SURFACE ATTACHMENT OF WELL-DEFINED REDOX-ACTIVE POLYMERS AND BLOCK POLYMERS VIA TERMINAL FUNCTIONAL-GROUPS

Redox-active polymers and block polymers containing terminal groups fo r covalent attachment to surfaces have been prepared and characterized . Ferrocene- and phenothiazine-based redox-active polymers were prepar ed by ring-opening metathesis polymerization (ROMP) using Mo initiator s of the type Mo(CHR)(NAr)(O-t-Bu)2 (R = tert-butyl or ferrocenyl, Ar = 2,6-diisopropylphenyl). The functional end groups introduced for sur face attachment chemistry were Si(OEt)3, pyridyl, bromobenzyl, and pyr enyl derivatives. Polymers containing Si(OEt)3 were successfully used to derivatize Pt, In2(Sn)O3, and n-Si electrodes, whereas analogues of those same polymers lacking Si(OEt)3 groups do not bind to these surf aces. Polymers terminated with pyridyl or bromobenzyl groups, introduc ed in the capping reaction using the appropriate aldehydes, react with electrodes pretreated with benzyl chloride or pyridine groups, respec tively, to give polymer-derivatized surfaces. Pyrene-capped polymers w ere made in an attempt to bind the polymers to carbon electrodes via s elective pyrene adsorption. However, the polymer itself strongly adsor bs, precluding a specific role for the pyrene group. On the basis of t he surface coverage found for the redox-active groups (approximately 1 X 10(-10) mol cm-2) and polymers (approximately 8 X 10(-12) mol cm-2) at the electrode surfaces, bound polymer chains hinder the access of unbound polymers to portions of the surface, thereby yielding a lower density of bound polymer than would be expected were the chain to exte nd away from the electrode surface.