Lviv Academy of Commerce

About: Lviv Academy of Commerce is a education organization based out in Lviv, Ukraine. It is known for research contribution in the topics: Contact angle & Adsorption. The organization has 26 authors who have published 46 publications receiving 847 citations.

Temperature-responsive properties of poly(4-vinylpyridine) coatings: influence of temperature on the wettability, morphology, and protein adsorption

Abstract: Although the pH-response of poly(vinylpyridine)-based systems is well-known and indeed used in several biomedical applications, the impact of temperature on the properties of this polymer has not been investigated in detail so far. Herein, we demonstrate the temperature-responsiveness and switchable wettability of two poly(4-vinylpyridine) coatings, mimicking the behavior of materials with lower critical solution temperature. The thermal response of P4VP spin-coated films, solvent cast on a glass, is weaker than that observed for P4VP-grafted brushes, fabricated via polymerization from an oligoperoxide grafted on an amino-silanized glass. Both the P4VP coatings exhibit a temperature dependence of the water contact angle with a well-defined transition at 13–14 °C. This transition is absent at acid pH levels wherein almost all pyridyl groups are protonated. The P4VP-grafted brushes were used to examine the impact of temperature on the surface morphology and protein adsorption. The coating surface, recorded with atomic force microscopy, evolved noticeably at alkaline pH, from being relatively smooth at 10 °C to structured and rough at 20 °C. In turn, at acid pH levels, flat surfaces with rare elevations were observed at both temperatures. The adsorption of bovine serum albumin and human fibrinogen was observed with fluorescence microscopy to be significantly more efficient for temperatures above the transition, indicating that P4VP coatings can act as a noteworthy switching material.

Synthesis and Postpolymerization Modification of Thermoresponsive Coatings Based on Pentaerythritol Monomethacrylate: Surface Analysis, Wettability, and Protein Adsorption.

Abstract: Properties of novel temperature-responsive hydroxyl-containing poly(pentaerythritol monomethacrylate) (PPM) coatings, polymerized from oligoperoxide grafted to glass surface premodified with (3-aminopropyl)triethoxysilane, are presented. Molecular composition, chemical state, thickness, and wettability are examined with time of flight-secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), ellipsometry, and contact angle measurements, respectively. Temperature-induced changes in hydrophobicity of grafted PPM brushes are revealed by water contact angle and ellipsometric measurements. Partial postpolymerization modification of hydroxyl groups (maximum a few percent), performed with acetyl chloride or pyromellitic acid chloride, is demonstrated to preserve thermal response of coatings. Adsorption of bovine serum albumin to PPM brushes, observed with fluorescence microscopy, is higher than on glass in contrast to similar hydroxyl-containing layers reported as nonfouling. Enhanced a...

Cholesterol-Based Grafted Polymer Brushes as Alignment Coating with Temperature-Tuned Anchoring for Nematic Liquid Crystals.

Abstract: Novel alignment coating with temperature-tuned anchoring for nematic liquid crystals (NLCs) was successfully fabricated in three step process, involving polymerization of poly(cholesteryl methacrylate) (PChMa) from oligoproxide grafted to the glass surface premodified with 3-aminopropyltriethoxysilane. Molecular composition, thickness, wettability of the PChMa coating and its alignment action for a NLC were examined with time of flight-secondary ion mass spectrometry, ellipsometry, contact angle measurements, polarization optical microscopy and commercially produced PolScope technique allowing for mapping of the optic axis and optical retardance within the microscope field view. We find that the PChMa coating provides a specific monotonous increase (decrease) in the tilt angle of the NLC director with respect to the substrates normal upon heating (cooling) referred to as anchoring tuning.

Migration, life satisfaction, return and development: the case of a deprived post-Soviet country (Ukraine)

Abstract: This article explores the nexus between life (dis)satisfaction, migration aspirations and return and development within the context of a previously relatively developed but in the meantime deprived post-Soviet country, Ukraine. It is based on a mixed method quantitative and qualitative study conducted from 2010 to 2013. Three key findings have been emerging. First, life dissatisfaction significantly contributes to the emergence of migration aspirations and thus is an important driver of migration. This points to a correlation between the state of development of a country, according life (dis)satisfaction of its populations’ and their propensity to migrate. Second, the study suggests that the better educated have stronger intentions to migrate abroad; this trend rather undermines the country’s capability to develop further. And third, our findings suggest that (a) expected dissatisfaction with life in Ukraine upon return undermines migrants’ aspirations to return or to stay and instead inspires remigration...