Recently, interest in the wettability control of thermos-stable polymer surface has increased, since the superhydrophobic surfaces of polymer coating can be applied in the prevention of chemical reactions and electrical conduction or in the low-flow-resistance coating for microfluidic devices. Nevertheless, thermos-stable polymer films with the high level of hydrophobicity have been hardly obtained in non-fluorinated polymers. This is attributed to the functional groups in thermo-stable polymer chains which have the intrinsic limitation to decrease surface energy. In this work, we developed facile method that the electrospray(ES) process with in situ imidization was applied to produce polyimide(PI) particles with controlled morphology, and the fabrication of coating layers of PI particles was performed through direct deposition of resulting particles. The reactive ES process combined with transformation of polymer chains provided the dimpled surfaces of resulting PI particles, which were induced by in situ imidization accompanying evaporation of solvent in sprayed droplets. It is founded that not only dimpled surfaces but also structures of particles were affected by the applied droplet size. Thus, the hollow PI particles were obtained besides the control of dimples on surfaces without any surfactants or templating additives. As a feasible approach to perform a surface coating on substrate, the microstructured layers consisting of PI particles were fabricated through ES deposition method. The resulting microstructures including protrusion, dimples and micro channels led to highly enhanced hydrophobicity up to superhydrophobic properties which would be a first example for polar non-fluorated polyimide coatings. Our approach suggests not only a strategy to prepare morphology-controlled, micro-structured PI coatings but also general method to produce functional coatings of PI in direct (non-templating) and general (using usual monomers for PI) manners.

Coating and fabrication of thermo-stable polymeric particles using electrospraying process

254th National Meeting (2017)

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