Tunable Blocking Agents for Temperature-Controlled Triazolinedione-Based Cross-Linking Reactions

Abstract

The remarkable reactivity of triazolinediones (TADs) toward olefin-type substrates marks them as highly attractive click reagents, in particular for polymer modification and cross-linking. Critically, their ultrafast reaction rates result in handling issues and a rather limited shelf life whereas a particular concern for polymer material applications is homogeneous network formation. Herein, we introduce 2-phenylindoles as highly promising blocking agents for TADs, giving bench-stable reagents at ambient temperature from which the initial TADs can be released upon heating. A set of 11 indoles with varying substitution patterns was synthesized, leading to a precise control for the temperature of deblocking within a broad range of 35–100 °C. The established indole–TAD platform was next applied to bivalent TAD reagents to enable on-demand TAD-based cross-linking reactions of a diene-containing polyurethane (M n = 12.5 kDa). Fine-tuning of the curing temperatures, down to 50 °C, was evidenced via rheological measurements.

From Sequence‐Defined Macromolecules to Macromolecular Pin Codes

“…Moreover, an observed activation energy E a,obs = 116.1 ± 8.5 kJ mol −1 could be derived from the kinetic study (Table S1, Supporting Information), which is in accordance with the values of previous studies on simple low molecular weight TAD‐indole systems (see Supporting Information for details). [ 32,33 ]…”

“…[ 38 ] In order to anticipate this potential issue, a second macromolecular pin code ( PC2 ) was synthesized using the alternative aromatic TAD‐COOH derivative L1b , as this was previously reported to significantly reduce the temperature of reversibility of the corresponding indole adduct compared to its aliphatic counterpart. [ 32,33 ] Similar to the first pin code, PC2 was again characterized using SEC (Figure 3b), LCMS, and NMR (see Supporting Information) during the pin code writing process and complemented by MALDI‐MS/MS to retrieve the encoded information (see Figure S2, Supporting Information). The thermal reversibility kinetics was also investigated by offline 1 H NMR (Figure S5, Supporting Information).…”

Bio-orthogonal triazolinedione (TAD) crosslinked protein nanocapsules affect protein adsorption and cell interaction

“…18 Recent studies performed by Du Prez and coworkers again showed its versatility in current applications in polymer science. [19][20][21] We show that particularly TAD's extraordinarily fast and specific reaction behavior leads to a remarkable responsiveness towards proteins in aqueous emulsion, forming nanocapsules with narrow size distribution, in spite of the reported sensitivity of TAD in regards to hydrolysis and reduction to the corresponding urazole derivative. [22][23][24][25] TAD-crosslinked protein nanocapsules were synthesized with bovine serum albumin (BSA), human serum albumin (HSA) or ovalbumin (OVA) via an inverse miniemulsion procedure.…”

Thermally amendable tailor‐made acrylate copolymers via RAFT polymerization and ultrafast alder‐ene “click” chemistry

“…The major demerit of such reactions is many of these processes (e.g., DA reaction) are time‐consuming and require elevated temperatures for completion of the reaction. The introduction of 1,2,4‐triazoline‐3,5‐dione (TAD) chemistry in macromolecular system attracted the attention of polymer chemists, as the TAD reactions are very fast and occurred within few seconds even at milder reaction conditions. Recently we reported the preparation of thermoreversible self‐healable polymer based on homopolymer of 2‐hydroxyethylmethacrylate (HEMA) via RAFT polymerization and Alder‐ene reaction using a TAD derivative.…”