Polymers representing soft materials exhibit a variety of functional properties undergoing energy storage, transport and conversion. Among them, we focus our attention on polyvinylidene fluoride (PVDF: -CH2CF2-) and its copolymer with trifluoroethylene (TrFE: -CHFCF2-). They attracted continuous interest over 40 years because of their intriguing ferroelectric and piezoelectric properties as well as various applications for information storage, actuators, sensors and electrical power generation. Their ferroelectricity originates in the molecular dipoles associated with positive H and negative F atoms attached perpendicular to the chain axes. The all-trans conformation and parallel packing induce alignment of all molecular dipoles in one direction to produce a large spontaneous polarization. In ultrathin films (<100nm), the spontaneous polarization can be switched by action of relatively low voltage. On heating, VDF/TrFE copolymers undergo multiple phase transitions from ferroelectric to molten phases via. anti-ferroelectric and paraelectric phases as a result of successive losses of intermolecular and intramolecular dipolar order. The polarization switching has been proven to progress based on nucleation-growth mechanisms by means of scanning probe. The switching time becomes shorter with increasing applied electric field, first obeying an exponential law and then transferred to a power law above 200MV/m to reach as fast as 1 ns at 1GV/m. Recent studies towards comprehensive understanding of basic mechanisms of piezoelectricity and its relaxation will be presented based on the accurate measurements and detailed analysis of dielectric relaxation and piezoelectric resonance spectra.
Prof. Takeo Furukawa received PhD in Engineering from the University of Tokyo in 1978. From 1968 to 1992, he worked as a scientific researcher in the Biopolymer Physics Laboratory, Institute of Physical and Chemical Research. During this period, as visiting professor, he engaged in research work in AT&T Bell Laboratory (USA) for four times (1979-1981, 1982, 1984 and 1988). Since 1993, he has been working as a professor at the Tokyo University of Science. Since 1981, Prof. Takeo Furukawa has been employed as a visiting professor by Rutgers University (USA), Malaya University (Malaysia), Kyoto University, Waseda University, Osaka University and many other Universities. Since 2010, he has been working as Distinguished Research Scientist of the Kobayashi Institute of Physical Research, and Professor Emeritus of the Tokyo University of Science, respectively. So far, as an Academic Icon, he has been invited every year to guide the staffs and graduate students of the Malaya University.