Stabilization of langmuir and langmuir blodgett cetyltrimethylammonium bromide monolayers by gluing with polystyrene sulfonate

Utku, Nezaket Nehir
Organic thin films have wide range application areas such as biosensors, permeation selective barriers, molecular electronics, optical devices and coatings. The properties of such films can be tuned by their composition, structure and uniformity. Stability of obtained films has also an important factor in the fabrication and the transfer of the films. For this aim, Langmuir is an elegant technique for both the production and deposition of monolayers onto a solid support. Herein, some optimization studies such as subphase temperature, pH, compression rate and transfer rate were performed with stearic acid (SA) and octadecane-1-thiol (ODT) which are the standard materials of Langmuir system. Concentration and subphase temperature were also optimized for cetyltrimethylammonium bromide (CTAB) which was used to prepare and organize the gold nanorods (GNRs) in a monolayer structure. Lately, it was reported that some water soluble materials can also form Langmuir monolayers but to produce a Langmuir compatible complex, an interaction with these water soluble materials with a water insoluble material is needed. However, CTAB was used by itself without any complex forming reagent and stable monolayers were obtained. Polymers, particularly water soluble ones, are used as a glue to improve the cohesiveness of LB films. This process is known as “gluing” where LB assemblies were cross-linked noncovalently through ionic and hydrophobic association with a water-soluble polymers. The effect of gluing on stability of CTAB monolayers was investigated. Poly(4- styrenesulfonate) (PSS) was used as a gluing agent. The addition of polymers into subphase led to an interaction between surfactant and polyelectrolyte and an increase in monolayer stability. In order to compare the effect of PSS on stability of the obtained monolayers, hysteresis loops (repeatedly compression-expansion cycles) were performed in the presence and absence of PSS in the subphase and it was concluded that more stabilized CTAB monolayers can be obtained by gluing. Moreover, glued CTAB multilayers can be prepared by Langmuir Blodgett technique. GNRs were synthesized by seed mediated growth approach. The aspect ratio of the rods were approximately 2.5. The characterization of GNRs was performed by UV spectrometry. Two characteristic rod plasmon absorptions were observed at 520 and 675 nm. The morphology of the GNRs was characterized by Scanning Electron Microscopy (SEM). After the deposition of negatively charged PSS glued CTAB monolayers, they were used for assembling the cationic gold nanorods on the surface of the substrate. Finally, the performance of the obtained structures as Surface Enhanced Raman Scattering (SERS) substrates were investigated utilizing brilliant cresyl blue (BCB) dye as a model compound.


Temperature-dependent thermoelastic properties of GaSb and InSb semiconductors: Identification through ab initio DFT simulations
Baloğlu, Eyüp Can; Toffoli, Hande; Dal, Hüsnü (2022-10-15)
© 2022 Elsevier B.V.III–V semiconductors are extensively used in infrared sensor applications due to their superior structural and optical properties. Due to the extremes in the manufacturing and operating temperatures of the sensors, the knowledge of temperature-dependent elastic constants of these materials is of great importance. However, reliable measurements across a large range of temperatures prove difficult due to limitations of experimental setups. Density functional theory calculations present an ...
Effect of crystallization on the electronic and optical properties of archetypical porphyrins
Malcıoğlu, Osman Barış; Bockstedte, Michel (Royal Society of Chemistry (RSC), 2020-02-21)
Thin porphyrin films as employed in modern optical devices or photovoltaic applications show deviating electronic and optical properties from the gasphase species. Any understanding of the physical origin may pave way to a specific engineering of these properties via ligand or substituent control. Here we investigate the impact of crystallization of prototypical porphyrins on the electronic levels and optical properties in the framework of density functional theory and many-body perturbation theory. Crystal...
Development of indium tin oxide (ITO) nanoparticle incorporated transparent conductive oxide thin films
Yavaş, Hakan; Durucan, Caner; Department of Metallurgical and Materials Engineering (2012)
Indium tin oxide (ITO) thin films have been used as transparent electrodes in many technological applications such as display panels, solar cells, touch screens and electrochromic devices. Commercial grade ITO thin films are usually deposited by sputtering. Solution-based coating methods, such as sol-gel however, can be simple and economic alternative method for obtaining oxide films and also ITO. In this thesis, “ITO sols” and “ITO nanoparticle-incorporated hybrid ITO coating sols” were prepared using indi...
Doğru Balbaşı, Çiğdem; Parlak, Mehmet; Department of Physics (2022-5-25)
CdZnTe is an II-VI group semiconductor material with significant properties used in many critical industrial applications, such as photovoltaic devices, photodiodes, photoconductors, room temperature gamma-ray spectroscopy, X-ray imaging, and infrared detectors. In Particular, CdZnTe is a promising material for solar cell application as an absorber layer due to its direct tunable bandgap property, high atomic number with strong absorption, excellent optoelectronic properties, and long-term stability. Howeve...
Production of hydrogenated nanocrystalline silicon based thin film transistor
Aliyeva, Tamila; Atılgan, İsmail; Department of Physics (2010)
The instability under bias voltage stress and low mobility of hydrogenated amorphous silicon (a-Si:H) thin film transistor (TFT), produced by plasma enhanced chemical vapor deposition (PECVD) technique, are the main problems impeding the implementation of active matrix arrays for light emitting diode display panels and their peripheral circuitry. Replacing a-Si:H by hydrogenated nanocrystalline silicon film (nc-Si:H) seems a solution due to its higher mobility and better stability. Therefore nc-Si:H TFT was...
Citation Formats
N. N. Utku, “Stabilization of langmuir and langmuir blodgett cetyltrimethylammonium bromide monolayers by gluing with polystyrene sulfonate,” M.S. - Master of Science, Middle East Technical University, 2015.