It is attractive to control the properties of macro objects and films by employing simple nanolayer composites, as in the case of nanoarchitectured Layer-by-Layer (LbL) coating. In this paper, we use chitosan as a surface-based pH buffer to protect adsorbed supramolecular fibres from pH-mediated disassembly. Protons are generated on a titania surface under illumination at 405 nm leading to an appreciable pH change on the surface. We find that supramolecular polymers that are highly sensitive to pH change will not disassemble after irradiation if a nanolayer of chitosan is present. We propose that chitosan can be used as an efficient pH-responsive protective layer for pH sensitive soft materials.

Crystallographic property such as crystallite size has been used for evaluation of the temperature up to which high intensity ultrasound can heat metal particles depending on physical properties of sonication medium and particle concentration. We used >100 μm metal particles as an in situ indicator for ultrasonically induced temperature in the particle interior. Based on powder X-ray diffraction monitoring of Al3Ni2 crystallite sizes after ultrasound treatment the average minimum temperature T particle(min) of sonicated particles in various sonication media was estimated. Additionally, it was found that crystallite size in ultrasonically treated metal particle depends on the frequency of interparticle collision. Through the adjustment of particle concentration, it is possible to either accelerate the atomic diffusion or force the melting and recrystallization processes. Overall, the energy released from collapsing cavitation bubble can be controllably transferred to the sonication matter through the appropriate choice of sonication medium and the adjustment of particle concentration.

An understanding of the nature and conditions of nonlinear processes in open systems is important for modulation of the microstructure of solids at a new level of complexity. We demonstrate that cavitation generated by high intensity ultrasound (HIUS) triggers nonlinear processes in microparticles and layers of titanium. We reveal a non-monotonic dependence of the size of grains in the treated solids on sonication time, and oscillation of titanium grain sizes vs. time of ultrasonic treatment, indicating the influence of two opposing forces: cavitation driven impact of shock heating and shear stress on surfaces. These nonlinear self-organization processes in solids promise new microstructured materials with applications among others in bio- and geosciences.

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