Enhanced electrical conductivity by macromolecular architecture: Hyperbranched electroactive and degradable block copolymers based on poly(ε-caprolactone) and aniline pentamer

We present macromolecular architecture design as a useful tool to enhance the conductivity of degradable polymers. Linear and hyperbranched copolymers with electrical conductivity and biodegradability were synthesized by an 'A ₂ + B_n (n = 2, 3, 4)' strategy using carboxyl-capped aniline pentamer (CCAP) and branched poly(ε-caprolactone)s (PCLs) by coupling reactions. A more hydrophilic surface and lower crystallinity of the doped emeraldine state of aniline pentamer (EMAP) copolymer was achieved compared with PCLs, and TGA results demonstrated that the CCAP contents in the copolymers were almost the same. The structure of the polymers was characterized by FT-IR, NMR, and SEC. Good electroactivity of the copolymers was confirmed by UV and cyclic voltammetry (CV), and CV showed three pairs of redox peaks. The hyperbranched copolymers had a higher conductivity than the linear ones. It is suggested that the higher conductivity of the hyperbranched copolymer is due to the ordered distribution of peripheral EMAP segments that more easily form a conductive network. Therefore, the conductivity of the polymers is improved and controlled by the macromolecular architecture.