pH-Mediated Interactions between Poly(acrylic acid) and Methylcellulose in the Formation of Ultrathin Multilayered Hydrogels and Spherical Nanoparticles

Abstract

Poly(acrylic acid) forms insoluble hydrogen-bonded interpolymer complexes with methylcellulose in aqueous solutions under acidic conditions. In this work the reaction heats and binding constants were determined for the complexation between poly(acrylic acid) and methylcellulose by isothermal titration calorimetry at different pH and findings are correlated with the aggregation processes occurring in this system. The principal contribution to the complexation heat results from primary polycomplex particle aggregation. Transmission electron microscopy of nanoparticles produced at pH 1.4 and 2.4 demonstrated that they are spherical and dense structures. The nanoparticles ranged from 80 to 200 nm, whereas particles formed at pH 3.2 were 20−30 nm and were stabilized against aggregation by a network of uncomplexed macromolecules. For the first time, multilayered materials were developed on the basis of hydrogen-bonded complexes of poly(acrylic acid) and methylcellulose using layer-by-layer deposition on a glass surface. The thickness of these films was a linear function of the number of deposition cycles. The materials were subsequently cross-linked by thermal treatment, resulting in ultrathin hydrogels which detached from the glass substrate upon swelling. The swelling capacity of ultrathin hydrogels differed from the swelling of the thicker films of a similar chemical composition.

Hydrogen‐Bonded Complexes and Blends of Poly(acrylic acid) and Methylcellulose: Nanoparticles and Mucoadhesive Films for Ocular Delivery of Riboflavin

“…It can be clearly seen that IPCs formed by mixing polymers at 50:50 wt% ratio have the smallest size of approximately 100–120 nm and these nanoparticles have a relatively narrow size distribution (Figure b). This polymer ratio is consistent with the IPC stoichiometry established earlier . When the composition of a polymer mixture deviates from the stoichiometric ratio the size of particles increases.…”

“…Previously, we have studied the complexation between PAA and MC in aqueous solutions by turbidimetric titration, isothermal titration calorimetry, transmission electron microscopy, and surface plasmon resonance (Biacore) and evaluated the effects of pH and solution concentration on the intensity of interactions and structure of IPCs formed . Rheological properties of PAA–MC complexes in aqueous solutions were also reported by other authors .…”

A Poly(acrylic acid)‐block‐Poly(L‐glutamic acid) Diblock Copolymer with Improved Cell Adhesion for Surface Modification

“…As we all know, the physical and chemical properties of multilayer films can be controlled by changing the deposition conditions (pH, salt concentration, solvent quality, etc.). [11,27] By controlling the assembly processes of surface modification, functional multilayer films with adjustable hydrophilicity/hydrophobicity could be obtained to satisfy different applications.…”

Layer‐by‐Layer Assembled Multilayer Films of Methoxypoly(ethylene glycol)‐block‐poly(α,L‐glutamic acid) and Chitosan with Reduced Cell Adhesion

“…[23,30] The molecular weight of the adsorbed and adsorbing layer polyelectrolyte plays an important role in the layer-by-layer processing of the weak polyelectrolytes. UV-vis spectra were used to measure the effect of the molecular weight of mPEGGA on the growth of multilayer films.…”