Thin films of block copolymer blends for enhanced performance of acoustic wave-based chemical sensors.

Robert J Lipert, Ruth Shinar, Bikas Vaidya, Andrew D Pris, Marc D Porter, Guojun Liu, Ted D Grabau, John P Dilger

Index: Anal. Chem. 74(24) , 6383-91, (2002)

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Abstract

The performance of quartz crystal oscillator-based volatile organic compound (VOC) sensors has been enhanced by using coatings made from poly(styrene-block-ethylene-co-butylene-block-styrene) block copolymers blended with resins and homopolymers. Enhanced performance is characterized by a wider operational temperature range (-10 to +50 degrees C) over which the sensors displayed, concurrently, an analyte sensitivity of >0.2 Hz/ppm toluene, minimal energy loss (resistance <120 ohms), and response times of <20 min (time required to reach 90% of full response). Atomic force microscopy images are consistent with a process in which the additive associates with the polystyrene portions of the microphase-separated block copolymer. This association reinforces the rigidity of the polystyrene network while allowing the rapid uptake of VOCs by the softer polyethylene/butylene phase.