A smectic main chain polymer, poly(tetramethyleneoxypropylene p,p′-bibenzoate), PPO4B, with thermal transitions Tg ) 26 °C and Ti ) 88.5 °C was studied in and after a drawing experiment. Variation of both strain rate and temperature resulted in materials with normal and anomalous orientations of smectic layers. Mechanical properties vary correspondingly. Samples from PPO4B were drawn at different strain rates and temperatures. The stress-strain curves were recorded. The resulting oriented materials were studied by wide-angle X-ray scattering. Normal orientation (i.e., smectic layer perpendicular to draw direction) is established at high strain rate and low temperature. Anomalous orientation is achieved at low strain rate and high temperature. At intermediate values of the processing parameters a bimodal structure of both normal and anomalous orientation is observed. Dynamic mechanical analysis measurements in tensile mode were carried out on strips cut from oriented sheets in three directions, 0°, 45°, and 90°in relation to the draw direction. The value of the storage modulus in the drawing direction is highest in the case of normal orientation (smectic layer perpendicular to the straining direction). The highest value of the storage modulus coincides with the direction perpendicular to most of the smectic layers. Thus, for anomalous orientation the worst mechanical properties are in the fiber direction.

A family of hybrid organoinorganic silica-based particles with varied chemical natures and morphologies has been synthesized to test their ability to develop coatings with underwater hydrophobicity. The particles were characterized by elemental microanalysis, scanning electron microscopy, and dynamic light scattering to evaluate the organic content, observe the morphology, and estimate the aggregate size, respectively. These morphologies were transferred into surface topographies by spraycoating dispersions made from the particles onto glass supports, resulting in coatings with an ample range of profiles and roughness but all of them being superhydrophobic. Atomic force microscopy and optical profilometry were used to map the coating surfaces and analyze the topography. Then, underwater hydrophobicity endurance was tested by immersion under a 2 cm 20 °C water column perpendicular to circular glass supports coated with the particles. The so-called mirror effect derived from the occurrence of the primary plastron (continuous air layer occluded between the surface and the water) was observed on the surface of all of the coatings tested. Apart from the dependency of plastrons on the water temperature and substrate shape, the plastron quality and lifetime is notably different depending on the particle morphology and thus on the coating topography. These experiments have demonstrated that the most persistent mirror effects, and therefore underwater superhydrophobicity, were produced on coatings that exhibited the smoothest topographies at the micrometric scale. In addition, these particle-only coatings can be made mechanically stable and robust by blending with a polymer matrix.

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The thermotropic phase behavior of P3O4B, a polybibenzoate with an asymmetric oxymethylenic spacer, has been analyzed by DSC, real-time synchrotron X-ray diffraction, and optical microscopy. The results show that the following phases are found on cooling: isotropic melt, S A mesophase, SC mesophase, and three-dimensional crystal. The subsequent melting reveals the enantiotropic character of P3O4B since the inverse phase sequence is found. Additionally, a clear recrystallization process is observed on melting, prior to the crystal-S C transition. The thermotropic properties of P3O4B are compared with those of its analogue polyester with an all-methylene spacer, poly(octamethylene p,p′bibenzoate), P8MB, and other polybibenzoates with oxymethylenic spacers. Compared with P8MB, significantly lower transition temperatures are found for P3O4B due to the higher flexibility and asymmetry of the spacer. The lowering is especially important for the formation of the final crystal structure, so that the mesophase temperature window is considerably enlarged in P3O4B, allowing to observe the transition SA to SC. Moreover, the comparison of the thermotropic properties of P3O4B with those of other polybibenzoates with oxymethylenic spacers reveals that P3O4B is the only one able to crystallize at the usual cooling rates of the calorimeter.

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