Proton uptake by poly(2‐vinylpyridine) coatings

Abstract

A titration technique has been used to directly measure the proton uptake by ion-exchange poly(2-vinylpyridine) coatings as a function of solution pH. Contrary to the common assumption that each nitrogen in the pyridine ring is attached to an H ϩ when the polymer film is fully protonated, the use of the titration technique has shown that the portion of the pyridine sites actually protonated does not exceed 25% anywhere in the pH range where the coating is stable. The pK a value for the poly(2-vinylpyridine) coating has also been estimated to be 4.5 from the titration curve.

Characterization of pH‐sensitive polymer layers by surface plasmon resonance and quartz crystal microbalance

“…A continuous deprotonation of P2VP with increasing pH is possible, because the fraction of protonated pyridine moieties is at maximum 25%. Tantavichet and coworkers reported an acid dissociation constant, p K a , of 4.5 for P2VP coatings . However, in our SPR experiments we see first significant pH responses of the layers at pH lower than 3.4 which is clearly lower than the reported p K a .…”

Preparation and characterization of pH-sensitive polyethersulfone hollow fiber membranes modified by poly(methyl methylacrylate-co-4-vinyl pyridine) copolymer

“…It is reported that the pK a of PVPy in solution is about 3.5-4.5 [8,9], which is not in agreement with that from Fig. 5(a).…”

“…Carboxyl group can be protonated at low pH leading to a volume shrinkage of the polymer, and dissociation into carboxylate ion at high pH resulting in a high charge density in the polymer, causing it to swell, and the representative monomers are acrylic acid (AA) and methacrylic acid (MAA) [6,7]. Pyridine group is an acidswellable group which can be protonated under acidic condition and the charge repulsion leads to an expansion in the overall dimensions of the polymer, and the representative monomers are 2-vinylpyridine and 4-vinylpyridine [8,9]. Other pH sensitive functional groups, such as imidazole, dibutylamine and tertiary amine methacrylates have also been investigated [10,11].…”

Carbohydrate-actuated nanofluidic diode: switchable current rectification in a nanopipette

“…48 Polyelectrolytes such as poly(vinylpyridine) can be analyzed by titration to characterize proton uptake. 49 However, the poor solubility of PVP-BA prevented titration analysis to find the apparent p K a .…”