Graft Copolymers with Conducting Polymer Backbones: A Versatile Route to Functional Materials

Abstract

Graft copolymers with a conducting polymer backbone are a promising class of materials for diverse applications including, but not limited to, organic electronics, stimuli-responsive surfaces, sensors, and biomedical devices. These materials take advantage of the unique electrochemical and optoelectronic properties of conducting polymers, complemented by chemical and/or physical properties of the grafted sidechains. In this Personal Account, we discuss our work in designing functional surfaces based on graft copolymers with a conducting polymer backbone, in the context of broader developments in the field. We review the synthetic approaches available for the rational design of conducting-polymer-based graft copolymers, and examine the types of functional surfaces and soluble materials that may be engineered using these techniques.

Dopant macroinitiator for electropolymerisation and functionalisation of conducting polymer thin films

“…It should be noted, however, that despite the higher initiator density on the macroinitiator, the incorporation of PeesBro in a CP matrix will decrease the actual density of grafting sites on the surfaces. For many of the applications of conducting polymers, a tool to alter the surface chemistry of the conductive substrate is very important regardless of whether the grafting to do so can achieve densely grafted true polymer brushes or not . Grafting efficiency from PeesBro with an approximate DP of 25, as described here, may also be compromised by the dopant leaching out of the CP film – especially when incorporated in more hydrophilic CPs which may swell during grafting in aqueous solution.…”

“…On PeesBro itself, the initiating site density is high enough to be well within the brush regime, however. For conducting polymers though, where many are challenging to functionalise without losing conductivity, there is a real benefit of being able to incorporate a handle to graft from to change overall film characteristics and wettability – regardless of whether true polymer brushes are produced or not …”

“…A flexible approach for the synthesis of CP‐based molecular brushes with surface‐confined backbones is to electropolymerise a CP ‘macroinitiator’ for controlled radical polymerisation (CRP) from monomers incorporating a reversible addition–fragmentation chain transfer agent or atom transfer radical polymerisation (ATRP)‐initiating site . Surface‐initiated CRP techniques allow for growth of polymer brushes with low polydispersity, can provide control over the molecular weight of grafted side chains, and give access to grafting of a wide range of monomers with desirable chemical functionalities …”

Advances in Conducting, Biodegradable and Biocompatible Copolymers for Biomedical Applications

“…Their approach was used to obtain ICPs with improved processability and mechanical properties, but focused on biosensing applications (Alkan et al, 1999;Kizilyar et al, 1999;Cirpan et al, 2001;Yagci and Toppare, 2003;Arica et al, 2005;Sahin et al, 2005;Uygun et al, 2010). There are a vast literature and excellent reviews on the grafting polymer chains for biointerfaces (Hackett et al, 2017), macromonomer techniques (Ito, 1998;Adachi and Tsukahara, 2015), functional materials (Strover et al, 2016), electroactive materials (Pron et al, 2010), biodegradable and electrically conducting polymers (Guo et al, 2013) and biomimetic conducting polymers (Hardy et al, 2013).…”

An amphiphilic, heterografted polythiophene copolymer containing biocompatible/biodegradable side chains for use as an (electro)active surface in biomedical applications

“…12 Furthermore, some graft copolymers that incorporates conducting polymers (CPs), where the -conjugated chains are connected with flexible, hydrophilic or hydrophobic side chains, are another interesting class with a particular property, sensitivity to external stimuli (electrical or chemical), caused by their conjugated structure. [13][14][15][16] Among CPs, polythiophene (PTh) and its derivatives are particularly important due to their high stability, controllable electrochemical behaviour, and ease chemical and structural modification. 17,18 On the other hand, biodegradable and biocompatible graft copolymers based on polycaprolactone (PCL) and polyethylene glycol (PEG) units are reported to be an important class in amphiphilic macromolecules for drug delivery [19][20][21][22][23] and bioimaging applications.…”