Applied Surface Science, Vol.356, 1229-1233, 2015
Acid-base equilibria of multilayered pseudo-polyelectrolytes
The use of weak polyelectrolytes in multilayer polymer systems provides a means of altering the physicochemical properties of these thin films. Previously, we have examined the limits of the polyanions by incorporating the pseudo-polyelectrolytes (pPE's), poly(4-vinylphenol) (PVPh) and poly[5-(2-trifluoromethyl-1,1,1-trifluoro-2-hydroxypropyl)-2-norbornene] (PNBHFA). These pPE's, although being polyacids, should have pK(a) values in the basic versus acidic pH range. In order to determine the pK(a(app)) value of these polymers, once multilayered onto Snowtex silica particles with the weak polyelectrolyte, poly(allylamine hydrochloride) (PAH), we employed zeta potential. PVPh demonstrated pK(a(app)) values ranging from 10.55 to 11.08 which varied based upon assembly pH conditions as well as layer number. PAH yielded pK(a(app)) values ranging between 9.81 and 10.99 when multilayered with PVPh and 9.91-11.04 when partnered with PNBHFA. However, from our study it would appear that PNBHFA does not interact with PAH electrostatically, but rather via H-bonding, and therefore should actually not be classified as a pPE. (C) 2015 Elsevier B.V. All rights reserved.