Poly-1-oxy-2-phenyltrimethylene as studied by 1H pulsed low resolution NMR: A Possible Oxygen Scavenger

Aromatic polymers can adsorb a large amount of oxygen on their aromatic rings. In semicrystalline aromatic polymers, the amount of adsorbed oxygen is much larger in the amorphous phase than in the crystalline counterpart. As a consequence, fully amorphous aromatic polymers are more suitable as oxygen scavengers than semicrystalline polymers. A pulsed low resolution H-1-NMR relaxation study on semicrystalline and fully amorphous poly-1-oxy-2-phenyltrimethylene (St-CO), deuteriated and not deuteriated on the backbone, is reported. T-1 relaxation values were measured at 30 and 57 MHz and compared with the values of two aromatic polymers previously studied, syndiotactic polystyrene (s-PS) and polyphenyleneoxide (PPO), both patented as oxygen scavengers. For all these polymers, using a set of equations, at each temperature, the amount of adsorbed oxygen was calculated. Very short T-1 values are observed at the low temperature point of PPO which is the best oxygen scavenger at low temperature, while St-CO adsorbs oxygen efficiently at room temperature. Thus, St-CO might be suitable to be used as an oxygen scavenger. In St-CO, a H-1 T-1g relaxation study on the rotating frame has also been performed. In the atactic copolymer, in the temperature range 150-160 K, a sharp transition was observed only in the presence of oxygen. In agreement with a previously given interpretation for analogous data, the observed transition might be related to low frequency motions present in low molecular weight components. (C) 1999 Elsevier Science Ltd. All rights reserved.