Ordered Fluids and Liquid Crystals

9 Occurrence of Different Mesomorphous Phases in Ternary Systems of Amphiphilic Substances and Water

Downloaded by RUTGERS UNIV on December 28, 2017 | http://pubs.acs.org Publication Date: January 1, 1967 | doi: 10.1021/ba-1967-0063.ch009

L E O M A N D E L L , K R I S T E R F O N T E L L , and

PER

EKWALL

Laboratory for Surface Chemistry, Royal Swedish Academy of Engineering Sciences, Stockholm, Sweden

A thorough study has been made of the system sodium caprylate -decanol-water at 20°C. Various mesophases in the heterogene ous regions can be separated by centrifugation under suitable conditions. The mesomorphous substance has different in ternal structures in different concentration regions, and these structures do not change continuously into one another but repre sent separate mesophases. The regions of existence of the various mesophases are separated by two- and three-phase regions, where two or three phases occur side by side in accordance with the re quirements of the phase rule. Similar conditions have been shown in a large number of other ternary systems. A systematic study of the dependence of phase equilibrium on molecular struc ture in such ternary systems has so far disclosed five main types of phase diagram.

J η a d d i t i o n to t h e order o n t h e m o l e c u l a r l e v e l , w h i c h is c h a r a c t e r i s t i c of systems w i t h t h e r m o t r o p i c m e s o m o r p h i s m , t h e l y o t r o p i c mesomorphous systems are also distinguished b y the arrangement of aggregates i n a s u p e r l a t t i c e . T h e s e systems e x h i b i t n o t o n l y t h e j o i n i n g a n d d i r e c t i n g forces between i n d i v i d u a l molecules b u t also t h e i n t e r a c t i o n between larger m o l e c u l a r aggregates—for instance, m i c e l l e - l i k e aggregates—and a c c o u n t m u s t be t a k e n of t h e i r i n t e r n a l a r r a n g e m e n t . T h i s w o u l d appear to e x p l a i n t h e v a r i e t y of t h e i n n e r s t r u c t u r e of t h e l y o t r o p i c mesomorphous systems. L i q u i d c r y s t a l l i n e p r o d u c t s are f o r m e d i n aqueous soap systems at h i g h concentrations. T h e existence of different mesophases i n s u c h systems w a s observed b y M c B a i n (17, 18). T o w a r d t h e end of t h e 1950's L u z z a t i et al. (11,14,15,16) discovered b y x - r a y d i f f r a c t i o n v a r i o u s m e s o m o r p h o u s s t r u c tures i n these t w o - c o m p o n e n t systems a n d regarded this as a proof t h a t t h e y c o n t a i n e d different mesophases, w h i c h , however, t h e y d i d n o t separate, 89 Porter and Johnson; Ordered Fluids and Liquid Crystals Advances in Chemistry; American Chemical Society: Washington, DC, 1967.


90

ORDERED FLUIDS A N D LIQUID CRYSTALS

T h e presence i n systems of soap a n d s o a p l i k e substances of a t h i r d c o m p o n e n t w i t h a m p h i p h i l i c a n d p r e d o m i n a n t l y l i p o p h i l i c properties s t r o n g l y promotes t h e f o r m a t i o n of aqueous m e s o m o r p h o u s phases. I n s u c h t e r n a r y systems a n extensive, c o n t i n u o u s c o n c e n t r a t i o n region c o n t a i n i n g mesomorphous substances often forms, f r o m f a i r l y l o w c o n c e n t r a tions u p w a r d . T h e v i e w c o m m o n l y h e l d d u r i n g t h e 1950's a n d l a t e r t h a t there is o n l y one mesomorphous phase i n t h i s region (1, 2, 3, 12, 13, 22) w o u l d seem to be i n c o r r e c t ; o u r x - r a y d i f f r a c t i o n studies h a v e disclosed t h a t the region contains areas of different i n n e r s t r u c t u r e of t h e m e s o m o r p h o u s m a t t e r a n d t h a t d i s t i n c t m e s o m o r p h o u s phases, each w i t h i t s o w n i n n e r s t r u c t u r e , properties, a n d area of existence, c a n be separated b y c e n t r i f u g a t i o n . B e t w e e n these areas are t w o - a n d three-phase regions, where, i n c o n f o r m i t y w i t h t h e phase rule, t h e phases occur side b y side (J+-8, 10, 19, 20, 21). Previous Investigations of Sodium Decanol-Water System

Caprylate-

W e first consider a m o d e l s y s t e m of s o d i u m c a p r y l a t e , decanol, a n d water. I n F i g u r e 1 a l l t h e c o n c e n t r a t i o n areas i n w h i c h a n y mesomorphous substance at a l l has been observed are i n c l u d e d i n one extensive region r e ferred t o as ' ' l i q u i d c r y s t a l / ' R e g i o n s L\ a n d L consist of homogeneous, 2

Decanol

Water

Na-caprylate

Figure 1.

Triangular diagram of three-component system sodium caprylate-decanol-water at 20°C.

L\. Homogeneous, isotropic solutions in water L. Homogeneous, isotropic solutions in decanol L\ + J'2· Two-phase region consisting of L\ and L2 Liquid crystal" area comprises all regions where mesomorphous matter exists. Areas denoted by - f contain mesomorphous matter and homogeneous isotropic solutions in equilibrium 2

u

Porter and Johnson; Ordered Fluids and Liquid Crystals Advances in Chemistry; American Chemical Society: Washington, DC, 1967.

9.

MANDELL ET AL.

Mesomorphous

91

Phases


Decanol

Water Figure 2.

Na-caprylate Triangular diagram of three-component system sodium caprylate-decanol-water at 20°C.

L\. Homogeneous, isotropic solutions in water L. Homogeneous, isotropic solutions in decanol L\ + L . Two-phase region consisting of L\ and L Li + L.C. Two-phase region consisting of L\ and mesomorphous matter L + L.C. Two-phase region consisting of L and mesomorphous matter Liquid crystal area comprises all regions where only mesomorphous matter exists. 2

2

2

2

2

i s o t r o p i c s o l u t i o n s ; i n L i w a t e r is t h e solvent, i n L , decanol. 2

L\ extends t o

t h e w a t e r corner (as a n a r r o w region close t o t h e base l i n e , j u s t discernable o n t h e scale of t h e figure.).

T h e region L\ + L

two-phase region where solutions L\ a n d L

2

2

o n t h e extreme left is a

are i n e q u i l i b r i u m .

Within

t h e large l i q u i d c r y s t a l region there are areas w i t h a n i s o t r o p i c s o l u t i o n L\ o r L , as w e l l as t h e m e s o m o r p h o u s 2

i n d i c a t e d b y a p l u s sign.

matter.

T h e sites of s u c h areas are

I n some cases t h e s o l u t i o n w i l l u l t i m a t e l y sep

arate m o r e o r less c o m p l e t e l y f r o m t h e m e s o m o r p h o u s s u b s t a n c e ; s e p a r a t i o n c a n be effected b y c e n t r i f u g a t i o n . taining solution a n d mesomorphous F i g u r e 2 is o b t a i n e d .

complete

W h e n these regions

con

m a t t e r are m a r k e d i n t h e d i a g r a m ,

H e r e , t h e l i q u i d c r y s t a l area c o n t a i n s o n l y c o n c e n

t r a t i o n regions where there is m e s o m o r p h o u s substance b u t n o solutions. X - r a y d i f f r a c t i o n has s h o w n t h a t t h e i n n e r s t r u c t u r e of t h e m e s o m o r p h o u s m a t t e r v a r i e s f r o m one p a r t of t h e l i q u i d c r y s t a l area t o a n o t h e r (5, 6, 10).

T h e o v e r - a l l p i c t u r e of t h e x - r a y d i f f r a c t i o n p i n h o l e p a t t e r n s

p r o v i d e d b y t h e substance i n t h i s area is t h e f o l l o w i n g (10) : a l l t h e p a t t e r n s show a diffuse, w e a k , w a t e r reflection w i t h a v a l u e of 1/3.2 A . a n o t h e r reflection w i t h a v a l u e of 1/4.5 A . flection

- 1

.

-

1

for S a n d

T h e fact t h a t t h e l a t t e r r e

is i d e n t i c a l i n p o s i t i o n a n d shape t o t h a t for l i q u i d paraffin c h a i n


92

ORDERED FLUIDS A N D LIQUID CRYSTALS

h y d r o c a r b o n s indicates t h a t t h e paraffin chains of t h e a m p h i p h i l i c c o m p o u n d s i n t h e mesomorphous substance are i n a m o r e o r less l i q u i d state. I n a d d i t i o n t o these reflections there is i n t h e " l o w a n g l e " r e g i o n — t h a t i s , at angles below 10°—a series of s h a r p lines, w h i c h are as d i s t i n c t as i f t h e y were g i v e n b y a t r u l y c r y s t a l l i n e substance.

T h e s e l o w angle p a t t e r n s ,

however, differ f r o m one p a r t of t h e l i q u i d c r y s t a l region t o another. A r o u n d position ·

x - r a y d i f f r a c t i o n p a t t e r n s designated as t y p e Ε are

o b t a i n e d (10) ( F i g u r e 3 ) .

A n a l y s i s of t h e p h o t o g r a m s gives t h e r a t i o b e


tween t h e B r a g g spacings as 1:

1 / V 3 : 1/ V~4—that i s , t h e y satisfy t h e

Figure 8. Low-angle x-ray diffraction pat terns of a mesomorphous substance with type Ε hexagonal structure Bragg spacing ratio 1:1/

V8:l/\/4

c r i t e r i o n f o r a t w o - d i m e n s i o n a l h e x a g o n a l arrangement. T h e d i f f r a c t i o n d i a g r a m has a s p o t t y appearance even w h e n t h e s a m p l e is r o t a t e d . T h e spots are often arranged i n a definite h e x a g o n a l p a t t e r n , a n d occasionally p h o t o g r a m s were o b t a i n e d w i t h three concentric six-rings w i t h a r e l a t i v e displacement of 30°. T h i s suggests a s y s t e m of h e x a g o n a l l y a r r a n g e d p a r a l l e l c y l i n d e r s . T h e c y l i n d e r s themselves are composed of a m p h i p h i l i c m a t t e r — c a p r y l a t e a n d d e c a n o l — a n d t h e i r core consists of h y d r o c a r b o n chains i n a l i q u i d o r s e m i l i q u i d s t a t e ; t h e h y d r o p h i l i c e n d groups are anchored t o t h e surface of t h e c y l i n d e r s a n d are i n contact w i t h t h e w a t e r s e p a r a t i n g t h e c y l i n d e r s . T h e u n i t cell p a r a m e t e r of t h i s hexagonal n e t w o r k is 30 t o 35 A . T h e same t y p e of x - r a y d i f f r a c t i o n p a t t e r n is o b t a i n e d i n t h e p a r t s of the s y s t e m a r o u n d p o s i t i o n | (10) ( F i g u r e 4 ) ; t h i s indicates t h a t here, too, is a s i m i l a r t w o - d i m e n s i o n a l h e x a g o n a l arrangement. T h e u n i t cell p a r a m e t e r for t h e h e x a g o n a l n e t w o r k , however, is u p t o 47 Α . , a v a l u e t h a t is inconsistent w i t h t h e above m o d e l since t h e p r o p o r t i o n of w a t e r is too l o w i n r e l a t i o n t o t h e a m o u n t of a m p h i p h i l i c substance. I t is therefore neces s a r y t o assume w h a t m a y be referred t o as a n inverse h e x a g o n a l s t r u c t u r e ,



9.

MANDELL ET AL.

Mesomorphous

93

Phases

Figure 4- Low-angle x-ray diffraction pat tern of a mesomor phous substance with type F hexagonal structure Bragg spacing ratio

1:1/V8:1/V4 w i t h l o n g p a r a l l e l w a t e r c y l i n d e r s i n h e x a g o n a l a r r a n g e m e n t , separated b y a l i q u i d or s e m i l i q u i d h y d r o c a r b o n e n v i r o n m e n t consisting of molecules of the a m p h i p h i l e s w i t h t h e h y d r o p h i l i c groups f a c i n g the water. W e c a l l this s t r u c t u r e t y p e F . I n the m i d d l e of t h e s y s t e m , a r o u n d p o i n t s X i n F i g u r e 2, a m e s o m o r p h i c s t r u c t u r e was encountered t h a t gave x - r a y d i f f r a c t i o n p a t t e r n s of a c o m p l e t e l y different k i n d (10) ( F i g u r e 5). T h e s e show u p t o three d i s t i n c t reflections, whose B r a g g spacings are i n the r a t i o 1 : 1 / 2 : 1 / 3 . Here, t h e n , is a n arrangement w i t h l i n e a r s y m m e t r y consisting of layers of a m p h i p h i l i c substance a l t e r n a t i n g w i t h layers of w a t e r molecules. T h e for m e r are o b v i o u s l y c o m p o s e d of double layers of a m p h i p h i l i c molecules, arranged w i t h the h y d r o p h i l i c groups facing o u t w a r d t o w a r d t h e w a t e r a n d

Figure 5. Low-angle x-ray diffraction patterns of mesomorphous substances with lamellar structures types D (left) and C (right) Bragg spacing ratio 1: Λ: Α λ

λ


O R D E R E D FLUIDS A N D LIQUID CRYSTALS «20 A

r

100

80 9

Phase Β Phase D

y

60 40 10

20

30

50

40

moles of H 0


2

molts of (No Cy + Decanol) 100 A

80

Phase Β

60

40 10

20 moles of H 0

30

40

2

moles of (N a Cy4-Decanol) 45 A Phase C

401-

35 PhaseD 30

8 10 12 moles of H 0

14

16

2

moles of (N a C y 4-Decanol) Figure 6. Dependence of Bragg spacing on water content of meso morphous substance, sodium caprylate-decanol-water, at 20°C. Upper. Center. Lower.

Transition from mesophase D to mesophase B. Molar ratio for decanol-sodium caprylate. Meso phase D = 2.4, mesophase Β = 1.4 to 1.9 Transition from mesophase C to mesophase B. Molar ratio for decanol-sodium caprylate X 1.56 Transition from mesophase D to mesophase C. Molar ratio for decanol-sodium caprylate X 1.56


9.

MANDELL ET AL.

Mesomorphous

Phases

95


the m o r e or less p a r a l l e l h y d r o c a r b o n chains i n w a r d , f o r m i n g a l i q u i d o r semiliquid hydrocarbon region w i t h i n the double layer. W e have, h o w ever, f o u n d three d i s t i n c t s u b t y p e s w i t h l i n e a r s y m m e t r y , w h i c h differ i n t h a t t h e i r B r a g g spacings v a r y d i f f e r e n t l y w i t h t h e w a t e r content of the mesomorphous substance ( F i g u r e 6) (5). T h e s e w e c a l l t y p e s D , C., a n d B . T h e m o s t extensive is t y p e D . I f a l l t h e mesomorphous m a t t e r of t h e l i q u i d c r y s t a l area belonged to one phase, there w o u l d be a c o n t i n u o u s change of t h e different i n n e r s t r u c tures i n t o another. H o w e v e r , t h i s was n o t t h e case, for each s t r u c t u r e represents a d i s t i n c t phase, a n d t h e areas c o n t a i n i n g homogeneous m e s o phases are separated f r o m one a n o t h e r b y t w o - a n d three-phase zones, w i t h i n w h i c h the t w o or three phases, r e s p e c t i v e l y , exist i n e q u i l i b r i u m (4, 5, 0, 10). Is There a True Equilibrium

State?

T o e x a m i n e t h e phase e q u i l i b r i a i n t h e s y s t e m m e n t i o n e d , m i x t u r e s of s o d i u m c a p r y l a t e , d e c a n o l , a n d w a t e r were p r e p a r e d i n different w a y s . T h e t i m e to r e a c h e q u i l i b r i u m was shortened b y m i x i n g , v i g o r o u s s h a k i n g , a n d p r o l o n g e d w a r m i n g . I n some experiments finely p o w d e r e d s o d i u m c a p r y l a t e a n d d e c a n o l were m i x e d t h o r o u g h l y a n d a l l o w e d to s t a n d at v a r i ous t e m p e r a t u r e s before w a t e r was a d d e d , e i t h e r i n s m a l l p o r t i o n s at d i f f e r ent i n t e r v a l s or a l l at once. T h e m i x t u r e was s u b s e q u e n t l y t r e a t e d at d i f ferent t e m p e r a t u r e s . I n o t h e r experiments s o d i u m c a p r y l a t e a n d w a t e r were m i x e d a n d h e a t e d u n t i l a homogeneous s o l u t i o n was o b t a i n e d or u n t i l there w a s no f u r t h e r c h a n g e ; d e c a n o l w a s t h e n a d d e d , e i t h e r i n s m a l l p o r tions at different i n t e r v a l s or as a single v o l u m e . I n t h e o t h e r e x p e r i m e n t s a l l three components were m i x e d , a n d the r e a c t i o n was p r o m o t e d b y t h o r o u g h m i x i n g a n d a g i t a t i o n for different periods a n d at a range of f a i r l y h i g h t e m p e r a t u r e s (100° to 1 8 0 ° C ) . A l l the m i x t u r e s were m i x e d i n glass a m p o u l e s , w h i c h were t h e n sealed. I r r e s p e c t i v e of t h e m e t h o d of t r e a t m e n t , a l l t h e samples were cooled to r o o m t e m p e r a t u r e w i t h c o n s t a n t a g i t a t i o n . T h e p e r i o d of storage was never less t h a n 24 h o u r s , even i f e q u i l i b r i u m h a d been o b t a i n e d i n a shorter t i m e , a n d some were stored for as l o n g as 13 weeks. W h a t e v e r t h e m e t h o d of p r e p a r a t i o n , t h e state of e q u i l i b r i u m o b t a i n e d for each m i x t u r e was a l w a y s t h e same (5, 6). T h a t t h e systems were i n t r u e e q u i l i b r i u m is e v i d e n t f r o m t h e findings g i v e n i n the f o l l o w i n g tables for samples w i t h t h e same c o m p o s i t i o n b u t different t r e a t m e n t . I r r e s p e c t i v e of t h e m e t h o d of t r e a t m e n t , samples h a v i n g t h e same c o m p o s i t i o n gave t h e same x - r a y d i f f r a c t i o n p a t t e r n s w i t h the same B r a g g s p a c i n g . T h e y also d i s p l a y e d the same m i c r o s c o p i c t e x t u r e a n d o t h e r ex t e r n a l properties. I n the examples presented i n T a b l e I c e n t r i f u g a t i o n d i d n o t result i n s e p a r a t i o n i n t o l a y e r s , n o r d i d i t disclose a n y difference i n x - r a y p a t t e r n or e x t e r n a l p r o p e r t i e s ; w e therefore concluded t h a t t h e samples were homogeneous f r o m t h e s t a n d p o i n t of phase. A l l the p r e p a r a t i o n s i n T a b l e s I I a n d I I I separated i n t w o l a y e r s , w h i c h differed i n c o m p o s i t i o n , x - r a y d i f f r a c t i o n p a t t e r n , a n d m i c r o s c o p i c t e x t u r e .


96

O R D E R E D

F L U I D S

A N D

L I Q U I D

Table I.

C R Y S T A L S

Samples from Storage

Initial Composition, % Sample

NaCy

E l

41.0

^l^n^

H0

Dec.

48.0

11.0

2

Treatment

Days

Heating to homogeneous solution(130°C.). Cooling to

23

20° in air by agitation (ca. 5°/ i ) Heating to homogeneous solution(130°). Cooling in stages to 20° over 5 days Heating to homogeneous solution(130°). Rapid cooling in ice bath. Warming in stages to 20°, over 5 days


m

E2

41.0

48.0

11.0

Ε 3

41.0

48.0

11.0

D 1

30.0

31.0

39.0

D 2

30.0

31.0

39.0

D3

30.0

31.0

39.0

n u t e

81

22

Heating to homogeneous solution(130°). Cooling to 20° in air by agitation (ca. 5 ° / minute) Heating to homogeneous solution(130°). Cooling i n stages to 20°, over 5 days Heating to homogeneous solution (130°). Rapid cooling in ice bath. Warming in stages to 20°, over 5 days

21

81

22

Table II. Preparations Samples w i t h the Same C o m p o s i t i o n Centrifuge

Data

Top

Approximate Storage Initial Composition, Sample I

E

2

b

3

C

4

d

5

e

NaCy

Distribution

Time %

„,

m

o

fry r

Days

Layer

%

W

4

p

M

g

T

i

m

e

^

fyO

Dec.

hrs.

3 9 . 5

3 9 . 5

2 1 . 0

9

100,000

17

3 9 . 5

3 9 . 5

2 1 . 0

7

100,000

39.5

3 9 . 5

2 1 . 0

30

3 9 . 5

3 9 . 5

2 1 . 0

39.5

3 9 . 5

2 1 . 0

Volume N

o

o

f

layers

T

o

p

B

o

t

t

o

m

Composition, NaCy

Ηφ

layer

2

5 8 . 0

4 2 . 0

3 9 . 0

3 2 . 9

2 8 . 1

16

2

5 7 . 0

4 3 . 0

3 8 . 8

3 2 . 8

28.4

100,000

15

2

5G.0

4 4 . 0

3 8 . 8

32.9

2 8 . 3

G

100,000

10

2

5 0 . 0

4 4 . 0

38.9

3 3 . 0

2 8 . 1

0

100,000

10

2

5 0 . 0

4 4 . 0

3 9 . 0

33.1

27.9

Treatment a

b

c

Heating

to

100°C.

%

layer

N o n h o m o g e -

neous solution. Cooling in air b y agitation (ca. 5 ° / m i n u t e ) Heating to homogeneous solution (ca. 160°). Cooling to 20° in air b y agitation (ca. 5 ° / m n i u t e ) A s preparation 2


Dee.

9.

M A N D E L L

Mesomorphous

E TA L .

97

Phases

One-Phase Regions X-Ray Diffraction Data


Bragg spacing, Α.

Structure

Centrifuge Data

Micro scopic Texture

Field, g

Time, hr.

32.0, 18.4, 15.9

Hexagonal type Ε

Type Ε

130,000

3

31.5,18.2,15.8

Hexagonal type Ε

Type Ε

130,000

4

31.6, 18.5, 15.9

Hexagonal type Ε

Type Ε

130,000

3

31.8, 16.0, 10.6

Linear type D

Type D

130,000

5

31.8,

16.0

Linear type D

Type D

130,000

4

32.2,

16.0

Linear typeD

Type D

130,000

6

Resuit

No separation. No change in properties

No separation. N o change in properties

from a Two-Phase Region but Different Treatment, Ε + Top

X-Ray

Micro

Bottom

Diffraction

texture

spacing, A.

Structure

Micro-

Data

Bragg

scopic

D

Layer

Composition, NaCy

%

X-Ray

Diffraction

scopic

H0

Dec.

texture

2

Layer

Type D

Linear, type D

40.7

48.0

11.3

Type Ε

Hexagonal, type Ε

Type D

Linear, type D

40.7

48.1

11.2

Type Ε

Hexagonal, type Ε

Type D

Linear, type D

40.6

48.2

11.2

Type Ε

Hexagonal, type Ε

Type D

Linear, type D

40.6

48.2

11.2

Type Ε

Hexagonal, type Ε

Type D

Linear, type D

40.8

48.4

10.8

Type Ε

Hexagonal, type Ε

d

e

30.2,

15.0

Data

Bragg Structure

spacing, A.

I 32.0, 18.3, I 16.0

H e a t i n g to homogeneous solution (ca. 1 6 0 ° ) . R a p i d cooling i n ice bath. W a r m i n g i n stages to 2 0 ° over 3 d a y s H e a t i n g to homogeneous solution (160°). C o o l i n g i n stages to 2 0 ° over 5 d a y s


98

ORDERED

FLUIDS A N D LIQUID

CRYSTALS

Table III. Preparations Samples w i t h Same Composition Centrifuge

Data

Top

Approximate Storage Initial


Sample

NaCy

Distribution 6?/

Volume

~To~p

Bottom

Time %

Composition,

t20°C.,

a

Days

Layer

%

Field,

Time,

g

No.

hr.

of

layers

Composition, NaCy

H2O

%

H2O'

Dec.

layer

layer

I

e

21.0

25.0

54.0

10

20,000

17

2

49

51

17.3

20.4

62.3

Dec.

2

6

21.0

25.0

54.0

30

20,000

19

2

50

50

17.3

20.2

62.5

3

C

21.0

25.0

54.0

40

20,000

16

2

52

48

17.3

20.4

62.3

4*

21.0

25.0

54.0

6

20,000

17

2

51

49

17.4

20.1

62.5

5·

21.0

25.0

54.0

6

20,000

17

2

51

49

17.4

20.2

62.4

6/

21.0

25.0

54.0

3

20,000

16

2

51

49

17.3

20.4

62.3

Treatment a

b c

H e a t i n g to homogeneous solution. C o o l i n g to 2 0 ° C . i n a i r b y a g i t a t i o n (ca. 5 ° / m i n u t e ) A s i n preparation 1 A s i n preparation 1

Table IV.

Preparation

Samples w i t h the Same Composition Top

Initial Composition, Sample

l

a

NaCy

^Time %

H2O

Dec.

36.0

47.2

16.8

at20°C.,

Centrifuge

Data

Micro-

Field

Time,

g

hr.

5

100,000

17

3

Days

Layer

No. layers

of

Composition, NaCy

%

scopic

H2O

Dec.

texture

36.2

34.3

29.5

Type D

2

b

36.0

47.2

16.8

28

70,000

16

3

36.4

33.5

30.1

Type D

3

C

36.0

47.2

16.8

6

100,000

16

3

36.1

34.2

29.7

Type D

47.2

16.8

100,000

17

3

36.2

34.3

29.5

Type D

4

Ordered Fluids and Liquid Crystals

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