Regularization of pattern formation in metal/SMP bi-layer structures

Abstract

In this paper, we demonstrate a fabrication method for ordered self-assembly using pre-programmed shape memory polymer (SMP) as the substrate in an organic-inorganic bi-layer structure. By heating the hybrid structure above the SMP's shape recovery temperature, the substrate expands because of positive CTE in one direction, while in the perpendicular direction it shrinks due to shape memory effect overpowering thermal expansion. Consequently, the thin film is subjected to an orthogonal compression-tension stress field and forms unidirectional wavy patterns. We further validate our conceptual design by adjusting the strain level of pre-programmed SMP substrates. The present study is expected to offer a convenient and simple path of fabricating unidirectional wavy patterns. Moreover, selective growth and ordering of patterns can become possible.