Optimization of graphene oxide layer-by-layer films to be used as an enhancer coating of optical fibers sensors

The stability of Graphene oxide (GO) layers obtained by the layer-by-layer (LbL) films was investigated having in view the development of tunnable surfaces for optical fibre sensors in aqueous environments. For this purpose layer-by-layer (LbL) films based polyethylenimine (PEI) and GO, were prepared and characterized. The kinetics of adsorption of PEI/GO LBL films revealed that the adsorbed amount per bilayer increases linearly with the number of bilayers as expected. Furthermore adsorbed amount per bilayer for short adsorption times tends to a constant value revealing that GO layer growth also follows the adsorption behaviour expected polyelectrolytes in which electrostatic interaction is ruling the process. Finally desorption studies carried out to infer about GO layer stability revealed that GO layers are more stable at higher solutions pHs and if the adsorption time for each layer is short. These results/conclusions allowed to infer on the possible range of applications of PEI/GO LbL films.