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Direct fluorination of polymers is a widely utilized technique for chemical modification. Such introduction of fluorine into the chemical structure of polymeric materials leads to laminates with highly fluorinated surface layer. The physicochemical properties of this layer are similar to those of perfluorinated polymers that differ by a unique combination of chemical resistance, weak adhesion, low cohesion, and permittivity, often barrier properties, etc. Surface modification by elemental fluorine allows one to avoid laborious synthesis of perfluoropolymers and impart such properties to industrial polymeric materials. The current review is devoted to a detailed consideration of wetting by water, energy characteristics of surfaces, adhesion, mechanical and electrical properties of the polymers, and composites after the direct fluorination.

Parylene is a widely used polymer possessing advantages such as simple and cheap production, possibility of fabrication on flexible substrates, transparency, and safety for the human body. Moreover, parylene can be used as an active layer of memristors—circuit design elements that are promising for the implementation of hardware neuromorphic systems. Recent studies show that memristors are not merely memory but also highly dynamical systems that can encode timing information. Here, a study of the switching kinetics and the timing second-order effects in memristors based on pristine and nanocomposite (with embedded silver nanoparticles) parylene is presented. The strong decrease in the resistive switching time and increase in the amplitude of the resistive state change after preliminary heating pulses are revealed. These effects are explained by the local heating of the parylene matrix by electric pulses, and the given explanation is supported by the numerical electrothermal model. Spike-timing-dependent plasticity with symmetrical nonoverlapping spikes is demonstrated. The obtained results indicate a possibility of the utilization of second-order effects in the development of the neuromorphic systems.

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In this study, an electrorheological effect of the suspensions containing porous chitosan particles in olive oil in a wide range of electric fields is reported. Porous chitosan particles were produced by freeze-drying. The structure of the filler was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray scattering. Electrorheological behavior of low-filled fluids (0.1, 0.2, 0.5, and 1.0 wt %) was studied in shear and oscillation modes. Rheological data were fitted by Bingham, Cho–Choi–Jhon, and Seo–Seo models. Conductivity measurements were carried out to characterize the electrophysical properties of studied fluids. Polarization processes were considered from the standpoint of the Cole–Cole equation. Natural biodegradable materials such as chitosan and olive oil were used as components. The fluids showed high response to electric field and stable cyclic operation in on/off mode at extremely low concentrations. The yield stress reaches about 100 Pa for a 1 wt % suspension under an electric field of just 1 kV/mm. The sedimentation stability of the samples dramatically increases when the percolation threshold is passed. The sedimentation ratio at 1 wt % of the filler content remains at the level of 90% after almost a month. Thus, suspensions were considered as an alternative to typical silicon oil-based electrorheological fluids.

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