Mixed Adsorbed Film of 1-Octadecanol and Dodecylammonium

23 Mixed Adsorbed Film of 1-Octadecanol and Dodecylammonium Chloride at the Hexane-Water Interface 1

Yoshiteru Hayami and Kinsi Motomura

2

Downloaded by UNIV LAVAL on February 16, 2013 | http://pubs.acs.org Publication Date: June 5, 1986 | doi: 10.1021/bk-1986-0311.ch023

1

Chikushi Jogakuen Junior College, Dazaifu, Fukuoka 818-01, Japan Department of Chemistry, Faculty of Science, Kyushu University 33, Fukuoka 812, Japan

2

The interfacial tension of mixed adsorbed films of 1-octadecanol and dodecylammonium chloride has been measured as a function of temperature at various bulk concentrations under atmospheric pressure. The transition interfacial pressure of 1-octadecanol film has been observed to increase with the addition of dodecylammonium chloride and then to disappear. The interfacial pressure vs mean area per adsorbed molecule curves have been illustrated at a constant mole fraction of adsorbed molecules. With the aid of the thermodynamic treatment developed previously, we find that the mutual interaction between 1-octadecanol and dodecylammonium chloride molecules in the expanded state is similar in magnitude to the interaction between the same kind of film-forming molecules. G e n e r a l l y , t h e r e a r e two approaches t o t h e i n v e s t i g a t i o n o f mixed a d s o r b e d f i l m s a t an o i l / w a t e r i n t e r f a c e . One way i s t o s t u d y mixed a d s o r p t i o n o f s u r f a c t a n t s from t h e same b u l k phase and t h e o t h e r i s t o s t u d y a d s o r p t i o n from b o t h o f t h e b u l k p h a s e s . The former has been done by many workers from t h e p h y s i c o c h e m i c a l v i e w p o i n t t o c l a r i f y t h e d i f f e r e n c e i n m o l e c u l a r i n t e r a c t i o n between t h e a d s o r b e d s t a t e and t h e b u l k s t a t e . The l a t t e r has been made m o s t l y from t h e p r a c t i c a l p o i n t o f view, e.g., s o l v e n t e x t r a c t i o n and complex-forming r e a c t i o n s t h a t t a k e p l a c e a t t h e i n t e r f a c e , though l i t t l e i s known c o n c e r n i n g t h e thermodynamic v i e w p o i n t (1) · The thermodynamic s t u d y i s a c t u a l l y u s e f u l t o e l u c i d a t e the behavior o f f i l m molecules i n the adsorbed s t a t e . I t i s i n t e r e s t i n g t o employ t h e system c o n s i s t i n g o f mixed a d s o r b e d f i l m o f 1 - o c t a d e c a n o l and dodecylammonium c h l o r i d e because t h e former shows t h e phase t r a n s i t i o n from an expanded t o a condensed s t a t e (2)· The i n t e r f a c i a l t e n s i o n was measured as a f u n c t i o n o f temperature a t v a r i o u s b u l k c o n c e n t r a t i o n s under a t m o s p h e r i c p r e s s u r e and t h e m o l e c u l a r i n t e r a c t i o n between f i l m - f o r m i n g components was considered. 0097-6156/ 86/ 0311 -0312506.00/ 0 © 1986 American Chemical Society

In Phenomena in Mixed Surfactant Systems; Scamehorn, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1986.

23.

1-Octadecanol and Dodecylammonium Chloride

HAYAMI A N D M O T O M U R A

313

Experimental 1-Octadecanol

was

recrystallized

vacuum d i s t i l l a t i o n / chromatography. mixture fact on

of

that

the

passing

distilled after

tension through

vs an

from a l k a l i n e

refluxing

confirmed


and water,

by

for

the

activated day.

of

The

interfacial

tension

description

of

the

curve.

of

interfacial was

of

by

distilled was

distilled

the

and the

was

Water

hexane

water

and water between

pendant

method

a

the

concentration

Hexane

tension

measured

apparatus

from

c o n f i r m e d by

alumina column. solution

by

gas-liquid

recrystallized

p u r i t y was

The p u r i t y

the

was

fractionation

by

c r i t i c a l micelle

permanganate

one

value

the

after

checked

concentration

Detailed

previously

and i t s

h a d no minimum n e a r

surface

after

from hexane

p u r i t y was

Dodecylammonium c h l o r i d e

ethanol it

and i t s

was

them. drop

was

method.

given

(3_) .

Results The T,

interfacial molality

tension

m^ o f

γ

dodecylammonium c h l o r i d e molality

was

Figure

1

temperature curves

except

for

the

have

from

condensed

temperature J2?2

the

various

chloride the

in

increased

shows

at

was

measured

1-octadecanol

water

up

to

plots

under

the

a

function

atmospheric

solubility

interfacial

for

m^ =

which

with

7.54

solution

tension

The

against A l l

the

dodecylammonium

the

phase

The phase

increasing

of

pressure.

mmol k g " l .

of

represents

state.

temperature

limit.

the

expanded

of

and m o l a l i t y

of

concentrated

to

as

hexane,

m^ v a l u e s

a break point

lowers

in

transition

transition

and d i s a p p e a r s

above

a

certain

value. In

with

the

the

present

thermodynamics interfacial

to

the

γ

nty u n d e r

298.15 for

values

Κ is

the

shown

of

increasing

the

at

in

Figure

state

against

and a

the

K.

In

it

is

the

the

lower

one

has

for

point

is

to

in

γ

apply

the

the

c o n c e n t r a t i o n s m^ a n d m ^ . 1,

the

concentration

The c u r v e

transition

variation order

required that

Κ from F i g u r e

that

2.

only

298.15

results,

298.15

condition

discuss at

variation mÇ i s

a higher

the

negative

condensed

seen

to

of

fixed

at slope

state.

increase

The

with

m^.

the

same m a n n e r , curves

we at

can

obtain

fixed

the

m^ v a l u e

interfacial at

298.15

tension

Κ shown

vs

in

3.

Contrary have

will

and plotted

γ

phase

concentration Figure

is

of

the

expanded

27?2 v a l u e In

we

experimental

tension

Taking with

paper,

concentrations

lower

to

the

γ

and h i g h e r

vs

zn^ c u r v e s

negative

and

condensed

states,

respectively.

the

slopes

γ

and γ

and

m^

r

of

vs

in

slopes

vs

Figure in

In curves

2,

Figure

the

curves

3 are

addition,

it

increase

the is

with

which

expanded

found increase

that i n mÇ

respectively.

Discussion Taking

into

immiscible soluble of

the

only

in Τ,

that

the

1-octadecanol

hexane

interfacial

temperature (4)

consideration and t h a t

and water

tension

pressure

p,

γ

solvents

are

practically

and dodecylammonium c h l o r i d e respectively,

c a n be

molality

expressed m^,

the as

a

total

function

and m o l a l i t y

are

differential

m^ a s

of follows

:


314


P H E N O M E N A IN M I X E D S U R F A C T A N T S Y S T E M S

0

1

2

3

w

-, kg , -1 m2 // mmol F i g u r e 2.

Interfacial

tension vs concentration

curves a t

1

c o n s t a n t m® and 298 15 Κ: (1) m ° = 0 mmol k g " ; (2) 2 3 7 ; (3) Q

7.54;

(4) 13.22;

(5) 18.66;

0

(6) 23.89;

(7) 29.41;

(8) 33.73.


23.



Ομ^/Βπξ)

dy = - AsdT + Avdp where

the

subscripts

respectively.

condition

of

- 2T%[d\x±/dm%) Tfpdn%

Tfp

1 and 2 are

chloride, The

àm^

1-octadecanol

On d e r i v i n g E q u a t i o n

electroneutrality

for

interfacial densities

dodecylammonium c h l o r i d e

of

are

the

(

+

used

the

layer.

1-octadecanol

TfPfm

(1)

and dodecylammonium 1, we h a v e

interfacial

evaluated,

^/RT{[(df/dm l)/f]

= - (^/^)

315

and

of

respectively,

by

(Ι/ιπξ)}

(2)

and

Γ" = - m^dy/dm ) W


2

Here,

the

correction for

calculating to

(3)

o/2RT

TiPrm

(5) ,

but

the

activity

not

in

a

low

concentration range.

2 to

the

γ

values

vs

of

results

concentration and

at

change

on the

vs

5 express

the

expanded

film

value

at The

curves phase

in Figure

transition

the

expanded

found f o r

the

decreases

with

with

constant

of

shown

to

the

in Figure

in

to

the

film,

that

both

the

and the

value

at

nty.

the

mean a r e a p e r the

can o b t a i n

6(a),

The

vs

condensed film

Equation the

discontinuous

condensed

increasing

make c l e a r

2 a n d 4, we

the

expanded

Π vs to

The

4 and on the

from

increasing

useful

Figures

m® a s

respectively,

are

4 a n d 5.

in limited

3 and

respectively.

shown i n F i g u r e s

i n t e r f a c i a l pressure

use

Equation

a n d m®,

is

A curves

of

as a f u n c t i o n o f

decreases

molecule

Application

used τηΐ? i s

2 and 3 g i v e s

constant

constant

making

It

is

in Figures

and from

respectively.

f

Γ§ b e c a u s e

curves

298.15 Κ a r e

Figure

coefficient

calculating

where

film

the

adsorbed behavior.

Π vs

By

A curves

Π and Ά are

at

defined,

by

Π = γ° - γ

(4)

and

Ά = 1 / * ( Γ ξ + Γ§)

(5)

Α

In

the

above

equations,

hexane/water Π values, film

of

that

the

interface

except

for

condensed

the

t r a n s i t i o n when In

obtained the pure

the

Π values,

the

The

Π vs at

i n t e r f a c i a l tension A v o g a d r o ' s number.

values

phase

area

the

Π values of

change

state

at

the

pure

pure

s h o u l d be

lowest

adsorbed noted

adsorbed f i l m

from

i n t e r f a c i a l pressure

IT v s

A curves

for

= 0,

at

constant

in Figure

6(b).

represent

the

dodecylammonium c h l o r i d e a t

exhibit

the

of

A l l the

of

decreases.

the

except

of

of It

m^.

the

3 a n d 5 a n d shown

of

curves

condensed

obtained

the

is give

expanded

from F i g u r e s

adsorbed f i l m

the A

given the

a s i m i l a r manner,

lowest

However, the

to

at

exhibit

the

is

= 0,

1-octadecanol curves

γ°

and N

the

phase

transition

are Again,

Π values

all of

the

g i v e n mîj v a l u e s . from

the

expanded

to

state. A curve of

a constant

a mixed i n s o l u b l e

composition

of

monolayer

is

generally

f i l m - f o r m i n g components


present



316



23.

l-Octadecanol and Dodecylammonium Chloride


Figure

5

constant (4)

2o0;

Interfacial density

D

w (5)

and 2 9 8 · 1 5

Κ:

(1)

of m

w

1-octadecanol = 0 mmol k g

-1

;

vs (2)

m

curves 0.4;

(3)

3o0.


317

at l 0; o



0

«

1

I

I

0

I

1

L

2

Ά / nm Figure

6.

curves

at

16;

(5)

(a)

Interfacial

constant

24;

(6)

28;

area per molecule (2)

0.4;

(3)

1.0;

(7)

curves (4)

pressure

(1)

m^z

32

(b)

0

at

2.0;

vs

mean a r e a p e r

m^ = 0 m m o l k g

Interfacial

constant (5)

\ ·

3 0 o

W m^z

(1)

(2)

4;

molecule (3)

pressure W

=

vs

8;

(4)

mean

0 mmol k g

o


-1

;

23. in

the

6(a) a

monolayer.

and 6(b)

similar

constant

X§

do

Π vs the

defined = Γ^/(Γξ

satisfy

A curve

value

of

for the

Π vs

condensed

A curves

might

be

those


We

is

in

are

at

to

= μί-(Τ,ρ,γ)

In

this

in

the

of

component

the

film

by

in we

Figures can

draw

holding

dodecylammonium

in

for

7.

small

Figure the

μ^ i s

adsorbed

of

It

mole

chloride

is

repulsion 7 are

more

purpose

seen

that

fraction

range.

between appropriate

of

adsorbed paper

surfactant

behavior

coefficients

pure

previous

In

Figure

electrostatic

behavior

thermodynamic

of

film

( , p , * § r

Substitution *l

= ai

where

a

1

is

the

amplified the

error all

Consequently, the

between expanded kind

of

value

the

constant

the we of is

(9)

mole

of

pure

component

film

is

Π in in

curves

Figure the

in

Taking

conversion at

the

effectively is

almost

unity

of

into the

lower

said

to

in

magnitude

to

the

the

account

mole the

interfacial be

the one

mean

density

interfacial

zero.

and hence

The

against

and dodecylammonium c h l o r i d e

similar

constituent

8.

i .

plotted

Figure 8 are

find f5

in

^ Η

adsorbed molecule

1-octadecanol state

Equation 8 results

expanded

inherent

area per

pressure,

Γ

area per

area Ά of X^ a t

fraction

that

Equation 7 into

+ Κ Τ θ 1 η ^ / 3 Π )

molecular

into

of

fairly

This

linear.

result

mutual

molecules between

implies

interaction the

molecules.


in

the

same


320

PHENOMENA IN MIXED SURFACTANT SYSTEMS

0

1

A / nm F i g u r e 7.

2

I n t e r f a c i a l p r e s s u r e v s mean a r e a p e r m o l e c u l e

at constant Q 0.4;

3

2

(1) ^

= 0;

curves

(2) 0.004; (3) 0.01; (4) 0.2; (5)

(6) 0.6; (7) 0.8; (8) 1.0.

F i g u r e 8.

Mean a r e a p e r m o l e c u l e

v s mole f r a c t i o n o f

dodecylammonium c h l o r i d e c u r v e s a t c o n s t a n t Π : ( l ) I I = (2) 10; (3) 15.

1

6mNm ;


23.

HAYAMI AND MOTOMURA


321

Literature Cited 1. Hutchinson, E. J. Colloid Sci. 1948, 3, 521-9. 2. Matubayasi, N.; Motomura, K.; Aratono, M.; Matuura, R. Bull. Chem. Soc. Jpn. 1978, 51, 2800-3. 3. Motomura, K.; Matubayasi, N.; Aratono, M.; Matuura, R. J. Colloid Interface Sci. 1978, 64, 356-61. 4. Motomura, K. Advan. Colloid Interface Sci. 1980, 12, 1-42. 5. Unpublished data. 6. Motomura, K.; Yano, T.; Ikematsu, M.; Matuo, H.; Matuura, R. J. Colloid Interface Sci. 1979, 69, 209-16.


Received January 15, 1986


Mixed Adsorbed Film of 1-Octadecanol and Dodecylammonium

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