Transport of gases and vapors in methacrylic copolymers of varying side chain length

The gas transport properties of copolymers of dodecyl methacrylate with ethyl methacrylate and hydroxypropyl methacrylate have been studied. The diffusion, solubility and permeability of oxygen, nitrogen, carbon dioxide, methane, ethane and ethylene have been measured in the temperature range 0–50 °C, and activation energies and heats of solution have been obtained. A comparison with the data available in the literature on acrylates and other methacrylates of varying aliphatic side chain length has been performed. The diffusion coefficient of gases increases with the side chain length in a way similar to that found for homologous acrylates. A representation of log(D) as a function of the inverse of the fractional free volume shows that all acrylates and methacrylates of lineal alkyl side chain fall on the same straight line.