JMES, 2017, 8 (4), pp. 1161-1167 1161
JMES, 2017 Volume 8, Issue 4, Page 1161-1167
1. Introduction
Polymer-surfactant mixture have attracted significant attention in the last few decades due to wide spread
applications both in practical and theoretical studies such as paints and coatings, detergents, cosmetics and drug
delivery due do their improved performance in surface activity, wetting, adsorption, solubilization,
emulsification, suspension and so forth, superior to that of single substances [1-4]. Thus, it is important to
understand the adsorption behavior of mixed polymer surfactant systems for specific applications. There has
been a continued interest to understand the adsorption behavior of polymer surfactant mixtures in terms of
composition and structure of polymer surfactant layers at the air – liquid interface.
The polymer surfactant mixtures can be grouped into weakly interacting systems such as neutral polymers and
charged or uncharged surfactants and strongly interacting systems such as oppositely charged polyelectrolyte-
surfactant mixtures. For strongly interacting systems, the surface tension is a function of surfactants
concentration exhibits complex behavior in the form of discontinuities before CMC. This is interpreted as a
manifestation of the surfactant/polymer mixed interactions [5].
Diblock copolymers are a class of amphiphile which show surface active properties similar to that of
surfactants. Due to this nature, they have the ability to adsorb at the interface and form micelles. Diblock
copolymer polyethylene oxide poly butylenes oxide (E
39
B
19
) are water soluble polymer which are surface active
agent, which have wide range applications in industry for detergency and as emulsifiers [5].
Surfactants are the surface active agents that lower the surface tension of water. These are the versatile chemical
compounds which are amphiphilic in nature consisting of hydrophilic head which may be anionic, cationic, non
Journal of materials and
Environmental Sciences
ISSN : 2028-2508
Copyright © 2017,
University of Mohammed Premier
Oujda Morocco
Surface and thermodynamic study of micellization of non ionic
surfactant/diblock copolymer system as revealed by surface tension and
conductivity
Noor Rehman
1
*, Hidayat Ullah
2
, Sultan Alam
3
, Abdul Khaliq Jan
1
,
Sher Wali Khan
1
and Muhammad Tariq
1
.
1
Department of Chemistry, Shaheed Benazir Bhutto University (18000), Sheringal Dir (Upper), KP, Pakistan.
2
Institute of Chemical Sciences, University of Peshawar (25000), KP, Pakistan.
3
Department of Chemistry, University of Malakand (18800), KP, Pakistan.
Abstract
Surface physico-chemical and thermodynamic properties of non ionic
surfactants (Tween 20 and Tween 80) with diblock copolymer poly
(oxyethylene/oxybutylene) (E
39
B
19
) at 298 K have been investigated by surface
tension and conductivity techniques. The surface tensiometery were used to
study the critical micelle concentration (CMC), surface excess concentration
(Г), minimum area per molecule (A), free energy of micellization (∆G
m
) and
free energy of adsorption (∆G
ads
). From the observed surface properties it was
concluded that the process of micellization is spontaneous and exothermic.
Conductometry technique was used to determine critical micelle concentration
(CMC), degree of ionization (α), degree of counter ion binding (β). The
addition of diblock copolymer to the surfactant solutions increase the values of
degree of ionization (α), degree of counter ion binding (β). Although it led to
decrease in the values of CMC indicating that the process of micellization is
more favorable and spontaneous.
Received 20 Nov 2016,
Revised 10 Jan 2017,
Accepted 15 Jan 2017
Keywords
Surface tension;
Conductivity;
Diblock copolymer;
Non ionic surfactants;
Thermodynamic
parameters
Noor Rehman
noorrehman@sbbu.edu.pk
+92 3355979230
http://www.jmaterenvironsci.com/