Deposição de filmes poliméricos através da técnica de eletrospray para aplicação em dosímetros ativos

Abstract

This project contains the construction of an electrospray equipment for the deposition of polymeric films (conjugated polymers with metallic nanoparticles) which can be used in active dosimeters. The equipment uses a high voltage source of direct current, with one of the poles connected to the beak of an injection pump and the other to a solution collector. In the first tries using a dyestuff in aqueous solution, perturbations in the design of the Taylor cone and formation of large droplets which harmed deposition were noted. It was required a flow which was lower than the minimum limit of the injection pump (lower than 1mL/h), for which was carried out the replacement of the injection pump step motor and the assembly of a new motor drive. New tries showed it was necessary to use small distances between the cathode and the anode to obtain the desired electric field. However, small distances would harm the evaporation of the solvent from the solution droplets before reaching the anode. To solve this problem, it was required the source to reach electrical voltages higher than 10kV, and so it was needed the construction of a new source using a flyback transformer as a continuous voltage elevator (DC). The increase of the electrical tension required greater security of the system because of the risk of electric shock and so it was needed a review of the electric current control of the high voltage source and arrangements of safety keys.