Abstract
Polyelectrolyte-surfactant complexes (PESC) are a class of materials
which form spontaneously by self-assembly driven by electrostatic and hydrophobic
interactions. PESC containing sodium lauryl ether sulfates (SLES) have found wide
application in hair care products like shampoo. Typically, SLES with only one or two
ethylene oxide (EO) groups are used for this application. We have studied the influence
of the size of the EO block (ranging from 0 to 30 EO groups) on complexation with
two model polycations: linear polyDADMAC and branched PEI. PESC size and
electrostatic properties were determined during stepwise titration of buffered polycation
solutions. The critical aggregation concentration (CAC) of PESC was determined by
surface tension measurements and fluorescence spectroscopy. For polyDADMAC, there
is no influence of the size of the EO block on the complexation behavior; the stiff
polycation governs the structure formation. For PEI, it was seen that the EO block size
does affect the structure of the complexes. The CAC value of the investigated
complexes turns out to be rather independent of the EO block size; however, the
CMC/CAC ratio decreases with increasing size of the EO block. This latter observation explains why the Lochhead-Goddard effect is most effective for small EO blocks.
Original language | English |
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Pages (from-to) | 6338-6347 |
Journal | Journal of Physical Chemistry |
Volume | 119 |
Issue number | 20 |
DOIs | |
Publication status | Published - 2015 |