chapter 5 interactions between bisphosphate geminis and...

Chapter 5

Interactions between Bisphosphate

Geminis and Sodium Lauryl Ether

Sulphate

110

5.1 Introduction

The physiochemical and surface active properties of mixed surfactants are of more inter-

est and useful than pure surfactants, for industrial applications. By virtue of differences

in the tail and head groups of the surfactants, mixed surfactants may show composi-

tion dependent micellization, mutual interaction, solvation, micellar shape, etc. For

the mixture of two surfactants undergoing micelle formation above a critical micelles

concentration (CMC), the solution properties fall either between or outside the solution

properties of the two-single surfactant solutions. This is also the case for the CMC of a

binary surfactant solution. Clint [Clint, 1975] has given the relation between mole frac-

tion and CMC of the ith component for ideal mixtures, and Rubingh [Rubingh, 1979]

has made a comprehensive theoretical attempt to deal with non-ideal mixture on the ba-

sis of the regular solution theory (RST). In solution containing two or more surfactants,

the tendency of aggregated structures to form is substantially different from that in so-

lutions having only pure water [Tikariha et al. , 2011]. Such different tendency results

in dramatic change in properties and behavior of mixed surfactants compared to that of

a single surfactant. Practical formulations often requires the addition of surfactants to

help in regulating the physical properties of the product or improve it’s stability. The

stability of the mixed micelles depends on two factors (i) coulombic interaction between

ionic head groups and (ii) chain length of the surfactant tail groups. In many practical

applications, the properties of surfactants are important and attractive [Rosen, 1989]. A

mixed micellar solution is a representation of a mixed micelle, mixed monolayer at the

air/water interface and mixed bilayer aggregate at the solid interface [Tikariha et al. ,

2011].

In the present work mixed micellization of anionic bisphosphate gemini surfactants

with sodium lauryl ether sulphate (SLES) was studied. Gemini surfactants were used as

an additive. The purpose of the present study is to investigate the interactions between

a mixed surfactant system (anionic monomeric surfactants with sulphate and anionic

gemini surfactant system with phosphate head group). To our knowledge there hasn’t

been any report published on the mixed micellization of the surfactant system consisting

111

of a phosphate gemini and SLES. SLES is a very important surfactant in many surfac-

tant based formulations, owing to it’s very good foaming power. The present study is an

attempt to find out the compatibility of phosphate gemini surfactants with SLES. This

study has been carried out by surface tension measurements, dynamic surface tension

analysis and foamability of the mixed surfactant systems (SLES + m− 3−m geminis

and SLES + m−5−m geminis). The effect of chain length of the gemini surfactant on

the interaction parameter was studied.

5.2 Materials and Methods

The as synthesized six bisphosphate gemini surfactants (m−3−m and m−5−m gem-

inis), described in chapter 2, were used. Commercial sample of sodium lauryl ether

sulfate (SLES) was obtained from M/s Galaxy Surfactants Pvt. Ltd., India. SLES com-

prised of 60% C12 chain and 40% C14 chain surfactant and the ethoxylation was 2 mol

per mol carbon chain. Distilled water was used for preparing all the surfactant solutions.

The equilibrium surface tension, dynamic surface tension and foamability measure-

ments were carried out using the same procedures discussed in earlier chapters. Hori-

zontal Impinging Jet, foaming apparatus was used for foamability studies.

O

S

O

NaO O

O

R2

R = C12H25

sodium lauryl ether sulphate

Figure 5.1: Structure of SLES

112

5.3 Results and Discussion

5.3.1 Critical Micelle Concentration (CMC)

The CMC of mixed micellar systems of SLES and anionic phosphate gemini surfactants

(m−3−m and m−5−m) in aqueous solutions was investigated, using surface tension

measurements. The surface tension was measured using Wilhelmy plate method on

Kruss K-11 tensiometer, at temperature 25 ± 10C. The CMC value of SLES was found

to be 0.99 mM , Amin value found to be 61 A2. The CMCs and interfacial properties

of the mixture of SLES/geminis was reported in Table 5.1 -5.2. The surface tension

plots were shown in figures 5.2- 5.8. The surface tension results were accurate within

the range of ±0.2 mN/m. It was observed that with increasing mole fraction of gem-

ini surfactants the CMC values decreases, this was observed for both m− 3−m and

m− 5−m geminis. The Amin values were changed drastically for the mixtures, more

than that of individual surfactants, which indicates that the adsorption of the mixed sur-

factants at air/water interface is less than compared to that of the individual surfactants.

Authors Rosen and Zhou [Rosen, 1982; Zhu et al. , 1991] also observed the same ex-

pansion behavior which was attributed to the dissimilarity in the nature of interaction

among hydrophobic groups and hydrophilic groups in the mixed adsorbed layer. In

case of structurally similar hydrocarbon tails, hydrophobic interactions occur at small

distances, whereas ion–dipole interactions among anisotropic head groups are effective

at relatively larger distances. In the case of SLES/m−3−m and SLES/m−5−m sys-

tems, larger Amin values were found because of the repulsive interactions instead of the

attractive forces between the hydrophobic as well as hydrophilic head groups of SLES

and gemini surfactants.

5.3.2 Interactions between mixed anionic surfactants

The commercial products are always comprised of a mixed surfactant system, because

economically synthesis of each component is not viable option. A mixed surfactant

system is often superior in performance to individual surfactants. There is a substantial

113

difference in the micellization tendency of mixtures of two or more surfactants as com-

pared to a single surfactant. This results in a dramatic change in properties and behavior

of mixed surfactants as compared to any single surfactant. Hence it is necessary to in-

vestigate the nature of interactions (synergistic/antagonistic) and the factors affecting

the interactions [Suradkar and Bhagwat, 2006]. A lower CMC of mixture than indi-

vidual surfactants is considered as synergy. The synergistic interactions between the

mixed surfactants is useful from the application point of view. The interaction between

the surfactants can be determined using models for mixed micellization. These mod-

els are based on an equilibrium thermodynamic approach [Ogino and Abe, 1993]. The

pseudo-phase separation model assumes that that the mixed micelle can be treated as

a separate phase. The pseudo-phase separation approach is a very useful tool for the

description of micelle formation [Hassan et al. , 1995]. Clint [Clint, 1975] proposed an

equation , for the CMC of the ideal mixture of two surfactants:

1Cmix

=x′1

C1+

(1− x′1)

C2(5.1)

Where x′1 is the bulk solution mole fraction of surfactant 1 in the mixture; C1, C2

and Cmix are the CMCs of the pure surfactant 1, 2 and mixed system, respectively.

The ideal solution theory has been successful in explaining the properties of mixtures

composed of surfactants with similar chemical structures, however deviations occur for

mixtures containing chemically dissimilar surfactants. The non-ideal behavior of mixed

surfactant systems was described by Rubingh [Rubingh, 1979], the model was based on

Regular Solution Theory. The non-ideal form of equation 5.1. can be given as;

1Cmix

=x′1

C1 f1+

(1− x′1)

C2 f2(5.2)

ln( f1) = β (1− x1)2 (5.3)

ln( f2) = β (x1)2 (5.4)

114

where x1 and x2 are the mole fractions of the surfactant 1 and surfactant 2, respec-

tively, in the mixed micelle. β is the interaction parameter that is usually obtained

by fitting the experimental data of mixture CMCs as a function of bulk mole fractions

x′1 of surfactant. Assuming a constant value of interaction parameter β , across the

whole range of mole fractions, it is possible to solve for x1 and hence predict the mixed

CMCs. The interaction parameter is a measure of the extent of net (pairwise) interaction

between the surfactants within the micelles resulting in their deviation from the ideal

behavior. In order to obtain valid interaction parameter β values that do not change sig-

nificantly with change in the ratio of surfactant in the mixture, the following conditions

must be met [Rosen, 2004];

1) The two surfactants must be molecularly homogeneous and free from surface

active impurities.

2) Since the derivation of equation 5.2 and 5.4 are based upon the assumption that

the mixed micelle or monolayer can be considered to contain only surfactants, these

structures are considered to contain no free water, and all the present water can be

considered to bound to the hydrophilic head groups,

3) Since equations 5.2 and 5.4 neglect counterion effects, all solutions containing

ionic surfactants should have the same total ionic strength, with a swamping excess of

any counterion.

The surfactant forms an aggregate or remains as a free monomer in a solution. The

total surfactant concentration is just incrementally larger than Cmix, then the monomer

composition coincides with the overall surfactant composition. This indicates that more

number of free surfactant monomers are present in the solution rather than micelles. The

number of micelles will be increased with an increase in total surfactant concentration.

The mixture CMC, Cmix, is fitted with eq 5.2, which is also known as a Margules one-

constant equation. Such a treatment gives a constant value of interaction parameter at

all bulk solution mole fractions x′1[Suradkar and Bhagwat, 2006].

The value of interaction parameter is then substituted in eq 5.2 to compute the values

of micellar mole fraction x1 at each bulk solution mole fraction x′1. The plots of Cmix

115

against Gemini bulk solution mole fraction x′1 are shown in Figures 5.10- 5.15.

The conditions for synergism or negative synergism in a mixture containing two

surfactants (in the absence of second liquid phase) have been shown mathematically

[Rosen, 1989] to be the following:

(1) For synergism, the interaction parameter must be negative and |β | > |ln(C1/C2)|.

(2) For negative synergism or antagonism, the interaction parameter β must be pos-

itive and |β | > |ln(C1/C2)| where C1 and C2 are the CMCs of individual surfactants.

Interactions between the surfactants in binary mixtures are the result of mainly two

contributions, one associated with interactions between hydrophobic moieties of the

two surfactants in the micellar core and the other with electrostatic interactions between

the head groups of both surfactants at the interface, besides the possibility of hydrogen

bonding cannot be ruled out [Sheikh et al. , 2011].

5.3.2.1 SLES/m-3-m gemini surfactants

The one parameter Margules equation was fit to the experimental data, to obtain single β

value for the entire mole fraction range of gemini surfactants. For the SLES/10−3−10

system, negative deviation was observed from the ideal behavior, except at gemini mole

fraction 0.6. At 0.6 mole fractions of gemini 10-3-10 the Cmix value increased, more

than ideal Cmix. The margules equation was fitted to the experimental Cmix values and

the single negative β value was obtained (-2.82) which means there are attractive in-

teractions or synergistic interactions exists between the mixed surfactants. A negative

interaction parameter means that the attractive interaction between two different sur-

factant monomers is stronger that the attractive interaction between the two individual

surfactant monomers with themselves or that the repulsive interaction between two dif-

ferent surfactant monomers is weaker than the self repulsion of the two individual sur-

factant monomers. However positive β value was obtained for the SLES/12− 3− 12

and SLES/16− 5− 16 (0.13 and 0.69 respectively) which indicates there is negative

synergism, i.e. antagonistic effect was observed. For SLES/12−3−12 system positive

deviation was observed in Cmix, but at 0.8 mole fraction of gemini 12−3−12 the Cmix

116

value was found to be almost similar to ideal Cmix which also suggests that micelliza-

tion is favored by gemini surfactant at higher gemini surfactant concentration. Similarly

the SLES/16−5−16 system also exhibits negative synergism and at mole fractions 0.6

and 0.8, micellization was favored by gemini surfactant. A positive interaction parame-

ter implies that the attractive interaction between the two different surfactant monomers

is weaker than the attractive interactions between the individual surfactant monomers

themselves or the self repulsion between two different surfactant monomers is stronger

than the self repulsion between the individual surfactant monomer themselves.

5.3.2.2 SLES/m-5-m gemini surfactants

A positive β value was obtained for these systems. The positive deviation from ideal

behavior shows antagonistic interactions between mixed surfactant. The β value was

found to be in the order of, 16-5-16 > 12-5-12 > 10-5-10 (1.90 > 0.39 > 0.20 respec-

tively).

Overall in the case of both m−3−m and m−5−m gemini surfactants the β value

increases with the increasing carbon chain length in the tail group of gemini surfactants,

as shown in fig. 5.9. The positive deviations can be attributed to the unfavorable interac-

tions or repulsive interactions between the sulphate head group of SLES and phosphate

head groups of geminis, also similar kind of interactions are possible between the un-

equal chains of SLES/gemini surfactants.

5.3.3 Dynamic surface tension

Dynamic surface tension measurements were carried out for the SLES (at CMC. 0.99

mM) and SLES (at CMC)/m− 3−m geminis (0.1 and 0.5 mM) and m− 5−m (0.1

and 0.5 mM) gemini surfactants, using Maximum bubble pressure method. The prin-

ciple and procedure of maximum bubble pressure was described in earlier chapters.

The dynamic surface activity parameters were listed in table 5.3. It was found that

with increasing gemini surfactant concentration in the mixture of SLES/m−3−m and

SLES/m− 5−m, the rate of dynamic surface tension reduction decreases, as shown

117

in figures 5.16, 5.18, 5.20, 5.20, 5.22, 5.24, 5.26. The reduced dynamic surface ten-

sion of the mixtures was studied, the plots of RDST versus log t are shown in figures

5.17, 5.19, 5.21, 5.23, 5.25, 5.27. The t∗ values and R1/2, found to decrease for the

SLES/10−3−10 in the order of 10−3−10 (0.1 mM) > 10−3−10 (0.5 mM). Similar

trend was observed for the SLES/12− 3− 12 gemini surfactant, the t∗ values found

to decrease in the order of 12− 3− 12 (0.1 mM) > 12− 3− 12 (0.5 mM). However

the trend was different for the SLES/16− 3− 16, the t∗ values and R1/2 values in-

creased in the order 16− 3− 16 (0.5 mM) > 16− 3− 16 (0.1 mM). The effect of the

increasing chain lengths of the geminis can be seen, as with the increasing chain length,

the R1/2 values decreases which suggests that the increased hydrophobicity, causes de-

crease in the adsorption of the molecules under dynamic condition. It was found that for

SLES/m−5−m system, the SLES/12−5−12 at 0.1 & 0.5 mM gemini concentration

the surface activity was found to increase than SLES (at CMC) alone. The dynamic

surface activity of 16-5-16 at 0.1 mM concentration found to increase by 20 times than

that of SLES. The m− 5−m gemini surfactants found to have good surface activity

under dynamic conditions compared to the m−3−m geminis.

5.3.4 Foamability

An apparatus for measurement of foamability of surfactant solution is recently devel-

oped in our laboratory. The setup generates foam by impacting a stream of liquid on

to a flat horizontal surface of the polydispersed foam generated during the process, the

setup separates the fine bubbles from coarse one. The rate of collection of fine foam

volume gives a measurement of foamability of the test solution. The details of this

method is described in earlier chapter. Experiments were carried out at an ambient tem-

perature (302 ± 2 K). Foam generation of various gemini surfactant solutions and their

monomeric surfactants were investigated by Horizontal Impinging Jet method.

The foamability of SLES (at CMC) and SLES/gemini surfactants aqueous solutions

was studied. The Foamability plots were shown in figures 5.28 - 5.33, and the foam-

ability results was enlisted in table 5.4. Overall it was found that the foamability of

118

SLES in the presence of the gemini surfactants decreases with the increase in gemini

surfactant concentration. This is due to the decreased surfactant availability for ad-

sorption at the interface. Since the newly formed interface must be stabilized by the

adsorption of surfactant to produce foam. The interface creation must be immediately

followed by interface stabilization in order to avoid coalescence of the formed bubbles.

The rate of the stabilization depends on the rate of interface stabilization. The reason

can be correlated to the surface density of the monomers of mixed surfactants present

at the interface. From table 5.1 and 5.2, it was found that the Amin values of the mix-

tures of SLES/gemini, increased significantly, which means the area per molecule at

the interface is larger means very less number of surfactant monomers are available to

adsorb at the interface, this results in the lowering of foamability of SLES. Also the

low foamability can be a attributed to the slow dynamics of SLES/gemini surfactant

mixture. The chain length effect was not observed in the case of m− 5−m gemini

surfactants, however at 0.1 mM m−3−m geminis the foamability increases in the or-

der of 16−3−16 > 12−3−12 > 10−3−10 but less than that of SLES without any

additives.

119

Table 5.1: m− 3−m gemini bulk solution mole fraction x′1, Mixture CMC Cmix ,

Micellar mole fraction x1, and Interaction Parameter β and interfacial properties forSLES/m−3−m gemini surfactant system.

Gemini x′1

CmixmeasuredmM

CmixidealmM β

Γmax1010mol/cm2

Amin

A2

10-3-10 0 0.99 0.990.2 0.13 0.403 0.52 3190.4 0.19 0.254 -2.82 0.52 3190.6 0.22 0.185 0.48 3460.8 0.11 0.146 0.7 2371 0.12 0.12

12-3-12 0 0.99 0.990.2 0.98 0.833 0.16 10380.4 0.64 0.719 0.20 8300.6 0.68 0.633 0.13 0.54 3070.8 0.50 0.565 0.45 3691 0.51 0.51

16-3-16 0 0.99 0.990.2 0.85 0.933 0.11 15090.4 0.54 0.833 0.69 0.17 9760.6 0.34 0.837 0.23 7220.8 0.3 0.797 0.27 6151 0.3 0.76

120

Table 5.2: m− 5−m gemini bulk solution mole fraction x′1, Mixture CMC Cmix ,

Micellar mole fraction x1, and Interaction Parameter β and interfacial properties forSLES/m−5−m gemini surfactant system.

Gemini x′1

CmixmeasuredmM

CmixidealmM β

Γmax1010mol/cm2

Amin

A2

10-5-10 0 0.990.2 1 0.933 0.20 8300.4 0.91 0.833 0.20 0.27 6150.6 0.87 0.837 0.24 6920.8 0.82 0.797 0.22 7541 0.76

12-5-12 0 0.9900.2 0.69 0.634 0.19 8740.4 0.49 0.466 0.25 6640.6 0.47 0.369 0.39 0.25 6640.8 0.29 0.305 0.33 5031 0.26

16-5-16 0 0.990.2 0.75 0.381 0.19 8740.4 0.84 0.236 1.90 0.15 11070.6 0.30 0.171 0.32 5190.8 0.10 0.134 0.37 4481 0.11

121

Table 5.3: Dynamic surface activity parameters of SLES and SLES/geminis

Surfactant Conc. n t∗ γm R1/2

(mM) (mN/s)SLES 0.99 0.37 0.263 28.9 5.67

10−3−10 0.1 0.218 0.03 35.2 0.620.5 0.263 0.02 32.7 0.45

12−3−12 0.1 0.243 0.16 36. 3.020.5 0.214 0.06 37.5 1.05

16−3−16 0.1 0.161 0.30 36.8 5.340.5 0.12 0.65 32.1 12.93

10−5−10 0.1 0.285 0.24 33 4.750.5 0.073 – 35.2 –

12−5−12 0.1 0.30 0.47 36.7 8.370.5 0.29 0.88 37.9 15.09

16−5−16 0.1 0.203 5.28 32.1 105.20.5 0.187 0.14 27.5 3.29

Table 5.4: Foamability of SLES and SLES/m−3−m and SLES/m−5−m geminis

Surfactant system Conc. (mM) Foamability (ml/s)SLES at CMC, 0.99 0.45

SLES/10−3−10 0.1 0.160.5 0.14

SLES/12−3−12 0.1 0.180.5 0.11

SLES/16−3−16 0.1 0.310.5 0.10

SLES/10−5−10 0.1 0.110.5 0.10

SLES/12−5−12 0.1 0.110.5 0.08

SLES/16−5−16 0.1 0.100.5 0.07

122

0.01 0.1 1 10Concentration (mM)

20

30

40

50

60

Surf

ace

tens

ion

(mN

/m)

Figure 5.2: Surface tension plot of SLES

123

0.01 0.1 120

30

40

50

60

70

0.01 0.1 120

30

40

50

60

70

0.01 0.1 120

30

40

50

60

70

0.01 0.1 120

30

40

50

60

70

Concentration (mM)

Surf

ace

tens

ion

(mN

/m)

x1’ = 0.8 x

1’ = 0.6

x1’ = 0.4 x

1’ = 0.2

Figure 5.3: Surface tension plots of SLES with 10−3−10 gemini surfactants

124

0.01 0.1 120

30

40

50

60

70

0.01 0.1 120

30

40

50

60

70

0.01 0.1 120

30

40

50

60

70

0.01 0.1 120

30

40

50

60

70

Surf

ace

tens

ion

(mN

/m)

Concentration (mM)

x1’ = 0.8 x

1’ = 0.6

x1’ = 0.4 x

1’ = 0.2


125

0.001 0.01 0.1 120

30

40

50

60

70

0.01 0.1 120

30

40

50

60

70

0.01 0.1 120

30

40

50

60

70

0.01 0.1 120

30

40

50

60

Surf

ace

tens

ion

(mN

/m)

Concentration (mM)

x1’ = 0.8 x

1’ = 0.6

x1’ = 0.4 x

1’ = 0.2


126

0.01 0.1 120

30

40

50

60

70

0.01 0.1 120

30

40

50

60

70

0.01 0.1 120

30

40

50

60

70

0.01 0.1 120

30

40

50

60

70

Surf

ace

tens

ion

(mN

/m)

Concentration (mM)

x1’ = 0.8 x

1’ = 0.6

x1’ = 0.4 x

1’ = 0.2


127

0.01 0.1 110

20

30

40

50

60

70

0.01 0.1 110

20

30

40

50

60

70

0.01 0.1 110

20

30

40

50

60

70

0.01 0.1 110

20

30

40

50

60

70

Surf

ace

tens

ion

(mN

/m)

Concentration (mM)

α = 0.8 α = 0.6

α = 0.4 α = 0.2


128

0.01 0.1 110

20

30

40

50

60

70

0.01 0.1 110

20

30

40

50

60

70

0.01 0.1 110

20

30

40

50

60

70

0.01 0.1 110

20

30

40

50

60

70

Surf

ace

tens

ion

(mN

/m)

Concentration (mM)

x1’= 0.8 x

1’= 0.6

x1’ = 0.4 x

1’ = 0.2


129

8 10 12 14 16 18Carbon chain length of gemini surfactants

-3

-2

-1

0

1

2

3m-3-m geminism-5-m geminis

β

Figure 5.9: Plot of interaction parameter (β ) between SLES and geminis versus chainlength

130

0 0.2 0.4 0.6 0.8 1Mole fraction of gemini 10-3-10

0

0.2

0.4

0.6

0.8

1

CM

C (

mM

)

Cmix measured

Margules equation fitC

mix ideal

β = −2.87

Figure 5.10: Plot of Cmix against mole fraction of gemini 10-3-10


0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

CM

C (

mM

)

Cmix measured


mix ideal

β = 0.13


131


0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

CM

C (

mM

)

Cmix measured


mix ideal

β = 0.69



0.6

0.7

0.8

0.9

1

CM

C (

mM

)

Cmix measured


mix ideal

β = 0.20


132


0.2

0.4

0.6

0.8

1

CM

C (

mM

)

Cmix measured


mix ideal

β = 0.39



0

0.2

0.4

0.6

0.8

1

CM

C (

mM

)

Cmix measured


mix ideal

β = 1.90


133

0.1 1 10 100Time (s)

25

30

35

40

45

50

Dyn

amic

Sur

face

tens

ion

(mN

/m)

SLES at cmc without additivesSLES at cmc + 0.1 mM 10-3-10SLES at cmc + 0.5 mM 10-3-10

Figure 5.16: Dynamic surface tension plot of SLES / 10-3-10 gemini

1 2 31/ sqrt t

25

30

35

40

45

50

55

Dyn

amic

sur

face

tens

ion

(mN

/m)

10-3-10 (0.1 mM)10-3-10 (0.5 mM)

0.1 1 10t

1

10

RD

ST

10-3-10 (0.1 mM)10-3-10 (0.5 mM)

SLES (at cmc) + 10-3-10

Figure 5.17: Plots of dynamic surface tension versus t−1/2 and RDST versus t of SLES/ 10-3-10 gemini

134

0.1 1 10 100Time (sec)

25

30

35

40

45

50

55

Dyn

amic

Sur

face

tens

ion

(mN

/m)

SLES at cmc without additivesSLES + 0.1 mM 12-3-12SLES + 0.5 mM 12-3-12

Figure 5.18: Dynamic surface tension plot of SLES / 12-3-12 gemini surfactant

0 0.5 1 1.5 2 2.5

t-1/2

34

36

38

40

42

44

46

48

50

Dyn

amic

sur

face

tens

ion

(mN

/m)

12-3-12 (0.1 mM)12-3-12 (0.5 mM)

SLES + 12-3-12

0.1 1 10 100t

1

10

RD

ST

12-3-12 (0.1 mM)12-3-12 (0.5 mM)

SLES + 12-3-12


135

0.1 1 10 100Time (s)

30

35

40

45

50

55

60

Dyn

amic

Sur

face

tens

ion

(mN

/m)

SLES at cmc, without additivesSLES + 0.1 mM 16-3-16SLES + 0.5 mM 16-3-16


0 0.5 1 1.5 2

t-1/2

20

25

30

35

40

45

50

55

60

Dyn

amic

Sur

face

tens

ion

(mN

/m)

16-3-16 (0.1 mM)16-3-16 (0.5 mM)

SLES + 16-3-16

0.01 0.1 1 10 100t

0.1

1

10

RD

ST

16-3-16 (0.1 mM)16-3-16 (0.5 mM)

SLES + 16-3-16


136

0.1 1 10 100Time (s)

25

30

35

40

45

50

55

Dyn

amic

sur

face

tens

ion

(mN

/m)

SLES at cmc, without additivesSLES + 0.1 mM 10-5-10 SLES + 0.5 mM 10-5-10


0 1 21/sqrt t

30

35

40

45

50

55

Dyn

amic

sur

face

tens

ion

(mN

/m)

10-5-10 (0.1 mM)10-5-10 (0.5 mM)

0.1 1 10 100t

1

10

RD

ST

10-5-10 (0.1 mM)10-5-10 (0.5 mM)

SLES + 10-5-10


137

0.1 1 10t (sec)

30

35

40

45

50

55

60

Dyn

amic

Sur

face

tens

ion

(mN

/m)

SLES + 12-5-12(0.1mM)SLES + 12-5-12 (0.5mM)


0 0.5 1 1.5 2 2.5

t-1/2

25

30

35

40

45

50

55

60

Dyn

amic

sur

face

tens

ion

(mN

/m)

12-5-12 (0.1 mM)12-5-12 (0.5 mM)

SLES + 12-5-12

1 10 100t

1

10

RD

ST

12-5-12 (0.1 mM)12-5-12 (0.5 mM)

SLES + 12-5-12


138

0.1 1 10 100Time (s)

30

35

40

45

50

55

60

Dyn

amic

sur

face

tens

ion

(mN

/m)

SLES at cmc without additivesSLES + 0.1 mM 16-5-16SLES + 0.5 mM 16-5-16


0 0.5 1 1.5 2

t-1/2

25

30

35

40

45

50

55

60

Dyn

amic

sur

face

tens

ion

(mN

/m)

16-5-16 (0.1 mM)16-5-16 (0.5 mM)

SLES + 16-5-16

0.1 1 10t

0.1

1

10

RD

ST

16-5-16 (0.1 mM)16-5-16 (0.5 mM)

SLES + 16-5-16


139

0 50 100 150Time (min)

0

5

10

15

20

25

30

Foam

Vol

ume

(ml)

SLES + 0.1 mM 10-3-10SLES + 0.5mM 10-3-10SLES without additive

Figure 5.28: Foamability of SLES / 10-3-10 gemini

0 100 200 300 400 500Time (min)

0

5

10

15

20

25

30

Foam

Vol

ume

(ml)

SLES + 0.1 mM 12-3-12SLES + 0.5 mM 12-3-12 SLES without additive


140

0 50 100 150 200 250 300Time (min)

0

5

10

15

20

25

30

Foam

vol

ume

(ml)

SLES without additivesSLES + 0.1 mM 16-3-16SLES + 0.5 mM 16-3-16


0 50 100 150 200 250 300Time (min)

0

5

10

15

20

25

30

Foam

Vol

ume

(ml)

SLES + 0.1 mM gemini 10-5-10SLES + 0.5 mM gemini 10-5-10


141

0 100 200 300 400Time (min)

0

5

10

15

20

25

30

Foam

Vol

ume

(ml)

SLES + 0.1 mM 12-5-12SLES + 0.5 mM 12-5-12

Figure 5.32: Foamability of SLES/12-5-12 gemini

0 100 200 300 400Time (min)

0

5

10

15

20

25

30

Foam

Vol

ume

(ml)

SLES + 0.1 mM 16-5-16 SLES + 0.5 mM 16-5-16

Figure 5.33: Foamability of SLES/16-5-16 gemini

142

Table 5.5: Equilibrium surface tension data for SLES/10-3-10 gemini mixture

α = 0.2 α = 0.4 α = 0.6 α = 0.8Conc. γ Conc. γ Conc. γ Conc. γ

(mM) (mN/m) (mM) (mN/m) (mM) (mN/m) (mM) (mN/m)0.01 64.94 0.01 67.08 0.01 68.28 0.03 67.300.03 54.68 0.03 62.3 0.03 66.67 0.05 55.110.05 45.32 0.05 57.72 0.05 63.93 0.07 47.710.07 41.84 0.07 49.56 0.07 51.74 0.09 42.380.09 39.66 0.09 43.85 0.09 48.15 0.1 37.960.1 34.87 0.1 41.12 0.1 44.77 0.2 33.570.2 30.08 0.2 34.05 0.2 37.42 0.3 33.130.3 29.65 0.3 33.02 0.3 36.29 0.5 32.370.5 29.87 0.5 32.37 0.5 34.54 0.7 32.910.7 29.32 0.7 31.26 0.7 33.89 1 32.481 29.43 1 32.31 1 33.46 1.3 32.37

1.3 28.78 1.3 31.93 1.3 33.24 1.5 32.691.5 28.56 1.5 31.61 1.5 33.35 1.7 32.262 28.23 1.7 32.15 2 32.64 2 31.72

2 32.48



(mM) (mN/m) (mM) (mN/m) (mM) (mN/m) (mM) (mN/m)0.01 56.61 0.01 60.32 0.01 68.75 0.01 66.380.03 51.27 0.03 53.79 0.03 59.37 0.02 61.630.05 47.15 0.05 49.05 0.05 54.63 0.03 57.710.07 44.40 0.07 45.48 0.07 51.78 0.05 54.150.09 43.57 0.09 44.18 0.09 49.16 0.07 50.230.1 42.07 0.1 42.75 0.1 47.15 0.09 47.860.3 35.59 0.2 35.51 0.2 41.01 0.1 46.080.5 32.96 0.3 32.78 0.3 39.79 0.2 41.800.7 30.61 0.5 30.41 0.5 39.61 0.3 38.830.9 28.25 0.7 29.44 0.7 30.41 0.5 35.271 26.90 0.9 29.51 0.9 30.10 0.7 34.05

1.5 26.54 1 29.95 1 30.03 0.8 33.582 26.49 1.5 29.85 1.5 30.69 0.9 33.81

2 30.67 1 33.13

143



(mM) (mN/m) (mM) (mN/m) (mM) (mN/m) (mM) (mN/m)0.01 49.86 0.01 59.29 0.01 59.83 0.001 68.630.03 45.33 0.02 52.88 0.02 55.90 0.003 66.970.05 43.31 0.03 51.73 0.03 51.23 0.005 64.950.07 41.75 0.05 47.74 0.05 49.05 0.007 63.410.09 39.55 0.07 43.58 0.07 46.23 0.01 62.750.1 38.41 0.09 41.43 0.09 43.16 0.02 59.020.2 36.04 0.1 39.51 0.1 41.72 0.03 55.220.3 33.66 0.3 32.90 0.2 34.48 0.05 50.110.5 31.83 0.5 31 0.3 31.95 0.07 46.200.7 30.05 0.7 29.93 0.5 30.69 0.09 42.990.9 29.10 0.9 29.44 0.7 29.63 0.1 41.821 29.46 1 29.51 0.9 29.15 02 33.732 29.81 1.5 29.58 1 29.79 0.3 31

2 29.81 1.5 29.44 0.5 30.410.7 30.05



(mM) (mN/m) (mM) (mN/m) (mM) (mN/m) (mM) (mN/m)0.01 59.61 0.01 60.32 0.01 68.75 0.001 68.630.03 54.27 0.03 53.79 0.03 59.37 0.003 66.970.05 47.15 0.05 51.05 0.05 54.63 0.005 64.950.07 43.40 0.07 48.48 0.07 51.78 0.007 63.410.09 42.57 0.09 45.18 0.09 49.16 0.01 62.750.1 41.07 0.1 44.84 0.1 47.15 0.02 59.020.3 35.59 0.2 41.51 0.2 43.19 0.03 55.220.5 30.96 0.3 39.78 0.3 39.79 0.05 50.110.9 26.25 0.5 35.41 0.5 33.61 0.07 46.201 25.90 0.7 30.44 0.7 30.41 0.09 42.99

1.5 25.45 0.9 28.51 0.9 29.10 0.1 41.822 26.49 1 27.95 1 29.03 0.2 33.73

1.5 26.85 1.5 29.69 0.3 312 26.25 2 30.67 0.5 30.413 26.38 0.7 30.05

144



(mM) (mN/m) (mM) (mN/m) (mM) (mN/m) (mM) (mN/m)0.01 56.41 0.01 64.72 0.01 64.48 0.01 61.870.03 49.40 0.02 61.27 0.02 60.09 0.02 58.540.05 45.84 0.03 55.10 0.03 56.05 0.03 54.030.07 42.16 0.05 49.52 0.05 50.11 0.05 46.910.09 38.72 0.07 46.31 0.07 46.08 0.07 43.230.1 36.54 0.09 41.80 0.09 42.28 0.09 39.310.3 29.58 0.1 39.90 0.1 40.61 0.1 38.120.5 26.73 0.3 31 0.3 34.56 0.2 32.660.7 24.59 0.5 27.91 0.5 29.69 0.3 25.060.9 23.88 0.7 26.85 0.7 28.39 0.5 24.471 24.55 0.9 27.44 0.9 26.96 0.7 23.28

1.5 24.71 1 28.15 1 26.73 0.9 23.052 25.66 1.5 28.98 1.5 26.51 1 24.11

2 28.51 2 26.13 1.5 23.162 24.59



(mM) (mN/m) (mM) (mN/m) (mM) (mN/m) (mM) (mN/m)0.01 60.68 0.01 56.41 0.01 62.58 0.01 61.630.02 54.27 0.02 50.59 0.02 58.54 0.02 52.730.03 52.37 0.03 46.08 0.03 53.79 0.03 48.450.05 48.33 0.05 42.50 0.05 47.15 0.05 42.400.07 45.96 0.07 40.47 0.07 43.35 0.07 38.240.09 43.94 0.09 38.84 0.09 39.16 0.09 34.880.1 42.63 0.1 38.12 0.1 36.82 0.1 33.730.2 36.46 0.3 35.27 0.2 32.31 0.2 31.360.3 33.85 0.5 32.66 0.3 26.73 0.3 30.640.5 30.86 0.7 29.34 0.5 25.66 0.5 30.050.7 28.27 0.9 28.47 0.7 27.32 0.7 29.580.9 28.15 1 29.58 0.9 27.20 0.9 29.101 28.63 1.5 29.69 1 27.68 1 28.98

1.5 27.91 2 30.88 1.5 28.152 29.10 2 28.39

145

Table 5.11: Dynamic surface tension data of SLES at CMC and SLES/10-3-10 geminisurfactant

SLES (at CMC) 10-3-10 (0.1 mM) 10-3-10 (0.5 mM)t (sec) γ (mN/m) t (sec) γ (mN/m) t (sec) γ (mN/m)11.2 38.4 0.15 46.2 0.4 42.40.27 46.4 0.25 46.2 0.44 42.40.56 44.8 0.32 45.6 1.04 40.61.37 43.2 0.35 45.6 1.52 40.24.08 41.6 0.39 44.6 1.58 40.25.32 40 0.42 44.6 2.21 38.26.63 38.4 0.94 42.4 4.16 38.2

7 38.4 1.52 42.4 5.62 36.67.83 38.4 1.84 40.8 10.15 34.410.05 38.4 2 40.8 18.7 30.4

15 38.4 3.08 40.2 20.2 30.420 38.4 4.04 40.2 31.2 30.425 38.4 6.96 39.630 38.4 13.66 38.6

16.9 38.220 36.225 3630 36

146


12-3-12 (0.1 mM) 12-3-12 (0.5 mM)t (sec) γ (mN/m) t (sec) γ (mN/m)0.55 46.6 0.21 45.40.9 45.8 0.28 45.4

1.74 44.4 0.57 44.81.91 44.4 0.77 44.82.92 43.6 0.86 44.83.7 42.8 0.98 44.8

4.12 42.6 1.08 42.26.7 42 1.19 44.2

7.06 42 1.64 42.87.92 41.8 1.84 42.89.15 41.8 2.09 42.2

10.25 40.2 3.05 41.610.6 39.6 3.81 41.610.8 39.6 6.1 40.824.2 38.2 6.12 40.830 34.2 10.05 39.6

15 38.820 36.225 34.830 34.8

147


16-3-16 (0.1 mM) 16-3-16 (0.5 mM)t (sec) γ (mN/m) t (sec) γ (mN/m)0.13 51.2 0.27 51.20.26 51.2 0.36 51.20.42 49.6 0.43 51.20.58 49.6 0.53 51.20.84 49.6 0.88 51.21.09 48 1.12 49.61.18 48 1.88 49.61.31 48 2.23 481.47 48 2.63 481.6 48 3.3 48

1.72 48 3.5 481.81 46.4 5.32 482.36 46.4 5.5 482.84 46.4 13.1 46.46.8 43.2 15.1 46.4

11.6 43.2 16 46.414.4 41.6 19.3 44.815.6 41.6 21.4 43.216.2 40 22.6 43.217.8 40 35.6 38.418.5 40 37.4 38.420 40 45.6 38.430 40 46.2 38.4

31.4 4032.4 40

148


10-5-10 (0.1 mM) 10-5-10 (0.5 mM)t (sec) γ (mN/m) t (sec) γ (mN/m)

0.1 49.2 0.12 45.60.25 49.2 0.33 45.60.33 48.2 0.5 45.20.47 48.2 1 44.80.5 48.2 2 44.2

0.76 47.6 3.8 43.61 45.8 4.2 43.6

1.22 45.2 5 43.61.31 44.8 5.75 42.21.53 44.8 6.5 41.6

4 42.6 7.1 41.24.08 42.6 8 41.24.26 42.6 9 41.2

8 42.6 10 39.89 40.6 15 39.8

10 40.6 19 35.211.05 40.2 25 3212.5 39.6 30 3215 39.6 32.8 32

15.9 39.216.8 38.420 38.425 36.427 36.4

28.4 36.430 36.4

149


12-5-12 (0.1 mM) 12-5-12 (0.5 mM)t (sec) γ (mN/m) t (sec) γ (mN/m)0.26 47.2 0.39 48.40.42 46.8 0.61 47.80.64 46.8 0.89 47.80.95 46.2 1.24 47.21.28 46.2 1.88 46.81.71 46.2 3.02 45.81.99 45.8 4.67 45.22.63 44.6 7.34 44.65.42 43 10.3 43.27.95 41.8 14.27 43.29.16 41.8 16.14 41.4

10.53 41.8 21.86 40.615.62 40.6 26.84 39.822.78 38.427.71 38.431.6 38.4

150


16-5-16 (0.1 mM) 16-5-16 (0.5 mM)t (sec) γ (mN/m) t (sec) γ (mN/m)0.15 56.8 0.14 49.80.25 56.2 0.19 49.20.56 55.8 0.38 48.60.68 55.8 0.55 48.21.1 54.6 0.86 47.6

2.72 53.8 0.98 47.64.6 51.4 1.16 46.8

5.48 51.4 1.81 45.85.65 51.4 3.11 44.46.31 49.2 4.53 43.86.5 49.2 5.21 43.26.8 49.2 9.25 42

7.16 49.2 14.54 39.87.24 49.2 18.91 38.67.68 49.2 25.79 36.28.04 48.6 30 36.28.52 46.48.68 46.48.8 46.4

9.45 46.412.35 43.4

20 36.230.2 35.432.6 35.433.2 35.435.6 35.4

151

Table 5.17: Foamability data of SLES at CMC and SLES/10-3-10 gemini surfactant

SLES (at CMC) 10-3-10 (0.1 mM) 10-3-10 (0.5 mM)t (min) Foam (ml) t (min) Foam (ml) t (min) Foam (ml)

1.11 1 6.04 1 25.53 12.35 2 12.49 2 40.18 23.2 3 19.2 3 49.36 3

14.43 4 23.05 4 57.43 416.55 5 29.43 5 62.4 519.3 6 33.45 6 69 621.3 7 40.5 7 77.15 7

23.81 8 47.45 8 85.14 826.12 9 51.47 9 91.37 928.28 10 60.27 140 98.24 1031.1 11 66.05 11 104.21 11

33.18 12 75.11 12 114.1 1235.35 13 82.41 13 118.24 1337.56 14 92.2 14 124 1440.06 15 110.44 15 130.34 1542.17 16 139.17 1644.17 1846.42 1950.48 2052.46 2154.55 22

57 2359.08 2460.3 25

152

Table 5.18: Foamability of SLES at CMC and SLES/12-3-12 gemini surfactant

12-3-12 (0.1 mM) 12-3-12 (0.5 mM)t (min) Foam (ml) t (min) Foam (ml)

40 1 19.06 170.46 2 52.56 293.58 3 90.13 3

108.04 4 131.35 4120.13 5 176.52 5133.15 6 219.16 6141.42 7 245.08 7151.12 8 264.1 8158.18 9 280.35 9164.49 10 294.01 10172.17 11 307.22 11179.22 12 317.33 12184.26 13 325.42 13190.26 14 335.02 14198.52 15 343.16 15

200 16 352.51 16204.49 17 361.44 17209.49 18 369.22 18215.08 19 377 19219.38 20 386 20224.14 21 394 21229.18 22 401 22233.49 23 409 23237.55 24 418 24241.58 25 425 25

153


16-3-16 (0.1 mM) 16-3-16 (0.5 mM)t (min) Foam (ml) t (min) Foam (ml)14.35 2 36 2

29 4 70 438 6 90 645 8 108 851 10 128 10

58.46 12 147 1265.3 14 166 14

71.33 16 184 1675 18 201 1883 20 219 2089 22 238 2294 24 256 2498 25 275 25


10-5-10 (0.1 mM) 10-5-10 (0.5 mM)t (min) Foam (ml) t (min) Foam (ml)11.19 2 36.13 222.47 4 59 4

34 6 82.15 646 8 107.09 8

68.2 10 124.9 1083.54 12 147.47 12109.3 14 165.29 14127.5 16 180.13 16144.2 18 192.6 18161.7 20 206.26 20181 22 232 22

203.8 24 260.6 24224.7 25 274.55 25

154


12-5-12 (0.1 mM) 12-5-12 (0.5 mM)t (min) Foam (ml) t (min) Foam (ml)27.58 1 33.58 2

56 2 59.16 4158 7 90 6175 8 120.54 8188 9 135.24 10

202.57 10 151 12216.53 11 165.17 14232.45 12 178 16244.14 13 206 18257.31 14 222 20267.39 15 247.36 22279.14 16 261 24290.7 17

300.13 18310.35 19

319 20331.57 21

342 22355 23

366.48 24375.42 25


16-5-16 (0.1 mM) 16-5-16 (0.5 mM)t (min) Foam (ml) t (min) Foam (ml)22.32 2 53.49 247.6 4 105 4

60.56 6 139.12 671.7 8 160 889.3 10 190.25 10

104.6 12 210 12121.25 14 240 14140.37 16 265.49 16

159 18 287.28 18177.36 20 312 20

201 22 337 22231 24 365.25 24

247.21 25 381 25

155

chapter 5 interactions between bisphosphate geminis and...

Documents