Intermolecular interactions of BODIPY and SWCNTs in solutions, a new approach to obtaining in a supercritical CO2 the PMMA/BODIPY/SWCNTs composites

Abstract

In the field of materials science, the preparation of new luminescent composite materials based on a mixture of various photoactive compounds with an extended absorption and fluorescence range from the visible to the infrared region is of particular interest. The range of applications for multicomponent photoactive composites is rapidly expanding, including light-harvesting devices and laser limiters. Accordingly, it remains essential to develop polymer dyeing technology that preserves the practically significant properties of the components while eliminating the use of toxic organic solvents and high temperatures.

We have created new polymer composites (PMMA/BODIPY/SWCNTs) based on poly(methyl methacrylate) (PMMA) and photoactive compounds of various natures: boron(III) dipyrromethenate (BODIPY) luminophores and semiconductor single-walled carbon nanotubes (SWCNTs), which have absorption and fluorescence ranges in the visible (green) and infrared regions of light, respectively. The concept of dispersing mixtures of BODIPY and SWCNTs in a PMMA polymer within a supercritical fluid environment was successfully demonstrated. In addition, at the first step, we analyzed the spectral properties of BODIPY solutions in the presence of various amounts of SWCNT suspensions (s-SWCNT) in ethanol (with the addition of cholic acid (CA) as a dispersing agent) and dimethylacetamide (DMAA).

Using computer simulation, we conducted an analysis of the possible influence of structural factors and intermolecular interactions between BODIPYs and SWCNTs on the optical properties of luminophores in solutions. The computer simulation indicated that non-covalent BODIPY·SWCNT structures form, exhibiting numerous electronic transitions and electron density redistribution within the nanotube (from one part to another) and between BODIPY and SWCNT within the supramolecular complex.

It has been experimentally established that BODIPY dyes demonstrate significant spectral properties both in ethanol solutions and in polymer composites containing SWCNTs. Initial results indicate that sc-CO2 solutions present an attractive possibility for immobilizing BODIPY/SWCNT mixtures into polymers, providing unique combinations of spectral characteristics. Thus, the proposed method is an effective way to develop new composites based on a mixture of photoactive compounds with an extended working spectral range from the visible to the infrared spectrum for various optical devices.