Nitroxide mediated controlled radical polymerization of α‐Methylene‐γ‐Butyrolactone

Abstract

AbstractThe controlled polymerization of α‐methylene‐γ‐butyrolactone (MBL, a naturally occurring sesquiterpene lactone found in tulips) was performed by nitroxide mediated polymerization (NMP) using the alkoxyamine Dispolreg 007 as the initiating system at 80 °C in 50 wt% DMSO. Features of a reversible‐deactivation radical polymerization (RDRP) were observed with a linear growth of the macro‐radical with conversion and a relatively low dispersity (Ð ≤ 1.45). The P(MBL) homopolymer chain ends were mostly re‐activatable as the chain extensions with styrene (S) and glycidyl methacrylate (GMA) in DMSO were successful. Interestingly, the polymerization of MBL initiated by 2‐methyl‐2‐[N‐tert‐butyl‐N‐(1‐diethoxyphosphoryl‐2,2‐dimethylpropyl)‐aminoxy]‐N‐propionyloxysuccinimide (known as NHS‐BlocBuilder) under various experimental conditions did not produce well‐defined P(MBL), possibly due to an excessively high equilibrium constant. However, the bulk copolymerization of MBL with 10–21 mol% of β‐myrcene (Myr, another renewable monomer from the terpene family) initiated by NHS‐BlocBuilder at 100–110 °C led to all the features of a controlled system. The SG1 chain end fidelity of the resulting P(MBL‐co‐Myr) copolymer was confirmed via 31P NMR and by re‐initiating successfully the copolymer chains with a mixture of GMA and Myr monomers at 120 °C in DMSO.