Polymer deposition morphology by electrospray deposition - Modifications through distance variation

Electrospray deposition (ESD) of highly diluted polymers was examined with regard to the deposited surface structure. Only the flight distance (flight time) onto the resulting deposited surface was varied from 20 to 200mm. An apparatus without any additional heating or gas flows was used. Polyacrylic acid (PAA) and polyallylamine (PAAm) in methanol were deposited on Si wafers. The polymer layers were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, derivatization reactions and Fourier transform infrared spectroscopy using a grazing incidence unit. SEM images illustrated the changing structures of PAA and PAAm. For PAA the deposited structure changed from a smooth film (20mm) to a film with individual droplets on the coated surface (100mm and 200mm), while for PAAm individual droplets can be seen at all distances. The ESD process with cascades of splitting droplets slows down for PAA after distances greater than 40mm. In contrast, the ESD process for PAAm is nearly stopped within the first flight distance of 20mm. Residual solvent analysis showed that most of the solvent evaporated within the first 20mm capillary-sample distance. •We deposited polyacrylic acid and polyallylamine by electrospray ionization (ESI).•The morphology in dependence of flight distance (20mm to 200mm) was analyzed.•The amount of residual solvent after deposition was determined.•ESI-process slows down for polyacrylic acid after 40mm flight distance.•ESI-Process is complete for polyallylamine within the first 20mm.