Spectroscopic Characterizations of Nonamphiphilic 2,5-Bis (5-Tert-Butyl-Benzoxazolyl)-Thiophene Molecules at the Air–water Interface and in Langmuir–blodgett Films

Abstract

This paper reports the π-A isotherm and spectroscopic characterizations of mixed Langmuir and Langmuir-Blodgett films of a nonamphiphilic thiophene derivative, namely, 2,5-Bis (5tert-butyl-benzoxazolyl)-thiophene (BBOT) molecules, mixed with polymethyl methacrylate (PMMA) and stearic acid (SA). The π-A isotherms and molefraction vs. area per molecule studies indicate some repulsive interaction between sample (BBOT) and matrix (PMMA or SA) molecules. At higher surface pressure in the SA mixed BBOT Langmuir monolayer, a phase transition occurs, which has been revealed by π-A isotherm studies. UV-vis absorption and fluorescence spectroscopic studies confirm this phase transition and closer association of BBOT molecules. Spectroscopic studies of LB films lifted at higher surface pressure clearly confirm the presence of dimmers and higher-order n-meric sites.

Nano Dimensional Hybrid Organo-clay Langmuir-Blodgett Films

“…The measurement of surface pressure ( A − π ) as a function of area per molecule (A) in the monolayer film is known as isotherm characteristics. This characteristic is easily obtained and contains much useful information about the monomolecular films at the air-water interface [3,5,8,24,25]. A conceptual illustration of the surface pressure versus area per molecule isotherm is shown in Fig.…”

“…It is also a common practice to coat the substrate with a highly hydrophobic or hydrophilic material. The rate at which the substrate is dipped or pulled through the monolayer must also be precisely controlled and kept constant at a very low value (typically 5 mm/min) [3,5,7,24]. The surface pressure for film deposition is normally chosen to be in the solid-like region.…”

“…Langmuir-Blodgett (LB) films are known for a high degree of organization of organic molecules [2][3][4][5][6][7][8][9][10]. Recently, LB technique has been extended to the preparation of hybrid organo-clay mono-and multilayers [11][12][13][14][15].…”

“…Controlling the structure of materials at the nanometer scale is of fundamental importance for tailoring the materials properties. Langmuir-Blodgett (LB) films are known for a high degree of organization of organic molecules [2][3][4][5][6][7][8][9][10]. Recently, LB technique has been extended to the preparation of hybrid organo-clay mono-and multilayers [11][12][13][14][15].…”

Optical Biosensors: A Revolution Towards Quantum Nanoscale Electronics Device Fabrication

“…Deposition techniques such as screen printing and ink-jet printing allow printing of materials at very high precision and speed, producing large numbers of inexpensive and reproducible biosensors. Thin-film deposition techniques such as Langmuir-Blodgett technology [ 14 ] and Layer by Layer (LbL) technique [ 15 ] reported in some of my previous work are suitable for production of layers of few nanometer thicknesses which is important for the development of optical biosensors. Figure 4 represents the process of immobilization of biomolecules on solid substrate.…”