Unusual Phase Behavior of the Mixture of Poly(acrylic acid) and Poly(diallyldimethylammonium chloride) in Acidic Media

Abstract

A new type of temperature-sensitive polymer systems based on mixtures of poly(acrylic acid) (PAA) and poly(diallyldimethylammonium chloride) (PDADMAC) in strongly acidic aqueous medium is described. The mixtures exhibit reversible separation into two liquid phases upon a decrease in temperature. The phase separation is induced by the intermolecular binding between PAA and PDADMAC due to iondipole interactions between protonated carboxylic groups of PAA and quaternary nitrogen atoms of PDADMAC. Molecular and hydrodynamic characteristics of the interpolymer complexes are probed by static and dynamic light scattering.

pH and Salt Effects on the Associative Phase Separation of Oppositely Charged Polyelectrolytes

“…This however does not explain higher at low pH compared to intermediate pH, where both polyions are almost fully charged. Another explanation could be the presence of additional, secondary interactions between polyions such as ion-dipole interactions speculated for the PAA-PDADMAC pair in an earlier study [43]. This effect could be included by using a non-zero Flory interaction between polyions , which is not considered here.…”

“…This necessitates the introduction of hydrophobic interactions ( = 0.75), which satisfactorily captures this asymmetry in the profile of . This assumption appears to be justified for PAA, since PAA is relatively insoluble at low pH when most carboxylic groups are protonated and form intra-chain hydrogen bonds [42,43]. The PAA-PDADMAC-KCl system shows a non-symmetric profile even for the theory without additional hydrophobic effects, since PDADMAC is fully ionized at all pH values.…”

Influence of the degree of ionization on the growth mechanism of poly(diallyldimethylammonium)/poly(acrylic acid) multilayers

“…This was also found in other work, for example, by Xu et al, who stated that the access to the charge on the quaternary ammonium group is sterically hindered. Possible interactions enabling the multilayer growth for such low degrees of ionization for PAA might be ion–dipole interactions between uncharged PAA carboxylic acid groups and charged PDADMA ammonium groups …”

“…Furthermore, the mass coverage Γ for (PDADMA/PAA) 10 at pH 3.85 (about 40 µg cm −2 ) is more than two times higher compared to the maximum mass coverage of (PAH/PAA) 10 at pH 5 (about 15 µg cm 2 , calculated from Δ f (about −900 Hz) using the Sauerbrey equation). These differences are due to the different nature of the respective polycations: PDADMA has about half the linear charge density of fully charged PAH and is able to form ion–dipole interactions with PAA . In addition, electrostatic interactions between PDADMA and PAA are known to be weaker as compared to PAH/PAA.…”

Pressure sensitive adhesives based on interpolymer complexes

“…The redissolution transition in initially multivalent ion-induced precipitated polyelectrolytes takes place with further addition of multivalent particles (polyions), as predicted for flexible linear polyelectrolyte chains in multivalent salt solutions[248,260]. type of temperature-sensitive polymer systems based on mixtures of poly(acrylic acid) (PAA) and poly(diallyldimethylammonium chloride) (PDADMAC) in strongly acidic aqueous medium is described in[261].The mixtures exhibit reversible separation into two liquid phases upon a decrease in temperature. The phase separation is induced by the intermolecular bonding between PAA and PDADMAC due to ion−dipole interactions between the protonated carboxylic groups of PAA and the quaternary nitrogen atoms of PDADMAC.…”