Investigation of molecular order and phase transitions of smectic poly(ester imide)s by means of small-angle X-ray scattering |
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Authors: | C Wutz N Stribeck D Gieseler |
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Institution: | Institut für Technische und Makromolekulare Chemie Universit?t Hamburg Bundesstrasse 45, 20146 Hamburg Germany, DE
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Abstract: | The molecular order and phase transitions of two smectic poly(ester imide)s based on aminobenzoic acid trimellitimide (PEI
1) or aminocinnamic acid trimellitimide (PEI 2) and α,ω-dihydroxydodecane were investigated by X-ray scattering. During cooling,
the polymers pass through monotropic smectic liquid-crystalline (LC) phases (SA, SC), which transform into higher-ordered smectic-crystalline phases (SE, SH). The smectic layer structure of about 3 nm gives rise to a sharp reflection at 2θ ≅ 3°. Peak shape analysis and analysis
of the interface distribution function revealed long-range longitudinal correlation among the mesogens in the LC phase but
short-range lateral correlation. The development of a broad reflection in the small-angle X-ray scattering (SAXS, 2θ < 1°)
indicates the formation of a lamellar two-phase system. The long-period changes reversibly between 10 and 30 nm with increasing
temperature. The crystalline lamellae comprise a number of smectic-crystalline layers with packed mesogens, while the noncrystalline
interlamellar regions keep their smectic-LC order. In the metastable SB phase, formed during annealing of quenched PEI 1, the diffuse SAXS indicates a random distribution of small, probably fringed,
crystals with hexagonal-packed mesogens. In the lamellar SE and SH phases, tie molecules play an important role, but chain folding cannot be excluded.
Received: 16 July 1999/Accepted: 28 April 2000 |
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Keywords: | Smectic Poly(ester imide)s Small-angle X-ray scattering Lamellar |
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