Experimental characterizations of the response of nematic liquid crystal droplets upon adsorption of nanoparticles from aqueous media

Download
2021-9-08
Şengül, Selin
Nematic liquid crystal (LC) droplets have been widely used for the detection of molecular species. In this study, we investigated the response of micrometer sized nematic LC droplets against the adsorption of nanoparticles from aqueous media. In the first part of this study, we synthesized ~100 nm-in-diameter silica nanoparticles and modified their surfaces to mediate either planar or homeotropic LC anchoring and a pH-dependent charge. Secondly, we carried out the adsorption of nanoparticles to the LC-aqueous interface and investigated the response of LC droplets upon adsorption. We showed surface functionality- and concentration-dependent configurations of the droplets consistent with the change in the surface anchoring and the formation of local heterogeneities upon adsorption of the nanoparticles to LC-aqueous interfaces. According to our results, the adsorption of nanoparticles modified with dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (DMOAP, homeotropic) exhibit a transition from bipolar to radial, whereas the adsorption of -COOH-terminated counterparts (planar) did not cause a configuration transition. By manipulating the electrostatic interactions, we controlled the adsorption of the nanoparticles to the LC-aqueous interfaces, providing access to the physicochemical properties of the nanoparticles. We demonstrated a temporal change in the droplet configurations caused by the adsorption of the nanoparticles functionalized with -COOH/DMOAP mixed monolayers. These results provide a basis for studies in applications for the detection of nano-sized species, for sensing applications that combine nanoparticles with LCs, and for the synthesis of anisotropic composite particles with complex structures.

Suggestions

Nanoparticle adsorption induced configurations of nematic liquid crystal droplets
Sengul, Selin; AYDOĞAN, NİHAL; Büküşoğlu, Emre (2022-02-01)
Nematic liquid crystal (LC) droplets have been widely used for the detection of molecular species. We investigate the response of micrometer sized nematic LC droplets against the adsorption of nanoparticles from aqueous media. We synthesized ti 100 nm-in-diameter silica nanoparticles and modified their sur-faces to mediate either planar or homeotropic LC anchoring and a pH-dependent charge. We show sur -face functionality-and concentration-dependent configurations of the droplets consistent with the change ...
Shape Effects on the Structure and Response of the Polymeric Particles Synthesized from Cholesteric Liquid Crystal Templates
Avşar, Deniz Işınsu; Büküşoğlu, Emre (2021-01-01)
: Liquid crystals (LCs) have been shown to provide molecular templates for the synthesis of polymeric particles. Past studies have revealed the elastic effects to dominate internal configuration of the LC molecular templates for the sizes below 10 µm. Sacrificial microwells were used in this study to study the effect of shapes of the particles synthesized from the cholesteric liquid crystals on their structure and response. Specifically, mixtures of diacrylate based reactive (RM257) and nonreactive mesogens...
Controlled synthesis of organic-inorganic composite particles
Erçelik, Elif; Büküşoğlu, Emre; Aydoğan, Nihal; Department of Chemical Engineering (2022-8-26)
Liquid crystal (LC) is a state of matter having long-range orientational order between crystalline solid and isotropic liquid, and its molecular orientation can be altered with external stimuli. The polymerization of liquid crystal droplets has been widely used for the synthesis of LC-templated functional materials due to its ordering property and fluidic behavior. In this study, we investigated the synthesis of composite particles with controlled internal and interfacial structure using surface-modified na...
Synthesis, structural characterization, DFT calculations and Hirshfeld surface analysis of (R)-2-((S)-2((S)(-)hydroxy(ferrocenyl)methyl)aziridin-1yl)butan-1-ol
Sen, Betul; Sevincek, Resul; BEKSULTANOVA, Nurzhan; Doğan, Özdemir (2018-12-05)
The title compound, C17H23FeNO2 (2), has been synthesized and its crystal structure has been determined from single crystal X-ray diffraction study. Crystals are monoclinic, a = 6.3541 (5), b = 10.1934 (5), c = 12.6744 (8) angstrom, beta = 92.898 (6)degrees, space group P2(1), Z = 2. The molecular geometry was also optimized using density functional theory (DFT/B3LYP) method with the 6-311G basis set in ground state. From the optimized geometry of the molecule, geometric parameters (bond lengths, bond angle...
Synthesis of CuO nanostructures on zeolite-Y and investigation of their CO2 adsorption properties
Boruban, Cansu; Nalbant Esentürk, Emren (2017-10-01)
Copper(II) oxide (CuO) nanoparticles (NPs) in two different morphologies, spiky and spherical, were synthesized on zeolite-Y by a modified impregnation method, and their CO2 adsorbing capabilities were investigated under standard conditions (1 atm and 298 K). The properties and CO2 adsorption performances of the hybrid systems were characterized by transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray, X-ray diffraction, X-ray photoelectron spectroscopy, atomic absorption s...
Citation Formats
S. Şengül, “Experimental characterizations of the response of nematic liquid crystal droplets upon adsorption of nanoparticles from aqueous media,” M.S. - Master of Science, Middle East Technical University, 2021.