Stimuli-responsive hydrogels have emerged as a class of materials that can be programmed to change shape and topography in response to changes in environmental conditions. This stimulus response in hydrogels is typically isotropic in nature. In this work, we report on the synthesis of anisotropic, mechanically active hydrogels using the self-assembly of the lyotropic chromonic liquid crystals (LCLC). Unlike conventional lyotropic LCs, LCLC s can be macroscopically aligned using patterned surfaces. In this work, perylene-3,4,9,10-tetracarboxylic dianhydride(PTCDA) is used to synthesize a polymerizable LCLC mesogen, ionic dimethacrylate derivative of perylene-3,4,9,10-tetracarboxylic diimide (PDI). The anisotropic hydrogels were generated through the radical polymerization of chromonic reactive mesogens(PDI) in their nematic state with n-isopropylacrylamide (NIPAM). The presence of NIPAM and the molecular ordering due to the presence of chromonic liquid crystal imparts anisotropic thermoresponsive behavior to the hydrogel. This anisotropic swelling in the chromonic hydrogel can be programmed. We discuss hydrogel sheets that actuate at temperatures that are compatible with living organisms (figure 1). This shape change behavior of the hydrogel will be discussed and will be correlated to the polymer network structure, morphology and liquid crystalline phase. Finally, we discuss the introduction of chiral dopants to create surfaces capable of reversible changes in topography.<br/>

Chromonic liquid crystal hydrogels

253rd National Meeting (2017)

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