Fabrication of ultra-thin graphene oxide films enhanced by bio-interfactants

Abstract

Graphene-based materials have been emerging at a fast pace since the isolation of a single crystal in 2004 and the Nobel prize in physics for that in 2010. Due to the outstanding properties of graphene, new lines of research aim to address challenges in production and methods to strongly attach graphene onto surfaces. Addressing this challenge requires (i) efficient transport of graphene to surfaces where it, (ii) remains strongly attached and (iii) manifests the sought graphene-like properties. This thesis aims to address these points by exploring synergetic interactions between graphene oxide and biomolecules that act as linkers (here named “bio-interfactants”). A layer- by-layer method was devised, which allowed the formation of ultra-thin coatings that safeguarded the overlapping graphene oxide flakes. In order to characterize the attainment of graphene-like properties, a mild thermal reduction of these newly- devised materials was conducted. It was found that the choice of the bio-interfactant played a crucial role in the efficiency of achieving these properties. Besides that, the bio-interfactants allowed further verticals assemblies by repeating the layer-by-layer process. In that case, too, the bio-interfactants played a role in the scaling of coating properties and allowed the tailoring of thicknesses from ~5.5 nm to ~233 nm. After thermal reduction, the lowest coating thicknesses could be achieved with high degree of homogeneity, and the thicker coatings presented some level of expansion (puffing). Finally, the coating presented here was found to be a suitable material when employed as a hair cosmetic. A study case about the cosmetic benefits of this material and its potential role as a fundamentally new technology for hair cosmetics is presented in this thesis, too.