Sequence-Regulated Copolymers via Tandem Catalysis of Living Radical Polymerization and In Situ Transesterification

Abstract

Sequence regulation of monomers is undoubtedly a challenging issue as an ultimate goal in polymer science. To efficiently produce sequence-controlled copolymers, we herein developed the versatile tandem catalysis, which concurrently and/or sequentially involved ruthenium-catalyzed living radical polymerization and in situ transesterification of methacrylates (monomers: RMA) with metal alkoxides (catalysts) and alcohols (ROH). Typically, gradient copolymers were directly obtained from the synchronization of the two reactions: the instantaneous monomer composition in feed gradually changed via the transesterification of R(1)MA into R(2)MA in the presence of R(2)OH during living polymerization to give R(1)MA/R(2)MA gradient copolymers. The gradient sequence of monomers along a chain was catalytically controlled by the reaction conditions such as temperature, concentration and/or species of catalysts, alcohols, and monomers. The sequence regulation of multimonomer units was also successfully achieved in one-pot by monomer-selective transesterification in concurrent tandem catalysis and iterative tandem catalysis, providing random-gradient copolymers and gradient-block counterparts, respectively. In contrast, sequential tandem catalysis via the variable initiation of either polymerization or in situ transesterification led to random or block copolymers. Due to the versatile adaptability of common and commercially available reagents (monomers, alcohols, catalysts), this tandem catalysis is one of the most efficient, convenient, and powerful tools to design tailor-made sequence-regulated copolymers.

Multimode Self-Folding Polymers via Reversible and Thermoresponsive Self-Assembly of Amphiphilic/Fluorous Random Copolymers

“…The synchronized consumption of two monomers supports the random incorporation of both amphiphilic PEGMA and fluorous R F MA into polymer chains without any biased sequence distribution such as gradient copolymers. 42 Owing to the perfluorinated segments, the copolymers exhibited unique refractive index properties in DMF: the increment of refractive index to the concentration (dn/dc) linearly decreased with increasing R F MA composition from 0 to 60 mol % per a chain ( Figure 2). As a result, the copolymer with 60 mol % 13FOMA unit (P8) uniquely showed a negative SEC signal in DMF.…”

Rapid and quantitative one-pot synthesis of sequence-controlled polymers by radical polymerization

“…Nature's precision in regulating monomer sequences also remains unmatched in non-natural macromolecules [6][7][8][9][10] . Among the various examples of sequence-regulated synthetic macromolecules, block copolymers exhibiting a large number and type of functional sequences -that is, multiblock copolymers-are unique and original structures that exhibit a type of primary structure (although the sequence control is typically limited by the monomer distribution within each block).…”

Sequence-controlled polymers via reversible-deactivation radical polymerization

“…[24][25][26] In this process, the metal alkoxide acts as the cocatalyst for Ru-LRP and concurrently as the catalyst for the transesterification. The transesterification occurs for the remaining methacrylate monomer with the alcohol under the metal alkoxide catalysis to generate the corresponding methacrylate at a moderate rate, which leads to a gradual change in the monomer composition.…”