A chemical vapor sensor based on a quartz crystal microbalance was fabricated with a 10-MHz quartz crystal oscillator. The quartz crystals were coated with four newly synthesized polymers and were studied for the detection of the nerve agent simulant dimethyl methylphosphonate vapor. The sensor was tested for immediate and extended periods of time. Various sensing parameters (e.g., the sensitivity, response time, and recovery time) were evaluated with respect to different coating materials. All the polymers showed fairly good baseline stability even after several cycles. The highest frequency drift of 23.8 Hz/kHz was observed for one of the polymers, whereas another polymer showed the best sensing stability over an extended period of 250 days. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 116: 3708-3717, 2010