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Sergiy Peleshanko

Publications and source records attributed to Sergiy Peleshanko.

7 recordsLinked to original sources
PubMed2007

Thermoresponsive reversible behavior of multistimuli pluronic-based pentablock copolymer at the air-water interface.

Surface behavior of the pH- and thermoresponsive amphiphilic ABCBA pentablock copolymer has been studied with respect to the environmental conditions. We demonstrate that the pentablock copolymer poly((diethylaminoethyl methacrylate)-b-(ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)-b-(diethylaminoethyl methacrylate)) possesses reversible temperature changes at the air-water interface in a narrow pH range of the water subphase. Significant diversity in the surface morphology of pentablock copolymer monolayers at different pH and temperatures observed were related to the corresponding reorganization of central and terminal blocks. Remarkable reversible variations of the surface pressure observed for the Langmuir monolayers at pH 7.4 in the course of heating and cooling between 27 and 50 degrees C is associated with conformational transformations of terminal blocks crossing the phase line in the vicinity of the lower critical solution temperature point. The observed thermoresponsive surface behavior can be exploited for modeling of the corresponding behavior of pentablock copolymers adsorbed onto various biointerfaces for intracellular delivery for deeper understanding of stimuli-responsive transformations relevant to controlled drug and biomolecules release and retention.

Journal Article↗
PubMed2006

Surface morphologies of Langmuir-Blodgett monolayers of PEOnPSn multiarm star copolymers.

Star polymers composed of equal numbers of poly(ethylene oxide) (PEO) and polystyrene (PS) arms with variable lengths and a large (up to 38 total) number of arms, PEO(n)PS(n), have been examined for their ability to form domain nanostructures at the air-water and air-solid interfaces. All PEO(n)PS(n) star polymers formed stable Langmuir-Blodgett (LB) monolayers transferable to a solid substrate. A range of nanoscale surface morphologies have been observed, ranging from cylindrical to circular domains to bicontinuous structures as the weight fraction of the PEO block varied from 19% to 88% and n from 8 to 19. For the PS-rich stars and at elevated surface pressure, a two-dimensional supramolecular netlike nanostructure was formed. In contrast, in the PEO-rich star polymer with the highest PEO content, we observed peculiar dendritic superstructures caused by intramolecular segregation of nonspherical core-shell micellar structures. On the basis of Langmuir isotherms and observed monolayer morphologies, three different models of possible surface behavior of the star polymers at the interfaces were proposed.

Journal Article↗
PubMed2004

Assembling of amphiphilic highly branched molecules in supramolecular nanofibers.

We found that the amplification of weak multiple interactions between numerous peripheral branches of irregular, flexible, polydisperse, and highly branched molecules can facilitate their self-assembly into nanofibrillar micellar structures at solid surfaces and the formation of perfect long microfibers in the course of crystallization from solution. The core-shell architecture of the amphiphilic dendritic molecules provides exceptional stability of one-dimensional nanofibrillar structures. The critical condition for the formation of the nanofibrillar structures is the presence of both alkyl tails in the outer shell and amine groups in the core/inner shell. The multiple intermolecular hydrogen bonding and polar interactions between flexible cores stabilize these nanofibers and make them robust albeit flexible. This example demonstrates that one-dimensional supramolecular assembling at different spatial scales (both nanofibers and microfibers) can be achieved without a tedious, multistep synthesis of shape-persistent molecules.

Journal Article↗
PubMed2004

Nanotube surface arrays: weaving, bending, and assembling on patterned silicon.

We report the fabrication of ordered arrays of oriented and bent carbon nanotube on a patterned silicon surface with a micron scale spacing extending over millimeter size surface areas. We suggest that the patterning is controlled by the hydrodynamic behavior of a fluid front and orientation and bending mechanisms are facilitated by the pinned carbon nanotubes trapped by the liquid-solid-vapor contact line. The bending of the pinned nanotubes occurs along the shrinking receding front of the drying microdroplets. The formation of stratified microfluidic layers is vital for stimulating periodic instabilities of the contact line.

Biomimetic Materials↗
PubMed2002

Amphiphilic hairy disks with branched hydrophilic tails and a hexa-peri-hexabenzocoronene core.

Amphiphilic discotic molecules with hydrophilic side branches consisting of hexaphenyl hexa-peri-hexabenzocoronene and hexabiphenyl hexa-peri-hexabiphenylcoronene as the aromatic core and hexa-substituted oligoethers as the branched peripheral chains have been synthesized, and their microstructure has been characterized. The discotic molecules based on dibranched oligoether side chains have been observed to self-organize into a well-ordered hexagonal columnar structure within liquid crystalline phases, which possessed an exceptionally high thermal stability and an unusually wide temperature range over >300 degrees C. We suggest that a combination of the large lateral dimensions of the rigid cores and disordered structure of the oxygen-containing branches tails is a driving force to the formation of a highly ordered columnar structure in the bulk state with enhanced molecular segregation. In contrast to the thermotropic phase behavior that favors the formation of highly ordered columnar aggregates through a strong stacking interaction, the hexabenzocoronene cores are packed in a face-on arrangement at the air/water interface and on solid surfaces with surface domains composed of an array of 7 x 7 molecules. We suggest a crablike molecular conformation and cluster-segregated monolayers with 6-fold symmetry and unusual face-on packing on a solid surface. Preliminary spectroscopic studies in the bulk state have shown that the molecules based on a hexaaromatic-substituted core may serve as functional supramolecular materials with high energy transfer characteristic within the columns due to near-perfect columnar ordering, which is unchanged over a wide temperature range. We believe that an absence of the crystallization phenomenon of side-branched oligoether chains is critical for the formation of long-range columnar ordering with strong intracolumnar correlation of conjugated disks important for high carrier mobility.

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