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Traditional adhesives often result in irreversible bonds, hindering disassembly and recycling processes. In response to the growing demand for sustainable practices, researchers have explored alternative bonding solutions. Debonding-on-demand adhesives represent a breakthrough, enabling selective weakening or breaking of adhesive bonds when desired and facilitating efficient disassembly, repair, and recycling of bonded materials. This has profound implications across industries, including packaging, footwear, automotive, and electronics, where the recycling of bonded components plays a crucial role in resource conservation. Herein, we present the incorporation of an imine-based polyol derived from vanillin and polyetheramine into a model, one-component, polyether-based polyurethane adhesives. Such systems retained their thermal performance, exhibiting onset degradation temperatures of ∼320 °C and glass transition temperatures of ∼-50 °C, similar to the reference adhesive. Additionally, they demonstrated adhesive performance comparable to that of the reference system, with lap-shear strengths ranging from 1.7 to 2.1 MPa. In addition to that, imine polyol incorporated adhesives offered enhanced recyclability through on-demand debonding of the bonded substrates to obtain adhesive-free surfaces by acidic hydrolysis of the imine functional groups. These findings undoubtedly contribute to the advancement of sustainable material practices and promote a circular economy, emphasizing the importance of adhesive technology in addressing environmental challenges.

Aromatic polyisocyanurate (PIR) aerogels are recognized as advanced porous materials and extensively studied due to their lightweight nature, high porosity, and specific surface area, which attribute to their outstanding thermal insulation properties. The inherent thermal stability of the PIR moieties, combined with great insulating performance, renders PIR aerogels highly suitable for building insulation applications. Nevertheless, materials containing isocyanurate obtained through direct trimerization of aromatic isocyanates exhibit brittleness, resulting in inferior mechanical performance. In order to enhance the processability of the PIR aerogels, we propose a cocyclotrimerization approach involving mixtures of mono- and difunctional aromatic isocyanates. This approach is designed to develop a PIR network with decreased cross-linking density and brittleness. Herein, we developed an array of PIR aerogels from different alkyl chain-modified isocyanate mixtures. The resulting PIR aerogels exhibited high porosity (>89%), a large surface area (∼300 m 2 /g), superinsulating performance with ultralow thermal conductivity (∼16.8 mW m -1 K -1 ), notable thermal stability ( T d5% ∼ 250 °C), improved mechanical performance, and intrinsic hydrophobicity without the need for postmodification. These high-performance organic aerogels hold significant promise for applications requiring superinsulating materials.

Moisture-curing one-component polyurethane systems in adhesive, sealant, and coating applications may show blister formation upon cure. Blisters can be formed when carbon dioxide, generated in the reaction with isocyanate and water, is trapped in the film. This problem can be mitigated by employing latent hardeners such as blocked polyamines, which are activated upon moisture exposure. The hydrolysis of the latent hardener yields the polyamine that quickly reacts with the isocyanate, forming urea linkages, and then chain extends the polymer. The hydrolysis also releases the blocking agent, which can potentially create an unpleasant odor. In this work, a series of di- and trifunctional aldimines were synthesized from commercially available polyamines, biobased hydroxymethyl furfural, and lauroyl chloride. Hydroxymethyl furfural was first esterified with lauroyl chloride and subsequently condensed with the polyamines to form the aldimines. The application of these novel aldimines in a model moisture-curing system allowed the preparation of blister- and odor-free castings. Based on our results, the mechanical performance of the different aldimines in casting and adhesive applications could be related to the polymer network density. This was dependent on the rate of the aldimine hydrolysis reaction to produce the polyamine. In particular, the use of aldimines prepared from polyether amines and 1,5-diamino-2-methylpentane showed excellent adhesive properties.