Self-Switchable Polymerization: A Smart Approach to Sequence-Controlled Degradable Copolymers

Abstract

In the quest for sustainable development, degradable polymers are attractive alternatives to traditional fossil-based plastics. As monocomponent degradable polymers often suffer from unsatisfactory performances, the utilization of corresponding copolymers with tailored block compositions is viable for improved properties. To this end, the emerging field of self-switchable polymerization offers a facile access to the on-demand synthesis of degradable copolymers with controlled sequences, in which the polymerizations were regulated by the monomers themselves. This Perspective outlines state-of-the-art self-switchable polymerization systems based on ring-opening (co)polymerization with various types of monomers. The scope of catalysts and monomer types are summarized. Comprehensive comparison between different types of monomers is offered along with an outlook on possible monomers in the future.

Tertiary and Quaternary Phosphonium Borane Bifunctional Catalysts for CO2/Epoxide Copolymerization: A Mechanistic Investigation Using In Situ Raman Spectroscopy

“…This strategy can be further extended to highly active bifunctional Co − and Al systems featuring pendant ammonium cations (Chart ). It has been proposed that the ammonium cation can interact with the anionic polymer chain-end, whereas the metal center binds/activates CO 2 and epoxide. , Owing to these advances, novel random/block copolymers of polyalkylene carbonates have been developed with emerging applications. − …”

Thioanhydride/isothiocyanate/epoxide ring-opening terpolymerisation: sequence selective enchainment of monomer mixtures and switchable catalysis

“…In ROCOP, switchable catalysis has been established as an elegant and valuable tool to synthesise blockpolymers with useful material properties. [24][25][26] Here a suitable catalyst first mediates the ROP of for example cyclic esters (e.g. εDL forming PDL) with epoxides present in the mixture until the second ROCOP monomer (e.g.…”

Switchable Polymerization: A Practicable Strategy to Produce Biodegradable Block Copolymers with Diverse Properties

“…Simultaneously, some specific monomers could at the same time act as the switching agents by automatically interrupting the original reaction with different catalytic cycles, such reaction is referred to as self-switchable (or "chemoselective") polymerization. [26] Regardless of its classifications, all catalysis follows the similar basic principles and regulations. Furthermore, these switchable polymerizations differ from orthogonal tandem catalysis, in which numerous catalysts work in tandem or sequentially, each tuned for a particular process.…”

“…The capacity to steer the catalyst between distinct polymerizations while selecting for specific monomers is referred to as “switching” in this catalysis. Simultaneously, some specific monomers could at the same time act as the switching agents by automatically interrupting the original reaction with different catalytic cycles, such reaction is referred to as self‐switchable (or “chemoselective”) polymerization [26] . Regardless of its classifications, all catalysis follows the similar basic principles and regulations.…”