Yury Shchipunov - Academia.edu (original) (raw)

Papers by Yury Shchipunov

Pure and Applied Chemistry, 2018

The study is aimed at imparting dimensional stability and some functionalities to cellulosic aero... more The study is aimed at imparting dimensional stability and some functionalities to cellulosic aerogels. The polysaccharide suffers from mechanical strength loss in wetted state that restricts its application. Improvement is achieved by mean of microfibrillation of cellulosic fibers combining intense mechanical treatment with freeze-thawing. Addition of the latter decreases the number of cycles. Aerogels prepared from microfibrillated cellulose by freeze-drying hold their dimensional stability in solutions that makes possible treating them chemically without loss in shape. Here a method of directional sol-gel processing is applied to mineralize such aerogels by titania. Owing to covalent bonds to cellulose macromolecules formed via the condensation reactions, titania coating possesses good adhesion, not separating at heating when it is transferred in anatase form. Its photocatalytic activity results in self-cleaning of cellulose aerogels under outdoor sunlight irradiation. Calcination...

Bimodal SBA-15 and polymethylsilsesquioxane monoliths with regulated mesoporous structure and macroporosity

Colloid and Polymer Science, 2015

Titania synthesized through regulated mineralization of cellulose and its photocatalytic activity

RSC Adv., 2014

ABSTRACT Cellulose used for thousands of years has been rediscovered recently as a novel smart ma... more ABSTRACT Cellulose used for thousands of years has been rediscovered recently as a novel smart material for various nanotechnological applications. Its insoluble fibrils are functionalized by using mineralization methods developed in nanochemistry. Here they are coated by titania synthesized in one stage by a new green approach. It consists of controlling the localization of very fast hydrolysis and condensation reactions. Cellulose fibrils are placed in ethylene glycol with such an amount of water that is absorbed entirely by the hygroscopic polysaccharide. This hydrating water works as a reaction centre when the precursor reaches it. Instant hydrolysis and following condensation reactions proceeding mainly on the fibrils provide their mineralization. Titania prepared at ambient conditions is in an amorphous state. It is transferred in crystalline forms under a variety of conditions including moderate temperature (80 °C), calcination in air and cellulose carbonization in an inert atmosphere. These treatments result in photocatalytic activity. Even cellulose treated at the moderate conditions demonstrates significant self-cleaning ability consisting of fast degradation of methylene blue under outdoor sunlight irradiation. Photocatalytic activity of carbon–titania hybrids includes a side reaction of the oxidation of the carbonized fibrils. Photocatalytic properties of some of the calcinated samples, not containing organics, were comparable with a commercial photocatalyst.

ChemInform Abstract: Water-Soluble Polyelectrolyte Complexes of Oppositely Charged Polysaccharides

ChemInform, 2010

ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Macromolecular Research, 2014

Multifunctional intelligent hydrogels were obtained from a simple combination of sodium alginate,... more Multifunctional intelligent hydrogels were obtained from a simple combination of sodium alginate, N-vinyl caprolactam, acrylamide (AM), and acrylamidoglycolic acid (AGA) by the advantages, such as temperature sensitivity of poly(N-vinyl caprolactam) (NVC) and pH sensitivity of poly(acrylamidoglycolic acid) and excellent mechanical properties of sodium alginate. The favorable hydrogen bonding interactions of hydrogel chains is able to protect the drug molecules from environmental degradation and also form highly controlled size and shape of silver nanoparticles. These stable silver nanoparticles might be effectively useful for silver releasing wound dressing applications.

In situ formation of chitosan hydrogels with anionic polysaccharides

Mendeleev Communications, 2009

ABSTRACT Solutions of various anionic polysaccharides were jellified through an in situ-forming p... more ABSTRACT Solutions of various anionic polysaccharides were jellified through an in situ-forming polyelectrolyte complex with chitosan whose solid dispersion was dissolved by slow acidification of hydrolyzing chemical acidulant glucono-δ-lactone.

Guest Editors' Preface

Composite Interfaces - COMPOS INTERFACE, 2009

Synthesis of Poly(methyl methacrylate)-Block-Poly(L-histidine) and Its Use as a Hybrid Silver Nanoparticle Conjugate

Journal of Nanoscience and Nanotechnology, 2010

ABSTRACT Poly[(methyl methacrylate)-block-poly(L-histidine)] (PMMA-b-PHIS) was synthesized by com... more ABSTRACT Poly[(methyl methacrylate)-block-poly(L-histidine)] (PMMA-b-PHIS) was synthesized by combining atom transfer radical polymerization and living ring-opening polymerization of alpha-amino acid-N-carboxyanhydride. The resulting hybrid block copolymer forms reverse micelles in the mixture solution of water and N,N-dimethylformamide (DMF) and self-assembles into PHIS/PMMA core/shell spheres with controllable size in the range of 80 to 250 nm depending on the micellization temperature. The self-assembly of PMMA-b-PHIS was carried out in H2O/DMF (3/7) mixture in the presence of AgNO3. Reduction of the resulting Ag ions encapsulated inside of the reverse micelles yielded an attractive Ag nanoparticle core/polymer shell conjugate system.

Fabrication of Organic Shell-Covered Gold Nanospheres with Near-Infrared Absorption

Journal of Nanoscience and Nanotechnology, 2012

A simple protocol is developed for the fabrication of stable organic shell-covered gold nanospher... more A simple protocol is developed for the fabrication of stable organic shell-covered gold nanospheres with near-infrared absorption characteristics. The designed strategy mainly concentrates on two steps: (i) the polymerization of gold nanoparticles (AuNPs) induced by 1,2-ethanedithiol in water/ethanol; (ii) conjugation of the polymerized AuNPs with marocyclic compound for the formation of the organic shell. In the first step, the 1,2-ethanedithiol containing two thiols towards both ends of the chain enables the successful polymerization of AuNPs due to the forceful appetency of thiols to AuNPs. In the second step, the polymerized AuNPs are covered by the marocyclic compound attributing to the hydrogel-bonding effect between NH and SH. Because of the organic shell, the stability and dispersibility of the obtained nanospheres are improved. The optical properties of the fabricated gold nanospheres (400 nm average diameter) are well investigated by the UV-vis absorption spectroscopy which exhibit intense near-infrared absorption at 972 nm in acetone. The strategy developed in this study is promising in that excellent stability and dispersibility of gold nanospheres can be achieved in a facile and economic way.

Journal of Nanoparticle Research, 2011

Titania/Hyperbranched polyglycidol (HBP) nanohybrids with tunable morphologies have been synthesi... more Titania/Hyperbranched polyglycidol (HBP) nanohybrids with tunable morphologies have been synthesized via a sol-gel process at ambient temperature. One-shot addition of varied amounts of titanium precursor tetraisopropoxide (TTIP) yields spherical titania/HBP solid particles with tunable size, while a controlled addition of TTIP results in spherical titania/HBP capsules. The average outer and inner diameters of the resultant capsules are also controllable according to the amount of TTIP via an Oswald ripening process. In addition, the modality of additional water supplied in the reaction systems can tune the morphologies of the resulting titania/HBP particles from nanocapsules to nanotubes owing to the accelerated hydrolysis rate of TTIP. The tunability in morphologies of the titania/HBP nanostructures ranging from solid spheres, capsules to tubes could be attributed to the self-assembly of a large amount of titania/HBP aggregates in a rapid, controlled and anisotropic manner, respectively. Surprisingly, by means of HBP contained in the resulting titania/ HBP nanostructures, the gold nanoparticles are in situ generated and encapsulated into titania/HBP matrix in the absence of additional reducing agent. The as-prepared gold nanoparticles functionalized titania/ HBP hybrids exhibit excellent catalytic function toward the reduction of 4-nitrophenol. This strategy demonstrates a typical example for functionalizing the titania/HBP hybrids targeted to specific applications.

Journal of Materials Chemistry, 2011

An a-diimine compound (DC) bearing multiple hydroxyl and amine groups presents excellent selfasse... more An a-diimine compound (DC) bearing multiple hydroxyl and amine groups presents excellent selfassembly behavior, yielding DC self-assemblies with tunable morphologies ranging from solid spheres, nanotubes and capsules via hydrogen bonds and p-p stacking interactions. These DC self-assemblies provide promising multifunctional hosts for varied metal species. As a typical example, Au nanoparticles are in situ generated and accommodated into both solid and hollow DC self-assemblies by one-pot and two-step fabrication processes, respectively, resulting in the formation of solid and hollow DC/Au hybrid nanostructures. Both solid and hollow DC self-assemblies also enable host Ni(II) ions to generate DC/Ni(II) catalysts for the efficient production of porous polyethylene (PE) beads consisting of numerous PE microspheres. Moreover, the yielded PE beads replicate the textural morphologies of the original DC/Ni(II) catalysts. These DC self-assemblies also might be further utilized to host varied metal species to fabricate versatile DC/metal nanoparticle (Ag, Pt, Pd, etc.) hybrids and porous polyolefin beads with desired morphologies.

Journal of Colloid and Interface Science, 2009

A variety of polymerized assemblies of cationic gemini surfactants has been demonstrated as a fun... more A variety of polymerized assemblies of cationic gemini surfactants has been demonstrated as a function of the electrolyte concentration in aqueous solution. The gemini surfactant consists of two cationic monomeric surfactants linked with an ethylene spacer at the level of the quaternary ammonium groups. Polymerizable methacryloxy groups are covalently attached to the terminal of the hydrocarbon chains. In the lower electrolyte concentration region, radical polymerization results in the formation of spherical aggregates [Langmuir 22 (2006) 8293]. However, in the higher electrolyte concentration region, elongated tubular hollow assemblies are observed with transmission electron microscopy, as a result of polymerization of vesicular hollow assemblies spontaneously formed in the aqueous solution. These experimental results suggest that it is possible to prepare different shapes of polymerized assemblies by changing the electrolyte concentration.

Interaction of ions with phosphatidylcholine and phosphatidylethanolamine at the n-heptane/water interface

Journal of Colloid and Interface Science, 1986

ABSTRACT

Bionanocomposites formed by in situ charged chitosan with clay

Green Chemistry, 2009

ABSTRACT Bionanocomposites are formed through the electrostatic interactions of exfoliated clay n... more ABSTRACT Bionanocomposites are formed through the electrostatic interactions of exfoliated clay nanoparticles initially dispersed in an aqueous solution with chitosan macromolecules that are gradually charged in the course of a progressive pH decrease by chemical acidulating agent to exclude the phase separation.

Water-Soluble Polyelectrolyte Complexes of Oppositely Charged Polysaccharides

Composite Interfaces, 2009

... Keywords Alginate, carrageenan, xanthan, chitosan, polyelectrolyte complex, hydrogel ... A hy... more ... Keywords Alginate, carrageenan, xanthan, chitosan, polyelectrolyte complex, hydrogel ... A hydrogel sample in amounts of 0.80.9 g was sealed hermetically into a pan, while a reference pan was filled with doubly distilled water of approximately the same amount (±20 mg). ...

One-pot biomimetic synthesis of monolithic titania through mineralization of polysaccharide

Colloids and Surfaces B: Biointerfaces, 2009

To obviate the common precipitation of titania after a precursor addition into aqueous or water-c... more To obviate the common precipitation of titania after a precursor addition into aqueous or water-containing solutions, here we are using ethylene glycol as the reaction media with dissolved polysaccharide xanthan. The water is introduced in a restricted amount to provide only the hydration of polysaccharide macromolecules. An introduced precursor is involved into instant hydrolysis and following condensation reactions where contacting with the hydrating water. This resulted in titania formation on carbohydrate macromolecules like the biomineralization in living organisms. The gelling of solution proceeded without the precipitation even when the precursor was taken in concentration of ca. 3 wt.%. Polysaccharide in these syntheses served as a template. By varying the concentrations of precursor, xanthan and water, it was possible to manipulate the metal oxide morphology. Fibrillar, particulate and plate-like structures presented that depended on the synthesizing conditions. Titania prepared at ambient conditions was amorphous. When it was calcined at temperatures between 300 and 900 degrees C, crystalline anatase and rutile were found at 300 and 700 degrees C, respectively.

Colloids and Surfaces B: Biointerfaces, 2011

High-temperature modification of titania in the form of nanoplatelets is synthesized fast in one ... more High-temperature modification of titania in the form of nanoplatelets is synthesized fast in one step at ambient conditions without any additional treatment like aging or calcination. Lecithin, which is the main component of lipid matrix of biological membranes, is first used as a structure-driven template. It is demonstrated that this natural surfactant can self-organize into lamellar L ␣ mesophase when small amounts of water are admixed in its solution in nonpolar solvent. The water locating mainly in lecithin polar region as hydration shell at this concentration triggers the hydrolysis-condensation reactions after the precursor addition that results in instantaneous titania formation in the form of crystalline nanoparticles. Planar lamellar sheets serve as the template specifying its crystallinity.

Bioinspired enzymatic synthesis of silica nanocrystals provided by recombinant silicatein from the marine sponge Latrunculia oparinae

Bioprocess and Biosystems Engineering, 2015

The process of silica formation in marine sponges is thought to be mediated by a family of cataly... more The process of silica formation in marine sponges is thought to be mediated by a family of catalytically active structure-directing enzymes called silicateins. It has been demonstrated in biomimicking syntheses that silicateins facilitated the formation of amorphous SiO2. Here, we present evidence that the silicatein LoSiLA1 from the marine sponge Latrunculia oparinae catalyzes the in vitro synthesis of hexa-tetrahedral SiO2 crystals of 200-300 nm. This was possible in the presence of the silica precursor tetrakis-(2-hydroxyethyl)-orthosilicate that is completely soluble in water and biocompatible, experiences hydrolysis-condensation at neutral pH and ambient conditions.