Ferroelectric co-crystalline polymers

Apolar syndiotactic polystyrene (s-PS) can easily form a stable clathrate co-crystalline phase with highly polar 4-nitroaniline molecules. The ferroelectric response of thin films containing the s-PS/4-nitroaniline clathrate phase has been investigated by scanning piezoresponse force microscopy (SPFM) and compared with the response of a poly(vinylidene-fluoride-trifluoroethylene) P(VDF-TrFE) copolymer film. Measurements show that ferroelectric polymer materials can be obtained by crystalline phases whose polarity is given by low-molecular-mass guest molecules rather than by polymer chain polarity. Moreover, as for P(VDF-TrFE), nanoimprinting processes can be applied to these materials by using the SPFM technique but, in the absence of external fields, the SPFM images are lost through an exponential intensity decay.