The phase and rheological behavior of combined cellulose and poly(N-vinylpyrrolidone) solutions in N-methylmorpholine-N-oxide with varying content of water are studied. At a PVP content of up to 30 wt % with respect to cellulose in the temperature range of 100–120°С the systems under study are emulsions and their rheological behavior is determined by the peculiar properties of the dispersed phase, the nature of the interfacial boundary, and its stability during the shear flow. This hypothesis is confirmed by the obtained dependences of the effective viscosity on the shear rate. The presence of PVP solution in the dispersed phase of emulsion does not worsen rheological properties, thus maintaining conditions for obtaining composite fibers similar to those for fiber spinning from cellulose solutions. Using the method of solid-phase dissolution of cellulose with the subsequent transfer of a solution to the viscous-flow state composite fibers can be obtained which opens prospects for their multipurpose use. The DSC study of the thermal behavior of the fibers indicates the intense interfacial interaction of the components. The mechanical characteristics of the fibers determined by tensile testing are comparable with the corresponding parameters of hydrated cellulose fibers.

New azochromophores (ACh) with terminal nitrile group have been synthesized. All compounds are crystalline at room temperature. Their melting points were measured by differential scanning calorimetry. The AСh containing carboxyl group have very high melting points. In this respect, carboxyl-free derivatives were preferred as azochromophoric additives to liquid crystal (LC) matrices. Blend compositions of the synthesized ACh with low molecular and polymer liquid crystals have been prepared and studied. From the point of view of homogeneity, the optimal content of ACh in low-molecular LC-matrices is 10 wt. %, whereas in polymer matrices, the ACh content does not exceed 5 wt. %. The thermal properties of the LC blend compositions, which were capable to the melt into isotropic phase due to LC order disruption caused by photoisomerization, have been studied. The ability of some blend compositions to undergo a UV-photoinduced isotropic phase transition at temperatures below the melting point of nematic matrix has been demonstrated. The times of UV-irradiation required for the implementation of trans-cis isomerisation and the times of visible light irradiation needed for recombination process have been assessed. The irradiation times were estimated by polarized optical microscopy.

Composite fibers containing boron(III) have been obtained based on solid solutions of cellulose in N-methylmorpholine-N-oxide and orthoboric acid with their subsequent transformation into a viscous-flow state. The rheological behavior of cellulose solutions with different content of orthoboric acid and water studied under conditions of continuous and dynamic shear loading has confirmed the intermolecular interaction between the components. It has been shown that the mechanical characteristics of the composite fibers obtained from a 16% solution in N-methylmorpholine-N-oxide are comparable to these for hydrated cellulose fibers. The process of transformation of the composite fibers of various compositions into carbon fiber has been investigated by means of thermogravimetric analysis and differential scanning calorimetry. Chemical, structural and morphological properties of composite hydrated cellulose fibers and carbon fibers obtained from them have been studied using FTIR-spectroscopy, X-ray diffraction, and scanning electron microscopy. The influence of boron(III) compounds on the carbonization process and the formation of graphite-like structures in carbon fiber has been investigated by Raman-spectroscopy.

The stimulated assembly/disassembly of particles is a technique allowing for precise spatial and temporal control over the resulting structures to be realized. The application of a photosensitive liquid crystal (LC) allows the use of a photo-initiated order–disorder transition for the ordering and redistribution of dispersed nanoparticles. The semiconductor quantum dots (QDs) among them are useful for the imaging of such redistribution through simple luminescent microscopy with excitation by laser radiation at a wavelength of 532 nm. Doping the LC matrix with azo-chromophore molecules allowed us to localize the light-driven phase transition of the LC from the organized to the isotropic phase inside the spot, illuminated by ultraviolet (UV) light through a slit. The phase transition leads to a redistribution of the QDs within the matrix, followed by QD-rich region formation. After the termination of UV illumination, the QDs were found to form droplets in the region where UV illumination resulted in a homogeneous distribution of the QDs. The translation of the sample through the UV-illuminated spot resulted in QD accumulation inside the isotropic phase at the borders of the isotropic phase. The results obtained provide a good agreement with the model calculations of nanoparticle diffusion at the LC phase–isotropic liquid interface.

Hydrophilic composite fibers of various compositions were prepared from mixtures of solid solutions of cellulose in N-methylmorpholine-N-oxide or its monohydrate and poly-N-vinylpyrrolidone after bringing them to the viscous-flow state. The rheological behavior of cellulose–poly-N-vinylpyrrolidone systems in N-methylmorpholine-N-oxide with various water contents was studied. At the poly-N-vinylpyrrolidone content of up to 30 wt % relative to cellulose and a temperature of 100–120°С, the systems under consideration are emulsions whose rheological behavior is determined by specific features of the dispersed phase, character of the interface, and its stability under shear flow. The poly-N-vinylpyrrolidone dispersed phase, as well as its preliminary immobilization on cellulose, does not worsen the rheological properties of the melt, which allows preparation of composite fibers under the conditions similar to those of the formation of hydrated cellulose fibers. The results of studying the fibers by scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry show that the fibers have dense microfibrillar structure without additional ordering caused by the phase interaction; they also demonstrate intense interphase interaction of the components. The mechanical characteristics of the fibers, determined by tensile tests, are comparable to those of hydrated cellulose fibers.