A new styryl-type monomer, 2-(4-vinylbenzyloxy)-1-naphthaldehyde thiosemicarbazone (VNT), was synthesized and then copolymerized with methyl methacrylate (MMA) by reversible addition fragmentation chain transfer polymerization affording a series of poly(MMA-co-VNT)s with different functional unit content, predetermined molecular weight, and narrow molecular-weight distribution. The desired copolymers were structurally confirmed by various spectroscopic characterizations. Colorimetric and fluorescent titration spectra revealed that the copolymers are highly selective toward fluoride anions over other competitive species including Cl-, Br-, I-, H2PO4-, AcO-, and HSO4-. On addition of F-, a remarkable colorless-to-yellow color change is easily observed by naked eyes. The influence of the copolymer composition and molecular weight on its sensing capacity was then carefully investigated. The results showed that higher VNT-incorporation amount within the copolymer chains leads to higher sensitivity toward F- ions. Interestingly, the chromogenic process of the polymeric sensor can be switched back and forth by successively adding F- and HSO4- anions into the dimethyl sulfoxide solution of the polymer, which may be represented by a complementary IMPLICATION/INHIBIT logic gate at molecular level using both the ions as the chemical inputs. Based on such a reversible and reproducible sensing system, we designed a molecular-scale sequential information processing circuit displaying writingreadingerasingreading behavior and multiwrite function in the form of binary logic. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 590-598, 2012