Layer structures: 10. Conformation and dynamics of long aliphatic spacers in smectic layers of poly(ester-imide)s based on 4-Aminobenzoic acid (cas 150-13-0) trimellitimide
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Add time:09/30/2019 Source:infona.pl
1,12-Dihydroxydodecane and 1,22-dihydroxydocosane were prepared from diacetylene precursors in such a way that the four central methylene groups were deuterated. These deuterated spacers were polycondensed with the acid chloride of N-(4 -carboxyphenyl)trimellitimide. Analogous poly(esterimide) were prepared from fully protonated spacers. Furthermore, copolyesters were synthesized from a 11 mixture of 1,12-dihydroxydodecane and 1,22-dihydroxydocosane, one of which contained a deuterated dodecane spacer, whereas in the analogous polyester the docosane spacer is deuterated. All poly(ester-imide)s were subjected to a thermal treatment yielding a smectic-E phase in the solid state. 1 3 C nuclear magnetic resonance (n.m.r.) cross polarization magic angle spinning CP/MAS spectra revealed that spacers with ≥ 12 methylene groups contain trans-trans conformations even up to 100°C. 2 H n.m.r. spectroscopic measurement revealed that the spacers are nearly immobile at - 180°C, but gain increasing mobility upon heating. Whereas the central segments of the docosane spacer can perform crank-shaft motions at ambient temperature, the motion of the dodecane spacer is restricted to kinks. At 100°C the middle segments of the spacers partly are capable of isotropic motion in the solid smectic-E phase.
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