Switch Catalysis To Deliver Multi‐Block Polyesters from Mixtures of Propene Oxide, Lactide, and Phthalic Anhydride

Abstract

Switchable polymerisation catalysis enables block polymer sequence selectivity from monomer mixtures, resulting in the formation of multiblock polyesters. The aluminium salphen catalyst switches between two different polymerisation mechanisms and selectively enchains mixtures of commercially available monomers: lactide, phthalic anhydride, and propene oxide. Sequential monomer mixture additions yield multi‐block polyesters featuring 3, 7, 11, 15, 19, 23, and 27 blocks. The unparalleled catalytic selectivity can be used to access completely new multi‐block polyesters relevant for future applications.

Understanding metal synergy in heterodinuclear catalysts for the copolymerization of CO2 and epoxides

“…CO2terpolymerizations and switchable catalytic processes are currently limited by low catalyst activities and so better catalysts should allow access to a broader range of CO2 containing materials and properties. [74][75][76][77][78] Beyond the field of CO2 utilization, there is increasing interest in main group/Co(II) heterodinuclear catalysts, relevant to those explored in this work, for processes including nitrogen activation,[79][80][81] electrophilic amination,82 CH and CF activation processes 83,84. …”

Orthogonal functionalization of alternating polyesters: selective patterning of (AB)n sequences

“…1B and Table S1 †). 29,30,58 The crude polymers were isolated by adding the reaction solution, diluted with minimal methylene chloride, dropwise into hexane. The 1 H NMR spectrum of P1 exhibits only signals for alternating polyester, there are no detectable ether linkages as evidenced by a lack of signals at 3.00-3.5 ppm ( Fig.…”

“…22,23 These chemistries can be successfully installed by post-functionalization reactions, perhaps most commonly by the thiol-ene reaction. [28][29][30][31][32][33][34][35][36][37][38] Relevant to this are several reports of its application using aliphatic polycarbonates prepared by CO 2 /epoxide ROCOP. [38][39][40][41][42][43][44][45][46][47][48][49][50] For example, Darensbourg and co-workers used it to make amphiphilic block polycarbonates that self-assembled into micelles.…”

“…[21][22][23] The selection of the catalyst is important to ensure the highly alternating structure and there are now quite a range of catalysts which effectively prevent epoxide homopolymerization. 21,[24][25][26][27][28][29][30] In addition to its impressive sequence selectivity, ROCOP is also amenable to manufacturing at scale since many epoxides and anhydrides are already produced and used by the chemical industry. 22 One draw-back of ROCOP is that several useful functional groups are incompatible and, in particular, substituents such as hydroxyl, primary/secondary amine, carboxylic acid and other protic species function as chain transfer agents.…”

Heterodinuclear complexes featuring Zn(ii) and M = Al(iii), Ga(iii) or In(iii) for cyclohexene oxide and CO2 copolymerisation

“…[31][32][33][34][35][36] Group 13 complexes also show good activity for mechanistically related reactions such as in the ringopening polymerisation of lactide, lactones or cyclic carbonates. [37][38][39][40][41][42] For the target macrocyclic catalysts, it was envisaged that combining the labile Zn(II) site with Group 13 elements could allow modification of metal Lewis acidity and alkoxide lability. When targeting new catalysts, it is proposed that both metals should have sufficiently small ionic radii to enable inplane coordination in the macrocycle cavity.…”