Ferroelectric and antiferroelectric properties are among the most spectacular manifestations of cooperative phenomena in condensed materials. These effects are observed in a wide diversity of materials, such as solids, composite ceramics, polymers, and liquid crystals. The most studied systems correspond to perovskites as inorganic materials, and chiral liquid crystals as organic materials.This work shows that ferroelectricity can also be detected in systems consisting of liquid-crystalline monomer±polymer mixtures possessing no chiral centers at allÐherein we present the first reported material of this nature.Chiral liquid-crystalline systems are very interesting, since their ferro-or antiferroelectric properties can be controlled structurally. The usually applied routine approach for preparing such materials is essentially based on the use of chiral liquid-crystalline substances possessing a tilted smectic phase. In such cases, spontaneous polarization arises as a secondary order parameter. [1±3] In 1996, we spearheaded the discovery of the first achiral, macroscopically polar liquid-crystalline system, consisting of an achiral side chain polymer and its monomer.[4] The clearcut antiferroelectric order was first demonstrated by us in non-chiral tilted smectics, where the local polarization is in the tilt plane. [5,6] Of particular interest is the fact that neither of the two components, by themselves, manifested this behavior. The mixtures show antiferroelectric polarization hysteresis curves in the smectic C phase and, after undergoing a poling process by cooling to the glassy state, revealed high pyroelectric responsesÐof potential interest for applications such as IR or piezo-detectors. [4] Almost at the same time, novel schemes were developed to successfully introduce antiferroelectric or ferroelectric properties into liquid-crystalline material systems without chiral centers. Bent-shaped molecules exhibit a different smecticlike ordering, with in-plane spontaneous polarization.[7] A previous successful scheme for designing achiral ferroelectric liquid crystals exploiting the so-called polyphylic effect was first realized by Tournilhac et al. [8] In this communication, we give the first report on new, achiral ferroelectric polymerÐhomologous-monomer mixtures. In accordance with our previous work, [5,6] the same nomenclature is used: PMnRm where P denotes the backbone polymer; Mn is a methacrylate group with n methylene units as the aliphatic spacer; Rm is a rigid resorcylphenylimine group core (R) possessing an alkoxy flying tail with m methylene units located in the para position and bonded to Mn. The composites consist of the side chain polymer PM6R12 and different monomers, such as M4R5, M4R6, and M4R8 (homologs of the M6R12 monomer), mixed in a 2:1 molar ratio. The aim of this work was to study the influence of the different monomers on the pyroelectric response for the PM6R12±M4R5, PM6R12±M4R6, and PM6R12±M4R8 composites. The molecular-length variation of the monomer with respect to the polymer side...
