Oxygen Scavenging and Oxygen Barrier Poly(1,2‐butadiene) Films Containing an Iron‐Complex Catalyst

Abstract

film containing linoleic acid without any change in the physical properties of PET and that the oxidation of linoleic acid suppressed the oxygen permeation, [9] although the amount of suppression was small. Multilayer active films with an oxygen scavenging layer sandwiched between passive barrier layers have been reported. [10][11][12] However, their oxygen absorption capacity was low and the fabrication procedure was tedious.Poly(1,4-butadiene) (1,4-PB) is oxidized upon exposure to atmospheric oxygen at room temperature [13,14] ; however, the low oxygen scavenging capacity of 1,4-PB severely limits its use in oxygen scavenging films. 1,4-PB has been examined as an oxygen scavenging material after the addition of a small amount of a transition metal catalyst, typically cobalt neodecanoates, to accelerate oxidation. [15,16] The oxygen scavenging capacity of 1,4-PB was explained by the oxidative consumption of its double bond. Tung et al. fabricated an oxygen scavenging film consisting of a styrene-butadiene-styrene copolymer and a cobalt complex catalyst, and the film had an oxygen scavenging capacity of 26 mL (oxygen gas at STP) g(film) −1 . [15] The 1,4-PB polymer substrate acted as a reducing agent for oxygen in the presence of a cobalt complex. The oxygen scavenging capacity of this type of film was increased to 90 mL (oxygen gas at STP) g(film) −1 by using homopolymer 1,4-butadiene. [16] However, although cobalt complexes, such as cobalt naphthenate, show high catalytic activity, their practical applications are limited due to their high toxicity. Furthermore, the oxygen scavenging capacity of the 1,4-PB/cobalt neodecanoate film was still below 100 mL (oxygen gas at STP) g(film) −1 and the oxidation reaction yield (i.e., consumption of the double bond) was less than 15%.In this paper, we select an iron complex as a less-toxic and environmentally friendly metal catalyst to incorporate into the polymer film and we tune its catalytic activity for the oxidation of double bonds. [17] In addition, we investigate poly(1,2-butadiene) (1,2-PB) as both the film substrate and the oxygen scavenging agent. The oxidative reactivity of the double bond in the side chain of 1,2-PB are expected to be much higher than that of 1,4-PB. Furthermore, solvent solubility and film formation of 1,2-PB are excellent due to the syndiotactic structure of the side chain. A small amount of the unsaturated hydrocarbon, methyl linoleate (ML), is added as a plasticizer for the polymer film and trigger for the 1,2-PB oxidation. Tough films of poly(1,2-butadiene) are prepared by introducing small amounts of the less toxic iron complex N,N′-bis(salicylidene)ethylenediamine-benzylimidazole and methyl linoleate. The catalytic activity of the iron complex for air oxidation of unsaturated groups is substantially higher than those of previously reported films. The oxygen scavenging capacity of the films is up to 200 mL (oxygen gas at STP) g(film) −1 after 1 month, based on oxidative consumption of the poly(1,2-butadiene) double bonds, which is more t...

Double-Function Oxygen Scavenger and Aromatic Food Packaging Films Based on LDPE/Polybutadiene and Peanut Aroma

“…To follow the chemical changes taking place during the oxygen absorption after UV activation, film s FTIR spectra were registered after the UV treatment and at 6 days of oxidation in air at 30 • C (Figure 4C,D). The oxidation of double bonds of PB led to a production of epoxides (bands between 800 and 1200 cm −1 ), carbonyl groups (band at 1750 cm −1 ) and hydroxyl groups (signal at 3400 cm −1 ) [14,16]. These changes were more noticeable for the PE/PA/PB13 formulation, whereas for the PE/PA/PB5 formulation these changes were less pronounced, although this film suffered from a higher UV exposure.…”

“…However, without the incorporation of TiO 2 as metal catalyst, after 30 days, only a value of 5 mL O 2 g −1 film was achieved for LDPE/PB (10 wt %) formulation. In another study, polybutadiene films were developed by using an iron complex N,Nbis(salicylidene)ethylenediamine-benzylimidazole as a catalyst and methyl linoleate [14]. The oxygen scavenging capacity of the films was up to 200 mL (oxygen gas at STP) g film −1 after 30 days, but the toxicity of the iron complex makes them inadequate for food packaging applications.…”

“…Accordingly, PB has been incorporated with a transition metal catalyst to promote oxidation process [13]. In this sense, Wang et al [14] developed an oxygen scavenging film consisting of a 1,2-polybutadiene with an iron complex by solvent casting reporting an oxygen scavenging capacity of 200 mL (oxygen gas at STP) g film −1 . Following this line, cobalt neodecanoate has also been incorporated together with PB by using cast extrusion [15] obtaining a scavenging capacity of 90 mL (oxygen gas at STP) g film −1 .…”

Green Synthesis and Characterization of Polymyrcene as an Oxygen Scavenging Sustainable Polymer for Active Food Packaging Applications

“…Oxygen present inside the packaging headspace is a contributing factor to the spoilage of food. This can reduce the nutritional value of food, make off flavors and alter colors, increase the growth of aerobic bacteria, and turn fats rancid, thus reducing the shelf life of food packed inside and affecting its quality. − The demand for oxygen scavenging packaging has been increasing for the past few decades. The global oxygen scavenger market value was 2.26 billion USD in 2021 and is expected to grow at a compound annual growth rate (CAGR) of 6.0% and is anticipated to reach 3.79 billion USD by 2030 .…”