文摘
Electropolymerized films of the functionalized pyrrole,pentafluorophenyl-3-(pyrrol-1-yl)propionate (PFP), werereacted with a solution-phase nucleophile, ferroceneethylamine. This reaction was chosen as a model representative of a postdeposition modification of the polymermembrane's properties. For the first time, a nondestructive method for direct chemical analysis of the reactionprofile within the electrodeposited polymer membraneafter nucleophilic substitution is presented. This wasachieved through the application of in situ neutron reflectivity with supplementary analytical information concerning the film's chemical composition obtained fromXPS, FT-IR, and electrochemical measurements. Theresults presented illustrate how, for a partially reacted filmresulting from a short reaction time, the extent of reactionwith ferrocene ethylamine is not homogeneous throughoutthe thickness of the film, but occurs predominantly at thepolymer/solution interface. We show that the progress ofthe reaction within the polymer film is limited by thetransport of reacting species in the dense regions of themembrane that are furthest from the solution interface.The data do not fit an alternative model in which there isspatially homogeneous progression of the reaction frontthroughout the bulk of the thin film polymer. Guided bythe neutron reflectivity measurements, suitable modifications were made to the electrodeposition method toprepare films whose architecture resulted in faster ratesof reaction.
