Polymer Science, Series C最新文献

Publications showing the prospects of combining computer simulation with atomic force microscopy in the study of polymer biological objects and materials for various purposes are analyzed. The problems that arise when these methods are used together are described. Three main directions are presented in which atomic force microscopy is used in conjunction with computer simulation: study of the surface topography of polymer materials; measurement of the force curve of the interaction of the atomic force probe with polymer structures; and determination of the energy of intermolecular interactions.

Nanocomposite networks of surfactant micellar chains and natural bentonite clay nanoplates are studied by rheometry, small-angle neutron scattering, and cryogenic transmission electron microscopy. It is shown that, in an aqueous medium in the presence of a small part of an anionic surfactant, sodium dodecyl sulfate, the molecules of a biodegradable zwitterionic surfactant, oleyl amidopropyl dimethyl carboxybetaine, form micron-length living micellar chains which entangle and form a network possessing well-defined viscoelastic properties. It is found that addition of negatively charged clay nanoplates leads to an increase in viscosity and relaxation time by an order of magnitude. This is explained by the incorporation of the nanoplates into the network as physical multifunctional crosslinks. The incorporation occurs via the attachment of semispherical end-caps of the micelles to the surface of the particles covered with a surfactant layer, as visualized by cryogenic transmission electron microscopy. As the amount of nanoplates is increased, the rheological properties reach plateau; this is associated with the attachment of all end parts of micelles to nanoplates. The developed nanocomposite soft networks based on safe and eco-friendly components are promising for various practical applications.

In recent years, the problem of polymer processing has become quite urgent owing to the accumulation of huge amounts of unprocessed polymer municipal solid waste in the environment. The authors discuss the main environmental problems associated with environmental pollution with polymer waste, as well as modern methods of separation, processing (including processing into secondary material resources and thermal processing into thermal and electrical energy) and assessment of the life cycles of polymer municipal solid waste.

Polylactide-based materials are often considered an alternative to materials produced from traditionally hardly degradable polymers. Porous polylactide membranes, matrices, and scaffolds are especially attractive for use in biomedicine. The review concerns the physicochemical basis and structural and morphological opportunities of various methods for the manufacture of porous polylactide, such as sintering, 3D printing, electrospinning, foaming, etching, and the processes of phase separation and orientational drawing. Special attention is focused on the effect of porous structure parameters on the rate of hydrolytic degradation of the polymer and the prospects for the development of application areas of similar porous materials.

The effect of cationic polyelectrolyte poly(diallyldimethylammonium chloride), anionic polyelectrolyte potassium lignohumate, and their interpolyelectrolyte complex on the aggregate composition and phytotoxicity of constructozem, an artificially constructed soil, is investigated. The original constructozem is characterized by a wide range of structural aggregates with a high proportion of large particles. Addition of the polycation to the constructozem completely destroys large aggregates, while addition of the polyanion has almost no effect on particle size distribution. The polycomplex sharply reduces the proportion of large particles and blocks the appearance of small particles, thereby significantly increasing the content of agronomically valuable aggregates in the constructozem and, at the same time, stimulating the growth and development of plants.

The possibilities of using special rheological properties of polymers in the petrochemical industry, in particular, at the stage of oil production in the modification of drilling fluids and oil displacement, the transportation of oil in pipeline systems, and the modification of properties of main hydrocarbon products are considered. In all the cases, polymers with different compositions and structures are used as modifiers of the rheological properties of process fluids based on water or hydrocarbons. In addition to the control of the viscosity characteristics of these fluids, polymers promote the manifestation of elasticity of the solutions created which may play a significant role in optimizing the process. The aspects of the use of polymers for decreasing the hydrodynamic resistance during the pumping of oil in trunk pipelines are discussed in most detail. When discussing options of the application of polymers special attention is paid to the related environmental problems.

The transition to green chemistry and biodegradable polymers is a logical stage in the development of modern chemical science and technology. In the framework of this review, the advantages, disadvantages, and potential of biodegradable polymers of synthetic and natural origin are compared using the example of polylactide and chitosan as traditional representatives of these classes of polymers, and the possibilities of their combination via obtaining composite materials or copolymers are assessed. The mechanochemical approach to the synthesis of graft copolymers of chitosan with oligolactides/polylactides is considered in more detail.

Evolution of the morphology of cellulose solutions in N-methylmorpholine-N-oxide during coagulation with a “soft” coagulant, isobutyl alcohol, at different temperatures is considered. Using optical interferometry and transmitted and scanning electron microscopy the mechanism of phase separation of the system to form a polymer phase is studied depending on the temperature of alcohol. It is shown that, in the case of a room temperature coagulant, a heterogeneous film with a droplet texture enlarging over thickness appears along the precipitation front. At a high temperature of alcohol the coagulation of the solution occurs in two stages. At the first stage the penetration of the coagulant into the jet of spinning solution leading to the formation of vacuoles occurs. The phase separation of the solution proceeds within the vacuoles as microreactors to form a polymer-concentrated shell and a polymer-diluted phase in the vacuole cavity. At the second stage the coagulant diffuses through the vacuole shell into the bulk of the solution and causes its uniform coagulation. The process of vacuole formation is visualized. The transverse cleavage of the film is analyzed by energy dispersive X-ray spectroscopy. The difference in the content of C, N, and O atoms on the walls of vacuoles and in the region of a film with a uniform cellular morphology is established.

The review discusses the application of polymers for the control of soil degradation caused by wind and water erosion. The background of the problem, current situation with the soil erosion in the world and Russian Federation, traditional methods for controlling erosion processes, and natural and synthetic soil amendments (soil conditioners) are described. Particular attention is paid to t traditional conditioners, polyacrylamide and its derivatives as well as conditioners obtained from interpolyelectrolyte complexes, the products of interaction of oppositely charged ionic polymers. The results of the laboratory experiments, field tests, and practical application of the conditioners are presented. A new type of soil conditioners based on interpolyelectrolyte complexes is described in detail, and the prospects of their application in antierosion technologies are considered.

The needs of modern surgery triggered the intensive development of transplantology, medical materials science, and tissue engineering. These directions require the use of innovative materials, among which porous polymers occupy one of the leading positions. The use of natural and synthetic polymers makes it possible to adjust the structure and combination of properties of a material to its particular application. This review generalizes and systematizes the results of recent studies describing requirements imposed on the structure and properties of synthetic (or artificial) porous polymer materials and implants on their basis and the advantages and limitations of synthesis methods. The most extensively employed, promising initial materials are considered, and the possible areas of application of polymer implants based on these materials are highlighted.