Polymer chain encapsulation followed by a quartz microbalance during electropolymerization of bithiophene-beta-cyclodextrin host-guest compounds in aqueous solution

Hydroxypropyl-beta-cyclodextrins (HP beta CD) which form 1:1 host-guest inc lusion compounds with bithiophene (BT) are used for the anodic electropolym erization of bithiophene in aqueous solution. Partial encapsulation of the polymer chains by cyclodextrins is suspected from the quartz balance respon se during polymer reduction by cyclic voltammetry or double-step chronoampe rometry. In this case, relatively thin films containing more than one HP be ta CD molecule for ten BT monomers are formed on platinum electrodes. On th e other hand, HP beta CD insertion or adsorption in the oxidized form of th e polymer, obtained under galvanostatic or potentiostatic conditions, was f ound to be dependent on experimental conditions (long polymerization time). These results tend to confirm that polymerization occurs outside the CD ca vity and that cyclodextrin insertion may occur by chain encapsulation after the polymer formation, (C) 1999 Elsevier Science S.A. All rights reserved.