Covalent adaptable networks (CANs) often make use of highly active external catalysts to provide swift exchange of the dynamic chemical bonds. Alternatively, milder species can act as internal catalysts when covalently attached to the matrix and in close proximity to the dynamic bonds. In this context, we introduce the dynamic exchange of phthalate monoesters as a novel chemistry platform for covalent adaptable networks. A low-molecular-weight (MW) model study shows that these monoesters undergo fast transesterification via a dissociative mechanism, caused by internal catalysis of the free carboxylic acid, which reversibly forms an activated phthalic anhydride intermediate. Using this dynamic chemistry, a wide series of CANs with a broad range of properties have been prepared by simply curing a mixture of diols and triols with bifunctional phthalic anhydrides. The dynamic nature of the networks was confirmed via recycling experiments for multiple cycles and via stress relaxation using rheology. The networks proved to be resistant to deformation but showed a marked temperature response in their rheological behavior, related to the swift exchange reactions that have a high activation energy (120 kJ/mol). While densely cross-linked and hydrolytically stable polyester networks with low soluble fractions can be obtained, we found that, by swelling the networks in a hot solvent, a gel-to-sol transition happened, which resulted in the full dissolution of the network.

Phthalate monoesters (PMEs) were recently introduced as a simple dynamic covalent bond for implementation in covalent adaptable networks (CANs), which undergo rapid transesterifications in the absence of catalysts, due to...

Polymer-dye conjugations are one of the common examples for polymer modifications. They represent a crucial step for imaging in optical microscopy or for tracing and marking macromolecules. In this work, we present a comparison between quick and efficient conjugation reactions that do not rely on the use of a metal catalyst, which could contaminate the resulting polymer and hinder its use for subsequent biological applications. Moreover, since the conjugation strategy needs to be compatible with the solvent system used to solubilise the polymer, we focussed our attention on assessing these conjugation approaches for their feasibility with a sample polymer that is only soluble in protic solvents. The methods studied include the ring-strain promoted azide-alkyne click reaction, thiol/maleimide conjugation as well as the 1,2,4-triazoline-3,5-dione (TAD) with a diene moiety, one of the latest click chemistries available.