Structured surfaces are attractive in various applications including stretchable electronics, photonics, wettability control, micro-fluidic devices, cell-based biosensors. They also have been used to measure the mechanical properties of thin films and to manufacture optical components such as diffraction gratings and optical diffusers. Various techniques have been employed for the fabrication of micro- and nano-structures on solid substrates, such as colloidal lithography, surface relief grating, electro spinning, or nano-imprinting. Especially, complex patterns with gradients of amplitudes and tailor-made geometries have remained a challenge.
Here, we describe a simple approach to fabricate periodic structure based on liquid crystalline (LC) monomer having reactive mesogenic group through utilizing surface modifications of plasma treatment in micro-scale. Upon curing using the plasma, the liquid LC monomer develops a depth-wise gradient in degree of cross-linking or solidification. Also, we are proposing an alternative and simple method for the formation of an anisotropic pattern through utilizing anisotropic nature of molecularly aligned LC in two-dimensional space. The proposed methods enable the pattern formation of well-aligned one- or two-dimensionally periodic micro-structures over the large area, without the additional template or patterning steps.