Kinetic parameters for step and flash imprint lithography photopolymerization

Abstract

Step and Flash Imprint Lithography (SFIL) is a high-resolution, yet low-cost nanopatterning technique that employs an acrylate-based, free-radical photo-polymerization to replicate a patterned template onto a substrate. Modeling the photo-polymerization requires knowledge of the values of several reaction parameters, which are unique to the acrylate formulation used in SFIL. The values of these parameters were experimentally determined for use in a previously described kinetic model. The rate coefficient for initiation, k_I, was determined by measuring the absorbance spectrum of the initiator, Darocur® 1173, and convolving it with the intensity spectrum from the irradiation source. The reaction coefficients k_p and k_t were measured using the dark polymerization method. The experimental values of both parameters were then mathematically modeled to reflect the changes that occur as a function of conversion. Measuring the kinetic parameters provides insight into the fundamental steps involved in the polymerization. © 2005 American Institute of Chemical Engineers AIChE J, 2006