Dopant macroinitiator for electropolymerisation and functionalisation of conducting polymer thin films

Abstract

Grafting of polymer brushes from conducting polymer (CP) thin films by controlled radical polymerisation provides a versatile route for the synthesis of functional, electroactive surfaces, with applications in diverse fields. However, one of the drawbacks of this approach is the difficulty of upscaling the synthesis due to the need for specialised CP precursor monomers functionalised with initiation sites. We herein describe an alternative approach to the synthesis of CP-based polymer brushes whereby atom transfer radical polymerisation initiation sites are attached to a macrodopant incorporated into CP films during electropolymerisation. The facile electropolymerisation of commonly studied CPs with an initiator-functionalised macrodopant -poly[(styrene sulfonate)-co-(2-bromopropionyloxyethyl methacrylate)] -is demonstrated. The composite polymer films thus synthesised were used as substrates for grafting of hydrophilic polymer brushes. Although poly(styrene sulfonate) is commonly used as a macrodopant in CP films, its initiator-functionalised derivatives have not previously been utilised in this manner. Despite the elegance of this approach, to the authors' knowledge, there have been no previous examples reported of utilising macromolecular dopants as initiators for subsequent grafting of polymer brushes.

Molecular “Building Block” and “Side Chain Engineering”: Approach to Synthesis of Multifunctional and Soluble Poly(pyrrole phenylene)s

“…[4,5] For instance, side chain engineering of CPs has rendered the material's solubility to facilitate large-area fabrication of organic devices and sensors through solution-based processes. [6,7] In addition In our pyrrole phenylene (PyP) termonomer design, the central benzene ring affords a handle for a variety of functionalization ( Figure 1b). Derivatization of the central benzene ring allowed functionalization of the polymer without significantly interfering with the electronic properties of the conjugated backbone.…”

“…Organic electronic materials, notably conjugated polymers (CPs), offer many advantageous properties for bioelectronics; the most valuable being both ionic and electrical conductivity (when doped), ease of chemical functionalization, and solution processability through the addition of side chains . For instance, side chain engineering of CPs has rendered the material's solubility to facilitate large‐area fabrication of organic devices and sensors through solution‐based processes . In addition to solubility, other features such as biomimetic functionalities, which include dry‐adhesion, stimuli‐responsiveness, sensing, mechanical stretchability, and self‐healing can be tailored and expressed through incorporation of polymeric side chains onto the CP, as demonstrated by us and others …”

“…Our PPyP backbone contained i) a methoxy side chain (temonomer 1 ), ii) an azide moiety ( 2 ), and iii) an initiating site for ATRP ( 3 ). Termonomer 1 served as spacer unit with the purpose of controlling the grafting density of the resulting graft copolymers, while termonomers 2 and 3 allowed for functionalization of PPyP by azide–alkyne “click” reactions and grafting of low dispersity polymeric side chains, respectively. Initially, polymeric brushes were grafted onto termonomer 3 by means of ATRP to provide solubility for the resulting PPyP .…”