Mechanistic Pathway for the Formation of Radial Polystyrenes Using Diacyl Chloride

Abstract

An efficient and useful synthetic route for the synthesis of linear and star polystyrenes (PS) is described, employing living anionic polymerization to link living polystyryl anions to inexpensive and readily available malonyl chloride and other coupling agents with higher functionality that were generated in situ at room temperature. The polymers prepared in this way were analyzed and characterized by size-exclusion chromatography (SEC), temperature gradient interaction chromatography (TGIC) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI–TOF MS). It was observed that with the increase in molecular weight of the living PS, the number of arms and weight fraction of higher arm polymers decrease significantly.

“Helicity Inversion”: Linkage Effects of Chiral Poly(n-hexyl isocyanate)s

“…The T•T-PHIC A(1–7) polymers were synthesized by living anionic polymerization, which is one of the most efficient techniques for a controlled polymer synthesis. Moreover, it provides the opportunity to study polymeric properties at a controlled MW and a narrow MWD . PHICs can be synthesized by this technique using additives, such as crown ethers or sodium tetraphenylborate (NaBPh 4 ) .…”

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 .…”

Applications of MALDI-TOF-MS in structural characterization of synthetic polymers

“…131 The analysis of the mechanistic pathway for the formation of radial polystyrenes using diacyl chloride indicated that MALDI-TOF-MS is a sensitive probe for the detailed analysis of the polymer coupling reactions. 132 Diblock dialternating terpolymers (Scheme S3†) were synthesized using a one pot method by Hadjichristidis et al and MALDI-TOF-MS provided evidence for the transition of the organocatalyst between two distinct polymerization cycles with high selectivity. 133…”