Polysiloxane surfactants for the dispersion of carbon nanotubes in non-polar organic solvents

TL;DR

This paper introduces two novel amphiphilic polysiloxane surfactants with conjugated groups, pyrene and porphyrin, that effectively disperse multi-wall and single-wall carbon nanotubes in non-polar solvents and siloxane matrices.

Contribution

Development of two new polysiloxane surfactants with conjugated groups for efficient dispersion of carbon nanotubes in non-polar solvents and siloxane matrices.

Findings

Pyrene-siloxane effectively disperses multi-wall nanotubes.

Porphyrin-siloxane disperses single-wall nanotubes.

Long siloxane tails improve solubility and stabilization.

Abstract

We develop two new amphiphilic molecules that are shown to act as efficient surfactants for carbon nanotubes in non-polar organic solvents. The active conjugated groups, which are highly attracted to graphene nanotube surface, are based on pyrene and porphyrin. We show that relatively short (C18) carbon tails are insufficient to provide stabilization. As our ultimate aim is to disperse and stabilize nanotubes in siloxane matrix (polymer and crosslinked elastomer), both surfactant molecules were made with long siloxane tails to facilitate solubility and steric stabilization. We show that pyrene-siloxane surfactant is very effective in dispersing multi-wall nanotubes, while the porphyrin-siloxane is making single-wall nanotubes soluble, both in petroleum ether and in siloxane matrix.