Liquid Crystalline Polymers by Metathesis Polymerization

Liquid crystalline polymers (LCPs) have gained attention as materials with interesting optical, mechanical and rheological properties. This review summarizes research on thermotropic liquid crystalline polymers synthesized by metathesis polymerization techniques. Ring opening metathesis polymerization (ROMP) is a versatile tool for preparing side chain liquid crystalline polymers (SCLCPs) with different mesogenic units. The living character of ROMP allows us to design well-defined polymers and copolymers with controlled molecular weight and molecular weight distributions. The mesophase type and the thermal transition temperatures are influenced not only by the attached mesogenic moiety but also by the stiffness of the polymer backbone, the spacer lengths between the main chain and the liquid crystalline entity, the Z/E isomerism, the tacticity, and so on. In addition, the use of acyclic diene metathesis polymerization (ADMET) or alternating diene metathesis polycondensation (ALTMET) offer new possibilities for creating new main chain liquid crystalline polymers (MCLCPs). A short discussion of new trends and potential applications for these polymers concludes the review.