Facile one‐pot synthesis of linear and radial block copolymers of styrene and isoprene through a novel coupling agent by living anionic polymerization

Abstract

A new methodology is successfully used for the concurrent synthesis of three different copolymers; diblock, triblock, and three-armed star-block copolymers of styrene and isoprene via the living anionic polymerization with control over the molecular weight and weight fractions of each block. The room temperature polymerization process has resulted in the well defined linear and radial block copolymers, when the living di-block of poly(styrene-b-isoprene) was coupled using cheap and readily available malonyl chloride as a novel coupling agent giving nearly 100% yield. The resulting block copolymers have narrow polydispersity index (PDI ¼ 1.01-1.09) with a good agreement between the calculated and the observed molecular weights. The results are further supported by fractionation of the block copolymers by reversed-phase temperature gradient interaction chromatography (RP-TGIC) technique followed by size exclusion chromatography (SEC).

End-Capping Reaction of Living Anionic Poly(benzyl methacrylate) with a Pentafluorophenyl Ester for a Norbornenyl-ω-End Macromonomer with a Long Flexible Spacer: Advantage in the Well-Controlled Synthesis of Ultrahigh-Molecular-Weight Bottlebrush Polymers

“…It is necessary to understand possible side reactions during the end-capping reaction of living anionic polymer with a functional acyl compound. ,, One way is the nucleophilic addition of living anionic polymer to the carbonyl carbon of an end-capped polymer . This reaction generates a coupled polymer with a nearly double MW.…”

“…This reaction leads to the production of the non-end-functionalized polymer. In some cases, the proton abstraction catalyzes the reaction between the deprotonated acyl compound and a normal one, , which generates a polymer with a bifunctional end. To avoid these side reactions, living anionic polymers with strong reactivities such as polystyryllithium must react with an epoxide compound to generate less reactive oxyanion before the end-capping reaction. , Lithium ester enolates of polymethacrylates have appropriate reactivities for the direct end-capping reaction with an acyl compound. , …”

“…We assumed the possible side reactions during the end-cappring reaction from the MW results of the macromonomers and bottlebrush polymers and the previous reports. ,, The end-capping reaction of PSt­(DPE) − Li + would simultaneously cause the proton abstraction of PSt­(DPE) − Li + from the acidic methylene moiety next to the carbonyl group in exo -NBC12-PFP . This side reaction would generate a non-end-functionalized polymer with a similar MW of NBC12-PSt .…”

Utility of Chromatographic and Spectroscopic Techniques for a Detailed Characterization of Poly(styrene-b-isoprene) Miktoarm Star Copolymers with Complex Architecture

“…Anionic polymerization using the high-vacuum technique has been proven to be a very powerful tool for the synthesis of well-defined macromolecules with complex macromolecular architectures. − Using this technique, a variety of well-defined block copolymers with star structure (miktoarm star copolymers) and with narrow molar mass and compositional dispersity have been synthesized in order to establish the relationship between the structure and properties (e.g., self-assembly in selective solvents and in bulk), which is essential for designing polymeric materials with predetermined properties and high-tech applications (nanolithography, drug delivery, etc. ). − …”

Controlled epoxidation of poly(styrene‐b‐isoprene‐b‐styrene) block copolymer for the development of nanostructured epoxy thermosets

“…Styrenic BCPs are the most widely used thermoplastic elastomers 11. They present a distinct molecular architecture with a hard thermoplastic block and a soft elastomeric block.…”