Network polymers of cobaltporphyrin derivatives are prepared by a facile click reaction via the Michael addition of acetoacetate-substituted tetraphenyl cobaltporphyrin and tri- or tetra-acrylates. The conversion is saturated for 1 h in the presence of a catalyst, which almost reaches the same gelation point of the formed network polymers. Deeply and homogeneously red-colored membranes with a sub-micrometer thickness are yielded on a porous supporting membrane. They are still tough even with a very high content of the rigid porphyrin residue. The oxygen permeability is high, at 10-100 Barrer, and the oxygen/nitrogen permselectivity (PO2/PN2) is significantly enhanced with the porphyrin content reaching 30, for the membranes with ca. 70 wt% porphyrin content.
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...
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