Hybrid Electrospinning Casting Method to Produce Multifunctional Flexible Transparent Conductive Films (Printed Electronics Europe 2013)

There is a strong need to develop new transparent electrodes that are robust enough to take the flexing requirements in a wide range of developing flexible electronics markets. In the past few years, we have been working on a patent pending process that can produce nanowire embedded polymer films with electrical conductivities in 250 -1000 ohm/sq with optical transmittances from 60% to over 95% in the visible range. With special testing equipment we developed, we found that the cyclic bending of these films to small radii of curvatures down to 1/3 mm-1(e.g. 1/4" radius rod) has little or no effect on their electrical conductivities whereas the industry standard ITO coated films rapidly degrade their electrical conductivities through crack formation mechanism An added benefit of these films is their unprecedented thermoformability as they can be stretched as much as 2 times the original length with moderate loss in conductivities as revealed by real time tracking of mechano-electric properties during deformation. This property makes them ideal for future flexible electronics including displays that require double curvature surfaces formed by thermoforming.

Dr. Miko Cakmak is Harold A. Morton Chair and Distinguished Professor of Polymer Engineering at The University of Akron. His area of expertise is on Identification, modeling and simulation of complex structural mechanisms that take place during the course of polymer processing operations of wide range of polymers subjected to solution, melt as well as rubbery state deformation. He also develops novel processes for products in the optics, electronics, and biomaterial device fields. Current activities are focused on real time measurements of true mechano-optical and mechano-electrical properties of polymers undergoing flexing, uni and biaxial deformation for optics and flexible electronics applications. He is actively developing novel processes to address the needs of emerging markets. Towards this goal, his group recently developed a hybrid Electrospinning/solution casting multipurpose processing platform to produce functional polymer films including conductive transparent flexible and stretchable films for flexible electronics. Additionally he designed and constructed pilot R2R machine that applies electric, magnetic, thermal fields to orient particles and phases in "Z" direction ( normal to the film plane) to produce films for functional applications including separation membranes and wide range of devices. All these near commercial scale machines are located at brand new National Polymer Innovation Center at the University of Akron dedicated to roll to roll manufacturing of functional polymer films.