Diffraction from thermotropic copolyester molecules

Abstract

Analytical expressions for the meridional scattering from highly oriented random copolyesters are presented. These procedures are utilised in developing the relationship of the features in the diffraction pattern to compositions and relative lengths of the constituent monomer units. The difference between the scattering patterns for random and block copolymers are discussed. The theory is applied to an example of a liquid crystal ffoming random copolyester.Key words: Co-polyester, liquid crystalline polymer, random copolymer, X-ray scattering, thermotropic polymer. Summary of terms

Effect of molecular weight on crystalline structure in thermotropic random copolymers

“…A typical SAED pattern obtained from a region approximately 2.5 p m in diameter in the BN150 sample is shown in Figure 2. It is important to note that the average molecular orientation is well-aligned with the shear direction (vertical), as observed by Viney et al 15 The presence of aperiodic meridional maxima seen here is indicative of random intramolecular sequencing, 1,2,[5][6][7][8] whereas the sharp equatorial reflections suggest finite crystalline ordering.6J6 DF images of these materials are obtained by tilting the electron beam so that a diffraction reflection is centered in the objective aperture. All of the DF micrographs shown in Figure 3 use the principal equatorial reflection as the source of diffraction contrast and clearly exhibit NPL crystallites.…”

Temperature dependant structural changes in thin films of random semifluorinated PMMA copolymers

“…These measurements were not possible in the frame of the work discussed here. Furthermore, another possibility to describe this phenomenon is to treat it in a similar manner like diffraction of random copolyesters (Mitchell and Windle, 1985). It is imaginable that the polymer chains stand like brushes on the substrate with liquid-like lateral correlation to each other.…”

Surface Effect of Silica Nano-Particles with Different Size on Thermotropic Liquid Crystalline Polyester Composites

“…The weight average molecular weight and molecular weight distribution of VECTRA A950 were reported to be 30,000 [12], and 2.45 [13], respectively. The random sequence distribution of this sample was also confirmed [14]- [19]. SNPs with average diameter of 51 nm were purchased from Kanto Chemical, and those with average diameter of 240 and 485 nm were the products of Amatecs.…”