Unlocking features of locked-unlocked anionic polymerization

Abstract

Unlocking features of the locked-unlocked anionic polymerization were investigated and reported.

Manipulating Molecular Weight Distributions via “Locked–Unlocked” Anionic Polymerization

“…Based on a comparison of the kinetics (k DSiHS ≪ k SS ), all of the end-capped chains could alternatingly propagate simultaneously (for elimination of the crossover effect). 27 In this way, a series of block copolymers consisting of PS with different MWDs and short blocks of DPE-SiH and St with alternating sequences were prepared. 28 1 H nuclear magnetic resonance (NMR) spectra and SEC curves for BP-PS-b-PSD (PS-b-PSD refer to a block copolymer consisting of polystyrene (PS) and an alternating oligomer of styrene and DPE-SiH (PSD)) exhibiting broad MWDs are shown in Figure 5.…”

“…Furthermore, as the synthetic route shown in Figure , the mixture of DPE-SiH and St was added into the uneven PSt-D SiO -Li solution unlocked by t -BuOK. Based on a comparison of the kinetics ( k DSiHS ≪ k SS ), all of the end-capped chains could alternatingly propagate simultaneously (for elimination of the crossover effect) . In this way, a series of block copolymers consisting of PS with different MWDs and short blocks of DPE-SiH and St with alternating sequences were prepared …”

Quo Vadis Carbanionic Polymerization?

“…Recently, they reported a “locked-unlocked” mechanism in living anionic polymerization, where the anionic species can be quantitatively locked by end-capping with 1-(tri-isopropoxymethylsilylphenyl)-1-phenylethylene (DPE-Si­(O-iPr) 3 ) and subsequently unlocked by adding an alkali metal alkoxide (Figure ). The authors investigated the features of this mechanism by sequential feeding strategies, which revealed a new method for better controlling the composition, the molecular weight distributions, and the sequence of polymers. , …”

“…198 The authors investigated the features of this mechanism by sequential feeding strategies, which revealed a new method for better controlling the composition, the molecular weight distributions, and the sequence of polymers. 201,202 The controlled functionalization of polymers via living anionic polymerization, either at the chain-end or in-chain, has drawn great attention because it provides a route to various cross-linking reactions, branched architectures, and supramolecular noncovalent bonds, among others. 38 Toward this direction, many reports were documented by employing anionic polymerization and postpolymerization reactions for synthezing noncovalent bonded block polymers (hydrogen bonding, stereocomplexation, etc.).…”