One-Step and Metal-Free Synthesis of Triblock Quaterpolymers by Concurrent and Switchable Polymerization

Abstract

A one-step and metal-free route to triblock quaterpolymers from mixtures of vinyl monomers, epoxides, anhydrides, and racemic lactide (rac-LA) has been described, which bridges three polymerization cycles involving ring-opening copolymerization (ROCOP) of epoxides/anhydrides, ring-opening polymerization (ROP) of rac-LA, and RAFT polymerization of vinyl monomers. Taking advantage of the switchable polymerization between ROCOP and ROP, concurrent chain propagation of ROCOP/RAFT and ROP/RAFT sequentially occurs by using a trithiocarbonate compound with carboxylic group (TTC–COOH) as a versatile chain transfer agent. The multiple-chain transfer effect enables independent and precise control over the molecular weights of the three blocks and ensures narrow distribution of the resultant triblock quaterpolymers (Đ < 1.20). This work demonstrates the possibility to acquire block copolymers with high degree of structural complexities in a single efficient process by combining different block polymerization strategies.

A simplified approach for the metal-free polymerization of propylene oxide

“…In view of the obvious correlation of PA and performance, this also seems a straightforward way to adapt the desired rate of polymerization by choice of catalyst according to PA. To the best of our knowledge, only a single example for a nitrogen base/borane catalyst setup targeting polymerization of epoxides has been published to date. 35 In a nal set of experiments, it was probed whether this userfriendly setup was also applicable to epoxides other than PO. Screening allyl glycidyl ether (AGE), tert-butyl glycidyl ether (tBuGE) and 1-butylene oxide (BO), it is found that these higher epoxide homologues entail a notable drop in speed of conversion while at the same time require a higher minimum PA of the applied organobase (Table S3 †).…”

Ortho-vanillin derived Al(iii) and Co(iii) catalyst systems for switchable catalysis using ε-decalactone, phthalic anhydride and cyclohexene oxide

“…Bicomponent catalysts comprising Et 3 B/DBU Lewis acid/base pairs, reported by Wang et al, were also capable of switchable catalysis from mixtures of propylene oxide (PO), PA and LA yielding P(PO-alt-PA)-b-PLA. 19 By installing a functional chain end-group, RAFT polymerisation of methyl methacrylate formed PMMA-b-P(PO-alt-PA)-b-PLA. In this Fig.…”

“…14 The polymer is fully degradable and the monomers are (ε-decalactone (ε-DL)), or could be (cyclohexene oxide (CHO), phthalic anhydride (PA)), biobased. 14,19,20 Currently, the catalysts used to make these block polyesters through switchable catalysis display low turnover frequencies for at least one of the catalytic cycles. Here, this deficiency is tackled by the developing catalyst systems displaying high activities for both the ROP of ε-DL and ROCOP of PA with CHO.…”

Developments in the Components of Metal‐Free Photoinitiated Organocatalyzed‐Atom Transfer Radical Polymerization (O‐ATRP)

“…The field of O-ATRP has proved to be one of the most successful modifications in devising a metal-free ATRP. The range of O-ATRP can be witnessed from its employment in synthesizing several versatile polymer structures, including the functionalization of various polymer chain ends, [94] polymer brush structures, [89] block, [95,96] multi-block, [97,98] and star polymeric structures. [99] The utilization of light enhances the control, leads to the removal of metal catalysts, and eventually benefits in extending this technique's applications.…”