SynopsisThe sorption and transport of several gases in poly(pheny1ene oxide) were measured at 35"C, and the results have been analyzed in terms of the dual sorption/mobility models which have been successfully employed for this purpose for other glassy polymers. Both the extent of sorption and rate of permeation of gases are quite large for poly(pheny1ene oxide) compared to other glassy polymers with rigid chain backbones. It is shown that the high extent of sorption is owing to the high glass transition temperature of this polymer, but this is not a significant factor in its high permeability to gases. The latter stems from large diffusion coefficients. It is shown that the capacity of the Langmuir mode of sorption inherent to glassy polymers is related to the value of the glass transition temperature in a general way for a wide variety of polymers. Observations about the diffusion coefficients for numerous gas-polymer pairs are discussed.

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Characterization of CO species adsorbed on well-degassed surfaces of polycrystalline MgO at low CO pressures (< 1300 Pa) and at and below room temperature was studied by using temperature-programmed desorption (TPD) and infrared (IR) spectroscopies. Mutual transformation between adsorbed species stable at room temperature, and their reactivities with 0 2 were also investigated. Adsorbed species are classified into five groups, KO, K1 (and K1' ), Kz, K3, and &. Among them species KO and K1 (and K1' ) are stable only below room temperature while species KZ to & are stable above this temperature. Species KO is a linear-type CO monomer with the C atom bonded to surface Mg2+ and has five subspecies depending on its circumstance, while all the other species K1 to & are formed on surface 02-to which the C atom is linked. A chained-type CO monomer, K1, is reversibly transformed at ca. 230 K in the presence of gaseous CO into a linear-type CO monomer, K1'. Species KZ is a chained-type tetramer of CO with a carbonyl CO bond and resonanced bonds. There are two subspecies, K~A and Km, which are formed by the addition of one CO molecule to corresponding trimer species, K~A and K~x , respectively, in the presence of gaseous CO. K~A and Kzx are reversibly transformed into K~A (at 400 K) and K~x (in 300-400 K), respectively, by the elimination of the CO added.There are two more subspecies, K~B and K~c , in species K3, but they have no corresponding KZ subspecies, and hence no transformations occur. All the K3 species seem to be a linear-type trimer with a ketenic group, >C=O=O, and are desorbed in 520-580 K. Species &, though detailed information is not obtained, consists of three subspecies &A, &B, and &c, but no transformations between species K3 and & are observed.

The adsorption of oxygen, under U.V. irradiation, on the surface of MgO outgassed at 1123 K has been studied at 77 K by temperature-programmed desorption and e.s.r. spectroscopy. During adsorption ozonide and superoxide ions were formed in equal amounts. The formation of these oxygen species is explained by the reaction of oxygen molecules with a short-lived exciton produced by the absorption of a photon at a surface 0,species in a very low coordination state. Thermal decomposition of the oxygen species adsorbed at 77 K has also been studied under a dynamic vacuum. It proceeds in four steps: (i) 0; is transformed into 0.-and 0, between 77 and 300 K; (ii) 0is changed into 0;-between 77 and 473 K; (iii) 0; is also transformed into Og-, with the evolution of 0, between 300 and 673 K; (iv) finally 0;is changed into 02and 0, between 673 and 1123 K. This mechanism is also consistent with energy considerations. The formation and thermal decomposition of superoxide ions proceeds similarly both on surfaces subjected to U.V. irradiation and on surfaces containing thermally preadsorbed hydrogen.