectroscopy showed that the carbon nanotubes did not chemically react with poly(acrylic acid) during the dispersion or precipitation and that the dispersion mainly involved physical adsorption of poly(acrylic acid) onto the nanotubes. Together with the carbon K-edge NEXAFS spectra, the cobalt L 3,2-edge NEXAFS spectra suggested that under the basic condition, the cobalt impurity within the nanotubes strongly reacted with poly(acrylic acid) resulting in complex formation. Cobalt reduces the adsorption of poly(acrylic acid) onto the nanotubes, which then reduced the nanotube dispersion and resulted in the precipitation.

This study was aimed to synthesize polymeric excipients with improved mucoadhesive, cohesive and in situ-gelling properties to assure a prolonged retention time of dosage forms at a given target site, thereby achieving an increased uptake and improved oral bioavailability of certain challenging therapeutic agents such as peptides and proteins. Accordingly, poly(acrylic acid)-cysteine-2-mercaptonicotinic acid (PAAcys-2MNA) conjugates were synthesized by the oxidative SeS coupling of PAA-cys (100-, 250-and 450 kDa) with 2-mercaptonicotinic acid (2MNA). Unmodified PAAs, PAAs-cys (thiomers) and PAA-cys-2MNA (100-, 250-and 450 kDa) conjugates were compressed into tablets to perform disintegration tests, mucoadhesion studies and rheological measurements. Moreover, cytotoxicty of the polymers was determined using Caco-2 cells. The resulting PAA-cys-2MNA (100-, 250-and 450 kDa) conjugates displayed 113.5 AE 12.7, 122.7 AE 12.2 and 117.3 AE 4.6 mmol/g of 2-mercaptonicotinic acid, respectively. Due to the immobilization of 2MNA, the PAA-cys-2MNA (pre-activated thiomers) conjugates exhibit comparatively higher swelling properties and disintegration time to the corresponding unmodified and thiolated polymers. On the rotating cylinder, tablets based on PAA-cys-2MNA (100-, 250-and 450 kDa) conjugates displayed 5.0-, 5.4-and 960-fold improved mucoadhesion time in comparison to the corresponding unmodified PAAs. Results achieved from tensile studies were found in good agreement with the results obtained by rotating cylinder method. The apparent viscosity of PAA-cys-2MNA (100-, 250-and 450 kDa) conjugates was improved 1.6-, 2.5-and 206.2-fold, respectively, in comparison to the corresponding unmodified PAAs. Moreover, pre-activated thiomers/mucin mixtures showed a time dependent increase in viscosity up to 24 h, leading to 7.0-, 18.9-and 2678-fold increased viscosity in comparison to unmodified PAAs (100-, 250-and 450 kDa), respectively. All polymers were found non-toxic over Caco-2 cells. Thus, on the basis of achieved results the pre-activated thiomers seem to represent a promising generation of mucoadhesive polymers which are safe to use for prolonged residence time of drug delivery systems to target various mucosa. Biomaterials j o u r n a l h o m e p a g e : w w w . e l s e v i e r. co m/ lo ca t e / b i o m a t e ri a l s 0142-9612/$ e see front matter Ó

The dispersion of alumina-coated TiO 2 particles by adsorption of the sodium salt of poly(acrylic) acid (PANa) was investigated in regard to the effective charge number of the particles. The effective surface charge number of the particles as well as the electrokinetic mobility only slightly increase with adsorption of PANa. Osmotic stress experiments have shown that PANa (MW 20 000) loses almost all of its effective charge once adsorbed. Moreover, small angle neutron scattering (SANS) experiments on suspensions at various volume fractions have shown that the structural arrangement of the particles is different in presence of adsorbed PANa only at very short distance (high volume fraction). These experimental evidences lead to the conclusion that the decrease of both the apparent viscosity and initial yield stress after adsorption of PANa can mostly be explained by a steric stabilization. The polyelectrolyte on the surface would prevent the weak but still undesirable aggregation of the particles when they collide. : S 0 9 2 7 -7 7 5 7 ( 0 0 ) 0 0 7 0 5 -6

Slurry formulations and processing parameters of the water-based tape casting of ceramic powders are reviewed. Additives include binders, like cellulose ethers, vinyl or acrylic-type polymers; plasticizers, like glycols; and dispersants, like ammonium salts of poly(acrylic acids). Mostly alumina powders have been employed. Hydrophobing of ceramic powders permits the aqueous processing even of water-reactive powders, like aluminium nitride. Non-toxicity and non-inflammability of water-based systems represent an alternative to organic solvent-based ones. Aqueous slurries are, on the other hand, complex multiphase systems, very sensitive to process variations. Statistical design of experiments was used for the improvement of the process.

a b s t r a c t pH-sensitive PVP-PAA hydrogels have been prepared by electron-beam-induced irradiation at pH close to pKa of carboxylic groups. Protonation of these groups promoted the formation of hydrogen bonds between the PAA and PVP segments within the crosslinked structure and caused interpolymer complex formation. To demonstrate possible future application of such gels, we tested them as simple chemical detectors. When loaded with glucose oxidase, the PAA-PVP gel's turbidity and shrinkage was triggered by the presence of glucose due to a drop in pH caused by the enzymatic reaction.

PVA/PAA/PEG/PVP nanofibers with HPMC and aloe vera were fabricated by electrospinning method. HPMC was added to the hybrid polymer solution as the water retention agent and aloe vera which are known over centuries were also added to the system to promote the healing of wounded or infected skin. The fabricated nanofiber mats were characterized using SEM, DSC, and FT-IR. SEM Images exhibited that the electrospun nanofibers were homogenous and linear. The nanofiber diameters ranged between 80-480 nm.

The grafting of hydrophilic monomers from the surface of PVC films and complex geometries, such as tubing, was executed by a novel two-step process: physisorption of a hydrophobic free radical initiator onto a polymer surface followed by radical polymerization with hydrophilic monomers. The key step is creating a hydrophobic/hydrophilic diffusional barrier that promotes radical generation upon heating at the polymer surface. Transmission infrared spectroscopy, X-ray photoelectron spectroscopy, surface wettability and capillary rise, gravimetric analysis, UV-vis spectroscopy and gel permeation chromatography were utilized to prove successful covalent grafting of poly(hydroxyethylmethacrylate), poly-(dimethylacrylamide), poly(hydroxyethylacrylate), poly(dimethylaminoethylmethacrylate), poly(acrylic acid), and poly(4-vinyl pyridine).

Magnetic nanoparticles prepared with iron oxides and N-benzyl-O-carboxymethylchitosan, an amphiphilic chitosan derivative, were prepared through the incorporation method and characterized by Fourier infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), Mössbauer spectroscopy, and magnetization measurements. The ␥-Fe 2 O 3 nanoparticles proved to be spherical and well crystallized, and some aggregation behavior was observed. The particles containing the polymer presented saturation magnetization of 18.4 emu g −1 and roughly superparamagnetic behavior. The material was used to adsorb three cationic dyes from aqueous solution (methylene blue, crystal violet, and malachite green). The adsorption process preferably followed the Langmuir-Freundlich isotherm and pseudo-second-order kinetic model. The removal of the dyes was optimized using a 3 2 factorial design, and the initial dye concentration proved to be more influential in dye adsorption than the temperature of the system.

A new, efficient, palladium-and chromium-free process for the electroless plating of acrylonitrile-butadiene-styrene (ABS) polymers has been developed. The process is based on the ion-exchange properties of poly(acrylic acid) (PAA) chemically grafted onto ABS via a simple and one-step method that prevents using classical surface conditioning. Hence, ABS electroless plating can be obtained in three steps, namely: (i) the grafting of PAA onto ABS, (ii) the copper Cu 0 seeding of the ABS surface, and (iii) the nickel or copper metallization using commercial-like electroless plating bath. IR, XPS, and SEM were used to characterize each step of the process, and the Cu loading was quantified by atomic absorption spectroscopy. This process successfully compares with the commercial one based on chromic acid etching and palladium-based seed layer, because the final metallic layer showed excellent adhesion with the ABS substrate.

Graft copolymerization of mixtures of acrylic acid (AA) and acrylamide (AAm) onto chitosan was carried out by using potassium persulfate (KPS) as a free radical initiator in the presence of methylenebisacrylamide (MBA) as a crosslinker. The effect of reaction variables, such as MBA concentration and AA/AAm ratio on the water absorbency capacity have been investigated. The polymer structures were confirmed by FTIR spectroscopy. Water absorbencies were compared for the hydrogels before and after alkaline hydrolysis. In the non-hydrolyzed hydrogel, enhanced water absorbency was obtained with increasing AA in monomer feed. However, after saponification, the sample with high AAm ratio exhibited more water absorbency. These behaviors were discussed according to structural parameters. The swelling kinetics of the superabsorbing hydrogels was studied as well. The hydrogels exhibited ampholytic and reversible pH-responsiveness characteristics. The swelling variations were explained according to swelling theory based on the hydrogel chemical structure. The hydrogels exhibited salt-sensitivity and cation exchange properties. The pHreversibility and on-off switching properties of the hydrogels make the intelligent polymers as good candidates for considering as potential carriers for bioactive agents, e.g. drugs.

Microbial lipases (E.C. 3.1.1.3) are the preferred biocatalysts for the synthesis of various fragrance compounds, such as linalool acetate, citronellal acetate, and geranyl acetate, in organic solvents over chemical synthesis. In this study, a purified alkaline extracellular lipase of Pseudomonas aeruginosa MTCC-4713 was efficiently immobilized onto a synthetic poly(AAc-co-HPMAcl-EGDMA) hydrogel by surface adsorption, and the bound lipase was evaluated for its hydrolytic potential toward various p-nitrophenyl acyl esters, which differed in their C-chain length. Among four series of hydrogels prepared by the variation of the concentrations of monomer and crosslinker, two hydrogels, namely, I 5d and I 20d , that exhibited relatively higher protein (lipase activity) bindings were selected to perform hydrolytic and synthetic (geranyl butyrate) reactions in aqueous and organic solvents. The hydrogel-bound lipase was highly hydrolytic toward p-nitrophenyl ester (C: 16; p-nitrophenyl palmitate). The hydrogel-immobilized lipase was quite stable and retained approximately 57.6% of its original hydrolytic activity after the fifth cycle of reuse under optimized conditions (pH 8.5, 658C). The hydrogel-immobilized lipase when used to perform the esterification of geraniol/butyric acid (400 : 100 mM) in n-heptane resulted in 98.8 mM geranyl butyrate at 658C under shaking (120 rpm) after 15 h of reaction time. The addition of a molecular sieve (3 Å 3 1.5 mm) to the reaction system at a concentration of 100 mg per reaction volume (1 mL) resulted in the complete conversion of the reactants into geranyl butyrate.

This article reviews the composition and synthesis of hydrogels, the character of their absorbed water, and permeation of solutes within their swollen matrices. The most important properties of hydrogels relevant to their biomedical applications are also identified, especially for use of hydrogels as drug and cell carriers, and as tissue engineering matrices.

Poly(acrylamide-co-acrylic acid) copolymeric hydrogel nanoparticles(HN) were prepared by precipitation polymerization technique using potassium per sulphate(PS) as reaction initiator and N, N - methylene-bis-acrylamide (MBA) as crosslinking agent.The prepared HN were characterized by FTIR and copolymerization was confirmed. From the swelling studies of the HN , it was found that the prepared copolymer showed comparatively higher swelling in rat caecal medium

Objectives. Resin-modified glass ionomer cements (RMGI) are hybrid materials prepared by incorporation of polymerizable components (typically 2-hydroxyethyl methacrylate (HEMA) with possible addition of multifunctional methacrylates) into a conventional acid–base mixture (a polymeric acid with powdered calcium fluoro-aluminosilicate glasses). During setting, the photopolymerization process and the acid–base reaction affect each other. The aim of this work was to examine the effect of a 45% aqueous solution of poly(acrylic acid) (PAA) and the liquid component of a commercial glass ionomer cement on HEMA and triethyleneglycol dimethacrylate (TEGDMA) photopolymerization.Methods. The polymerization was initiated by 2,2-dimethoxy-2-phenylacetophenone (DMPA) and camphorquinone (CQ)/coinitiator system. The reaction course was monitored under Ar and air by isothermal differential scanning calorimetry.Results. The main effect of addition of polyacid solution (PAA and commercial) up to 10 wt% to HEMA on the polymerization initiated with DMPA was earlier onset of autoacceleration. For the process initiated by the CQ-based system, the addition of 5 wt% of PAA solution strongly accelerated the polymerization and increased the conversion, both in Ar atmosphere as well as in air. TEGDMA photopolymerization was not influenced or slightly retarded by the presence of 3 wt% of PAA solution (the upper limit of solubility), depending on the initiating system used.Significance. Under initiation conditions used in curing of commercial dental products (CQ-based two component initiating system), the presence of polyacid-aqueous solution in HEMA-based photocurable component increases markedly the polymerization rate and the conversion both in Ar atmosphere as well as in air. This result contributes to a characterization of the setting process of RMGIs.

A study has been performed on both the spray drying of ceramic slurries to determine how the characteristics of the spray dried powder can be affected by the process parameters and the sintering of these agglomerated powders. Two materials have been investigated: yttria partially stabilized ziconia (PSZ) and zirconium silicate. Indeed spray drying enables the fabrication of powder by aggregation of different small particles using an appropriate organic binder. The rapid heat and mass transfer which occurs during drying combined with the presence of various slurry compounds result in dried granules having a large variety of shapes, from uniform solid elongated, pancake, donut-shaped, needlelike or hollow granules. First experiments have been focused on the slurry parameters: dispersant amount, binder type and pH. The colloidal stability of aqueous ceramic suspensions as a function of poly(acrylic) acid content, pH and binder nature has been investigated. The addition of a binder may modify the state of dispersion. Thanks to sedimentation tests, stable (dispersed) and unstable (flocculated) suspensions were defined. Then, dried granules have been produced by means of a single droplet drying method. Individual slurry droplets were suspended using a hypodermic syringe in a stream of heated air. The aim was to assess the effect of the state of dispersion and sedimentation stability of the slurry on the drying of a single droplet. It has been shown that granules prepared from a dispersed slurry (low Ratio Sediment Height-RSH < 50% for PSZ) result in hollow shapes that contain a single large open pore. Changing the nature of the binder from latex to poly(vinyl) alcohol (PVA) has an effect on the wall thickness of the hollow granules. Conversely, granules obtained from a flocculated slurry (high RSH > 60% for PSZ) result in solid granules. The sedimentation volume, which represents the state of dispersion of the suspension, is the major factor controlling the droplet drying mechanism. According to the former results, powders have been elaborated by the spray drying process using several slurries formulations. Image analyses have been performed on the granules to determine their morphologies. The shape of the agglomerated powder was mostly spherical and hollow. These results confirmed the morphologies predictions of the drying test. Finally, the evolution of the morphology of the PSZ spray dried hollow powder after sintering in an oxyacetylene flame or an atmospheric furnace was investigated. When the powder is sintered in a furnace, low shrinkage and approximately no shape variations were noticed, whereas using an oxyacetylene flame tends to densify the powder. D

Layer-by-layer assembly was used to produce highly conductive thin films of carbon black and polymer. Positively and negativelycharged polyelectrolytes, polyethylenimine (PEI) and poly(acrylic acid) (PAA), were used to stabilize carbon black in aqueous mixtures that were then deposited onto a PET substrate. The effects of sonication and pH adjustment of deposition mixtures on the conductivity and transparency of deposited films was studied, along with drying temperature. Sonication and oven drying at 70°C produced films with the lowest sheet resistance (1500 X/sq), which is a bulk resistivity below 0.2 X cm for a 14-bilayer film that is 1.3 lm thick. These two variables improve packing and connectivity amongst carbon black particles that results in increased electrical conductivity. Increasing the pH of the PAA-stabilized mixture and decreasing the pH of the PEI-stabilized mixture resulted in transparent films due to increased polymer charge density. These pH-adjusted films have much higher sheet resistance values than their non-adjusted counterparts due to their reduced thickness and patchy deposition. Varying the number of bilayers allows both sheet resistance and optical transparency to be tailored over a broad range. Carbon black-filled thin films able to achieve these levels of resistivity and transparency may find application in a variety of optoelectronic applications.

Addition of carboxylate-containing polymeric materials to a metastable supersaturated calcium carbonate solution greatly reduced calcite crystal growth rates at constant supersaturation and pH = 8.5. Calcite crystallization rates were decreased to half their value in pure solutions by a tannic acid concentration of about 0.3 ppm (parts per million); a fulvic acid concentration of about 0.2 ppm; and a poly(acrylic acid) concentration of about 0.0175 ppm. An equation relating the calcite crystallization rate and the additive concentration follows an expression based on a Langmuir adsorption model. However, the Langmuir isotherm plot has two linear segments suggesting that these polyelectrolyte inhibitors may selectively adsorb initially at the fastest growing crystal faces. This relation between polyelectrolyte concentration and calcite growth rates implies inhibition by carboxylate-containing polymeric materials involves blockage of crystal growth sites on the calcite surface.

Novel interpenetrating polymer network (IPN) nanogels composed of poly(acrylic acid) and gelatin were synthesised by one pot inverse miniemulsion (IME) technique. This is based on the concept of nanoreactor and cross-checked from template polymerization technique. Acrylic acid (AA) monomer stabilized around the gelatin macromolecules in each droplet was polymerized using ammonium persulfate (APS) and tetramethyl ethylene diamine (TEMED) in 1:5 molar ratio and cross-linked with N,N-methylene bisacrylamide (BIS) to form semi-IPN (sIPN) nanogels, which were sequentially cross-linked using glutaraldehyde (Glu) to form IPNs. Span 20, an FDA approved surfactant was employed for the formation of homopolymer, sIPN and IPN nanogels. Formation of stable gelatin-AA droplets were observed at 2% surfactant concentration. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) studies of purified nanogels showed small, spherical IPN nanogels with an average diameter of 255 nm. In contrast, sIPN prepared using the same method gave nanogels of larger size. Fourier-transform infrared (FT-IR) spectroscopy, SEM, DLS, X-ray photoelectron spectroscopy (XPS) and zeta potential studies confirm the interpenetration of the two networks. Leaching of free PAA chains in sIPN upon dialysis against distilled water leads to porous nanogels. The non-uniform surface of IPN nanogels seen in transmission electron microscopy (TEM) images suggests the phase separation of two polymer networks. An increase of N/C ratio from 0.07 to 0.17 (from PAA gel to IPN) and O/C ratio from 0.22 to 0.37 (from gelatin gel to IPN) of the nanogels by XPS measurements showed that both polymer components at the nanogel surface are interpenetrated. These nanogels have tailoring properties in order to use them as high potential drug delivery vehicles for cancer targeting.

The safety and efficacy of gentamycin sulphate (GS)-or vancomycin hydrochloride (VCl)-loaded polymer devices based on poly(acrylic acid) and gelatin crosslinked selectively using 0.3 mol % N,N 0 -methylene bisacrylamide and 1 wt% glutaraldehyde were evaluated by varying the drug concentration onto the devices. The placebo and drug-loaded device of AxGx (acrylic acid:gelatin: 1:1 w/w) were employed for the treatment of experimental osteomyelitis in rabbit. Rabbits were categorized into four groups. Twelve rabbits in each group were treated with 1271mg of AxGx-1a (22% w/w GS), 1271mg of AxGx-1b (44% w/w GS), 1671mg of AxGx-1b (44% w/w GS) and 16 7 1 mg of AxGx-1c (44% w/w VCl). The drug concentration was measured following implantation in the adjacent tissue of femoral cavity, and serum. In femoral cavity maximum drug concentration was found on the 7th day with all the four types of devices. No drug was found after 21 days, at the local site with devices AxGx-1a and AxGx-1b (12 7 1 mg), whereas it was detected after 6 weeks with 1671 mg device (44% w/w GS or VCl). Macroscopic evaluation after treatment revealed that swelling, redness, local warmth and drainage decreased depending upon the drug loading of the implants. Sequential radiographs, histology, microbiologic assay and scanning electron micrography demonstrated devices AxGx-1b and AxGx-1c (16 7 1mg of 44% w/w drug loading) to be the most suitable device, which heals the infection after 6 weeks of treatment. No significant difference (p>0.05) in the rate of healing was observed between GS-and VCl-loaded devices. None of the implant showed toxic level of drug in serum at any given time.

Initially interpenetrating network (IPN) hydrogel was prepared by dispersing xanthan gum (XG) into poly(vinyl alcohol) (PVA) backbone in an aqueous medium. Polyacrylic acid (PAA)/Poly (vinyl alcohol)-Xanthan gum IPN superabsorbent composite were fabricated well by dispersing the prepared IPN hydrogel in acrylic acid and polymerized in a complete aqueous environment through chemical cross-linking method. These superabsorbent polymeric composites were analytically evaluated by scanning electron microscopy (SEM), Fourier Transform Infrared Spectra (FTIR), Thermal analysis (DSC) and X-ray diffraction (XRD) analysis. Simultaneously water absorbency, swelling kinetics and water retention abilities of this prepared superabsorbent polymeric composites were also investigated systematically.

We show in this work that template electrodeposition of nickel at room temperature from a nickel sulphamate bath prepared in a new hexagonal liquid crystalline phase of water-Triton X-100-poly (acrylic acid) results in a highly porous surface. The roughness factor value of about 3620 obtained for this coating is the highest value reported in the literature for any electrodeposited nickel. The scanning electron microscopy (SEM) and scanning tunneling microscopy (STM) pictures show the formation of porous deposit with granular features in between the pores. The single electrode double layer capacitance value measured for the deposit is 338 mF cm −2 , which translates into a specific capacitance of 50 F g −1 without any post-thermal treatment of the electrode, suggesting its utility in super capacitors. Electrochemical studies using cyclic voltammetry (CV), Tafel plots and electrochemical impedance spectroscopy (EIS) and comparison of these results with some existing high surface area Ni catalysts show that the material has potential application as an excellent hydrogen evolving cathode.

Rheological properties of aqueous solutions and hydrogels formed by an amphiphilic star block copolymer, poly(acrylic acid)-block-polystyrene (PAA54-b-PS6)4, were investigated as a function of the polymer concentration (Cp), temperature, and added salt concentration. The water-soluble polymer synthesised by atom transfer radical polymerization (ATRP) was found to form hydrogels at room temperature at polymer concentrations, Cp, over 22g/L due to the interpolymer

Bioartificial polymeric materials based on blends of dextran and poly(vinyl alcohol-co-acrylic acid) P(VA-co-AA) were prepared in the form of films and characterised to evaluate the miscibility of the natural component with the synthetic one. The idea of this work was to compatibilise PVA and dextran by introducing carboxylic groups along the PVA chains.

Three gamma crosslinked polymeric hydrogels were synthesized and evaluated as lead ion sorbents. A crosslinked poly(acrylic acid) hydrogel was compared with two 4-vinylpiridine-grafted poly(acrylic acid) hydrogels (26.74 and 48.1% 4-vinylpiridine). The retention properties for Pb(II) from aqueous solutions of these three polymers were investigated by batch equilibrium procedure. The effects of pH, contact time and Pb(II) concentration were evaluated. The optimal pH range for all polymers was 4-6. The lightly grafted polymer (PAAc-g-4VP at 26.74%) exhibited a Pb(II) removal close to 80% at 5 h and above 90% at 24 h. The maximum Pb(II) removal was 117.9 mg g −1 of polymer and followed the Freundlich adsorption model. XPS characterization indicates that the carboxyl groups are involved in the Pb(II) removal.

A series of new crosslinkers, polyethylene glycol diacrylate 400(PEGDA), and polyethylene glycol dimethacrylate 300(PEGDMA) as long-chain crosslinkers, were utilized to prepare crosslinked poly (acrylic acid) microgels via precipitation polymerization in organic solvent. To investigate the effect of crossslinker type on structure and properties of the polymer, samples synthesized with long chain crosslinkers were compared with polymer synthesized with a short chain one [N,N′-Methylenebisacrylamide (MBA)]. Fourier transform infrared (FTIR)spectroscopy analysis was used for elucidating the structure of the samples and apparent viscosity was employed to determine optimum crosslinker concentration. The alcohol absorbency, gel content, and Tg were improved by utilizing PEGDA as the crosslinker. Rheological measurements of the water-swollen gels showed superior storage modulus with the long chain crosslinker. The Flory–Rehner equation and rubber elasticity theory were used for calculating and were separately discussed in terms of their effect on the structure-properties relationships of the microgels. In addition, the viscosity coefficient (m) and flow behavior index (n) of the Ostwald equation were studied. The microgels follow the close packed hard sphere model and also a power law behavior.

In this work, we designed contact-killing ionically cross-linked polymeric thin films using Layer-by-Layer (LbL) technology. A polycation, N,N-dodecyl,methyl-polyethylenimine, with microbicidal activity was layered with a polyanion, such as poly(acrylic acid), to create LbL films highly effective against both airborne and waterborne Escherichia coli and Staphylococcus aureus (Gram negative and positive bacteria, respectively), as well as influenza A/WSN (H1N1) virus. The dependence of the microbicidal activity on the pH during and post-assembly of LbL film formation, the nature of the polycation and polyanion, the number of layers in the LbL film, and other experimental variables was investigated quantitatively.

The paper describes a new apparatus for measuring the thermal conductivity of liquids based on a transient hot-wire method. The apparatus has been used to measure the thermal conductivity of propylene carbonate (C4H603). The measurements have been carried out in the temperature range 284-313 K and at saturation pressure. The accuracy of the data is within __ 1.5 %.

The driving force and the end point of the shrinkage process, during dehydration, were evaluated using poly(acryl amide) and poly(acrylic acid) gels, as a model of food systems. The maximal shrinkage of the gels is practically the extent of their full collapse when water is removed and replaced by air. The drastically diminishing polymer mobility due to transition into its glassy state is one of the two mechanisms that determine the end point of the contraction process. Addition of low molecular weight solutes, such as sugars, lowers the moisture content required for the onset of the glass transition and thus extends the rubbery region at which shrinkage may take place. However, their own volume of the sugars sets a bottom limit for contraction, thus resulting in less shrinkage the higher the sugar content. The second mechanism that stops contraction may come into eect when a rigid ®ller is present in the system. The percolation of its particulates, while the polymer is in its rubbery state, forms a rigid solid matrix that resists further bulk shrinkage. However, until it reaches its glassy state, the polymeric network may continue its contraction around the ®ller particulates, thus forming a porous structure. #

Hydrogels based on chitosan, maltodextrin and gum arabic with and without magnetite nanoparticles were employed as adsorbents for removing Cd 2+ from aqueous solutions. Adsorption kinetics employing the Fickian equation inferred that the diffusion mechanism of water into hydrogels may be conducted by both the diffusion process and macromolecular structure relaxation and may be affected by the presence of magnetite nanoparticles. This effect is related to the increase in reticulation points in the hydrogel network. The following were best parameters for removing Cd 2+ from aqueous solutions: pH range from 4.5 to 5.5; initial metal concentration of 200 mg L −1 ; and dried hydrogel mass of 100 mg. Using nonlinearized isotherms described by Langmuir, Freundlich and Redlich-Peterson, it was inferred that there may be a variation in the physiochemical phenomena involving Cd 2+ adsorption and the results fit better to the Langmuir or Redlich-Peterson models than the Freundlich model. The present study confirms that magnetic hydrogels and Cd 2+ may be recovered after the application of an external magnetic field, unlike hydrogels without magnetic properties, which are generally recovered through the use of a chemical solvent, such as HCl or HNO 3 .

The self-assembling behaviour of a four-arm amphiphilic star block copolymer, (PMMA 73 -b-PAA 143 ) 4 , with poly(methyl methacrylate) inner blocks and poly(acrylic acid) outer blocks in ratio 1:2 (PMMA:PAA) has been investigated in aqueous solutions as a function of pH by dynamic light scattering and cryo-transmission electron microscopy. At low pH (pH 5) the amphiphile forms in the presence of salt both spherical and worm-like micellar aggregates that coexist in solution. At high pH (pH > 12) the solution contains mainly spherical micelles and a small number of larger aggregates that have 'pearl-necklace' structure, indicating the disintegration of the worm-like species. In addition to the experiments, computer simulations of the four-arm amphiphilic star block copolymer with the same ratio of the blocks as above were conducted using a coarse-grained model. The simulations predict the formation of the worm-like micellar aggregates at low pH and the spherical ones at high pH. The changes in the morphology of the aggregates are related to the higher degree of ionization of poly(acrylic acid) blocks at high pH and to the swelling of the corona of the micelles by the higher osmotic pressure due to trapped counterions.