TY  - JOUR
A1  - Sborikas, Martynas
A1  - Qiu, Xunlin
A1  - Wirges, Werner
A1  - Gerhard, Reimund
A1  - Jenninger, Werner
A1  - Lovera, Deliani
T1  - Screen printing for producing ferroelectret systems with polymer-electret films and well-defined cavities
JF  - Applied physics : A, Materials science & processing
N2  - We report a process for preparing polymer ferroelectrets by means of screen printing-a technology that is widely used for the two-dimensional patterning of printed layers. In order to produce polymer-film systems with cavities that are suitable for bipolar electric charging, a screen-printing paste is deposited through a screen with a pre-designed pattern onto the surface of a polymer electret film. Another such polymer film is placed on top of the printed pattern, and well-defined cavities are formed in-between. During heating and curing, the polymer films are tightly bonded to the patterned paste layer so that a stable three-layer system is obtained. In the present work, polycarbonate (PC) films have been employed as electret layers. Screen printing, curing and charging led to PC ferroelectret systems with a piezoelectric d (33) coefficient of about 28 pC/N that is stable up to 100 C-a similar to. Due to the rather soft patterned layer, d (33) strongly decreases already for static pressures of tens of kPa. The results demonstrate the suitability of screen printing for the preparation of ferroelectret systems.
Y1  - 2014
U6  - https://doi.org/10.1007/s00339-013-7998-3
SN  - 0947-8396
SN  - 1432-0630
VL  - 114
IS  - 2
SP  - 515
EP  - 520
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Zhao, Qiang
A1  - Dunlop, John William Chapman
A1  - Qiu, Xunlin
A1  - Huang, Feihe
A1  - Zhang, Zibin
A1  - Heyda, Jan
A1  - Dzubiella, Joachim
A1  - Antonietti, Markus
A1  - Yuan, Jiayin
T1  - An instant multi-responsive porous polymer actuator driven by solvent molecule sorption
JF  - Nature Communications
N2  - Fast actuation speed, large-shape deformation and robust responsiveness are critical to synthetic soft actuators. A simultaneous optimization of all these aspects without trade-offs remains unresolved. Here we describe porous polymer actuators that bend in response to acetone vapour (24 kPa, 20 degrees C) at a speed of an order of magnitude faster than the state-of-the-art, coupled with a large-scale locomotion. They are meanwhile multi-responsive towards a variety of organic vapours in both the dry and wet states, thus distinctive from the traditional gel actuation systems that become inactive when dried. The actuator is easy-to-make and survives even after hydrothermal processing (200 degrees C, 24 h) and pressing-pressure (100 MPa) treatments. In addition, the beneficial responsiveness is transferable, being able to turn 'inert' objects into actuators through surface coating. This advanced actuator arises from the unique combination of porous morphology, gradient structure and the interaction between solvent molecules and actuator materials.
Y1  - 2014
U6  - https://doi.org/10.1038/ncomms5293
SN  - 2041-1723
VL  - 5
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Qiu, Xunlin
A1  - Wirges, Werner
A1  - Gerhard, Reimund
T1  - Polarization and Hysteresis in Tubular-Channel Fluoroethylenepropylene-Copolymer Ferroelectrets
JF  - Ferroelectrics
N2  - Polarization-vs.-applied-voltage hysteresis curves are recorded on tubular-channel fluoroethylene-propylene (FEP) copolymer ferroelectrets by means of a modified Sawyer-Tower circuit. Dielectric barrier discharges (DBDs) inside the cavities are triggered when the applied voltage is sufficiently high. During the DBDs, the cavities become man-made macroscopic dipoles which build up an effective polarization in the ferroelectret. Therefore, a phenomenological hysteresis curve is observed. From the hysteresis loop, the remanent polarization and the coercive field can be determined. Furthermore, the polarization can be related to the respective piezoelectric coefficient of the ferroelectret. The proposed method is easy to implement and is useful for characterization, further development and optimization of ferro- or piezoelectrets.
KW  - Ferroelectrets
KW  - piezoelectrets
KW  - tubular-channel polymer systems
KW  - dielectric barrier discharge (DBD)
KW  - fluoroethylenepropylene (FEP) copolymer
KW  - piezoelectricity-polarization relation
Y1  - 2014
U6  - https://doi.org/10.1080/00150193.2014.964603
SN  - 0015-0193
SN  - 1563-5112
VL  - 472
IS  - 1
SP  - 100
EP  - 109
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  -