Interpolymer complexes of hydroxypropylmethylcellulose with polycarboxylic acids in aqueous solutions

Abstract

The interactions between hydroxypropylmethylcellulose (HPMC) and poly(acrylic acid) (PAA) as well as poly(methacrylic acid) (PMAA) resulting in formation of hydrophobic interpolymer complexes (IPC) via hydrogen bonding have been studied in aqueous solutions in acidic medium. The formation of IPC of two different compositions (2:1 and 4:1) has been detected for complexes of PAA and HPMC. The critical pH values for complexation of HPMC with PAA and PMAA were determined by the turbidimetric method. It was found that PAA shows the lower complexation ability compared to PMAA due to the more hydrophobic nature of the latter polyacid. The temperature-induced phase separation in HPMC-PAA solution mixtures depends greatly on the components ratio and PAA molecular weight. The complexation ability of hydroxypropylmethylcellulose with respect to poly(acrylic acid) was found to be similar to the complexation ability of methylcellulose, lower than that of hydroxypropylcellulose and higher than that of hydroxyethylcellulose.

Temperature‐Responsive Water‐Soluble Copolymers Based on 2‐Hydroxyethyl Acrylate and Butyl Acrylate

“…However, the PAA sample with M w of 2 kDa does not appear to form insoluble complexes even at low pH. Previously, we also studied the complexation of this small molecular weight PAA sample with polyacrylamide, [24] hydroxyethylcellulose, [25] hydroxypropylmethylcellulose, [26] poly(ethylene oxide) [27] and poly(N-vinylpyrrolidone) (PVP) [28] and found that the IPC are formed only in the case of PAA-PVP. The existence of the polymers critical molecular weight, below which the complexes are not formed, has been suggested as a reason for non-complexation of PAA 2 kDa with most of the non-ionic polymers.…”

“…Previously, the appearance of this dual sensitivity was reported for complexes of PAA with poly(methyl vinyl ether), [30] poly(N,N-diethylacrylamide) [31] and some cellulose ethers. [26] It has also been emphasised that the [PAA]:[temperature-responsive polymer] ratio affects the temperature of phase separation (T PS ) of the mixture, significantly. Depending on the polymers ratio a slight increase or significant decrease in T PS has been reported.…”

“…Also, it was found that the molecular weight of the interacting PAA and the presence of salts in solutions may affect the T PS . [26] In the present study, we have explored the effect of the polymers ratio, molecular weight of PAA and solution pH on the solution phase behaviour of PAA/HEA-co-BA mixtures at different temperatures. First, we have studied the effect of polymer ratios on the solution turbidity at various temperatures using the PAA samples with three different molecular weights (100, 250 and 750 kDa).…”

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.…”

Fractional complexation in a miscible polymer blend. Calorimetry and size exclusion chromatography

“…1:1, 1:2, 1:4, etc. 3,10,11 The term 'fixed mean stoichiometry' of a complex was identified with the minimum on the viscosity versus composition curve. 8,14 It is generally accepted that a gel-like interpolymer complex has a ladder-like structure of co-operative hydrogen bonds, in contrast to the loose random hydrogen bond structure of a soluble blend.…”