Surface Segregation Phenomena in Blends of Cellulose Esters

The principle of surface segregation and subsequent self-assembly of mixtures of molecules has been utilized to create cellulosic films that have properties characteristic of smart materials. This has been achieved by solventcasting a blend of cellulose propionate and an fluorine (F)-containing cellulose ester derivative. Evidence suggests that surface segregation of the F-containing species takes place spontaneously in cellulosic systems. Cellulose propionate films containing a small amount of F-containing cellulose derivative exhibit a much lower surface free energy (i.e. are more hydrophobic) than predicted by the rule of mixing, and this indicates surface segregation. The current research examined the influence of the chemistry of the fluorine-containing component (type of derivative and chemistry of the F-containing group) on the segregation process.