Flow behavior of hydroxypropyl methyl cellulose/polyacrylic acid interpolymer complexes in aqueous media

Abstract

The intermolecular complexation of non‐ionic polymers with weak acids having chemically complementary structures is an important approach to modify the viscosity of polymer solutions. In this study intermolecular complexation of hydroxypropyl methyl cellulose (HPMC) with polyacrylic acid (PAA) in an aqueous medium was studied. The study focuses on the factors affecting the complexation and rheological behavior of the HPMC/PAA system including the stoichiometric ratio of the two polymers, the molecular weight of the PAA, and the pH and ionic strength of the medium. Results showed that interpolymer complexation occurred between HPMC and PAA at low pH. It was attributed to hydrogen bonding between the COOH group of the PAA and the OH group of the HPMC. Under basic conditions (above the critical pH) the viscosity of the interpolymer complex increased accompanied by a transition from a compact interpolymer complexation structure to an extended conformation of interpolymer associates. Introduction of monovalent and multivalent salts (at > pHcritical) decreased the viscosity of the HPMC/PAA interpolymer associates and favored the formation of interpolymer complexes between the two polymers. Copyright © 2012 Society of Chemical Industry

Effect of Cationic Polyelectrolyte on the Flow Behavior of Hydroxypropyl Methyl Cellulose/Polyacrylic Acid Interpolymer Complexes

“…Complexation between cellulose derivatives, such as HPMC, and poly(acrylic acid) (PAA) has been reported previously. [14][15][16][17] It was found that the polymers form IPC in acidic medium (such as pH 3.0) and it was confirmed that hydrogen bonding was a major driving force of this interaction. [14] At higher pH values (pH 9), due to ionization of the PAA, interpolymer associates may form accompanied with an increase in viscosity of the solution mixture.…”

“…A detailed discussion on the formation HPMC/PAA IPCs and associates as a function of pH and ionic strength of the medium can be found in our previous paper. [17] 3.2.2. HPMC/PEI polymer mixtures.…”

“…In the spectrum a broad, intense peak was observed in the Figure 9. FTIR spectra of (a) pure PAA, [17] (b) precipitate obtained by PEI addition (1 wt%) to the HPMC/PAA complex at pH 3, (c) HPMC/PAA interpolymer complex at pH 3, polymer ratio 3: 0.5, and (d) pure HPMC. [17] 2850-3700 cm −1 range.…”

“…[10,14,17] However, the effect of a cationic polymer, such as PEI, on the flow behavior and complexation of the same system has not been studied yet to our knowledge. Therefore, the aim of the current study was to investigate the influence of PEI on the interactions in HPMC/PAA solution mixtures and the possible use of PEI as a destructive agent for the HPMC/PAA IPCs.…”

“…[14] At higher pH values (pH 9), due to ionization of the PAA, interpolymer associates may form accompanied with an increase in viscosity of the solution mixture. [17] Additionally, factors such as the molecular weight of both polymers, their molar or weight ratios in the solution mixtures, temperature, and ionic strength of the medium may also influence the IPC formation behavior and the structure of the complexes. [10,18] It is also known that some organic solvents (such as dimethylformamide and dimethylsulfoxide), which are called destructive agents, may lead to a complete destruction of the IPCs.…”