SOME FURTHER OBSERVATIONS ON THE SYSTEMS CELLULOSE TRIFLUOROACETIC-ACID CH2CL2 AND CELLULOSE TRIACETATE TFA CH2CL2

There is little or no trifluoroacetylation of cellulose dissolved in TFA-CH2Cl2 admixtures. Both cellulose and cellulose triacetate (CTA) are slowly degraded in the solvent. Cellulose forms a mesophase as low as 4% (w/w) concentration, but CTA has a much higher critical concentration, 20% (w/w), in TFA-CH2Cl2. The cellulose behaves as a rigid rod in TFA-CH2Cl2 (70/30 v/v) and its persistence length calculated using the lattice model approximates its chain length, presumably due to extensive interaction with the solvent. As expected, due to low polymer-solvent interactions, the persistence length of CTA in TFA-CH2Cl2 is only one-fourth the chain length.