Research Grants/Fellowships/SBIR

Final Report: Biocatalytic Polymer Synthesis in and from Carbon Dioxide for Pollution Prevention

EPA Grant Number: R825338
Title: Biocatalytic Polymer Synthesis in and from Carbon Dioxide for Pollution Prevention
Investigators: Russell, Alan J.
Institution: University of Pittsburgh - Main Campus
EPA Project Officer: Karn, Barbara
Project Period: October 1, 1996 through September 30, 1999
Project Amount: $180,000
RFA: Technology for a Sustainable Environment (1996) RFA Text |  Recipients Lists
Research Category: Nanotechnology , Sustainability , Pollution Prevention/Sustainable Development



Our goals were to: (1) investigate polytransesteri-fication of butanediol and various adipic acid esters under conditions to enhance diol synthesis, and assess molecular weight control of polytransesterification of butanediol and various adipic acid esters using pressure as a variable in supercritical carbon dioxide (CO2); (2) investigate in detail the possibility of continuous synthesis of polyester polyols in supercritical CO2; and (3) generate a computer model for prediction of chain extension and termination during enzyme catalyzed synthesis of polyesters in supercritical fluids.

Summary/Accomplishments (Outputs/Outcomes):

Because we wished to use supercritical CO2 as the solvent for polytransesterification, we initially decided to tackle the issue of enhancing monomer solubility in this reaction medium. Literature has widely supported the hypothesis that fluorinated compounds are more soluble in CO2 than their hydrogenated counterparts. Therefore, the phase behavior of fluorinated diols and divinyl adipate, an activated diester, in supercritical CO2 was investigated at 323K. The phase behavior of equimolar mixtures of divinyl adipate with the most CO2 -soluble diol, 3,3,4,4,5,5,6,6-octafluorooctan-1,8-diol, also was determined. In each case, the fluorinated diol was significantly more soluble than its hydrocarbon counterpart. However, divinyl adipate was much more soluble in CO2 than any of the fluorinated diols. Therefore, no attempt was made to fluorinate the divinyl adipate structure.

Once it was determined that these potential monomers were CO2-soluble, we then began to investigate the biocatalytic synthesis of fluorinated polyesters from divinyl adipate and each of the fluorinated diols. The effects of time, continuous enzyme addition, enzyme concentration, and diol chain length were studied to determine the factors that would limit chain extension, such as enzyme inactivation, enzyme specificity, the equilibrium position for the reaction, hydrolytic side reactions, and polymer precipitation. An enzyme screen demonstrated that NovozymO 435, an immobilized lipase from Candida antarctica, was the most effective in producing the fluorinated polyester. Molecular weight and polydispersity analyses were performed by means of gel permeation chromatography. End group analysis was accomplished through the use of Matrix Assisted Laser Desorption/Ionization-Time of Flight mass spectroscopy (MALDI-TOF). Polymer molecular weight steadily increased and then leveled off after approximately 30 hours, with a weight average molecular weight of 1773 Da. The majority of polymer chains were terminated with either hydroxyl or vinyl groups. Polymers that were synthesized from bulk monomers had higher molecular weights, but higher enzyme concentrations were required. Enzyme specificity towards shorter chain fluorinated diols appeared to be the governing factor in limiting chain growth. However, polymer molecular weight increased further (Mw = 8094 Da) when a fluorinated diol that contained an additional methylene spacer between the fluorine atoms and hydroxyl groups was used. Our published work (below) on the pressure dependence of polymer synthesis in CO2 led to the conclusion that we must first find ways to increase solubility before we are able to synthesize high molecular weight polymers.

Once these polymers were synthesized, the solubility of a polyester made from divinyl adipate and 2,2,3,3-tetrafluoro-1,4-butanediol in supercritical CO2 also was determined and was found to be less soluble than the monomers it was synthesized from. The biocatalytic synthesis of a fluorinated polyester from divinyl adipate and 3,3,4,4,5,5,6,6-octafluorooctan-1,8-diol also was performed in supercritical CO2 at approximately 1800 psi. This resulted in a polymer with a weight average molecular weight of 8232 Da.

In our work to synthesize to polyols, we first undertook a detailed investigation of why biocatalytic synthesis behaves in the way it does. This first ever detailed description of the kinetics of the biocatalytic polytransesterification led to an understanding of opportunities and limitations. We were able to model the process computationally, and then use that model to increase the efficiency of polymerization by almost 10,000 fold. We can now synthesize polymers of 20,000 molecular weight in hours, at low enzyme concentration and with predominantly diol functionality.

Journal Articles on this Report : 11 Displayed | Download in RIS Format

Other project views: All 22 publications 14 publications in selected types All 11 journal articles
Type Citation Project Document Sources
Journal Article Chaudhary AK, Critchley G, Beckman EJ, Russell AJ. Biocatalytic polyester synthesis: analysis of the evolution of molecular weight and end-group functionality. Biotechnology and Bioengineering 1997;55(1):227-239. R825338 (Final)
not available
Journal Article Chaudhary AK, Lopez J, Beckman EJ, Russell AJ. Biocatalytic solvent-free polymerization to produce high molecular weight polyesters. Biotechnology Progress 1997;13(3):318-325. R825338 (Final)
not available
Journal Article Chaudhary AK, Beckman EJ, Russell AJ. Nonequal Reactivity Model for Biocatalytic Polytransesterification. Aiche Journal 1998;44(3):753-764 R825338 (Final)
not available
Journal Article Chaudhary AK, Beckman EJ, Russell AJ. Rapid biocatalytic polytransesterification: reaction kinetics in an exothermic reaction. Biotechnology and Bioengineering 1998;59(4):428-437. R825338 (Final)
not available
Journal Article Kline BJ, Beckman EJ, Russell AJ. One step biocatalytic synthesis of linear polyesters with pendant hydroxyl groups. Journal of the American Chemical Society 1998;120(37):9475-9480. R825338 (Final)
not available
Journal Article Kline BJ, Lele S, Lenart PJ, Beckman EJ, Russell AJ. Use of a batch-stirred reactor to rationally tailor biocatalytic polytransesterification. Biotechnology and Bioengineering 2000;67(4):424-434. R825338 (Final)
not available
Journal Article Kline BJ, Lele SS, Beckman EJ, Russell AJ. Role of diffusion in biocatalytic polytransesterification. AIChE Journal 2001;47(2):489-499. R825338 (Final)
R828131 (2002)
not available
Journal Article Mesiano AJ, Beckman EJ, Russell AJ. Supercritical biocatalysis. Chemical Reviews 1999;99(2):623-633. R825338 (Final)
not available
Journal Article Mesiano AJ, Beckman EJ, Russell AJ. Biocatalytic synthesis of fluorinated polyesters. Biotechnology Progress 2000;16(1):64-68. R825338 (Final)
R828131 (2002)
not available
Journal Article Rodney RL, Stagno JL, Beckman EJ, Russell AJ. Enzymatic synthesis of carbonate monomers and polycarbonates. Biotechnology and Bioengineering 1999;62(3):259-266
abstract available  
R825338 (Final)
not available
Journal Article Rodney RL, Allinson BT, Beckman EJ, Russell AJ. Enzyme catalyzed polycondensation reactions for the synthesis of aromatic polycarbonates and polyesters. Biotechnology and Bioengineering 1999;65(4):485-489. R825338 (Final)
not available
Supplemental Keywords:

green chemistry, clean technology, innovative technology, environmental chemistry., Scientific Discipline, Sustainable Industry/Business, Chemical Engineering, cleaner production/pollution prevention, Environmental Chemistry, Environmental Engineering, cleaner production, waste minimization, waste reduction, environmentally conscious manufacturing, biocatalytic polymer synthesis, process modification, CO2 - based systems, innovative technology, pollution prevention, source reduction, alternative chemical synthesis, biocatalysis, environmentally-friendly chemical synthesis, green chemistry

Progress and Final Reports:
Original Abstract