Properties of Langmuir-Blodgett Films Based on Organosoluble Polyelectrolyte-Surfactant Complex and Oxazine Dye

Preparation procedure of organosoluble stoichiometric polycomplex based on cationic polyelectrolyte and anionic surfactant has been described. It was shown the formation of mixed monolayers consisting of polyelectrolyte-surfactant complex and dye molecules at the water-air interface. Assembling conditions of fluorescent nanosized solid Langmuir-Blodgett films based on polycomplex and dye Nile Red were defined and the spectral-luminescent properties of obtained films were studied. Absorption and fluorescence spectra of mixed Langmuir-Blodgett films revealed that electrostatic interaction between polycomplex and dye molecules is responsible for formation of dimers. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3500

Preparation, Characterization and Catalytic Activity of Gold Nanoparticles Stabilized by Hydrophilic Polymers

Optical properties, structure, size and morphology of colloidal gold nanoparticles (AuNPs) stabilized by a series of hydrophilic polymers possessing nonionic, anionic, cationic and amphoteric nature were characterized by visible spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD) and scanning electron microscopy (SEM), transmission electron microscopy (TEM). The polymer-protected AuNPs were prepared by “one-pot” synthetic protocol. The kinetics of formation of AuNPs was determined. The influence of the molecular weight (Mw) of polymers and concentration of AuNPs on the size of AuNPs was shown. The catalytic activity of polymer-protected AuNPs with respect to hydrogenation of 4-nitrophenol was studied. High conversion degree of 4-nitrophenol to 4-aminophenol was evaluated by visible spectroscopy. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3503

Synthesis, Characterization and Catalytic Property of Polymer Protected Gold and Silver Nanoparticles

Gold (AuNPs) and silver (AgNPs) nanoparticles protected by hydrophilic polymers were prepared by “one-pot” synthetic protocol. Absorption spectra, size, morphology and structure of obtained nanoparticles were investigated by UV-Vis spectroscopy, dynamic light scattering (DLS), and transmission electron mi-croscopy (TEM). The catalytic activity of polymer-protected AuNPs and AgNPs supported on the surface of aluminum oxide was evaluated with respect to decomposition of hydrogen peroxide. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3509

Temperature and Salt Responsivity of Anionic, Cationic and Amphoteric Nanogels Based on N-Isopropylacrylamide, 2-Acrylamido-2-Methyl-1-Propanesulfonic Acid Sodium Salt and (3-Acrylamidopropyl) Trimethylammonium Chloride

Three different nanogels possessing anionic, cationic and amphoteric character were synthesized via conven-tional redox initiated free radical copolymerization of N-isopropylacrylamide (NIPAM), 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS) and (3-acrylamidopropyl) trimethylammonium chloride (APTAC). The negatively charged [NIPAM]:[AMPS] = 90:10 mol.%, positively charged [NIPAM]:[APTAC] = = 90:10 mol.%, and charge-balanced amphoteric nanogels [NIPAM]:[APTAC]:[AMPS] = 90:5:5 mol.% ab-breviated as NIPAM90-AMPS10, NIPAM90-APTAC10, and NIPAM90-APTAC5-AMPS5, respectively, were characterized by FTIR spectroscopy, TGA, UV-Vis spectroscopy and DLS measurements. The temperature and salt responsive properties of nanogels in aqueous and aqueous-salt solutions were studied in the tempera-ture range of 25–60 °C and ionic strength (μ) of 0.001–1.0 M NaCl. Anionic NIPAM90-AMPS10 and cationic NIPAM90-APTAC10 nanogels, exhibit a pronounced polyelectrolyte effect in aqueous-salt solution due to screening of the negative or positive charges by low-molecular-weight salt. Whereas the charge-balanced amphoteric nanogel NIPAM90-APTAC5-AMPS5 exhibits an antipolyelectrolyte effect due to the screening of electrostatic attraction between opposite charges by low-molecular-weight salt. The difference between the temperature-dependent behaviors of anionic, cationic and amphoteric nanogels is explained by shrinking (polyelectrolyte effect) and expanding (antipolyelectrolyte effect) of macromolecular chains in aqueous-salt solutions

Catalytic Properties of Gel-Immobilized Gold Nanoparticles in Decomposition Of Hydrogen Peroxide

This paper reports the study of hydrogen peroxide decomposition catalyzed by polymer-protected gold nanoparticles (AuNPs) immobilized within polyacrylamide hydrogel. The stabilization of AuNPs was achieved using hydrophilic polymers. Embedding of AuNPs stabilized with various polymers into polyacrylamide hydrogels was carried out using three ways: “in situ” polymerization, sorption and boronhydride methods. Size, shape and morphology of AuNPs were characterized by various physicochemical methods

Ophthalmic drug delivery system based on the complex of gellan and ofloxacin

Complex formation between a natural polysaccharide – gellan and an antimicrobial drug – ofloxacin was studied in aqueous solution. Conductimetric and potentiometric titration curves revealed that gellan and ofloxacin forms a water-soluble complex of composition 2:1 mol/mol stabilized by ionic and hydrogen bonds. The formation of the gellan-ofloxacin complex was confirmed by FTIR spectroscopy, dynamic light scattering, zeta-potential and thermogravimetric analysis. The average hydrodynamic size of the complex was found 307±5 nm and its zetapotential was negative and equal to -15 mV. Thin films of the gellan-ofloxacin complex, gelled in 0.3 wt.% of CaCl2, were used to study the release kinetics of ofloxacin in distilled water and phosphate buffer. The drug release kinetics evaluated by UV-Vis spectroscopy at λmax = 289 nm and calculated by the Ritger-Peppas model correspond to non-Fickian diffusion in distilled water and Case II transport (zero-order kinetics) in phosphate buffer. The cumulative release of ofloxacin from the gellan-ofloxacin films was equal to 96±2% and 36±2% in phosphate buffer and distilled water, respectively. It is expected that the gellan-ofloxacin complex is able to form in situ gel on the surface of the eye and to prolong the drug residence time in the tear fluid.Peer reviewe

Synthesis and characterization of novel thermo- and salt-sensitive amphoteric terpolymers based on acrylamide derivatives

A novel linear amphoteric terpolymers based on neutral monomer - N-isopropylacrylamide (NIPAM), anionic monomer - 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS), and cationic monomer - (3-acrylamidopropyl) trimethylammonium chloride (APTAC) were synthesized by free-radical polymerization in aqueous solution and characterized by methods of H-1 NMR and FTIR spectroscopy, TGA, GPC, Dynamic light scattering (DLS) and zeta-potential. The thermal and salt sensitivity of amphoteric ternary polymers of various compositions, particularly, [NIPAM]:[AMPS]:[APTAC] = 90:2.5:7.5; 90:5:5; 90:7.5:2.5 mol.% were studied in aqueous and aqueous-salt solutions in the temperature range from 25 to 60 degrees C and at the NaCl ionic strength. interval from 10(-3) to 1M. It was found that due to hydrophobic/hydrophilic balance, the temperature dependent conformational and phase change of macromolecular chains becomes sensitive to salt addition and allows the fine-tuning of the phase transition. In aqueous and aqueous-salt solutions, the average hydrodynamic size of amphoteric terpolymers is varied from 8 to 300 nm exhibiting bimodal distribution at room temperature. The number average (M-n) and weight average (M-w) molecular weights, polydispersity index (PDI), and zeta-potentials of amphoteric terpolymers in aqueous solutions were determined.Peer reviewe

Preparation and Swelling Characteristics of Semi-interpenetrating Polymer Networks Composed of Poly(acrylamide-co-acrylic acid)/ Linear Poly(ethyleneimine) or Poly(ethyleneimine)-metal Complexes

Semi-interpenetrating polymeric networks (SIPNs) consisting of poly(acrylamide-co-acrylic acid) p(AAm-AAc) hydrogel matrix and linear polyethyleneimine (LPEI), polymer-metal complexes of LPEI with nickel (LPEI-Ni2+), cobalt (LPEI-Co2+) and zinc ions (LPEI-Zn2+) were prepared by template polymerization: crosslinked AAm-AAc chains were formed in aqueous solution by crosslinking copolymerization of equimolar mixture of AAm and AAc in the presence of N,N-methylenebisacrylamide and LPEI, LPEI-Ni2+, LPEI-Co2+, and LPEI-Zn2+ respectively. The swelling degree of SIPNs in water and swelling kinetics in 0.1N NaOH and 5% NH4OH were determined. The exponential relation Mt/M∞ = ktn (where Mt is the mass of water absorbed at time t and M∞ is the mass of water absorbed at equilibrium) was used for calculation of the exponent (n) describing the mechanism of water transport through these SIPN. The dynamic swelling behavior of SIPNs in alkaline media corresponds to anomalous swelling mechanism

Semi-interpenetrating Polymer Networks of Polyelectrolytes

This review is devoted to synthetic pathways, swelling-deswelling behavior, physico-chemical and physico-mechanical properties as well as stimuli-sensitivity of semi-interpenetrating polymer networks (SIPNs) based on crosslinked and linear polymers. The main attention is paid to systems composed of neutral or charged three-dimensional networks with embedded neutral or charged macromolecules. The peculiarities of template (co)polymerization of hydrophilic monomers in the presence of water-soluble polymers as a matrix are emphasized. Nonionic hydrogel matrixes, namely polyacrylamide, poly(acrylamideco-acrylic acid), poly(N-isopropylacrylamide) that are able to exhibit the sensitivity to dielectric permittivity, pH and temperature are mostly considered. Typical water-soluble polymers which serve as a matrix and are immobilized within networks represent the sensitive to environment water-soluble nonionic, anionic, cationic and amphoteric ones. Some examples of alginate and chitosan based SIPNs are demonstrated because these polysaccharides distinguish by commercial availability and biodegradability. Synthetic protocols of the organic-inorganic hybrid SIPN as well as hydrogel-protein SIPN are given. The SIPNs obtained by interpolyelectrolyte reactions, e.g. by interaction of ionic networks with oppositely charged linear macromolecules at gel-solution interface are also exemplified. The SIPNs containing enzymes, catalytic active functional groups, polymer-metal complexes, and nanoparticles exhibit high catalytic activity in hydrolysis, hydrogenation and decomposition of low-molecular-weight substrates. Structural, morphological, physico-chemical and physico-mechanical properties of SIPNs are determined by both network structure and nature of immobilized linear polymers. Application aspects of SIPN include drug delivery systems, pervaporation and fuel cell membranes, gel-immobilized nanosized catalysts, solar technology etc

Anionic polysaccharide-gellan as perspective polymer for potential application in medicine and oil recovery : a mini-review

Potential application of gellan in medicine and oil recovery based on literature survey and own results of authors has been presented in this mini-review. Purification and fractionation procedures of commercial gellan gum have been described. The application of gellan gum and its modified derivatives in medicine, in particular, as drug delivery systems accompanied by mucoadhesivity has been briefly considered. Gold nanoparticles immobilized within gellan and poly(2-ethyl-2-oxazoline)-grafted gellan have been demonstrated for photothermal treatment of Ehrlich cancer cell. Potential application of gellan in oil recovery has been considered. The prospect of organizing the gellan production in Kazakhstan has been outlined