Size-Controlled Fabrication of Polyaniline Microfibers Based on 3D Hydrodynamic Focusing Approach.

Owing to the relatively high conductivity and unique redox behavior, polyaniline (PANI) has been one of the most technologically promising conducting polymers. Although various methodologies have been developed, fabrication of PANI microfibers has been a challenging task owing to the poor solubility in most organic solvents. By taking advantage of a microfluidic technology and organic soluble acid labile t-Boc-protected PANI (t-Boc-PANI) as the conducting polymer precursor, fabrication of PANI microfibers in a size-controlled manner is possible. Introduction of a THF solution containing t-Boc-PANI, and dodecylbenzenesulfonic acid (DBSA) as a core flow, and water as a sheath flow into a microfluidic channel with a 3D hydrodynamic focusing effect results in crystallization of the polymer fiber. By changing the flow rate, linear PANI microfibers that range from 16.2 to 39.4 µm in diameter are readily obtained.

Polymerizable Supramolecular Approach to Highly Conductive PEDOT:PSS Patterns.

Owing to its high conductivity, solution processability, mechanical flexibility, and transparency, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been extensively explored for use in functional devices including solar cells, sensors, light-emitting diodes, and supercapacitors. The ability to fabricate patterned PEDOT:PSS on a solid substrate is of significant importance to develop practical applications of this conducting polymer. Herein, we describe a new approach to obtain PEDOT:PSS patterns that are based on a polymerizable supramolecular concept. Specifically, we found that UV irradiation of a photopolymerizable diacetylene containing PEDOT:PSS film followed by development in deionized water and subsequent treatment with sulfuric acid (glass and silicon wafer) or formic acid (PET) produces micron-sized PEDOT:PSS patterns on solid substrates. The newly designed photolithographic method, which can be employed to generate highly conductive (>1000 S/cm) PEDOT:PSS patterns, has many advantages including the use of aqueous process conditions, a reduced number of process steps, and no requirement for plasma etching procedures.

An Electrolyte-Free Conducting Polymer Actuator that Displays Electrothermal Bending and Flapping Wing Motions under a Magnetic Field.

Electroactive materials that change shape in response to electrical stimulation can serve as actuators. Electroactive actuators of this type have great utility in a variety of technologies, including biomimetic artificial muscles, robotics, and sensors. Electroactive actuators developed to date often suffer from problems associated with the need to use electrolytes, slow response times, high driving voltages, and short cycle lifetimes. Herein, we report an electrolyte-free, single component, polymer electroactive actuator, which has a fast response time, high durability, and requires a low driving voltage (<5 V). The process employed for production of this material involves wet-spinning of a preorganized camphorsulfonic acid (CSA)-doped polyaniline (PANI) gel, which generates long, flexible, and conductive (∼270 S/cm) microfibers. Reversible bending motions take place upon application of an alternating current (AC) to the PANI polymer. This motion, promoted by a significantly low driving voltage (<0.5 V) in the presence of an external magnetic field, has a very large swinging speed (9000 swings/min) that lies in the range of those of flies and bees (1000-15000 swings/min) and is fatigue-resistant (>1000000 cycles).