Role of microenvironment in the mixed Langmuir-Blodgett films

TL;DR

This study investigates the structural, spectroscopic, and morphological properties of mixed Langmuir-Blodgett films containing carbazole, PMMA, and stearic acid, revealing microcrystalline aggregation and environment-sensitive optical features.

Contribution

It provides new insights into the incorporation, aggregation, and spectroscopic behavior of non-amphiphilic carbazole in mixed LB films with PMMA and stearic acid.

Findings

CA is incorporated into PMMA and SA matrices.

Microcrystalline aggregates of CA are formed in the films.

Spectroscopic features indicate formation of low-dimensional aggregates.

Abstract

This paper reports the pi-A isotherms and spectroscopic characteristics of mixed Langmuir and Langmuir-Blodgett (LB) films of non-amphiphilic carbazole (CA) molecules mixed with polymethyl methacrylate (PMMA) and stearic acid (SA). pi-A isotherm studies of mixed monolayer and as well as also the collapse pressure study of isotherms definitely conclude that CA is incorporated into PMMA and SA matrices. However CA is stacked in the PMMA/SA chains and forms microcrystalline aggregates as is evidenced from the scanning electron micrograph picture. Nature of these aggregated species in the mixed LB films has been revealed by UV-Vis absorption and fluorescence spectroscopic studies. The presence of two different kinds of band systems in the fluorescence spectra of the mixed LB films have been observed. This may be due to the formation of low dimensional aggregates in the mixed LB films. Intensity distribution of different band system is highly sensitive to the microenvironment of two different matrices as well as also on the film thickness