Surface-initiated ring-opening metathesis polymerization (SI-ROMP): Synthesis and electropolymerization of terthiophene-functionalized olefin peripheral dendrons

We report on the synthesis and electrodeposition of peripheral olefin dendrons with electropolymerizable focal point terthiophene units. These films were utilized for surface initiated ring-opening metathesis polymerization (SI-ROMP) of norbornene to form grafted polynorbornene brushes. The dendrons were first electrodeposited on an electrode surface, forming a highly dense and uniform polythiophene-type film, and their electrochemical behavior was investigated. Subsequently, after activation with a transition metal metathesis catalyst, polynorbornene brushes were grown from the electrodeposited films which were found to be highly dependent on the density of exposed olefin functional groups and dendron generation. The change in film morphology was examined by atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) was used to prove polynorbornene brush film growth and composition on top of the electropolymerized layer. Brush growth kinetics experiments were also carried out to understand the correlation between the structure of the dendrons and polynorbornene brush growth mechanism. The method presented in this paper provides a facile route to prepare robust, uniform, and controllable polymer brushes grafted from an underlying π-conjugated polymer layer.