ABSTRACT
Polyvinyl chloride (PVC) is a synthetic polymer with a wide range of applications with impact on our daily life. It can undergo photodegradation with toxic products that are hazardous to both human health and the environment. In addition, photodegradation shortens the useful lifetime of the material. Elongation of the effective lifespan of PVC is, therefore, a salient area of research. Recently, a lot of attention has been directed toward the design, preparation, and usage of new additives that are capable of reducing the photodecomposition of PVC. This work investigates the synthesis of new levofloxacin-tin complexes and their potential exploitation against the photodecomposition of PVC. Several levofloxacin-tin complexes have been synthesized, in high yields, by a simple procedure and characterized. The potential use of the additives as photostabilizers for PVC has been investigated through the determination of weight loss, molecular weight depression, formation of fragments containing carbonyl and alkene groups, and surface morphology of irradiated PVC films. The results show that the new additives are effective in reducing the photodegradation of PVC. The new levofloxacin-tin complexes act as absorbers of ultraviolet light and quenchers of highly reactive species such as free radicals produced during photodegradation. They are more effective photostabilizers compared with organotin complexes previously reported. The complexes containing aromatic substituents were more effective than those counterparts having aliphatic residues.
ABSTRACT
Polyvinyl chloride is used in the manufacturing of a wide range of products, but it is susceptible to degradation if exposed to high temperatures and sunlight. There is therefore a need to continuously explore the design, synthesis, and application of new and improved additives to reduce the photodegradation of polyvinyl chloride in harsh environments and for outdoor applications. This research investigates the use of new norfloxacin-tin complexes as additives to inhibit the photodegradation of polyvinyl chloride to make it last longer. Reactions between norfloxacin and substituted tin chlorides, in different molar ratios and in methanol under reflux conditions, gave the corresponding organotin complexes in high yields. The chemical structures of the synthesized complexes were established, and their effect on the photodegradation of polyvinyl chloride due to ultraviolet-visible irradiation was investigated. Norfloxacin-tin complexes were added to polyvinyl chloride at very low concentrations and homogenous thin films were made. The films were irradiated for a period of up to 300 h, and the damage that occurred was assessed using infrared spectroscopy, polymeric materials weight loss, depression in molecular weight, and surface inspection. The degree of photodegradation in the polymeric materials was much less in the blends containing norfloxacin-tin complexes compared to the case where no additives were used. The use of the additives leads to a reduction in photodegradation (e.g., a reduction in the formation of short-chain polymeric fragments, weight loss, average molecular weight depletion, and roughness factor) of irradiated polyvinyl chloride. The norfloxacin-tin complexes contain aromatic moieties (aryl and heterocycle), heteroatoms (nitrogen, oxygen, and fluorine), and an acidic center (tin atom). Therefore, they act as efficient photostabilizers by absorbing the ultraviolet radiation and scavenging hydrogen chloride, peroxides, and radical species, thereby slowing the photodegradation of polyvinyl chloride.
