Nitroxide‐mediated radical copolymerization of methyl methacrylate controlled with a minimal amount of 9‐(4‐vinylbenzyl)‐9H‐carbazole

Abstract

The controlled nitroxide-mediated homopolymerization of 9-(4-vinylbenzyl)-9H-carbazole (VBK) and the copolymerization of methyl methacrylate (MMA) with varying amounts of VBK were accomplished by using 10 mol % {tert-butyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]amino} nitroxide relative to 2-({tert-butyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]ami-no}oxy)-2-methylpropionic acid (BlocBuilder TM ) in dimethylformamide at temperatures from 80 to 125 C. As little as 1 mol % of VBK in the feed was required to obtain a controlled copolymerization of an MMA/VBK mixture, resulting in a linear increase in molecular weight versus conversion with a narrow molecular weight distribution (M w /M n % 1.3). Preferential incorporation of VBK into the copolymer was indicated by the MMA/VBK reactivity ratios determined: r VBK ¼ 2.7 6 1.5 and r MMA ¼ 0.24 6 0.14. The copolymers were found significantly ''living'' by performing subsequent chain extensions with a fresh batch of VBK and by 31 P NMR spectroscopy analysis. VBK was found to be an effective controlling comonomer for NMP of MMA, and such low levels of VBK comonomer ensured transparency in the final copolymer.

Nitroxide‐Mediated Polymerization of 2‐Hydroxyethyl Methacrylate (HEMA) Controlled with Low Concentrations of Acrylonitrile and Styrene

“…This was attributed to an excessively high equilibrium constant K , which strongly favored the production of propagating radicals, thus leading to irreversible termination . Notwithstanding the limited success from homopolymerization of methacrylic esters via NMP, the copolymerization approach was proven applicable for NMP of many methacrylates . A preliminary experiment copolymerizing HEMA with AN in 1,4‐dioxane failed due to lack of solubility and thus the solvent was switched to DMF.…”

“…For example, it has been used in the polymerization of methyl methacrylate (MMA), methacrylic acid (MAA), benzyl methacrylate, (dimethylamino) ethyl methacrylate, and poly(ethylene glycol) methyl ether methacrylate . The most widely used comonomers via this approach are styrene or styrenic derivatives, 9‐(4‐vinylbenzyl)‐9H‐carbazole (VBK), and acrylonitrile …”

“…The choice of the controlling comonomer can have a secondary purpose; it can impart functionality. For example, it can be used to add water‐solubility (e.g., styrene sulfonic acid, sodium salt) or fluorescent properties (VBK) . In some cases, the media used for the polymerization may prevent usage of a monomer.…”

Amphiphilic Poly(4‐acryloylmorpholine)/Poly[2‐(N‐carbazolyl)ethyl acrylate] Random and Block Copolymers Synthesized by NMP

“…Recently, our group has reported the controlled synthesis of fluorescent homopolymers and copolymers based on 9‐(4‐vinylbenzyl)‐9 H ‐carbazole (VBK)32 using BlocBuilder. However, poly(VBK) has a high glass transition temperature ( T g ≈ 177 °C)33 and is therefore not necessarily ideal for film processing/casting 34.…”

From NMP to RAFT and Thiol‐Ene Chemistry by In Situ Functionalization of Nitroxide Chain Ends

“…specific conditions) [4][5][6][7] , acrylamides [8] , acrylonitrile [9] , and even 1,3-dienes [10][11][12] . Furthermore NMP allows for the design of complex macromolecular architectures such as block, graft and star copolymers [9,13,14] .…”