GAS-TRANSPORT PROPERTIES OF A SERIES OF HIGH T-G POLYNORBORNENES WITHALIPHATIC PENDANT GROUPS

A study of gas transport properties of novel polynorbornenes with incr easing length of an aliphatic pendant group R (CH3-, CH3(CH2)(3), CH3( CH2)(5)-, CH3(CH2)(9)-) has been performed. These polymers were synthe sized using novel organometallic complex catalysts via an addition pol ymerization route. This reaction route maintained the bridged norborne ne ring structure in the final polymer backbone. Gas permeability and glass transition temperature were found to be higher than those for po lynorbornenes prepared by ring-opening metathesis and reported in the literature. It was shown that for noncondensable gases such as Hz and He the selectivity over N-2 decreased when the length of the pendant g roup increased, but remained relatively stable for the more condensabl e gases (O-2 and CO2). The permeability coefficient is correlated well to the inverse of the fractional free volume of the polymers. The mor e condensable gases showed a deviation from this correlation for the l ongest pendant group, probably due to an increase of the solubility ef fect. This polymer series demonstrated a simultaneous increase in perm eability and selectivity, uncommon for polymers. (C) 1998 John Wiley & Sons, Inc.