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Lamellae orientation effect on local polarized domain in P(VDF/TrFE) copolymer: Application in data storage

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Abstract

In our previous article we achieved a high planar orientation of the poly(vinylidene fluoride and trifluoroethylene) [P(VDF/TrFE)] crystalline lamellae.1 This short article focuses and reports our studies on the effect of this lamella orientation on its local polarized domains. Two samples A and B are considered in this investigation. In many parts of the film area, the lamella nanocrytals were oriented parallel to the substrate along a unidirectional axis by a newly conceived method, which consists of depositing a thin film on the clean surface of distilled water (sample A). In the second type (sample B), a film was prepared on highly oriented pyrolytic graphite (HOPG) by spin-coating, showing random and entangled lamellae in the amorphous phase. Atomic force microscopy (AFM) has been used to investigate morphological development and the local poled domain during an applied bias voltage for both A and B samples. The results showed that a minimum bias voltage of +3 V was enough to observe the local poled domain in the case of oriented lamellae (sample A) while there was no piezoresponse measured in the case of random lamellae (sample B). When we increased the applied bias voltage, sample B showed a recorded local domain as a piezoresponse while in the case of sample A the local domain was enlarged. We can suggest that, during the preparation of sample A, the macromolecules had a preferential stable position where the dipole moments did not need a strong bias voltage to be switched but cross to the coercive voltage Vc. The character of oriented lamella nanocrytals can minimize the poling voltage in ferroelectric organic ultrathin films and will have an advantageous influence on production of a high-functionality mass memory device in data storage. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1410–1413, 2005

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