(7c) Coarse-grained simulations of side chain liquid crystal polymers with different types of attachments

Attaching liquid crystal (LC) moieties to polymer chains creates a mechanically robust material that can have liquid crystalline ordering of various degrees throughout the material or within mesoscale domains. Controlling this ordering, especially for crosslinked materials, is of interest to obtain different mechanical responses to temperature or other stimuli for soft robotics or other applications. Here, we simulate simple coarse-grained melt systems to show how synthetically tunable architectural features can lead to different types of ordering and responses to temperature. Our systems have a relatively flexible polymer backbone with short side chains terminated by ellipsoidal LC groups. The LC groups can be attached in an end-on or side-on configuration, such that the long axis of the LC group is either aligned with the last side chain bond or perpendicular to it, which leads to significantly different LC-to-isotropic transition temperatures and mesoscale structures. Specifically, end-on systems tend to form layered mesoscale structures of LC groups and polymer backbones, while side-on systems form a honeycomb like pattern of LC groups with nematic ordering around the polymer backbones. Similar structures were observed in analogous experimental systems. We also find that mixing the types of attachments of LC groups within the same system disrupts this ordering and leads to a lower transition temperature, suggesting a potential route to tune the transition temperature and degree of ordering. The methodological details required to effectively model these systems as well as their mechanical properties will also be discussed.