COMPARATIVE-ANALYSIS OF THE STRUCTURE OF 2 THERMOTROPIC LC COPOLYESTERS

A comparative study of the structures of two thermotropic liquid cryst al copolyesters (LCP) was carried out. The first copolymer, LCP-1, com prises three different monomer units of equal length, whereas the seco nd copolymer, LCP-2, contains two monomer units which differ significa ntly in length. Both copolymers exhibit random structure. it was estab lished that despite the irregular structure both copolymers have the a bility to crystallize. Moreover, during crystallization of LCP-I micro phase separation into two phases occurs. Each phase has an orthorhombi c crystal structure but with slightly different parameters of the unit cell. The reason for this difference is probably associated with conf iguration isomerism because of possible head-to-head or head-to-tail a dditions during synthesis of the copolyester. Upon annealing, the maxi mum degrees of crystallinity are 35% and 25% for LCP-1 and LCP-2, resp ectively. The noncrystalline fraction of the material, whose content e xceeds appreciably the content of the crystalline phase, shows a LC sm ectic structure. However, the fundamental difference between the two c opolymers is that, in the case of LCP-1, the periodic layer structure is observed, whereas for LCP-2 the layer structure is aperiodic. The a bove phenomena are universal, and this makes it possible to predict th e structure and character of temperature behavior of any representativ e of the class of fully aromatic rigid-chain copolyesters only from th e chemical formula of the copolymer.