Complex Fluids Group University of São Paulo, Brazil LYO-BANANA MESOPHASES COMPOSED BY A MIXTURE OF APOLAR SOLVENTS AND BENT- SHAPED MOLECULES O. G. Martins 1, Y. Huang 2, A. Jákli 2, H. Sawade 2 e A. M. Figueiredo Neto 1 1 Instituto de Física, Universidade de São Paulo, Brazil 2 Liquid Crystal Institute, Kent State University, USA

Complex Fluids Group University of São Paulo, Brazil Molecules with the “form” of

Complex Fluids Group University of São Paulo, Brazil

Complex Fluids Group University of São Paulo, Brazil B 1 phase of the “smectic type”

Complex Fluids Group University of São Paulo, Brazil B i, with i from 1 to 7 B2B2 B 5 smectic, with 2D rectangular ordering in the layers 1) With ferroelectric switching (symmetry C 2v ), smectic 2) 2D ordering B 1 smectic, with 2D rectangular ordering in the layers B 7 structure not well determined [probably of the type 1) above]

Complex Fluids Group University of São Paulo, Brazil 3) phases with intercalated molecules B 6 smectic, with tilted molecules 4) Crystalline phases B 3 and B 4

Complex Fluids Group University of São Paulo, Brazil xilene molecular mass: 108

Complex Fluids Group University of São Paulo, Brazil B 7 phase in the temperature range from 90 to 133 o C Smectic with spacing layer of 38.5Å, and a complex in-layer structure. Helical filaments at the transition from the ISO phase. -“telephone-wire-like” texture

Complex Fluids Group University of São Paulo, Brazil xilene weaken the dipole- dipole interaction

Complex Fluids Group University of São Paulo, Brazil C 10 H 21 named C10 C 14 H 29 named C14 Cr B 2 ISO 68 o C127 o C 118 o C140 o C C14 C10 In São Paulo and Kent

Complex Fluids Group University of São Paulo, Brazil The solvent n – hexadecane: CH 3 – (CH 2 ) 14 - CH 3 boiling point: 287 o C density: 0.77g/cm 3 molecular weight: Doping (in weight %): 20 and 40

Complex Fluids Group University of São Paulo, Brazil C10,T=22 o C Crystalline phase X Ray Diffraction 4.4 Å 51.4 Å C14,T=23 o C d b

Complex Fluids Group University of São Paulo, Brazil C14,T=23 o C, 20wt% B 3 phase, oriented d = 54.7Å > d 0 wt% b = 4.6Å  b 0 wt% hexadecane

Complex Fluids Group University of São Paulo, Brazil C14,T=79 o C, 20wt% B 3 phase, non oriented d = 55.6Å > d 0 wt% b = 4.6Å  b 0 wt%

Complex Fluids Group University of São Paulo, Brazil C14,T=23 o C, 40wt% C14,T=79 o C, 40wt%

Complex Fluids Group University of São Paulo, Brazil C14,T=80 o C, 0wt% B 2 phase

Complex Fluids Group University of São Paulo, Brazil C14,T=25 o C, 20wt% B 3 phase

Complex Fluids Group University of São Paulo, Brazil 1) The doping with 20 and 40 wt % of hexadecane 2) The doping with xilene (p and m) a) stabilized a B 3 phase b) destabilized the B 2 phase a) Reduced the clearing point b) Reduced the transition enthalpy

Complex Fluids Group University of São Paulo, Brazil

Complex Fluids Group University of São Paulo, Brazil