Side-chain liquid-crystalline homopolymers and copolymers. Structure and rheology

We report on the structure and the viscoelastic properties of two side-chai n liquid-crystalline polymers with different spacer length in the melt and fiber states and of their Copolymers with a semicrystalline block. Optical microscopy, X-ray scattering, and differential scanning calorimetry are emp loyed for the structure investigation and rheology for the dynamics. The sm ectic and nematic liquid-crystalline polymers exhibit non-Newtonian low-fre quency response and violate the empirical principle of time-temperature sup erposition with the effect being more pronounced in the former. Fibers draw n from the melt exhibit significantly different structure from the melt sam ples. In the diblock copolymer composed of smectic/crystalline blocks, the strong first-order isotropic-to-smectic transition induces the weak disorde r-to-lamellar transition between the dissimilar blocks in the diblock.