Continuous polymerization in supercritical carbon dioxide

I&EC 51

George W. Roberts, groberts@eos.ncsu.edu1, T. Liu1, T. S. Ahmed1, and Joseph M. DeSimone, desimone@unc.edu2. (1) Department of Chemical and Biomolecular Engineering, North Carolina State University, CB#: 7905, Raleigh, NC 27695-7905, (2) Departments of Chemical and Biomolecular Engineering (NCSU); Departments of Chemistry and Pharmacology (UNC), North Carolina State University; University of North Carolina at Chapel Hill, CB# 3290, Caudill Labs, Chapel Hill, NC 27599-3290
Supercritical carbon dioxide (scCO2) is a low-cost, environmentally-friendly medium for carrying out polymerization reactions. A number of chain-growth and step-growth polymers have been synthesized in scCO2, primarily in small batch reactors. Only a few polymerizations have been carried out continuously in scCO2, despite the practical and scientific advantages of continuous operation.

Poly(vinylidene fluoride), poly(acrylic acid), and poly(vinylidene fluoride-co-hexafluoropropylene) have been synthesized in scCO2 using a continuous stirred-tank reactor (CSTR). The first two polymers are formed via precipitation polymerization. The copolymer can be formed by either precipitation or solution polymerization, depending on the CO2 pressure, monomer concentration, molecular weight, and hexafluoropropylene content.

The effects of reaction conditions on the polymerization rate and the molecular weight distribution were studied for the three polymer systems. The behavior of the polymerization rate and the evolution of molecular weight was distinctly different for acrylic acid than for the fluoromonomers. The differences suggest differences in the mechanisms of polymerization.

 

Industrial and Engineering Chemistry Divisional Fellow Award Symposium - Dr. Ruben Carbonell
8:30 AM-11:25 AM, Tuesday, April 8, 2008 Morial Convention Center -- Rm. 231, Oral

Division of Industrial & Engineering Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008