Synthesis of polymers with on-demand sequence structures via dually switchable and interconvertible polymerizations

Abstract

The synthesis of polymers with on-demand sequence structures is very important not only for academic researchers but also for industry. However, despite the existing polymerization techniques, it is still difficult to achieve copolymer chains with on-demand sequence structures. Here we report a dually switchable and controlled interconvertible polymerization system; in this system, two distinct orthogonal polymerizations can be selectively switched ON/OFF independent of each other and they can be interconverted promptly and quantitatively according to external stimuli. Thus, the external stimuli can manipulate the insertion of distinct monomers into the resulting copolymer chains temporally, spatially, and orthogonally, allowing the on-demand precise arrangement of sequence structures in the resulting polymers. This dually switchable and interconvertible polymerization system provides a powerful tool for synthesizing materials that are not accessible by other polymerization methods.

Rhodanine-based Knoevenagel reaction and ring-opening polymerization for efficiently constructing multicyclic polymers

“…It is reported that the ring-opening product of thiirane could easily insert into C–S bond in C(=S)–S containing molecules, such as trithiocarbonate, or dithiocarbonyl compounds 44 , 46 , 48 . Rhodanine has the highly polarized C=S and weak C–S in the ring, and hence, anion could attack C=S bond easily.…”

“…The conversions of MMA and MRDA both reached~99% to produce copolymer 1 with~10 rhodanine rings per chain. Then excess AIBN was added to remove the trithiocarbonate end groups, preventing it from interfering in following ring-opening polymerization 44 (Supplementary Fig. 46).…”

“…Most important, due to the five˗membered cyclic structure and electron˗withdrawing groups on both sides, the – CH 2 – unit in the rhodanine ring is very active to aldehyde molecules via Knoevenagel reaction 43 under mild conditions, which has very high efficiency and selectivity. On the other hand, Nishikubo and our groups previously have found that quaternary onium salts could catalyze the anionic ring-opening polymerization (AROP) of thiirane monomers using trithiocarbonate 44 , 45 , thioester 46 , 47 , dithiocarbonyl 48 , or thiourethane compounds 49 , 50 as initiators, in which quaternary onium salt catalyzes thiirane monomer to open the ring, producing a thiolate. The thiolate further attacks the carbonyl carbon of initiator to form intermediate.…”

PET-RAFT Polymerization Catalyzed by Small Organic Molecule under Green Light Irradiation

“…Boyer et al [3] reported photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization using Ir(ppy) 3 as a photocatalyst, which can be performed even in the presence of air. In addition, as a useful tool, this technique played an important role in the synthesis of multi-block copolymers [4,5], various stereopolymers [6], copolymers with well-defined sequence structures and sophisticated microstructures [7], and discrete oligomers [8]. Hawker et al reported that Ir(ppy) 3 could be utilized in visible light-induced atom transfer radical polymerization of methacrylates [9], acrylates [10], and to fabricate a 3D polymer brush [11].…”

Sensors and sensibility : Tailoring the mechano-responsivity of macromolecules & polymer materials

“…Removing the main source of chain-length dependent optical properties, which is a particularity of conjugated polymers doped with a minority fraction of acceptors, requires to ensure all chains carry at least one acceptor, or ideally that the acceptor positioning within the chain is wellcontrolled. Sequence-controlled polymerisation methods have seen a surge in development in the past year for non-semiconducting polymers [60,61,62,63,64], yet these methods remain to be explored to create sequencecontrolled conjugated polymers, where efforts have been limited to the synthesis of well-defined conjugated oligomers [19,18], that are wellbelow the length where the interesting coupling between chain conformation and optical response emerges.…”