Fig. 1. Chemical Structures of amylose tris(ethylcarbamate) (1. ATEC), amylose tris(n-butylcarbamate) (2. ATBC), and amylose tris(n-hexylcarbamate) (3. ATHC).
Lyotropic liquid crystallinity was investigated for amylose tris(n-butylcarbamate) (ATBC), amylose tris(ethylcarabamate) (ATEC), and amylose tris(n-hexylcarbamate) (ATHC) in tetrahydrofuran (THF) and ethyl lactates (ELs) by using phase separation experiments, polarized microscopic observation, small-angle X-ray diffraction, and circular dichroism measurements. Concentrated THF solution of ATBC has selective reflection at visible light wavelength, indicating the formation of cholesteric phase. A current theory well explains the phase diagram of ATBC, ATEC, and ATHC in THF. On the other hand, ELs solution forms smectic phase and it has significantly different phase diagram, that is, the biphasic range is much wider than that in THF. In other words, highly concentrated smectic phase can be obtained from semidilute and rather low viscosity ELs solution. This is likely because amylose alkylcarbamate chains may have significant anisotropic intermolecular attractive interaction in between polymer chains in ELs or intermolecular interactions between the chain ends are much more different from those in THF.
Fig. 1. Chemical Structures of amylose tris(ethylcarbamate) (1. ATEC), amylose tris(n-butylcarbamate) (2. ATBC), and amylose tris(n-hexylcarbamate) (3. ATHC).
Fig. 2. Comparison of experimental phase boundary concentrations for ATBC (circles), ATEC (triangles), and ATHC (squares) along with those for cellulose tris(phenylcarbamate) CTPC all in THF at 25 °C (inverse triangles). Filled and unfilled symbols denote experimental cI and cA, and solid and dashed curves are theoretical cI and cA, respectively. (Color online)
Fig. 3. SAXS intensity profiles for ATBC in ELs at 25 ° C.