Cyclotetrasiloxane Frameworks for the Chemoenzymatic Synthesis of Oligoesters

• Published in: RSC Advances
• Main Authors: Zelisko, Paul M, Frampton, Mark B., Jones, Tim RB
• Format: Article in Journal/Newspaper
• Language: English
• Published: Royal Society of Chemistry 2015
• Subjects: silicon chemistry; cyclosiloxane; siloxane; lipase; biotechnology; biocatalysis; transesterification; Canada; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/10464/6987; https://doi.org/10.1039/C4RA14828B

Immobilized lipase B from Candida antarctica (Novozym® 435, N435) was utilized as part of a chemoenzymatic strategy for the synthesis of branched polyesters based on a cyclotetrasiloxane core in the absence of solvent. Nuclear magnetic resonance spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry were utilized to monitor the reactions between tetraester cyclotetrasiloxanes and aliphatic diols. The enzyme-mediated esterification reactions can achieve 65– 80% consumption of starting materials in 24–48 h. Longer reaction times, 72–96 h, resulted in the formation of cross-linked gel-like networks. Gel permeation chromatography of the polymers indicated that the masses were Mw ¼ 11 400, 13 100, and 19 400 g mol 1 for the substrate pairs of C7D4 ester/ octane-1,8-diol, C10D4 ester/pentane-1,5-diol and C10D4 ester/octane-1,8-diol respectively, after 48 h. Extending the polymerization for an additional 24 h with the C10D4 ester/octane-1,8-diol pair gave Mw ¼ 86 800 g mol 1. To the best of our knowledge this represents the first report using lipase catalysis to produce branched polymers that are built from a cyclotetrasiloxane core. Natural Sciences and Engineering Research Council (NSERC) of Canada Brock University Advanced Biomanufacturing Centre