pH-sensitive characteristics of poly(acrylic acid)-functionalized anodic aluminum oxide (AAO) membranes

Abstract

A simplified method to prepare pore-filled pH-responsive membranes was provided by using anodic aluminum oxide (AAO) membrane as supported matrix. To introduce reactive groups for grafting weak polyelectrolyte, silica-AAO composite membrane was prepared by depositing silica onto the AAO membrane through sol-gel method. The obtained composite membrane keeps the ideal pore structures of the original AAO membrane. Poly(acrylic acid) as responsive polymer was grafted onto the silica-AAO composite membranes by activating with 3-glycidoxypropyl trimethoxysilane. The obtained pH-responsive membranes showed evident pH-sensitivity, and the pH-valve effect was observed at the pH between 3 and 5. Electrochemical impedance spectroscopy demonstrates the membrane resistance increases from 4.3 x 10(5) Omega cm(2) at pH 2 to 1.3 x 10(6) Omega cm(2) at pH 6. (C) 2011 Elsevier B.V. All rights reserved.