What Is the Right Chain Length? Liquid Crystalline Network Tuning by Molecular Design

Abstract

Liquid crystalline networks (LCNs) are stimuli-responsive polymers with programmable actuation properties, including fast response times and tunable force generation. Their reversible deformations can be achieved under light irradiation when polymers are functionalized with photoresponsive molecules such as azobenzenes. All of these features need to be adapted for each specific application, and this is possible by tuning the material properties through molecular design. In this study, we demonstrate how to tailor both mechanical properties and light-dependent force development thanks to the synthesis of mesogenic cross-linkers with different alkyl chains. Acting on this molecular parameter allows modulating the maximum actuation force, while modifying the cross-linking degree is a more advantageous strategy to get fast activation. Our results provide valuable insights into the relationship between the molecular structure and material performance, paving the way for a rational design of innovative responsive materials.