Polymer Science, Series A最新文献

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.

Water-soluble random copolymer of N-vinylformamide with sodium 4-styrenesulfonate is synthesized by free radical copolymerization. Copolymer fractions are studied by the methods of molecular hydrodynamics: viscometry, translational diffusion, and sedimentation velocity in dilute aqueous solutions. Molecular characteristics and scaling relations are obtained. Considerable differences in the conformational behavior of molecules of the copolymer and N-vinylformamide and sodium 4-styrenesulfonate homopolymers are discussed.

Viscoelastic properties of magnetoactive elastomers with spherical and plate-shaped filler have been studied. Four series of samples based on silicone elastomer and carbonyl iron microparticles have been prepared. A series of samples with a concentration of magnetic filler from 30 to 60 wt % which differed in the shape of filler particles (spherical and platelike) and in their distribution in the polymer matrix (isotropic and anisotropic). The magnetorheological properties of the obtained magnetoactive elastomers have been examined by dynamic mechanical analysis. Storage modulus values for samples of different compositions are in the range of 10–100 kPa. It has been shown that anisotropic materials are stiffer than the isotropic counterparts and demonstrate a higher magnetorheological effect: the increase in the elastic modulus of an anisotropic sample with the maximum filler content exceeds an order of magnitude in a magnetic field of 1 T. At the same filler concentrations, materials based on platelike iron are stiffer than those based on spherical iron. At low magnetic filler concentrations, the use of platelike iron makes it possible to achieve a higher magnetic response of the material; at high filler concentrations, the increase in the elastic modulus is greater for samples based on spherical particles. The anisotropic materials exhibit a more pronounced Payne effect.

New modifications of a polyampholyte sorbent based on carbamide (urea), formaldehyde, and aminoacetic acid, differing in the reagents ratio during the synthesis, have been prepared. It has been shown that the optimal synthesis temperature is 90°C. Thermal stability of the polyampholyte has been analyzed. Sorption properties of the polyampholyte towards d-element ions have been investigated. The effect of the synthesis temperature on specific volume and static exchange capacity of the polyampholyte has been considered. The influence of the medium pH on sorption of copper(II) ions with the polyampholyte has been evaluated. It has been found that the sorption degree by the considered sorbents is the highest at pH from 5.5 to 6.5. The polyampholyte prepared at the urea, formaldehyde, and aminoacetic acid ratio 2 : 5 : 0.7 has revealed the highest sorption capacity towards the d-element ions. The sorption rate has been maximum at the solution temperature of 20°C. The adsorption has been shown to follow the Freundlich equation.

The heat resistance of adhesive joints of SVM heterocyclic aramid fibers and cyanoacrylate glue has been studied based on the adhesion failure temperature in an adhesion cell formed by a loop tightened into a knot. For the first time, data on the heat resistance of adhesive joints of fibers with a polymer matrix under static load with constant shear stress have been obtained. Using the example of two types of glue, the influence of filler in the glue and fibers on the glass transition temperature of polycyanoacrylate and the heat resistance of the adhesive joint is shown. The activation energy of adhesion failure was calculated, and the dependence of the thermal stability of the adhesive joint on the shear stress was shown to be of the Arrhenius type.