Effect of Solute on Solubilization Ability and Micellar Structure of

Dodecylbenzenesulfonate

Experimental and Molecular Dynamics Study

Huang-chin Hung, Jeffrey Potoff, G.S Shreve

Department of Chemical Engineering and Material Science, Wayne State University, Detroit MI

Flow chart

Determination of CMC.

Interfacial Properties of PG210 and Dyna 270 at 25 C.

The Mechanism of Fluorescence Quenching.

Pyrene Fluorescence Quenching

Experimental for DBS/Dodecane System

Dodecane/DBS Micelle

-5

-4

-3

-2

-1

0

0 200 400 600 800 1000

time (ns)

log

(I/I

ma

x)

3g pyrene 9g pyrene 18g pyrene 36g pyrene

Aggregation Number Calculated from Pyrene Fluorescence Quenching Test.

 

pyrene (mg/l) 3 9 18 36 Average STD

Dodecane/DBS 19.3 20.5 26.3 21.3 21.85 1.78

Benzene/DBS 19.9 17.1 14.1 15.3 16.60 1.46

M olecular D ynam ic S im ulation usingC H AR M M Program

Param eter fi le s truc ture fi le C oordina te fi le

coordina te fi le result fi le

s im ula tion

energy m inim iza tion

Input fi le

Water Penetration into the Micelle

Water Density of the Systems

00.20.40.60.8

11.2

0 2 4 6 8 10 12 14 16 18 20 22 24 26

r (A)

dens

ity (g

/cm

3)

DBS/Dodecane DBS/Benzene

Structure of Molecules

Radial Distribution Function of DBS/Dodecane Micelle

Water Density of the Systems

00.20.40.60.8

11.2

0 2 4 6 8 10 12 14 16 18 20 22 24 26

radius (A)

de

ns

ity

(1

g/c

m3

)

DBS/Dodecane DBS/Benzene

0

2

4

6

8

10

0 2 4 6 8 10 12 14 16 18 20 22 24 26

r (A)

g(r)

C1-C1 CD2-CD2 S-S C1-C1 (Dodecane)

Radial Distribution Function of DBS/Benzene Micelle

02468

101214161820

0 2 4 6 8 10 12 14 16 18 20 22 24 26radius (A)

C1-C1 CD2-CD2 S-S CD2-CD2 (Benzene)

Localization of Solute in Micelle

Density of Solute in Micelle

0

0.5

1

1.5

2

2.5

3

0 2 4 6 8 10 12 14 16 18 20 22 24 26

Distance from COM

Dens

ity (g

/cm3)

Benzene Dodecane

Conclusion

Benzene molecules can stay at outer layer of the micelle which increase the area per head group and lower the effectiness of the surfactant.

Dodecane molecules stay only at core of the micelle and form a very hydrophobic region with the tail of surfactant. Smaller area per head group and higher effectiness of surfactant are observed.

Future Study

Derive the free energy of micellation from the area per head group of MD result

Derive the dielectricity constant of the head group as well as the hydrophobic interaction of the surfactant tails.

Randomize the initial coordinates of micelles and study the dynamics of micelle formation

Extend the study to Biosurfactants

Acknowledgements

EPA Research Grant RG R827 132-01-0 to G.S Shreve.

Dr. Don Gregory Accelerys. Dr. Yiannis Kaznessis. Dr. John F. Endicott and Dr. Patrick G.

McNamara, Chemistry WSU. Kevin Hall, BS. WSU.