Complex Fluids Group

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LYO-BANANA MESOPHASES COMPOSED BY A MIXTURE OF
APOLAR SOLVENTS AND BENT-SHAPED MOLECULES
O. G. Martins1, Y. Huang2, A. Jákli2, H. Sawade2
e A. M. Figueiredo Neto1 1Instituto de Física,
Universidade de São Paulo, Brazil 2Liquid Crystal
Institute, Kent State University, USA

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• University of São Paulo, Brazil

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Molecules with the form of
BANANA
1925
1996

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• University of São Paulo, Brazil

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STRUCTURES

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B1 phase of the smectic type

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PHASES
Bi ,with i from 1 to 7
1) With ferroelectric switching
B2
(symmetry C2v), smectic
B5 smectic, with 2D rectangular ordering in
the layers
2) 2D ordering
B1 smectic, with 2D rectangular ordering in
the layers
B7 structure not well determined probably
of the type
1)
above

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3) phases with intercalated molecules
B6 smectic , with tilted molecules
4) Crystalline phases
B3 and B4

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xilene molecular mass 108

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B7 phase in the temperature range from 90 to 133oC
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

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xilene weaken the dipole- dipole interaction

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In São Paulo and Kent
C10H21 named C10
C14H29 named C14
Cr B2 ISO
68oC
127oC
C14
118oC
140oC
C10

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The solvent
n hexadecane CH3 (CH2)14 - CH3
boiling point 287oC density 0.77g/cm3 molecular
weight 226.4
Doping (in weight ) 20 and 40

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X Ray Diffraction
Crystalline phase
C10 ,T22oC
d
C14 ,T23oC
b
4.4 Å 51.4 Å

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C14 ,T23oC, 20wt
B3 phase, oriented
d 54.7Å gt d0 wt b 4.6Å ? b0 wt
hexadecane

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C14 ,T79oC, 20wt
B3 phase, non oriented
d 55.6Å gt d0 wt b 4.6Å ? b0 wt

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C14 ,T23oC, 40wt
C14 ,T79oC, 40wt

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C14 ,T80oC, 0wt
B2 phase

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C14 ,T25oC, 20wt
B3 phase

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CONCLUSIONS
1) The doping with 20 and 40 wt of hexadecane
a) stabilized a B3 phase
b) destabilized the B2 phase
2) The doping with xilene (p and m)
a) Reduced the clearing point
b) Reduced the transition enthalpy

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• University of São Paulo, Brazil

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• University of São Paulo, Brazil