Structure and dynamics of functionalized polyethylene surfaces

Abstract

We have used spectroscopically labeled polyethylene films to investigate the effects of solvent upon the reactivity, mobility and accessibility of functional groups at the polyethylene-solvent interface. These results showed that the functional groups at the polyethylene interface exist in a solvent-dependent heterogeneous environment. The heterogeneity of the polyethylene interface was illustrated primarily by the reactivity of functional groups in the polyethylene interface. The kinetics of protonation of p-methyl red and dansyl labels at the polyethylene interface exhibited three kinetically distinct regions. These regions of the polyethylene interface were defined according to the observed differences in the rates of protonation which we believe reflect differences in the ability of the soluble acid to diffuse into different regions of the polyethylene interface. The results obtained in fluorescence quenching of the dansyl labeled films also showed that the functional groups which react with the soluble acid exist in the most solution-like environment, and the functional groups which are unreactive towards reagents in solution are located in the most polymer-like environment, i.e. the bulk polyethylene. The heterogeneity of the functional group environment was also observed as non-first-order kinetics of the stereoisomerization of p-methyl red labels in entrapment functionalized films. We have not defined the specific structural or chemical properties which give rise to the different regions in the polyethylene-solvent interface.