Poly(vinyl chloride) (PVC) is an important synthetic plastic that is produced in large quantities (millions of tons) annually. Additives to PVC are necessary to allow its use in many applications, particularly in harsh conditions. In regard to this, investigation of the synthesis of trimethoprim–tin complexes and their use as PVC additives is reported. Trimethoprim–tin complexes were obtained from the reaction of trimethoprim and tin chlorides using simple procedures. Trimethoprim–tin complexes (0.5% by weight) were added to PVC to produce homogenous mixtures and thin films were made. The effect of ultraviolet irradiation on the surface and properties of the PVC films was investigated. The level of both photodecomposition and photo-oxidation of PVC films containing trimethoprim–tin complexes was observed to be lower than for the blank film. The effectiveness of tin complexes as PVC photostabilizers reflects the aromaticity of the additives. The complex containing three phenyl groups attached to the tin cation showed the most stabilizing effect on PVC. The complex containing two phenyl groups was next, with the one containing butyl substituents resulting in the least stabilization of PVC. A number of mechanisms have been proposed to explain the role of the synthesized complexes in PVC photostabilization.
Environmental problems associated with the growing levels of carbon dioxide in the atmosphere due to the burning of fossil fuels to satisfy the high demand for energy are a pressing concern. Therefore, the design of new materials for carbon dioxide storage has received increasing research attention. In this work, we report the synthesis of three new Schiff bases containing a trimethoprim unit and the investigation of their application as adsorbents for carbon dioxide capture. The reaction of trimethoprim and aromatic aldehydes in acid medium gave the corresponding Schiff bases in 83%–87% yields. The Schiff bases exhibited surface areas ranging from 4.15 to 20.33 m2/g, pore volumes of 0.0036–0.0086 cm3/g, and average pore diameters of 6.64–1.4 nm. An excellent carbon dioxide uptake (27–46 wt%) was achieved at high temperature and pressure (313 K and 40 bar, respectively) using the Schiff bases. The 3-hydroxyphenyl-substituted Schiff base, which exhibited a meta-arrangement, provided the highest carbon dioxide uptake (46 wt%) due to its higher surface area, pore volume, and pore diameter compared with the other two derivatives with a para-arrangement.
The scale of production of polystyrene has escalated in the recent past in order to meet growing demand. As a result, a large quantity of polystyrene waste continues to be generated along with associated health and environmental problems. One way to tackle such problems is to lengthen the lifetime of polystyrene, especially for outdoor applications. Our approach is the synthesis and application of new ultraviolet photostabilizers for polystyrene and this research is focused on four cephalexin Schiff bases. The reaction of cephalexin and 3-hydroxybenzaldehyde, 4-dimethylaminobenzaldehyde, 4-methoxybenzaldehyde, and 4-bromobanzaldehyde under acidic condition afforded the corresponding Schiff bases in high yields. The Schiff bases were characterized and their surfaces were examined. The Schiff bases were mixed with polystyrene to form homogenous blends and their effectiveness as photostabilizers was explored using different methods. The methods included monitoring the changes in the infrared spectra, weight loss, depression in molecular weight, and surface morphology on irradiation. In the presence of the Schiff bases, the formation of carbonyl group fragments, weight loss, and decrease in molecular weight of polystyrene were lower when compared with pure polystyrene. In addition, undesirable changes in the surface such as the appearance of dark spots, cracks, and roughness were minimal for irradiated polystyrene containing cephalexin Schiff bases. Mechanisms by which cephalexin Schiff bases stabilize polystyrene against photodegradation have also been suggested.
Poly(vinyl chloride) PVC materials are used in many industrial and household outdoor applications which exposed to sunlight ultraviolet. This exposure motivates photo-degradation of the PVC and hence, reduces its life time and leads to undesirable physical properties. Herein, three new Schiff bases containing a trimethoprim moiety were investigated as photo-stabilizers for poly(vinyl chloride) against photo-decomposition. Merely 0.5% by weight of these Schiff bases was mixed with the polymer to form blend films with thickness of (40 µm). The films were irradiated for a period of time from 0 to 300 h and the irradiation impact on the PVC stabilization was monitored every 50 h. The efficiency of these additives as photo-stabilizers was investigated as a function of different parameters during the course of irradiation, such as weight loss, growing carbonyl and alkene groups as well as the surface morphology of the prepared films. The changes during irradiation were obvious for the blank films in comparison to the films containing the new additives. Therefore, these Schiff bases were found to act as photo-degradation inhibitors through reducing the elimination of hydrogen chloride molecules and as free radical scavengers or peroxide decomposers.
Various polyvinyl chloride thin films containing captopril and several metal (cobalt, copper, and nickel) oxide nanoparticles were produced. Low concentrations of both captopril (0.5% by weight) and metal oxides (0.01% by weight) were used to produce transparent films. The role played by both captopril and metal oxide nanoparticles as ultraviolet blockers for pho-todegradation of polyvinyl chloride was investigated. The addition of both metal oxides and captopril to polyvinyl chloride films enhances the stability of polymeric materials more than captopril alone. Observation of weight loss, changes in infrared spectra and surface morphology of blends on irradiation showed that a combination of captopril and nickel oxide nanopar-ticles efficiently blocks ultraviolet light and provides a high level of protection to polyvinyl chloride.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.