Substituted Organotin Complexes of 4-Methoxybenzoic Acid for Reduction of Poly(vinyl Chloride) Photodegradation

Abstract

Poly(vinyl chloride) suffers from degradation through oxidation and decomposition when exposed to radiation and high temperatures. Stabilizers are added to polymeric materials to inhibit their degradation and enable their use for a longer duration in harsh environments. The design of new additives to stabilize poly(vinyl chloride) is therefore desirable. The current study includes the synthesis of new tin complexes of 4-methoxybenzoic acid and investigates their potential as photostabilizers for poly(vinyl chloride). The reaction of 4-methoxybenzoic acid and substituted tin chlorides gave the corresponding substituted tin complexes in good yields. The structures of the complexes were confirmed using analytical and spectroscopic methods. Poly(vinyl chloride) was doped with a small quantity (0.5%) of the tin complexes and homogenous thin films were made. The effects of the additives on the stability of the polymeric material on irradiation with ultraviolet light were assessed using different methods. Weight loss, production of small polymeric fragments, and drops in molecular weight were lower in the presence of the additives. The surface of poly(vinyl chloride), after irradiation, showed less damage in the films containing additives. The additives, in particular those containing aromatic (phenyl groups) substitutes, inhibited the photodegradation of polymeric films significantly. Such additives act as efficient ultraviolet absorbers, peroxide quenchers, and hydrogen chloride scavengers.

Synthesis of New Norfloxacin–Tin Complexes to Mitigate the Effect of Ultraviolet-Visible Irradiation in Polyvinyl Chloride Films

“…The reduction in the R q using 1 – 4 was higher than those obtained with other additives, such as tin complexes of naproxen ( R q = 5.2) [ 34 ], carvedilol ( R q = 6.4) [ 35 ], furosemide ( R q = 6.6) [ 36 ], captopril ( R q = 7.0) [ 37 ], valsartan ( R q = 7.4) [ 38 ], telmisartan ( R q = 9.4) [ 39 ], and trimethoprim ( R q = 6.6) [11.3]. However, tin complexes of ciprofloxacin ( R q = 16.6) [ 41 ], 4-(benzylideneamino)benzenesulfonamide ( R q = 18.4) [ 42 ], and of 4-methoxybenzoic acid ( R q = 16.6) [ 43 ] led to greater reduction in the R q of the irradiated PVC films. These additives have higher content of aromatic moieties and heteroatoms compared with those investigated in the current study.…”

“…The intrinsic viscosity [η] can be used to determine the M V of PVC and was measured in THF for irradiated films. The M V was calculated using Equation (3) [ 43 , 50 ]. …”

“…Examples include polybenzimidazoles [ 27 ], polyphosphates [ 28 ], Schiff bases [ 29 , 30 , 31 , 32 ], and pigments [ 33 ]. Various aromatic tin complexes have also been investigated as PVC additives with promising results [ 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ]. In the current paper, we describe the synthesis of four novel norfloxacin–tin complexes and their effectiveness in reducing photodegradation of irradiated PVC films.…”

Synthesis of Methyldopa–Tin Complexes and Their Applicability as Photostabilizers for the Protection of Polyvinyl Chloride against Photolysis

“…The use of methyldopa–tin complexes led to a significant improvement in the Rq and showed great efficiency in stabilizing PVC compared to many other PVC additives that have recently been reported [ 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 ]. For example, organotin complexes containing naproxen [ 62 ], carvedilol [ 63 ], furosemide [ 64 ], valsartan [ 65 ], telmisartan [ 66 ], trimethoprim [ 67 ], norfloxacin [ 68 ], and levofloxacin [ 69 ] led to a reduction in the Rq by 5.2–15.4 fold.…”

Modifications of Polymers through the Addition of Ultraviolet Absorbers to Reduce the Aging Effect of Accelerated and Natural Irradiation

“…Recently, we synthesized a range of UV stabilizers (e.g., aromatics, heterocycles, Schiff bases, organometallic complexes, and polyphosphates) and tested their efficiency for the stabilization of polymers [ 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 ]. These additives, at a low concentration of 0.5% by weight, led to a significant improvement in the photostability of polymers.…”