Separation of the effects of pH and polymer concentration on the swelling pressure and elastic modulus of a pH-responsive hydrogel

POLYMER

卷:47

Article

Horkay, Ferenc ; Han, Man-Hee ; Han, In Suk ; Bang, In-Seok ; Magda, Jules J.

关键词: elastic shear modulus;    pH-responsive hydrogel;    osmotic pressure;   

DOI  :  10.1016/j.polymer.2006.08.037

来源: Elsevier

【 摘 要 】

The elastic shear modulus G and swelling pressure omega are studied for a basic, pH-responsive hydrogel synthesized by crosslinking copolymerization of co-monomers hydroxypropyl methacrylate and N,N-dimethylaminoethyl methacrylate with crosslinker tetraethylene glycol dimethacrylate. Under normal conditions of use as a smart material, hydrogel swelling ratio Q and pH vary simultaneously, but here G and w values are presented as a function of pH with Q held constant and vice versa. At fixed pH, G decreases with increase in Q in a power law dependence, as predicted by the Flory-Rehner model. However, at fixed Q, G increases with decrease in pH (i.e., increase in degree of ionization). The pH effect is more pronounced than the volume effect, thus the hydrogel stiffens as it swells in response to pH change. At high pH, to values of the uncharged hydrogel obey the Flory-Rehner model, whereas explicit ionic contributions can be identified at lower pH values. (c) 2006 Elsevier Ltd. All rights reserved.

【 授权许可】

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