Control of hydrophobicity via surface micro-patterning with polymer inkjet printing

Abstract

In recent, polymer inkjet printing has gained an increasing attention as a free-form fabrication method for three-dimensional, micro-patterned structures and been explored as a way of printing electrical and optical devices. Because of its bright prospect, many researchers have tried to find out the optimum processing conditions of polymer inkjet printing. Process variables are the printing type, nozzle, substrate, image resolution, surface treatment of substrate, etc. Properties of polymer ink are the concentration, viscosity, surface tension, contact angle, dispersibility of insoluble particles, etc.

In this study, polycaprolactone (PCL) was used as a representative polymer to adjust variable inkjet process parameters. The results demonstrate that PCL ink and jetting process have to meet certain conditions in terms of concentration, viscosity, surface tension, and velocity. Well defined micropatterned PCL structures were obtained in the following processing conditions: PCL 15 g/dL in DMSO on O2 or C4F8 plasma treated glass substrate, 3~20 cps, 25~45 N/m, 6~12 m/s. The topology of printed polymer patterns was characterized by SEM and a 3D surface profiler. Overall results imply that polymer inkjet printing hold great promise but more advanced studies are required to explore its possibility and limitations.