From Epoxide to Cyclodithiocarbonate Telechelic Polycyclooctene through Chain-Transfer Ring-Opening Metathesis Polymerization (ROMP): Precursors to Non-Isocyanate Polyurethanes (NIPUs)

Telechelic polycyclooctenes (PCOEs) have been successfully synthesized by ring-opening metathesis polymerization (ROMP)/cross-metathesis (CM) of cyclooctene (COE) using Grubbs’ second-generation catalyst (G2) in the presence of epoxide-functionalized chain-transfer agents (CTAs). The monofunctional epoxide oxiran-2-ylmethyl acrylate CTA (1) afforded the isomerized α-(glycidyl alkenoate),ω-propenyl functional (IMF) PCOEs. The use of 1,4-benzoquinone (BZQ) as additive completely inhibited the CC isomerization process, thereby leading selectively to α-(glycidyl alkenoate),ω-vinyl telechelic (MF) PCOE. On the other hand, difunctional epoxide CTAs, bis­(oxiran-2-ylmethyl) fumarate (3), bis­(oxiran-2-ylmethyl) maleate (4), bis­(oxiran-2-ylmethyl) (E)-hex-3-enedioate (5), and (Z)-1,4-bis­(oxiran-2-ylmethoxy)­but-2-ene (6), selectively afforded the corresponding α,ω-di­(glycidyl alkenoate) telechelic PCOEs (DF) along with minor amounts of cyclic nonfunctional (CNF) PCOE. In the presence of these difunctional symmetric CTAs, the mechanism is proposed to proceed through a tandem one-pot CM/ROMP/ring-closing metathesis (RCM) approach. CM was more effective with Z- than E-configurated CTAs (4 > 6 ≫ 3 ≫ 5), regardless of the presence of a methylene group in-between the CC double bond and the glycidyl moiety. Subsequent dithiocarbonatation of the α,ω-diepoxide telechelic PCOEs upon reaction with CS₂ in the presence of LiBr quantitatively afforded the first examples of bis­(cyclodithio­carbonate) end-functional PCOEs. Ensuing aminolysis of the bis­(cyclodithio­carbonate) telechelic PCOEs with the polyether (triethylene glycol) diamine JEFFAMINE EDR-148 quantitatively afforded, at room temperature without any added catalyst, the desired poly­(mercapto­thiourethane)­s NIPUs, as evidenced from FTIR spectroscopy, TGA, and DSC analyses.