Open-circuit direct piezoelectric coefficients g31 of bi-axially stretched PVDF and chiral PLLA are reported. This measure is decisive for sensor, generator and energy harvesting applications. We use an in-situ method with contactless voltage measurement during a conventional tensile-test, greatly improving measurement precision (error less than 10%).

Direct piezoelectric g 31 voltage coefficient was measured in situ as a function of applied tensile stress for films of polyvinylidene fluoride (PVDF). Measurements were performed under quasi-static conditions with applied strain rates of 0.5-1.5 mm/min for strains up to 12%. Open-circuit voltage was measured with a contact-less electrostatic voltmeter. Obtained results show a strong dependence of the g 31 coefficient of mono-oriented PVDF films on the applied stress, with a maximum value of the coefficient in the transition region between elastic and plastic deformation zones. The effect of sample geometry on the apparent g 31 coefficient is shown and discussed. The anisotropy of the piezoelectric effect is studied by means of g 31 and g 32 measurements. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43248.

Printed organic electronics has attracted considerable interest in recent years as it enables the fabrication of large-scale, low-cost electronic devices, and thus offers significant possibilities in terms of developing new applications in various fields. Easy processing is a prerequisite for the development of low-cost, flexible and printed plastics electronics. Among processing techniques, meniscus guided coating methods are considered simple, efficient, and low-cost methods to fabricate electronic devices in industry. One of the major challenges is the control of thin film morphology, molecular orientations and directional alignment of polymer films during coating processes. Herein, the recent progress of emerging field of meniscus guided 2 printing organic semiconductor materials is discussed. The first part of this report briefly summarizes recent advances in meniscus guided coating techniques. The second part discusses periodic deposits and patterned deposition at moving contact lines, where the mass-transport influences film morphology due to convection at the triple contact line. The last section summarizes our strategy to fabricate large-scale patterning of πconjugated polymers using meniscus guided method. I)