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Abstract
For decades, materials scientists have taken inspiration from biological systems, emulating nature’s design principles to study and develop synthetic materials capable of addressing humanity’s most pressing challenges. Among these biological phenomena, trainability—the ability of tissues and bones to strengthen and adapt through localized reorganization in response to mechanical stress—stands out as particularly intriguing. Drawing on this concept, this dissertation investigates soft polymeric materials as potentially trainable systems, focusing on dynamic liquid crystal elastomers (LCEs) whose mechanical adaptability arises from mesogenic reorganization and reconfigurability enabled by dynamic bonds. In Chapter 1, the background on trainable materials will be presented along with the important design criteria for synthetic trainable materials. In addition, dynamic LCEs will be identified as potential candidates to study trainability in synthetic soft materials. In Chapter 2, the synthesis and reprogrammability of aza-Michael based dynamic LCEs will be optimized by cleverly controlling the presence or absence of phenolic catalysts. In Chapter 3, LCE based metamaterials will be utilized to achieve pluripotent functionality by training the same material in two distinct ways for different functions- auxetic response and allosteric behavior. In Chapter 4, the trainability in LCEs will be further expanded, particularly focusing on dynamic LCEs, where effects of dynamic bond strength will be studied on the thermomechanical and liquid crystalline properties of LCEs. These understandings will then inform on the trianabilites of dynamic LCEs under various thermal and mechanical training protocols targeted to achieve different actuation as well as mechanical responses. The actuation responses are included in the supplementary information section where the actuators exhibit self-sustained actuation motions. In Chapter 5, anomalous X-ray scattering technique will be utilized to characterize the structural distribution of liquid crystalline as well as amorphous regions in polydomain as well as monodomain orientations of dynamic diselenide LCEs. In Chapter 6, the summary of the dissertation will be provided along with outlook for future research directions.