Nonelectrical poling in ferroelectric polythioureas

摘要

A new poling method utilizing the cooperativity and strong hydrogen bonding force of thiourea groups is proposed in ferroelectric polythioureas [poly(octamethylene thiourea) and poly(nonamethyleno thiourea)]. The method, which is named "surface energy poling," takes advantage of the surface energy difference of the polar amorphous material to form remanent polarization. A polythiourea film sandwiched between a metal with higher surface energy and polytetrafluoroethylenes with lower surface energy was heated up to Tc [1.15×Tg (glass transition temperature)] and cooled slowly to room temperature. The resulting film showed a pyroelectric constant of 10 Μ/m2K, giving evidence of remanent polarization. This method is similar to the orientation process in liquid crystal devices.