Conductive polymer (CP) coatings can improve the performance of metallic bioelectrodes in implantable devices, a benefit which is partially attributed to the “softer” material interface. However, due to the nature of CP fabrication on metallic substrates, accurate quantification of mechanical properties has been difficult to achieve. This study demonstrates that peak‐force quantitative nanomechanical mapping (PF‐QNM) is a robust technique for determining the modulus of CP coatings. The effect of dopant size, chemistry, and film hydration on the mechanical properties of poly(3,4‐ethylene dioxythiophene) (PEDOT) is also examined. Analysis of PEDOT doped with poly(styrene sulfonate) produced across five different thicknesses confirms the utility of PF‐QNM in yielding quantitative, repeatable moduli in both the dry and hydrated state. By doping PEDOT with paratoluene sulfonate and perchlorate (ClO4) it is shown that the hydrophilicity and the size of the dopant are both critical factors influencing CP mechanical properties in the hydrated environment. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 666–675

Traditionally, conductive materials for electrodes are based on high modulus metals or alloys. Development of bioelectrodes that mimic the mechanical properties of the soft, low modulus tissues in which they are implanted is a rapidly expanding field of research. Many polymers exist that more closely match tissue mechanics than metals; however, the majority do not conduct charge. Integrating conductive properties via incorporation of metals and other conductors into nonconductive polymers is a successful approach to producing polymers that can be used in electrical interfacing devices. When combining conductive materials with nonconductive polymer matrices, there is often a tradeoff between the electrical and mechanical properties. This review analyzes the advantages and disadvantages of approaches involving coating or layer formation, composite formation via dispersion of conductive inclusions through polymer matrices, and in situ growth of a conductive network within polymers.

This study examines the efficacy of primary and secondary nucleation for electrochemical polymerisation of conductive polymers within poly(vinyl alcohol) methacrylate hydrogels. The two methods of nucleation investigated were a primary heterogeneous mechanism via introduction of conductive bulk metallic glass (Mg64Zn30Ca5Na1) particles and a secondary mechanism via introduction of “pre-polymerised” conducting polymer within the hydrogel (PEDOT:PSS). Evidence of nucleation was not seen in the bulk metallic glass loaded gels, however, the PEDOT:PSS loaded gels produced charge storage capacities over 15 mC/cm2 when sufficient polymer was loaded. These studies support the hypothesis that secondary nucleation is an efficient approach to producing stand-alone conducting hydrogels.

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