UV-activated surface modification of photo-cleavage polymer for contact printing applications

Polymer electronics is an emerging technology for the last decade. For cost-efficient mass production and for thin, flexible polymer electronic systems, large area patterning processes may be an interesting option as an economic production method and will potentially play an important role in polymer electronics manufacturing. High resolution patterning methods for defining the separation between electrodes in electronic devices are important in manufacturing. The control of surface wettability during contact printing is an interesting approach because of its wide variety of applications. Stimuli-responsive surfaces make it possible to control the wettability of the surface and have been demonstrated by various methods, including UV light-irradiation. Herein, a new strategy was demonstrated using free radical initiator to induce mold release between PDMS mold and the resins under UV irradiation. For example, by applying a thin layer of benzoyl peroxide (BPO) on PDMS surface, an increase of contact angle is achieved after UV irradiation. This method can be used as a transfer mechanism from mold to substrate. It was noticed that sufficient time of BPO deposition for the PDMS mold surface treatment is required for this strategy. Optimum concentration of BPO and suitable solvent system are concerns in the effectiveness of surface treatment. From this study, some preliminary insight in studying the controlling factors for the UV activation of free radicals on PDMS surface was shown. It can be shown that the molecular structure, polarity of materials, UV sensitivity of the free radical initiators, and solvent used, have direct effect on the efficiency of the wettability change under the UV irradiation. By knowing the controlling factors of UV assisted stimuli responses, printing can be improved and be applied in many other cases.