Complex Fluids Group University of São Paulo, Brazil

Complex Fluids GroupUniversity of São Paulo,

Brazil

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, Brazil2Liquid Crystal Institute, Kent State University, USA


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Molecules with the “form” of

H

N

O

O

RR

N

O

O

H

R R

O

O

H H

N N

O

O

H

N

O

O

O O

N

O

O

H

9’

10’

128

5

1

23

4

67

9

1011

B

AA’

B ’

long axis C

1996

1925


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(+) Chirality

Synclin icAntiferro

Anticlin icFerro

Anticlin icAntiferro

Synclin icFerro

Racemic

E = 0 E = 0E < -E t h E < -E thE > E th E > E th

C

z

z

bn

c

b

BA Homogeneouslychiral

(- ) Chirality


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a

c B1 phase of the “smectic type”

k

m

n n

n

n

n

n

n

n

m

m

m

m

m

m

m

C P

C B2

C B1

C G

z

y x

z


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Bi ,with i from 1 to 7

B2 B5 smectic, with 2D rectangular ordering in the layers

1) With ferroelectric switching

(symmetry C2v), smectic

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 temperaturerange from 90 to 133oC

Smectic with spacing layer of38.5Å, and a complex in-layerstructure. Helical filaments atthe transition from the ISO phase.-“telephone-wire-like” texture


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xilene weaken the dipole-dipole interaction


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C10H21 named C10 C14H29 named C14

Cr B2 ISO

68oC 127oC

118oC 140oC

C14

C10

In São Paulo and Kent


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The solvent

n – hexadecane: CH3 – (CH2)14 - CH3

boiling point: 287oCdensity: 0.77g/cm3

molecular weight: 226.4

Doping (in weight %): 20 and 40


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C10 ,T=22oC

Crystalline phase

X Ray Diffraction

4.4 Å51.4 Å

C14 ,T=23oCd

b


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C14 ,T=23oC, 20wt%

B3 phase, oriented

d = 54.7Å > d0 wt%

b = 4.6Å b0 wt%

hexadecane


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C14 ,T=79oC, 20wt%

B3 phase, non oriented

d = 55.6Å > d0 wt%

b = 4.6Å b0 wt%


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C14 ,T=23oC, 40wt%

C14 ,T=79oC, 40wt%


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0.0e+0

0.2e-3

0.5e-3

0.7e-3

1.0e-3

0.1e-2

0.1e-2

Inte

nsit

y (

I )

3 4 5 6 7 8 9d [A°]

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

Inte

nsit

y (

I )

10 20 30 40 50 60 70 80d [A°]

C14 ,T=80oC, 0wt%

B2 phase


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C14 ,T=25oC, 20wt%

B3 phase0.0e+0

1.0e-3

0.2e-2

0.3e-2

0.4e-2

0.5e-2

0.6e-2

0.7e-2

0.8e-2

Inte

nsit

y (

I )

20 30 40 50 60 70 80 90d [A°]

0.0e+0

1.0e-4

0.2e-3

0.3e-3

0.4e-3

0.5e-3

0.6e-3

0.7e-3In

tens

ity

( I

)

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5d [A°]


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1) The doping with 20 and 40 wt % of hexadecane

2) The doping with xilene (p and m)

a) stabilized a B3 phase

b) destabilized the B2 phase

a) Reduced the clearing point

b) Reduced the transition enthalpy


Brazil

Complex Fluids Group University of São Paulo, Brazil

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