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The electrochemical doping/dedoping kinetics, and the organic electrochemical transistor (OECT) performance of a series of polythiophene homopolymers with ethylene glycol units in their side chains using both kosmotropic and chaotropic anion solutions were studied. We compare their performance to a reference polymer, the polythiophene derivative with diethylene glycol side chains, poly(3-{[2-(2-methoxyethoxy)ethoxy]methyl}thiophene-2,5-diyl) (P3MEEMT). We find larger OECT material figure of merit, μC *, where μ is the carrier mobility and C * is the volumetric capacitance, and faster doping kinetics with more oxygen atoms on the side chains, and if the oxygen atom is farther from the polythiophene backbone. Replacing the oxygen atom close to the polythiophene backbone with an alkyl unit increases the film π-stacking crystallinity (higher electronic conductivity in the undoped film) but sacrifices the available doping sites (lower volumetric capacitance C * in OECT). We show that this variation in C * is the dominant factor in changing the μC * product for this family of polymers. With more oxygen atoms on the side chain, or with the oxygen atom farther from the polymer backbone, we observe both more passive swelling and higher C *. In addition, we show that, compared to the doping speed, the dedoping speed, as measured via spectroelectrochemistry, is both generally faster and less dependent on ion species or side chain oxygen content. Last, through OECT, electrochemical impedance spectroscopy (EIS) and spectroelectrochemistry measurements, we show that the chaotropic anion PF 6 − facilitates higher doping levels, faster doping kinetics, and lower doping thresholds compared to the kosmotropic anion Cl − , although the exact differences depend on the polymer side chains. Our results highlight the importance of balancing μ and C * when designing molecular structures for OECT active layers. 

Machining complex thin-wall components (such as compressor disks and casings in aircraft engines) has been a challenging task because workpiece deformations and vibrations not only compromise the surface integrity but also induce residual stresses in the final products. This paper offers a physics-based method that accounts for the damping effects and external loads for reconstructing the dynamic displacement and strain fields of a thin-wall workpiece in real-time with non-contact displacement measurements during machining. Given that part dynamic behaviors can be characterized by superposition of mode shapes, the time-varying displacement and strain fields are reconstructed with modal coefficients that are updated in real time using in situ measurements. The reconstruction method has been numerically verified with finite element analyses with the sensor locations optimized using a genetic algorithm; both static and dynamic field reconstructions are analyzed. Tradeoffs between the number of sensors and the reconstruction efficiency in terms of computation time and error are discussed. The method has been evaluated experimentally on a lathe machine testbed, where the dynamics of the distributed physical fields have been successfully captured and analyzed, demonstrating its practicality as a real-time tool for continuously monitoring the displacement and strain distributions across a disk workpiece during machining.