Investigation of molecular order and phase transitions of smectic poly(ester imide)s by means of small-angle X-ray scattering

Autor: D. Gieseler, Christoph Wutz, Norbert Stribeck
Rok vydání: 2000
Předmět:
Zdroj: Colloid & Polymer Science. 278:1061-1069
ISSN: 1435-1536
0303-402X
DOI: 10.1007/s003960000370
Popis: 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.
Databáze: OpenAIRE
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