Fluorescent Viscosity Sensor Film of Molecular-Scale Porous Polymer with Intramolecular pi-Stack Structure

Abstract

A new class of high-quality solid-state viscosity sensors that satisfy with thermal, chemical, and mechanical stabilities was reported. poly [1-phenyl-2-(p-trimethylsilyl)phenylacetylene] (PTMSDPA), a representative of diphenylacetylene polymer derivatives, has an excellent fluorescence (FL) response to external stimuli of various chemicals. The functional log-log equations of viscosity sensitivity of the PTMSDPA films were expressed well as a linear equation of log (I/I0) = C + x log ?. Especially, the probe dependent constant (x) for hydrocarbons was as high as 0.50, which is comparable to that of the in-solution rotor dye of DCVJ that is known as the most viscosity-sensitive probe molecule. Also, the x values of the present sensor in hydrocarbons, alcohols, and silicon oils significantly differed from each other due to the difference in the molecular affinities and sizes of the fluids. This result strongly suggests the molecular affinity between sensor and media should be considered to accurately evaluate the viscosity sensitivity of the sensor material.