Polythiophene-g-poly(dimethylaminoethyl methacrylate) doped methyl cellulose hydrogel behaving like a polymeric AND logic gate

Abstract

The variation of photoluminescence (PL) property of polythiophene-g-poly(dimethylaminoethyl methacrylate) (PT-g-PDMA, PD) with temperature and pH is used to develop a fully polymeric fluorescent AND logic gate type material using methyl cellulose (MC) hydrogel. The PL intensity gradually increases with increasing temperature of the PD doped aqueous MC solution and with increasing pH of the medium. In contrast, the PL-intensity of the PD solution decreases with increase in temperature for all of the pH values studied here due to collapsing of PDMA chains on the PT core, signifying that the PL intensity increases in the MC gel after compensating for the above decrease. The truth table suggests that it acts as an AND fluorescent molecular logic gate type system with fluorescence as output and temperature and pH as inputs. The maximum sensitivity of this logic gate is at higher pH (pH 9.2) than at neutral or acidic pH (pH 4) and at 45 °C. The reason is discussed from the viewpoint of the change in polarity at the microenvironment of the polythiophene chain in PD in the MC gel due to the change in temperature and pH.