Controlled Nitroxide-Mediated Radical Polymerization of Styrene, Styrene/Acrylonitrile Mixtures, and Dienes Using a Nitrone

Abstract

Radical polymerization of styrene and copolymerization of styrene and acrylonitrile (60/ 40) are controlled when conducted in the presence of N-tert-butyl-R-isopropylnitrone, which is easily synthesized from cheap reagents. However, for the control to be effective, the nitrone has to be prereacted with the radical initiator. Nitroxides are then formed "in situ", such that this nitrone system is an attractive alternative for the classical nitroxide-mediated polymerization (NMP), which may require a multistep synthesis of nitroxides or alkoxyamines. The choice of the radical initiator is important because it dictates the structure of the nitroxide and thus its capacity to control the radical polymerization. Well-defined poly(styrene)-b-poly(styrene-co-acrylonitrile), poly(styrene)-b-poly(n-butyl acrylate), and poly(styrene)-bpoly(isoprene) copolymers have been successfully synthesized by this process.

Ability of nitrones of various structures to control the radical polymerization of styrene mediated by in situ formed nitroxides

“…N-tert-butyl-α-isopropylnitrone 1 (Scheme 2), was pre-reacted with styrene and BPO at 85 °C, followed by polymerization at 110 °C [42]. During this pre-reaction, nitroxides are formed with a hardly predictable structure, because the nitrone can react with different radicals, i.e.…”

“…At high temperature, the polymerization was pseudo-living, the polymerization of styrene could be resumed and PS-b-PnBuA was synthesized by sequential polymerization of styrene and n-butylacrylate with the intermediate recovery of the PS chains. The use of N-tert-butyl-α-isopropylnitrone (nitrone 1, Scheme 2) together with BPO proved efficiency in controlled bulk polymerization of styrene at 110 °C [42]. Well-defined styrene containing random and block copolymers (PSAN, PS-b-PSAN, PS-b-PnBuA and PS-b-PIP) with a low polydispersity were accordingly synthesized (where PIP stands for polyisoprene).…”

Nitroxide decomposition: Implications toward nitroxide design for applications in living free‐radical polymerization

“…41 These polymerizations demonstrated good control with styrene monomers, but 45,56,[82][83][84][85][86][87] has allowed the extension of NMP to a much wider range of nonstyrenic olefin monomers. These a-hydrogen-bearing nitroxides are stable and easily handled at room temperature but do undergo bimolecular disproportionation under the thermal conditions of polymerization.…”

Compatibilization of Poly(styrene‐acrylonitrile) (SAN)/Poly(ethylene) Blends via Amine Functionalization of SAN Chain Ends

“…[39] CRP can be used to create useful SAN copolymers with low polydispersity and controlled structure, including block copolymers. SAN copolymers can easily be made using NMP, [40][41][42] ATRP [43][44][45] and RAFT. [46,47] CRP techniques are also very useful in synthesizing functional polymers.…”

“…[40,52] Controlled radical polymerization (CRP) can be used to create useful SAN copolymers with low polydispersity and controlled microstructure, such as segmented block copolymers. SAN copolymers can easily be made using nitroxide mediated polymerization (NMP), [40][41][42] atom transfer radical polymerization (ATRP), [43,45,53] and reverse atom transfer radical polymerization (RAFT). [46,47,54] The ability to form SAN-containing block copolymers allows for additional tailoring of properties for the blend.…”