History of Liquid Crystalline PolymersrnThe liquid crystalline (LC) state was first observed by Austrian botanist and chemist F.Reinitzer more than a century ago,and it was then confirmed in 1888 by German physicist O.Lehmann who named such a state of matter as“liquid crystal” in 1900.While low molecular mass (LMM)liquid crystals were successfully used in LC displays (LCDs),the development of LC polymers (LCPs) followed an independent path.Conceptually,LCPs are prepared with the incorporation of mesogenic groups that are responsible for the formation of LC mesophases,such as rod-like (calamitic) and discotic ones,into polymer chains.Depending on where the mesogens are attached,traditionally there are three major categories of LCPs.Main-chain LCPs (MCLCPs) have mesogens in the polymer backbone,while mesogens of side-chain LCPs (SCLCPs) are incorporated as side groups in a polymer with a relatively flexible main chain.In main-chain/side-chain combined LCPs (MCSCLCPs),mesogens are in both the backbone and side chains.Other classes of LCPs include mesogen-jacketed LCPs (MJLCPs),dendronized LCPs,and LC networks (LCNs).