Master of Chaos and Order: Opposite Microstructures of PCL‐co‐PGA‐co‐PLA Accessible by a Single Catalyst**

Abstract

One catalyst, two reaction set‐ups, three monomers and unlimited macromolecular microstructural designs: The iron guanidine complex [FeCl2(TMG5NMe2asme)] (1) polymerizes lactide faster than the industrially used Sn(Oct)2 and shows high activity towards glycolide and ϵ‐caprolactone. Its distinguished features enable the synthesis of both block and random‐like copolymers in the melt by a simple change of the polymerization set‐up. Sequential addition of monomers yields highly ordered block copolymers including the symmetrical PLA‐b‐PGA‐b‐PCL‐b‐PGA‐b‐PLA pentablock copolymers, while polymerizations of monomer mixtures feature enhanced transesterifications and pave the way to di‐ and terpolymers with highly dispersed repeating unit distributions. A robust catalyst active under industrially applicable conditions and producing copolymers with desired microstructures is a major step towards biocompatible polymers with tailor‐made properties as alternatives for traditional plastics on the way towards a sustainable, circular material flow.

Open Loop Recycling – Guanidine Iron(II) Polymerization Catalyst for the Depolymerization of Polylactide

“…Compared to simpler catalytic systems, C1 has higher costs but is comparable to other discrete metal catalysts. Due to its versatile applications: polymerization of different cyclic esters, [23] depolymerization with different nucleophiles, and its recyclability, the hybrid guanidine catalyst features intriguing properties for a catalyst designed for a sustainable, circular plastics economy.…”

Iron(ii) carboxylates and simple carboxamides: an inexpensive and modular catalyst system for the synthesis of PLLA and PLLA-PCL block copolymers

“…Poly( l -lactic acid) (PLLA) 7,8 and poly(ε-caprolactone) (PCL) 9,10 are complimentary polymers with regard to their mechanical properties, drug permeabilities, and physiological degradation rates. 11,12 Consequently, copolymers of the two monomers l -lactide and ε-caprolactone can provide materials with tailor-made properties for a wide range of applications. Precise control over the copolymerisation reaction enables the preparation of a range of different microstructures ranging from diblock to completely random distributions of the monomer units.…”

“…Only a few catalysts were demonstrated to give reasonably good activity and control over the molar mass of the obtained polymer. 11,37,52 Many of these studies were performed in solution, sometimes using the toxic propylene oxide as solvent and precursor to the initiating species. [53][54][55][56][57] Polymerisation in the melt is preferable with regard to processing and environmental impact.…”

“…Very recently, the same catalyst was successfully applied to the copolymerisation of LA and CL. 11 It is important to note that in copolymerisation, the reaction rates of each monomer differ with different catalysts, and the rates directly impact the copolymer sequence structure. With large reactivity differences between the different monomers, fully random copolymers cannot be produced; rather, gradient structures are obtained.…”

Understanding the structure–activity relationship and performance of highly active novel ATRP catalysts

“…We are focusing on guanidine ligands due to their excellent N donor properties and a large versatility in ligand design. 29,30 Besides exhibiting good activity in ATRP, 31–41 guanidine based catalysts can be used for oxygen activation, 42 ring-opening polymerisation, 43 and photochemistry 44 and further as model complexes for the entatic state of electron transfer proteins. 45 Our previous studies on guanidine quinolinyl (GUAqu) catalysts in ATRP show that the solubility, electronic properties, and therefore the catalytic activity can be increased by the substitution of the quinolinyl backbone.…”