Studies on the Texture of Nematic Solutions of Rodlike Polymers. 2. Development and Relaxation of Loop Disclinations

Abstract

Features of the development and relaxation of loop defects in the texture of nematic solutions of two rodlike polymers are discussed. Examples given for solutions of poly(1,4-phenylene terephthalamide) and poly(1,4-phenylene-2,6-benzobisthiazole) show the overall similarity of the behavior for these two materials. The development of the mottled texture observed shortly after the solution is extruded into a rectangular capillary, to form a tangle of defect lines which then evolves to form individual loops, is discussed. The differing relaxation dynamics of individual loops observed in the final stages of coarsening near the cell center and close to a surface are presented, along with novel effects observed in the interaction of such loops with an external magnetic field.

Lattice Bending in Electrooptically Active Poly(nonylbithiazole) and Poly(nonylbisoxazole)

“…Quantitative, one-dimensional analyses of curvature have been previously performed using level set methods 27 to characterize the relaxation mechanisms of disclination loops. 28,29 Here, geometrical calculations are used to produce twodimensional maps of local curvature to enable the assessment of the spatial arrangement of the deformation.…”

“…A method for quantitatively characterizing the curvature deformation shown in HRTEM images is described, followed by a discussion of the mechanisms of deformation and the main factors expected to influence them. Quantitative, one-dimensional analyses of curvature have been previously performed using level set methods to characterize the relaxation mechanisms of disclination loops. , Here, geometrical calculations are used to produce two-dimensional maps of local curvature to enable the assessment of the spatial arrangement of the deformation.…”

Cracks and Topological Defects in Lyotropic Nematic Gels

“…DOI Topological defects and cracks are common in many condensed matter systems. Quenching and frustration induce various types of defects in liquid crystals and crystalline solids [1,2], and cracks arise from external and internal stresses in crystalline [3,4] and amorphous solids [5][6][7][8]. We explore the formation of cracks and defects in lyotropic nematic gels, materials that couple orientational ordering of embedded rods to an amorphous cross-linked polymer matrix.…”