Reverse temperature-dependent swelling pathway of trifluoroacetic acid in cellulose

CELL 1

Z. Conrad Zhang, conrad.zhang@pnl.gov1, Haibo Zhao1, Johnathan E Holladay, john.holladay@pnl.gov1, J. M. White, jm.white@pnl.gov2, and Yong Wang, yongwang@pnl.gov3. (1) Institute for Interfacial Catalysis, Pacific Northwest National Lab, 902 Battelle Blvd, P.O. Box 999, MSIN: K8-93, Richland, WA 99352, (2) Institute for Interfacial Catalysis, Pacific Northwest National Lab and University of Texas, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, (3) Institute for Interfacial Catalysis, Pacific Northwest National Laboratory, MS K8-93, P. O. Box 999, Richland, WA 99352
An inverse temperature effect was observed during cellulose decrystallization in trifluoroacetic acid (TFA). Decreasing the TFA treatment temperature dramatically accelerate the cellulose decrystallization process. It only took 100 minutes to completely decrystallize cellulose at 0 °C in TFA, a result that was not achieved for 48 hours at 25°C in the same medium. No esterification reaction or cellulose macrofibrils morphology change was caused by TFA treatment at 0 °C. TFA molecules penetrate into the crystalline region as a cyclic dimmer form. Increasing temperature leads to more TFA monomers, which will react with cellulose molecules to form ester. The water formed in esterification may also inhibit the diffusion rate of TFA into cellulose crystalline region. TFA cyclic dimer molecules are unable to form strong hydrogen bonds with the OH groups on cellulose. Therefore, the swelling mechanism of TFA in cellulose must be different from that of traditional hydrogen breaker such as NMMO and liquid ammonia.
 

Industrial Products from Renewable Materials: Molecular to Macroscopic Scale
8:00 AM-11:50 AM, Sunday, 10 September 2006 Palace -- Pacific Heights, Oral

Division of Cellulose & Renewable Materials

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006