Preparation of a novel pH-responsive silver nanoparticle/poly (HEMA-PEGMA-MAA) composite hydrogel

In this paper, series of novel pH-responsive silver (Ag) nanoparticle/poly(2-hydroxyethyl methacrylate (HEMA)poly(ethylene glycol) methyl ether methacrylate (PEGMA)-methacrylic acid (MAA)) composite hydrogel were successfully prepared by in situ reducing Ag+ ions anchored in the hydrogel by the deprotonized carboxyl acid groups. X-ray diffraction (XRD), UV-vis spectrophotometry, transmission electron microscopy (TEM) and electric conductivity tests were used to characterize the composite system. It was found that the size and morphology of the reduced Ag nanoparticles in the composite hydrogels could be changed by loading the Ag+ ions at various swelling ratios of hydrogel. Moreover, compared to the pure poly(HEMA-PEGMA-MAA) hydrogel, not only did the Ag nanoparticle/poly(HEMA-PEGMAMAA) composite hydrogels exhibit much higher swelling ratio and faster deswelling rate, but also higher pH switchable electrical properties upon controlling the interparticle distance under pH stimulus. The pH responsive natiocomposite hydrogel reported here might be a potentially smart material in the range of applications including electronics, biosensors and drug-delivery devices. (C) 2007 Elsevier Ltd. All rights reserved.