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Adsorption of Lead Ions onto N -Isopropylacrylamide and Acrylic Acid Copolymer Microgels

The interaction of hydrolyzable lead ions with thermosensitive microgel dispersions of N -isopropylacrylamide modified with a range of acrylic acid comonomer concentrations has been investigated. The hydrodynamic diameter of the microgel particles was observed, by dynamic light scattering, to reversibly alter due to changes in either temperature or pH, or due to the presence of lead ions. The hydrodynamic diameter of all the microgel particles decreases with increasing temperature. However, upon increasing the pH, the anionic microgel particles increase in diameter at a fixed temperature, while in the presence of Pb(II) at pH 5, the hydrodynamic diameter of the anionic microgel particles decreases. The size of the homopolymer microgel does not vary with pH, nor in the presence of Pb(II). The adsorption isotherms of hydrolysable Pb(II) with the microgel particles were established as a function of pH. Lead ion adsorption was observed to not significantly alter with temperature and was demonstrated to be completely reversible to pH adjustment.

Journal Article↗

Photopolymerization of Acrylate Films under an Imposed Spatial Irradiation: Thermodynamics of Relief Self-Development

UV irradiation through a lined mask of acrylate-based self-developing materials leads to the formation of a relief in the irradiated areas. Investigation of the effect of various properties, through a known two-layer model, showed the paramount importance of surface state on relief height. Both relief height and inhibition time of the growing kinetics are shown to be directly dependent on two surface properties: surface free energy and viscosity of the condensed state of the gaseous atmosphere adjoining the film.

Journal Article↗

Low Hydrophobically Modified Poly(Acrylic Acid) Stabilizing Macroemulsions: Relationship between Copolymer Structure and Emulsions Properties

Low hydrophobically modified (with dodecylamide chain) linear poly(acrylic acid) sodium salts (LHMPAANa) of various degrees of grafting (tau) and molecular weights were synthesized and used as emulsifiers of the n-dodecane/water (NaNO3 10(-3) M) system. Stability and flow properties of the resulting n-dodecane in water emulsions (dispersed phase volume fraction = 0.5) were investigated as a function of tau (tau = 0 to 10% in mol), molecular weight (5000, 50,000, and 150,000 g/mol) and polymer concentration (0 to 10%). It was clearly shown that viscosification (via an associating mechanism of LHMPAANa) of the external phase of emulsions is a key factor in explaining dispersion breakdown. However, a complete description of the phenomenon could not be achieved without considering the adsorption of the polymer at the liquid-liquid interface which depends closely on tau but not much on molecular weight. The molecular weight effects were found to be restricted to the viscosification of the outer phase. Copyright 1998 Academic Press. Copyright 1998Academic Press

Journal Article↗

Structure and Extent of Adsorbed Gelatin on Acrylic Latex and Polystyrene Colloidal Particles.

The extent and structure of the adsorbed layer of gelatin onto colloidal particles is measured using dynamic light scattering, small-angle neutron scattering, and dilution viscometry. Adsorption isotherms are measured using solution depletion of fluorescein-5-isothiocyanate tagged gelatin. The results show that the adsorbed gelatin layer at saturation on acrylic-based latex (pH 6.5, 0.01 M sodium acetate) has approximately twice the average density of the free gelatin in solution, while for the adsorption onto polystyrene latex (pH 8.7, deionized water), it has nearly the same average density. The energetics of gelatin affinity is calculated from the temperature dependence of the adsorption equilibrium constant. It was found that the enthalpy of adsorption of a net negatively charged gelatin onto a negatively charged surface is favorable. An additional, favorable entropy of adsorption is measured for the polystyrene latex, for which hydrophobic interactions are important. Selective, competitive adsorption of nonionic and anionic surfactants confirms the specific source of the adsorption interactions. Copyright 1998 Academic Press.

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The Interfacial Tension between Acrylic Monomers and Polymers and Non-ionic Surfactants Investigated by the Automatic Sessile Drop Method.

Time dependent interfacial tensions between CCl4, butyl acrylate (BA), and methyl methacrylate (MMA) and water have been measured, using nine different aryl and alkyl poly(oxyethylene) surfactants with between 10 and 40 OE-groups. The effect of adding BA/MMA and BA/MMA/acrylic acid (AA) polymers to the monomer systems has also been evaluated. In all systems the interfacial tension, after a very fast initial drop, decreases slowly due to dissolution of the surfactant inside the oil. The magnitude of this decrease is dependent on the hydrophilicity of the surfactant and the oil. The equilibrium values, when plotted against the HLB of the surfactants show a minimum that shifts toward higher HLB as the oil's polarity increases. BA and CCl4 show similar behavior, but with MMA as a more polar oil. Added polymer generally lowers the time dependent decrease because of decreased surfactant solubility in monomer/polymer mixtures. The BA/MMA copolymer also generally increases the interfacial tension both with and without surfactants, but the increase is less with surfactants around the surface tension minimum. A BA/MMA/AA terpolymer neutralizes or even reverses the increasing effect in the BA/polymer system because of this polymer's more hydrophilic nature. Copyright 1999 Academic Press.

Journal Article↗

Surface Chemical Studies on the Competitive Adsorption of Poly(acrylic acid) and Poly(vinyl alcohol) onto Alumina.

The adsorption of poly(acrylic acid) (PAA) and poly(vinyl alcohol) (PVA) onto alumina has been studied as a function of pH, both individually and in the presence of each other. The adsorption density of PAA is found to decrease with an increase of pH while that of PVA shows the opposite trend. In a binary system containing PAA and PVA, the presence of PVA does not affect the adsorption of PAA onto alumina, but the addition of PAA diminishes the adsorption of PVA in the pH range investigated. The adsorption isotherm of PAA at acidic pH exhibits high-affinity Langmuirian behavior. The isotherms for PVA appear rounded and are of the low-affinity type. Once again the adsorption isotherms of PAA remain unaltered in the presence of PVA whereas those of PVA are significantly affected resulting in a lowering of the adsorption density consequent to PAA addition. A variation in the sequence of addition of PAA and PVA does not affect the adsorption behavior of either of the polymers. The electrokinetic behavior of alumina with PAA is hardly influenced by the addition of PVA. On the other hand, the electrophoretic mobility of alumina in the presence of PVA is significantly altered in the presence of PAA and closely resembles the trend observed with PAA alone. Desorption studies reveal that over 80% of PVA could be desorbed in the pH range 3-9 whereas in the case of PAA, the percent desorption increases from 20 to about 70% as the pH is increased from about 3 to 8. Solution conductivity tests confirm interaction of aluminum species and PAA in the bulk solution. FTIR spectroscopic data provide evidence in support of hydrogen bonding and chemical interaction in the case of the PAA-alumina system and hydrogen bonding with respect to the PVA-alumina interaction. Copyright 1999 Academic Press.

Journal Article↗

Aggregation Behavior of Mono-endcapped Hydrophobically Modified Poly(sodium acrylate)s in Aqueous Solution.

Titration microcalorimetry and steady-state fluorescence spectroscopy have been used to study the aggregation of mono-endcapped hydrophobically modified poly(sodium acrylate)s in aqueous solution. Polymers with molecular weights varying between 800 and 31,700 were synthesized by radical polymerization using an initiator and chain transfer agent. The resulting polymers form hydrophobic microdomains in aqueous solutions. The following conditions were applied: no salt and pH 5 and 9, respectively; 1 M sodium citrate and pH 9. At pH 5 the critical aggregation concentration (CAC, the concentration at which microdomains are formed) increases with increasing molecular weight of the polymers. The concentration range for aggregation is about 0.2-2.4 mM. At pH 9 the carboxylic acid groups are deprotonated and electrostatic repulsions are introduced; therefore the concentration for aggregation rises to about 80 mM. Interestingly, in case of polymers having M(n)<1400 the CAC decreases with increasing molecular weight due to a counterion-concentration gradient toward the hydrophobic microdomain. Near the microdomain the counterion binding is increased, reducing the electrostatic repulsions and allowing for lower aggregation concentrations. In the presence of 1 M sodium citrate this anomalous trend is suppressed to a large extent; since the overall counterion binding is increased and the CAC is lower. The concentration for aggregation is then in the same range as at pH 5 in the absence of salt. Copyright 2000 Academic Press.

Journal Article↗

The Film Formation of Polymer Particles in Drying Thin Films of Aqueous Acrylic Latices.

The aim of this study is to determine the factors that contribute to the process of film formation of binder particles in drying aqueous dispersion coatings, based on acrylic polymers. It is known that concentrated latices of uniform size show iridescent, colored light patterns. These colors are caused by interparticle interference, and they are only present when the latex particles are ordered in a regular structure. The interparticle interference can be characterized by measuring the transmission as a function of wavelength of the incident light. It appeared that the changes of the interparticle interference of a drying latex film can be related to changes in the interparticle distance and displacement. It was also found that the interparticle distance becomes "negative" upon coalescence of the latex particles. This means that from this point on, the change in interparticle interference is directly related to the indentation or deformation of the latex particles. It became clear that the coalescence process differs from deformation mechanisms accepted in the literature. It seems that the deformation of the particles follows a biaxial mechanism. This means that the particles deform only in one direction, perpendicular to the film surface. Copyright 2000 Academic Press.

Journal Article↗

Artificial fusion of the knee joint with intramedullary nail and acrylic cementation following radical excision for tumor.

Extensive local excisions of skeletal tumors in the knee region create reconstruction problems with several alternative solutions. Custom-made endoprostheses now compete with joint homografts and fusion with autogenous bone-grafts. Artificial fusion utilizing an extra long Küntscher-nail and acrylic cement as a spacer is a fourth possibility with the advantages of immediate ambulation and weight-bearing, here presented in two cases. The expected disadvantages of loosening in long time survivors can be taken care of using one of the above-mentioned alternatives. This revision can be made after completion of adjunctive chemotherapy or later when called for by the occurrence of pain or instability.

Adult↗

Implantable enzyme capsules for cancer chemotherapy from bakers' yeast cytosine deaminase immobilized on epoxy-acrylic resin and urethane prepolymer.

For trial use in the local chemotherapy of cancer by a combination of cytosine deaminase (EC 3.5.4.1) and 5-fluorocytosine (J. Biotechnol., (1985), 2, 13-21), 40 U of partially purified cytosine deaminase was obtained from 500 g of commercial compressed bakers' yeast. The enzyme, which is unstable, was immobilized to stabilize it by the use of commercial epoxy-acrylic beads (Eupergit C). The immobilized enzyme was made into enzyme capsules with cellulose tubing for dialysis to encapsulate it or urethane polymer to entrap it, which materials are biocompatible. The activity of the intact cellulose capsules thus made was 0.4% that of the immobilized enzyme inside. The enzyme capsules also were stable. Ten days after the cellulose capsules were implanted in rats, 25% of the starting activity remained. When the polyurethane capsules were tested in vitro for 9 mo for thermostability at 37 degrees C, the activity decreased rapidly (with a half-life of 28 d) during the first 4 mo, and then slowly (half-life, about 100 d) during the next 5 mo. A calculation to transform the biphasic decline into a sum of the exponential decline of two components of enzymic activities with different strengths and half-lives showed that the larger half-life was 5 mo.

Antineoplastic Agents↗

Synthesis and applications of poly(acryl p-aminobenzenesulfonamideamidine- p-aminobenzenesulfonylamide) chelating fiber for pre-concentrating and separating trace Bi(III), Hg(III), Au(III) and Pd(IV) from solution samples.

Poly(acryl p-aminobenzenesulfonamideamidine- p-aminobenzenesulfonylamide) chelating fiber containing "S", "N", and "O" elements was synthesized from polyacrylonitrile fiber and p-aminobenzene sulfonamide and used to enrich and separate trace Bi(III), Hg(III), Au(III), and Pd(IV) ions from wastewater and ore sample solution. The enrichment acidity, flow rate, elution conditions, reuse, interference ions, saturated adsorption capacity, constant of adsorption rate, analytical accuracy, and actual samples on chelating fiber were investigated by means of inductively coupled plasma optical emission spectrometry (ICP-OES) with satisfactory results. Solutions of 100 ng mL(-1) of Bi(III), Hg(III), Au(III), and Pd(IV) ions can be enriched quantitatively by this chelating fiber at a rate of 1.0 mL min(-1) at pH 4 and desorbed quantitatively with 20 mL of 0.25 M HCl and 2% CS(NH(2))(2) solution at 50 degrees C (with recovery >/=97%). When the chelating fiber was reused for 20 times, the recoveries of the analyzed ions enriched by the fiber were still over 95% (except for Hg(III)). One thousand-fold excesses of Mn(2+), Ca(2+), Zn(2+), Mg(2+), Fe(3+), Cu(2+), Ni(2+), Al(3+), and Ba(2+) ions and thousands-fold excesses of Na(+ )and K(+) cause little interference in the pre-concentration and determination of the analyzed ions. The saturated adsorption capacity of Bi(III), Hg(III), Au(III), and Pd(IV) was 4.850 x 10(-4), 3.235 x 10(-4), 2.807 x 10(-4), and 3.386 x 10(-4) mol g(-1), respectively. The constants of adsorption rate were 0.409 min(-1) for Bi, 0.122 min(-1) for Hg, 0.039 min(-1) for Au, and 0.080 min(-1 )for Pd. The relative standard deviations (RSDs) for the enrichment and determination of 10 ng mL(-1) Bi(III), Hg(III), Au(III), and Pd(IV) were lower than 2.3%. The results obtained for these ions in actual samples by this method were basically in agreement with the given values with average errors of less than 1.0%. FT-IR spectra shows that the existence of -SO(2)-Ar, -H(2)N-Ar, O=C-NH-, HN=C-NH-, and -HN-SO(2) functional groups are verified in the chelating fiber. From the FT-IR spectroscopy, we can see that Hg(III), Au(III), and Pd(IV) are mainly combined with nitrogen and sulfur (or oxygen), and Bi(III) is mainly combined with nitrogen (or oxygen) of the groups to form a chelating complex.

Journal Article↗

Chip electrochromatography of polycyclic aromatic hydrocarbons on an acrylate-based UV-initiated porous polymer monolith.

The first rigorous evaluation of a UV-initiated porous polymer monolith (PPM) as a stationary phase for chip electrochromatography (ChEC) is described. All channels in an offset T-injector-design-chip (25-microm deep by 50-microm wide channels) were filled by capillary action with an acrylate-based PPM precursor solution and polymerized in situ using 365 nm light for several minutes. Photodefinability of the monolith cast in the channels during the polymerization process was also demonstrated by masking off the injection arms during photoinitiation. The chromatographic performance of this chip was compared with that of chips completely filled with monolith. The detection window was photodefined after polymerization using the detection laser (257 nm doubled argon ion laser) to depolymerize the detection window. A successful ChEC separation of 10 out of 13 polycyclic aromatic hydrocarbons (PAH) was performed with on-column, off-packing laser-induced fluorescence detection at 257 nm. Van Deemter plots for early-, middle-, and late-eluting compounds showed the minimum plate height to be 5 microm. The average number of theoretical plates per meter for the PAH was 200,000. Several factors contributed to irreproducible results. Oxygen was observed to dynamically quench the fluorescence of the sample over time. Improved sealing of the reservoirs solved this problem. A within-chip variability in the retention time of 2-10% RSD was observed. These results demonstrate the feasibility and reliability of the PPM as a solid reversed-phase for electroosmotic flow-driven chip-based chromatography in microscale total analysis systems.

Journal Article↗

Superselective embolization in posttraumatic priapism with glubran 2 acrylic glue.

Two patients with posttraumatic priapism underwent transcatheter embolization using microcoils, resulting in temporary penile detumescence and an apparent resolution of the artero-venous fistula. In both cases, priapism recurred 24 hours after the procedure and was successfully treated through selective transcatheter embolization of the nidus using acrylic glue (Glubran 2). The patients showed complete recovery of sexual activity within 30 days from the procedure and persistent exclusion of the artero-venous fistula after a 12-month follow-up.

Adhesives↗

Acetabulum malignancies: technique and impact on pain of percutaneous injection of acrylic surgical cement.

The aim of our study was to describe the technique of percutaneous injection of acrylic surgical cement into acetabulum malignancies [percutaneous acetabuloplasty (PCA)] and determine its efficiency in relieving pain. Eighteen patients (8 men, 10 women; aged 40-81 years) with painful acetabular malignancies (18 lesions; 17 metastases, 1 multifocal bone sarcoma) were treated with PCA. Procedures were done using lateral approach with fluoroscopic guidance. The 18 procedures were evaluated and resulted in 4 (22 %) total improvement, 7 (39 %) clear improvement, 4 (22 %) moderate improvement, 1 (6 %) no improvement, and 2 (11 %) worsening in keeping with a cement leak in contact with the sciatic nerve and a leak towards the joint. Follow-up ranged from 2 to 48 months (average 9.4 months). We observed 2 cases of recurrence of pain at 6 and 39 months, both in keeping with local tumoral progression. PCA of malignancies is a minimally invasive and low-cost procedure that provides immediate and long-term pain relief.

Acetabulum↗

Immobilization of urease by using chitosan-alginate and poly(acrylamide-co-acrylic acid)/kappa-carrageenan supports.

Jack bean urease (urea aminohydrolase, E.C. 3.5.1.5) was entrapped into chitosan-alginate polyelectrolyte complexes (C-A PEC) and poly(acrylamide-co-acrylic acid)/kappa-carrageenan (P(AAm-co-AA)/carrageenan) hydrogels for the potential use in immobilization of urease, not previously reported. The effects of pH, temperature, storage stability, reuse number, and thermal stability on the free and immobilized urease were examined. For the free and immobilized urease into C-A PEC and P(AAm-co-AA)/carrageenan, the optimum pH was found to be 7.5 and 8, respectively. The optimum temperature of the free and immobilized enzymes was also observed to be 55 and 60 degrees C, respectively. Michaelis-Menten constant (K(m)) values for both immobilized urease were also observed smaller than free enzyme. The storage stability values of immobilized enzyme systems were observed as 48 and 70%, respectively, after 70 days. In addition to this, it was observed that, after 20th use in 5 days, the retained activities for immobilized enzyme into C-A PEC and P(AAm-co-AA)/carrageenan matrixes were found as 55 and 89%, respectively. Thermal stability of the free urease was also increased by a result of immobilization.

Acrylamides↗

Acrylic scaffolds with interconnected spherical pores and controlled hydrophilicity for tissue engineering.

Polymer scaffolds are obtained in which the geometric characteristics (pore size, connectivity, porosity) and the physico-chemical properties of the resulting material can be controlled in an independent way. The interconnected porous structure was obtained using a template of sintered PMMA microspheres of controlled size. Copolymerization of hydrophobic ethyl acrylate and hydrophilic hydroxyethyl methacrylate comonomers took place in the free space of the template, different comonomer ratio gave rise to different hydrophilicity degrees of the material keeping the same pore architecture. The morphology of the resulting scaffolds was investigated by scanning electron microscopy (SEM), the porosity of the material calculated, and the mechanical properties compared with those of the bulk (non porous) material of the same composition.

Absorption↗

Biological response of new activated acrylic bone cements with antiseptic properties. Histomorphometric analysis.

The biological response to an acrylic bone cement cured with 4,4'-bis-dimethylamino benzydrol (BZN) as activator of reduced cytotoxicity and antiseptic properties, has been carried out and compared with that obtained for CMW 3 cement. Histomorphometrical data (undecalcified trichromic Goldner staining) were obtained by measuring the most significant variables at the bone-cement interface. Quantitative results of tissue response revealed that newly formed bone and connective tissue were maximum at 4 weeks whereas bone marrow increased with time of implantation for both cements. Statistical analysis (p < 0.05) showed no significant differences in newly formed bone and bone marrow with time and between both groups, however, connective tissue significantly decreased between 4 weeks and 12 weeks for BZN cement, and between 12 weeks and 24 weeks for CMW3. By comparing both cements at each time, lower significant percentage of connective tissue at the bone-cement interface of the BZN cement, was obtained at 12 and 24 weeks, however, a very low amount of connective tissue was found for both cements. All the results indicate that the new activated system could be applied clinically in a relatively short time, after the corresponding preclinical study.

Animals↗