Polymer Science, Series A最新文献

The surface modification of polycaprolactone and polycaprolactone/polylactide mixed films was carried out by preliminary surface activation in NaOH. Subsequent layer-by-layer deposition of coatings based on polyelectrolyte complexes of the oppositely charged polysaccharides: chitosan and hyaluronic acid, was carried out. The effect of surface activation was studied using contact angle measurements, surface analysis and gravimetric data. The characterization of the polyelectrolyte complex coatings using gravimetric analysis, goniometric and micrometer measurements, scanning electron, optical and fluorescence microscopy, and FTIR-ATR spectroscopy confirmed the formation of a uniform coating with a thickness of about 30 μm, which is not prone to peeling from the substrate.

The synthesis of peptide nanocomposites from water-soluble components has many advantages. However, this raises the question of maintaining the functional properties and chemical structure of composites solid layers during long-term storage at ambient conditions. The processes of structural transformations during different stages of crystallization of hectapeptide composites with silver and gold nanoparticles in humid atmosphere were studied. The influence of temperature, humidity, nature of the substrate, its wetting, conformation of peptide molecules on the structure and electrophysical properties of the composites was considered also. Similarly to polymers two stages of crystallization were found: the initial fast and the subsequent slow. Unlike polymers, an increase in temperature does not affect this process, but even slows it down. Despite significant changes in the surface morphology of composites their electrophysical properties and conformation of molecules do not change. An increase in humidity accelerates the processes of the structural transitions. The results show that the changes in the surface morphology of PT composites under the influence of humidity relate only to the PT matrix itself and not to their locations or conformation of molecule.

Basalt fibres are gaining interest in the fibre-reinforced thermoplastic industries around the world. In this work, basalt and glass short fibres reinforced polypropylene composites were produced using twin-screw extrusion and followed by injection molding. To carry out a comprehensive study on physical and mechanical properties, the composites were produced with different proportions of fibre loadings (for both fibres 5, 10, and 20 wt %). Composites were characterized and studied for tensile (at different strain rates), flexural (at different speeds), impact, dynamic mechanical analysis, density, tensile-relaxation, melt flow index test, and rheometric properties. Results indicate that tensile, flexural, dynamic mechanical analysis, and tensile-relaxation properties increased with increasing fibre proportions in the polypropylene matrix. The melt flow and rheometric behaviors of polypropylene decreased significantly with the addition of short fibres into the matrix. The overall results showed that basalt fibres can be potentially used as replacements for glass fibre to develop these thermoplastic composites.

New monomers of the biquinoline series—diyldimethanamines—have been synthesized, and polymers having biquinoline units in the main chain and their metal–polymer complexes with cuprous chloride have been obtained using these monomers. The resulting starting compounds and polymers have been studied using NMR spectroscopy, HPLC, and simultaneous thermal (thermogravimetric and differential thermal) analysis, and the mechanical characteristics of the polymers and metal–polymer complexes have been examined. It has been shown that the structure and physicochemical properties of the polymers based on synthesized diyldimethanediamines largely depend on the position of groups in the biquinoline moiety and the presence of interchain coordination bonds in the polymer.

For the first time, the interaction of polyvinyl alcohol and a copolymer of sodium salts of styrenesulfonic and maleic acids in aqueous solutions has been studied using the techniques of static and dynamic light scattering and capillary viscometry. It has been shown that hydrogen-bonded complexes are formed between them, with compaction of polyvinyl alcohol coils occurring in dilute solutions and additional structuring of the solution in semidilute solutions. The activation parameters (enthalpy and entropy) of viscous flow have been assessed, confirming the formation of the complexes. The concentration regimes of solutions of polyvinyl alcohol, the copolymer, and the complexes have been studied. It has been shown that the semidilute entanglement-free regime disappears in solutions of the complexes.

The effect of thermal prehistory and mechanical field on the morphology and physicomechanical and thermal properties of poly(vinyl alcohol) cryogels has been studied. Using the methods of rheometry, DSC, and X-day diffraction analysis it is revealed that an increase in the heat treatment temperature of cryogels causes a rise of the melting temperature and a change in the crystallinity of PVA cryogels, as is typical for the annealing phenomenon. It is established that the annealing of PVA cryogels formed under repeated freezing with simultaneous forced compression contributes to the formation of cryogels with the spatial network being stable up to the onset of solvent boiling.

Polyacrylic acid is a biocompatible and biodegradable polymer that has been widely investigated for use in drug delivery. It has a number of properties that make polyacrylic acid a promising material for various applications, including ability to form hydrogels, mucoadhesive properties, and stimuli-responsive behavior. Polyacrylic acid hydrogels can be used to deliver drugs to a variety of tissues and organs. They can be prepared in a variety of forms, including injectable gels, films, and tablets. These hydrogels can be loaded with a variety of drugs, including proteins, peptides, and small molecules. The mucoadhesive properties of polyacrylic acid make it a good choice for delivering drugs to the eye, nose, and skin. Polyacrylic acid can adhere to these mucosal surfaces, which can help to prolong the drug’s release and improve its bioavailability. The stimuli-responsive behavior of polyacrylic acid can be used to develop drug delivery systems that release drugs in response to specific stimuli, such as changes in pH, temperature, or ionic strength. This can be used to control the release of drugs in a way that is tailored to the specific needs of the patient. The research on the use of polyacrylic acid in drug delivery is ongoing. As our understanding of its properties and behavior improves, we can expect to see even more innovative and effective drug delivery systems developed in the future.

Perpendicular di-block copolymer domains are produced when poly(styrene-block-methylmethacrylate (PS-b-PMMA) is spun onto a disordered layer of zinc oxide nanoparticles, followed by thermal annealing in vacuum. The ZnO layer creates a rough surface on the silicon substrate, inducing vertical cylinders of PMMA. The subsequent development of a PS template is illustrated. The wet etching process removed the vertically oriented PMMA nanodomains in the PS matrix. The morphology of the PS mask showed ordered nanopores with diameters around 20 nm. The effect of surface roughness and di-block film thickness on forming perpendicular cylindrical domains of PS-b-PMMA is analyzed. For a typical thickness of PS-b-PMMA film around 33 nm, a specific surface roughness parameter of 0.07 is obtained. These results are compared with other reports on this topic.

Buffer solutions of random (co)polymers of N-(3-(diethylamino)propyl)-N-methylacrylamide and N,N-dipropylacrylamide, which contain from 0 to 95 mol % of N-(3-(diethylamino)propyl)-N-methyl-acrylamide units and have close molecular weights and the same degrees of polymerization (170 ± 10) are studied by the methods of potentiometric titration, light scattering, turbidimetry, refractometry, and viscometry. The samples are synthesized by the interaction of poly(acryloyl chloride) with N,N-diethyl-N ′-methyl-1,3-propanediamine and dipropylamine. The aqueous solutions are investigated in the concentration range from 0.0001 to 0.0350 g/cm³ and in pH range from 7.0 to 13.0. Temperature dependences of optical transmission I*, scattered light intensity I, and hydrodynamic sizes of scattering objects are obtained. Phase separation temperatures are determined. The results obtained are comparable with the data available for the previously studied copolymers but containing N-(3-(diethylamino)propyl)-N-methylacrylamide and N,N–diethyl-acrylamide units. It is shown that the structural phase transition and the characteristics of aqueous solutions for the compared copolymers depend on the structure of the (co)polymers and their composition.

A thorough understanding of pesticide fate in soil and replacement of traditional pesticide formulations with polymeric controlled release pesticide formulations may provide a preventive approach for safer and more effective application of pesticides in the field. In this direction, the present study discusses the soil adsorption study of atrazine herbicide on Indian soil and synthesis of polymeric controlled release formulation based on Azadirachta indica (Neem) (AI) leaf powder and sodium alginate. The value of Ground Ubiquity Score (GUS) for atrazine herbicide has been observed 2.58 which classifies it as a transition pesticide in terms of ground water contamination with higher Environment Exposure Potential (EEP) in Indian soil. Polymeric controlled release pesticide formulations (CRPFs) were synthesized by ionotropic gelation method with three different crosslinking ions i.e. Ca²⁺, Ba²⁺, and Al³⁺. These CRPFs have been characterized by FTIR, SEM-EDAX and TGA. Polymeric CRPFs released the herbicide in controlled manner for a period of 300 h and followed non-Fickian diffusion mechanism. AI-Alginate-Ca beads showed maximum cumulative release 14.99 mg/g in 300 h, followed by BaCl₂ and AlCl₃ crosslinked beads. The release study showed that the Polymeric CRPFs can be effective in controlling the release and adverse effects of atrazine in the environment.