Polythiols are versatile polymers that are known to be synthesized using a range of methods with various backbones. Thiols are very unstable due to their high reactivity. To prevent side reactions and unwanted cross-linking, protecting groups are required. Dithiocarbonate has been used to protect the thiol groups on poly(norbornenes); however, it does not allow enough stability to be stored for long periods of time. The purpose of this project is to form a stable protecting group to increase the longevity and usefulness of polythiols. In this project, norbornene was used due to its easily controllable architecture. Aldehyde groups on 5-norbornene-2-carboxaldehyde were converted into an epoxide via the Corey-Chaykovsky reaction and purified by vacuum distillation. The epoxy was then reacted with thioacetate or thiophenol to form the stable thioether protecting group. Characterization of the monomer included ATR-IR, gas chromatography-mass spectrometry, and NMR analysis. The protected monomer was polymerized using Grubbs’ first-generation catalyst. Characterization of the polymer included differential scanning calorimetry, gel permeation chromatography, and NMR. Conditions to deprotect the polythioether were examined. The thioacetate can be easily modified using click chemistry. These modified polymers can be obtained in high yields that are easily purifiable. With new stable protecting groups, polythiols can be used more widely and efficiently.

Formation of poly(norbornene) thioacetate and deprotection into polythiols

255th National Meeting (2018)

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