title: Aqueous cholesteric liquid crystals using uncharged rodlike polypeptides.
abstract: The aqueous, lyotropic liquid-crystalline phase behavior of the alpha-helical polypeptide, poly(N(epsilon)-2-[2-(2-methoxyethoxy)ethoxy]acetyl-lysine) (1), has been studied using optical microscopy and X-ray scattering. Solutions of optically pure 1 were found to form cholesteric liquid crystals at volume fractions that decreased with increasing average chain length. At very high volume fractions, the formation of a hexagonal mesophase was observed. The pitch of the cholesteric phase could be varied by a mixture of enantiomeric samples L-1 and D-1, where the pitch increased as the mixture approached equimolar. The cholesteric phases could be untwisted, using either magnetic field or shear flow, into nematic phases, which relaxed into cholesterics upon removal of field or shear. We have found that the phase diagram of 1 in aqueous solution parallels that of poly(gamma-benzyl glutamate) in organic solvents, thus providing a useful system for liquid-crystal applications requiring water as solvent.
authors.affiliation: Department of Materials, Materials Research Laboratory, University of California, Santa Barbara, 93106, USA.
authors.forename: Enrico G
authors.initials: EG
authors.lastname: Bellomo
authors.forename: Patrick
authors.initials: P
authors.lastname: Davidson
authors.forename: Marianne
authors.initials: M
authors.lastname: Impéror-Clerc
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Deming
mesh_terms: D055095:Optics and Photonics; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D011107:Polylysine / Q000031:analogs & derivatives* / Q000737:chemistry; D017433:Protein Structure, Secondary; D012542:Scattering, Radiation; D014965:X-Rays
chemical_list: C003172:poly-gamma-benzyl-L-glutamate; D011107:Polylysine; D011099:Polyglutamic Acid