Synthesis of pH-responsive organic-inorganic polymer hybrids using anthocyanins

Abstract

Anthocyanin-stained transparent pH-responsive organic-inorganic polymer hybrids composed of poly(vinyl alcohol)(PVA) and silica gel (SiO2) were synthesized. PVA, tetramethoxysilane (TMOS), and anthocyanin were dissolved in methanol/distilled water (v/v = 1/2) and stirred for 1 h. The solution was placed at 60℃ for 2 weeks, followed by drying under reduced pressure at 60℃ for 48 h to obtain the corresponding organic-inorganic polymer hybrid (PVA/SiO2 = 5/5).The obtained polymer hybrid showed pH responsive color change such as a reddish-purple color at pH 1.97, an orange color at pH 6.74, and a yellow color at pH 12.38 in buffer solutions. The absorbance of the organic-inorganic polymer hybrid film composed of PVA/SiO2 = 9/1 at 522 nm was measured from pH 1.94 to pH 6.01. As a result, the absorbance tended to decrease with increasing pH value. This result suggested the possibility of using the organic-inorganic polymer hybrid film for pH measuring tools.