Comparative structural studies of poly(heptamethylene p,p′‐bibenzoate) by X‐ray diffraction, positron annihilation and microhardness

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Abstract
The structure of quenched samples of a polybibenzoate with a spacer containing seven methylene units has been studied by wide angle X‐ray scattering (WAXS), microhardness (MH) methods and positron annihilation lifetime spectroscopy (PALS). It was established that the quenched samples of poly(heptamethylene p,p′‐bibenzoate) (P7MB) contain three phases simultaneously: smectic liquid crystalline, amorphous, and a small amount of crystalline one. The d‐spacing of the crystal peaks, together with the crystal and smectic domain dimensions in the direction normal to the mesogen planes and the factor of paracrystallinity, were calculated. The average distance between macromolecules determined from the position of the amorphous halo correlates with the open pore diameter obtained by the PALS analysis. On the basis of MH measurements it was considered that the phases are not uniformly distributed in the depth of the sample, so that the smectic phase prevails in the surface layer while the inner layers are partially crystalline.© 2003 Society of Chemical Industry
Funding Information
  • Bulgarian Academy of Sciences
  • Spanish Council for Scientific Research (CSIC) (2001 BG 0003)
  • CICYT (MAT 2001-1731)

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