RESULTS AND DISCUSSION
Determination of the adsorption isotherm of
DBSA on cotton fabric
The adsorption isotherm of DBSA on cotton with
0.15M NaCl, pH 4, at 308C is shown in Figure 3. The
amount of surfactant adsorption reached a constant
value at around 0.6 mM of equilibrium surfactant
concentration. This can be compared with the reference
value for the CMC of DBSA of 1.2 mM.
22 The
reduction in the CMC of DBSA is due to the presence
of electrolyte in the surfactant solution which
decreases electrical repulsion between the surfactant
head groups in the micelles. The maximum amount
of DBSA adsorption on the cotton fabric was
20 lmol/g cotton. In admicellar polymerization, the
concentration of surfactant should be just below or
near its CMC to ensure significant coverage while
avoiding emulsion polymerization. From the adsorption
isotherm, a concentration of 0.6 mM DBSA
which is near the CMC was chosen for the admicellar
polymerization reaction