Imprinting of polymer at low temperature and pressure

Abstract

We have developed a method to pattern polymeric materials, including nonthermoplastic polymers and biomaterials, at low temperature and low pressure. In this method, plasticizers are added to increase the chain mobility of the polymers, resulting in lower imprinting temperature and/or pressure. Three established imprinting and transfer techniques were chosen to demonstrate this method: conventional nanoimprint lithography (NIL), microcontact printing (μCP), and soft ink-pad (SIP). These three techniques were used to pattern poly(3,4-ethylenedioxythiophene) (PEDOT) and chitosan. PEDOT and chitosan were chosen because both of them are nonthermoplastic polymer and therefore cannot be easily patterned using conventional NIL. Imprinting of PEDOT and chitosan films from the poly(dimethylsiloxane) mold was achieved at a low pressure of 10kPa and 25°C by controlled addition of glycerol as a plasticizer using conventional NIL; well-defined arrays of 2μm wide, 185nm high PEDOT dots have also been demonstrated by μCP; and residual-layer-free recessed PEDOT circles 2μm in diameter were formed by SIP. In contrast, patterning of PEDOT film without plasticizer requires higher temperature (80°C) and pressure (10MPa), which could cause severe deformation of the transferred patterns. This method of plasticizer-assisted imprint lithography broadens the applicability of NIL to a wide range of polymeric materials.