Lucca Trachsel

Covalent adaptable networks (CANs) offer a compelling strategy to unite the mechanical robustness of thermosets with the reprocessability of thermoplastics, yet achieving simultaneous durability, processability, and true recyclability remains challenging. We introduce diketoenamine (DKE) vitrimers derived from β ‐triketone methacrylate monomers and demonstrate how rational monomer design dictates network processability, viscoelasticity, and recyclability. By systematically varying the spacer length between the β ‐triketone (TK) moiety and the polymer backbone, we identify a key structure–property relationship that dictates vitrimer behavior. Networks bearing TK pendants minimally displaced from the backbone suppress creep but exhibit limited stress relaxation, whereas extended spacers yield lower glass transition temperatures, higher effective crosslink densities, and efficient stress dissipation, enabling optical transparency and reprocessability. Extending this platform to ultra‐high molecular‐weight prepolymers introduces physical entanglements as secondary crosslinks, further enhancing dimensional stability without compromising processability. Both mechanical and chemical recycling validate the closed‐loop circularity of these materials. These results establish TK methacrylates as a versatile platform for designing high‐performance vitrimers that integrate durability, reprocessability, and true closed‐loop recyclability.

Developing polymeric materials that combine precise, modular functionalization with programmed backbone degradability remains an outstanding challenge in macromolecular engineering. Herein, we present a molecular design strategy that integrates orthogonal postpolymerization modification with selective, stimulus-responsive backbone degradability within a single macromolecular platform. The ring-opening polymerization of 1,2-dithiolanes introduces cleavable disulfide linkages into polymer backbones, providing a powerful route to degradable materials under biologically relevant reducing conditions. By incorporating a β-triketone (TK) moiety into an α-lipoic-acid-derived 1,2-dithiolane, we synthesized triketone–lipoic acid (TKLA), a dual-functional monomer that combines click-type, catalyst-free amine ligation with programmed backbone degradability. Leveraging photoinduced electron/energy-transfer reversible addition–fragmentation chain-transfer (PET-RAFT) copolymerization of TKLA with acrylate and acrylamide monomers, we accessed well-defined copolymers containing both pendant TK groups and disulfide-rich backbones in a single synthetic step. Under mild conditions, TK-bearing copolymers react quantitatively with a broad scope of amines to form β,β′-diketoenamines (DKEs), enabling modular installation of hydrophilic, hydrophobic, charged, and bioactive substituents. Importantly, these DKE moieties are not static but participate in associative transamination, allowing dynamic exchange and reconfiguration of installed functionalities. Meanwhile, the disulfide-containing backbones fragment cleanly and selectively under reducing environments, affording controlled deconstruction while preserving, or transforming, the appended side-chain chemistry. Overall, the integration of efficient, chemoselective β-triketone–amine condensation with LA-based degradability within a single monomer framework establishes a molecular design strategy for constructing functional, recyclable, and stimuli-responsive polymer architectures.

Inorganic nanoparticles (NP), particularly gold nanoparticles, hold great promise for biomedical applications. However, one of the major challenges in the implementation of therapeutic applications based on inorganic nanoparticles is the individuation of appropriate coatings, which are indeed responsible for stability, escape from the immune system, and further functionalization. In this paper, we explore the properties of the multi-azide-containing and highly nonfouling polymer PAcrAm-g-(PMCA, NH2, ND), based on poly(oxazoline) derivatives grafted to a poly(acrylamide), as a coating for gold nanoparticles that can grant stability and easiness of derivatization and can prevent nonspecific protein adhesion on gold nanoparticles (Au-NP). We found that the addition of the polymer to citrate-stabilized gold nanoparticles led to the formation of NP suspensions with excellent colloidal stability, as confirmed by dynamic light scattering (DLS), ζ potential, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) investigations. In addition, the AuNP coating strongly decreases the protein adsorption corona and does not activate dendritic cells (DCs), showing low immunogenicity and potentially decreasing the NP clearance by the mononuclear phagocyte system.

Vinyl ketone polymers, including poly(phenyl vinyl ketone) and poly(p-chlorophenyl vinyl ketone), were successfully synthesized under light using atom transfer radical polymerization (ATRP). This marks the first successful attempt at ATRP of vinyl ketones. The polymerization kinetics revealed chain growth and maintained livingness, as further evidenced by successful chain extension using ethyl acrylate. The efficient main-chain cleavability of the polymers was confirmed under UV light. While the attainment of low dispersity remains an enduring challenge, this work offers promising potential for future success.

α‐Lipoic acid (LA) has recently emerged as an attractive, inexpensive monomer for synthesizing degradable polymers via ring‐opening of its 1,2‐dithiolane, introducing easily cleavable disulfide linkages into polymer backbones. Reversible addition–fragmentation chain transfer (RAFT) copolymerization with vinyl monomers enables access to degradable poly(disulfide)s with controlled molecular weights. However, conventional thermal RAFT methods suffer from oxygen sensitivity, limited LA incorporation (Đ = 1.1–1.6), and LA incorporations up to 68 mol%. The method is compatible with a broad range of functional comonomers, including hydrophilic, charged, and zwitterionic acrylates and acrylamides, yielding water‐soluble degradable polymers. The resulting copolymers are readily degradable by disulfide‐reducing agents, UV light, and ambient sunlight. Overall, this mild and efficient platform overcomes the limitations of thermal RAFT, providing improved access to functional, high‐molecular‐weight degradable LA copolymers, suggesting potential applications as biocompatible plastics and biomedical materials.

α‐Lipoic acid (LA) has recently emerged as an attractive, inexpensive monomer for synthesizing degradable polymers via ring‐opening of its 1,2‐dithiolane, introducing easily cleavable disulfide linkages into polymer backbones. Reversible addition–fragmentation chain transfer (RAFT) copolymerization with vinyl monomers enables access to degradable poly(disulfide)s with controlled molecular weights. However, conventional thermal RAFT methods suffer from oxygen sensitivity, limited LA incorporation (Đ = 1.1–1.6), and LA incorporations up to 68 mol%. The method is compatible with a broad range of functional comonomers, including hydrophilic, charged, and zwitterionic acrylates and acrylamides, yielding water‐soluble degradable polymers. The resulting copolymers are readily degradable by disulfide‐reducing agents, UV light, and ambient sunlight. Overall, this mild and efficient platform overcomes the limitations of thermal RAFT, providing improved access to functional, high‐molecular‐weight degradable LA copolymers, suggesting potential applications as biocompatible plastics and biomedical materials.

Photoinduced reversible-deactivation radical polymerization (photoRDRP) techniques enable the synthesis of well-defined polymers under mild conditions. However, oxygen inhibition remains a key challenge, requiring either complex deoxygenation methods or in situ oxygen-scavenging strategies. Here, we report a red light-driven, fully oxygen-tolerant reversible addition-fragmentation chain transfer (RAFT) polymerization mediated by methylene blue (MB⁺) as a photosensitizer and triethanolamine (TEOA) as an electron donor. This operationally simple method enables polymerization in fully open-to-air vials without stirring, even under direct sunlight, underscoring the robustness and accessibility of the system. Using MB⁺ in the presence of a sacrificial electron donor, the polymerization proceeds to high monomer conversions (>90%), with excellent temporal control, predictable molecular weights, and low dispersities (Đ < 1.3) across a wide range of conditions. The system is compatible with a broad scope of hydrophilic (meth)acrylamide and (meth)acrylate monomers, including those bearing charged and zwitterionic side groups. Notably, this methodology enables access to ultrahigh molecular weight (UHMW, >1,000,000) polymers under ambient conditions, an outcome rarely achieved in oxygen-tolerant RDRP. This metal-free, red light-driven photoRAFT platform offers a scalable, efficient, and biocompatible strategy for controlled polymer synthesis, with potential applications in bioconjugation, functional coatings, and high-throughput screening.

Bottlebrush (BB) polymers, with their densely grafted side chains and unique architecture, are highly advantageous for drug delivery due to their high functional group density for drug conjugation, unimolecular nature, and enhanced biodistribution properties. These attributes enable extended blood circulation half-life, improved tumor tissue penetration, and high tumoral drug accumulation. However, the typically nondegradable, all-carbon backbones of most BB polymers limit their suitability for applications requiring controlled clearance and biodegradability. To address this, we developed degradable BB polymers with poly(disulfide) backbones synthesized via reversible addition-fragmentation chain transfer (RAFT) copolymerization of α-lipoic acid (LA), a renewable and readily available compound, with acrylate-based inimers. These copolymers feature degradable backbones and initiating sites for subsequent BB synthesis. Using an atom transfer radical polymerization (ATRP) grafting-from methodology, we synthesized BB polymers with relatively low dispersities (Đ = 1.30-1.53), high backbone degrees of polymerization (DP_bb), and high molar masses (M_n,MALS = 650-2700 kg/mol). The easily cleavable disulfide bonds enabled backbone degradation under mild reducing conditions. Beyond hydrophilic BB with tri(ethylene glycol) methyl ether acrylate (TEGA) side chains, we synthesized BB with cationic, anionic, and zwitterionic side chains, demonstrating broad monomer compatibility. This scalable approach produces water-soluble, degradable BB polymers with tunable architectures and predictable molecular weights. By addressing the need for degradability in BB polymers, this work advances their potential for drug delivery, offering enhanced functionality, biocompatibility, and sustainability.

The spontaneous condensation of amines with β-triketones (TK), forming β,β′-diketoenamines (DKE) and releasing water as the sole byproduct, exhibits many of the hallmarks of “click” reactions. Such characteristics render TKs as a highly advantageous platform for efficient polymer diversification, even in biological contexts. Leveraging reversible addition–fragmentation chain transfer (RAFT) and photoiniferter polymerization of novel TK-containing vinylic monomers, we synthesized polymers containing pendent TKs with excellent control of molecular weights, even in excess of 10⁶ g mol^–1. Under mild, catalyst-free conditions, poly(β-triketone methacrylate) could be modified with a diverse scope of amines containing a plethora of functional groups. The high efficiency of this functionalization approach was further emphasized when grafting-to with poly(ethylene glycol)-amine resulting in bottlebrushes with molecular weights reaching 2.0 × 10⁷ g mol^–1. Critically, while the formed DKE linkages are stable under ambient conditions, they undergo catalyst-free, dynamic transamination at elevated temperatures, paving the way for associative covalent adaptable networks. Overall, we introduce pendent triketone moieties into methacrylate and acrylamide polymers, establishing a novel postpolymerization modification technique that facilitates catalyst-free ligation of amines under highly permissible conditions.