The Polymer Society of Korea

Abstract

Liquid crystalline ordering in biopolymer networks offers a promising route for tuning anisotropic responses in soft materials. Here, we report a DNA–gold nanorod hydrogel exhibiting a nonmonotonic dependence of strain induced plasmonic alignment on DNA concentration. The hydrogel is formed through a thermal process based on DNA denaturation and rehybridization, yielding a physically crosslinked network without chemical crosslinkers. Surprisingly, mechanochromic color modulation appears only within a limited concentration range. Insufficient liquid crystalline organization at low concentrations prevents strain transfer to embedded nanorods, whereas excessive DNA packing at high concentrations generates dense polydomain textures that disrupt nanorod reorientation. The underlying mechanism is examined by rheology combined with strain dependent optical anisotropy. Finally, spatially programmable mechano optical encryption is demonstrated using concentration controlled DNA hydrogels.