We studied peculiarities of the structural reconstruction within holographically recorded gratings on the surface of several different amorphous azobenzene-containing polymers. Under illumination with a light interference pattern, two processes take place in this type of polymer. The first process is the light-induced orientation of azobenzene units perpendicular to the polarization plane of the incident light. The second one is a transfer of macromolecules along the grating vector (i.e. perpendicular to the grating lines). These two processes result in the creation of a volume orientation grating (alternating regions of different direction or degree of molecular orientation) and a surface relief grating (SRG)-i.e. modulation of film thickness. One can assume that both orientation of molecules and their movement might change the local mechanical properties of the material. Therefore, formation of the SRG is expected to result also in modulation of the local stiffness of the polymer film. To reveal and investigate these stiffness changes within the grating, spin-coated polymer films were prepared and the gratings were recorded on them in two different ways: with an orthogonal circular or orthogonal linear polarization of two recording light beams. A combination of atomic force microscopy (AFM) and ultrasonic force microscopy (UFM) techniques was applied for SRG development monitoring. We demonstrate that formation of the phase gratings depends on the chemical structure of polymers being used, polymer film thickness, and recording parameters, with the height of grating structures (depth of modulation) increasing with both the exposure time and the film thickness. UFM images suggest that the slopes of the topographic peaks in the phase gratings exhibit an increased stiffness with respect to the grating depressions.

The thermal conductivity of polymer composites is measured for several tubular carbon nanofillers (nanotubes, fibres, and whiskers). The highest enhancement in the thermal conductivity is observed for functionalized multiwalled carbon nanotubes (90% enhancement for 1 vol. %) and Pyrograf carbon fibres (80%). We model the experimental data using an effective thermal medium theory and determine the thermal interface resistance (RK) at the filler-matrix interface. Our results show that the geometry of the nanofibres and the interface resistance are two key factors in engineering heat transport in a composite.

Two amorphous side-chain copolymethacrylates containing 60% azobenzene chromophores (PII, PIV) were irradiated homogeneously with a linear polarized Ar+ ion laser beam at 488 nm. From polarized UV/VIS spectra the maximum of the photoinduced dichroism was calculated (dPII=0.25, dPIV=0.35). No intensity dependence of this values was notified. PIV was irradiated under holographic conditions with a grating period of 30 m. Two types of polarization gratings, circular orthogonal and linear orthogonal ones were inscribed. Using a microscope spectrometer polarized UV/VIS spectra were measured within the grating period with a lateral resolution of about 2 m. The induced local dichroism was measured and the different modulation of the molecular orientation in the recorded gratings was confirmed by this direct experiment. PII was used to monitor the grows up stages of the surface relief grating, starting from the molecular photoorientation until the surface deformation. Parallel t o the online observed diffraction efficiency, the offline surface profile measurements were done by AFM. The details of surface topography and the reversibility of the process are discussed and an interesting possibility of the surface structuring is demonstrated

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