The development of polysiloxane based chemically modified field effect transistors (CHEMFETs) for heavy metal ions is described. Different polar siloxane copolymers have been synthesized via an anionic copolymerization of hexamethylcyclotrisiloxane, [3-(methacryloxy)propyl]pentamethylcyclotrisiloxane and pentamethylcyclotrisiloxanes with a pendant polar group, e.g. ester, ether, amide, keto or cyan group. Well-structured monomodal molecular weight polymers were obtained with molecular weight distributions from 1.3 to 1.7. The siloxane copolymers were used as sensing membranes for Ag+, Cd2+ sand Pb2+ selective CHEMFETs. The intrinsic elastomeric properties of the polysiloxane membrane makes the use of a plasticizer superfluous, which should have a favourable effect on the durability of these CHEMFETs. Siloxane copolymers with 3-cyanopropyl side groups are already intrinsically selective for Ag+ ions and this can be further enhanced by the addition of an Ag+ selective ionophore I. Good Cd2+ selectivity was obtained for CHEMFETs with 3-acetoxypropyl functionalized siloxane membranes in which the Cd2+ selective ionophore 2 was incorporated. CHEMFETs with a [3-(p-acetylphenoxy)propyl]polysiloxane membrane containing the Pb2+ selective ionophore 3 showed good selective responses towards Pb2+.
|Journal||Journal of the Chemical Society. Perkin transactions II|
|Publication status||Published - 1996|