100th Anniversary of Macromolecular Science Viewpoint: Needs for Plastics Packaging Circularity.

Plastic packaging has gained an increasing amount of attention in all aspects of society. Over the past several decades, plastics became the material of choice due to their excellent properties, performance, and economics, but the end of life of plastics is not well managed. This has led to plastic waste in our environment, especially the oceans, rivers, and estuaries, driving legislative, industrial, and voluntary initiatives to make the necessary pivot to circularity.

Design of a thermally controlled sequence of triazolinedione-based click and transclick reactions.

The reaction of triazolinediones (TADs) and indoles is of particular interest for polymer chemistry applications, as it is a very fast and irreversible additive-free process at room temperature, but can be turned into a dynamic covalent bond forming process at elevated temperatures, giving a reliable bond exchange or 'transclick' reaction. In this paper, we report an in-depth study aimed at controlling the TAD-indole reversible click reactions through rational design of modified indole reaction partners. This has resulted in the identification of a novel class of easily accessible indole derivatives that give dynamic TAD-adduct formation at significantly lower temperatures.

Macromolecular Coupling in Seconds of Triazolinedione End-Functionalized Polymers Prepared by RAFT Polymerization.

The ultrafast and additive-free triazolinedione-click reaction with electron rich (di)enes is a powerful method for the ultrafast ligation of polymer segments. A versatile method is described for the introduction of clickable TAD end groups in various polymer segments, using reversible addition-fragmentation chain transfer polymerization. These triazolinedione-functionalized prepolymers were subsequently used for macromolecular functionalization with a low molecular weight diene and block copolymer synthesis of different types within seconds, at ambient conditions, through the coupling with diene-functionalized polymers such as poly(ethylene glycol) and poly(isobornyl acrylate).

Biomass Approach toward Robust, Sustainable, Multiple-Shape-Memory Materials.

We report biomass-derived, shape-memory materials prepared via simple reactions, including "grafting from" ATRP and TAD click chemistry. Although the biomass, including plant oils and cellulose nanocrystals, has heterogeneous chemical structures in nature, these materials exhibit excellent multiple shape-memory properties toward temperature, water, and organic solvents, which are comparable to petroleum counterparts. The work presented herein provides burgeoning opportunities to design the next-generation, low-cost, biomass-prevalent, green materials for niche applications.

Triazolinediones as Highly Enabling Synthetic Tools.

Triazolinediones (TADs) are unique reagents in organic synthesis that have also found wide applications in different research disciplines, in spite of their somewhat "exotic" reputation. In this review, we offer two case studies that demonstrate the possibilities of these versatile and reliable synthetic tools, namely, in the field of polymer science as well as in more recently emerging applications in the field of click chemistry. As the general use of triazolinediones has always been hampered by the limited commercial and synthetic availability of such reagents, we also offer a review of the available TAD reagents, together with a detailed discussion of their synthesis and reactivity.

Triazolinediones enable ultrafast and reversible click chemistry for the design of dynamic polymer systems.

With its focus on synthetic reactions that are highly specific and reliable, 'click' chemistry has become a valuable tool for many scientific research areas and applications. Combining the modular, covalently bonded nature of click-chemistry linkages with an ability to reverse these linkages and reuse the constituent reactants in another click reaction, however, is a feature that is not found in most click reactions. Here we show that triazolinedione compounds can be used in click-chemistry applications.

Chemistry of crosslinking processes for self-healing polymers.

Recent developments in material design have seen an exponential increase of polymers and polymer composites that can repair themselves in response to damage. In this review, a distinction is made between extrinsic materials, where the self-healing property is obtained by adding healing agents to the material to be repaired, and intrinsic materials, where self-healing is achieved by the material itself through its chemical nature. An overview of the crosslinking chemistries used in self-healing materials will be given, discussing the advantages and drawbacks of each system.