Hydration of Hydroxypropylmethyl Cellulose: Effects of pH and Molecular Mass

Abstract

Magnetic resonance imaging was used to study the diffusion of a water solution of hydrochloric acid (HCl) and sodium hydrochloride (NaOH) into hydroxypropylmethyl cellulose matrices. Polymer in the form of a cylinder was hydrated in a water solvent of pH = 2, 7, and 12 at 37• C and monitored at equal intervals with a 300 MHz Bruker AVANCE. The spatially resolved spin-spin relaxations times and spin densities, along with a change in the dimension of the glass core of the polymer were determined for hydroxypropylmethyl cellulose tablets as a function of hydration times. The data showed the effects of the pH solvent and of the molecular mass of the polymer on the swelling process, spin-spin relaxation time, and diffusion of solvent molecules into hydroxypropylmethyl cellulose matrices. The time dependence of the diffusion front, effective T 2 , and proton-density ρ analysis clearly indicate a case II diffusion mechanism in the system composed of a water solution of hydrochloric acid (pH = 2) and hydroxypropylmethyl cellulose, whereas in the case of water solutions with pH = 7 and 12 the anomalous and case I diffusion are observed, respectively.

Spatially resolved solvent interaction with glassy HPMC polymers studied by magnetic resonance microscopy

“…3b we can see, when going from the external edge of the gel layer to the direction of the dry core of polymer, a small decrease of the spin-spin relaxation times up to 1.5 mm of the gel layer thickness and then an almost constant value of relaxation time. For comparison we also measured a similar profile for the water solvent with pH ¼ 7 and 2 where the observed decrease of T 2 were equal to about 170 ms for acidic and 70 ms for neutral solvent [16,17]. Therefore we can conclude that in the case of the alkaline solvent, the spin-spin relaxation time of the solution is almost constant in the gel layer of the HPMC polymer.…”

“…Other values of n indicate anomalous transport kinetics i.e. a combined mechanism of Fickian and Case II transport [16,24,25]. Eq.…”

“…This work is a part of our studies on solvent interaction with glassy HPMC polymers [6,16,17]. The penetration and mobility of alkaline water solvent in the HPMC matrices with different molecular mass and the influence of the solvent on swelling properties of the polymers were studied and will be considered in the paper.…”

Structural analysis of fructans produced by acetic acid bacteria reveals a relation to hydrocolloid function

“…HPMC is a good gelling agent in forming intermolecularly stabilized networks, which consist of multiple polymer chains entrapping high amounts of solvents such as water (Tritt-Goc, Kowalczuk, & Pislewski, 2005). Furthermore, this polymer was shown to enhance the hydration and water binding capacities of gluten (Barcenas, De la O-Keller, & Rosell, 2009) and proposed to inhibit starch retrogradation (Collar, Martinez, & Rosell, 2001;Guarda et al, 2004).…”

Swellable Hydrogel-based Systems for Controlled Drug Delivery

“…However, despite some experimental evidences of Case II/anomalous transport in polymers used for swellable hydrogel-based delivery systems [32][33][34], none of the mechanistic models developed to describe drug release have included this feature, considering an instantaneous rearrangement of the polymer chains and therefore limiting their attention to the Zone III (Figure 1) behavior.…”