Polyurethane (PUR) adhesives with thermoreversible bonds offer a sustainable solution to improve the recyclability of multilayer packaging by enabling the separation of individual layers. Diels-Alder (DA) moieties incorporated into the PUR network can break at low temperatures (< 100ºC) and reassemble on cooling, providing a low energy, reversible process for adhesive recovery. Recently, we have shown that small amounts of graphene can remotely trigger the retro-DA reaction under short NIR irradiation (< 90 s) [1]. This work evaluates the effect of graphene on the properties of PUR adhesives with DA bonds, highlighting the mechanical reversibility and cyclability upon thermal heating and IR irradiation.
Combined indentation and rheological studies consistently show that small amounts of graphene initially reduce the modulus by interfering with the network formation. However, the intrinsic stiffness of graphene compensates for this effect with further filler additions. Under NIR irradiation, adhesives with graphene show a noticeable hardness decrease, which is related to loss of network integrity due to DA bond cleavage. This is followed by a rapid hardness recovery, stabilising at around 100 minutes at values higher than those of the initial material. This cycle is reproducible on subsequent irradiation. Results are in agreement with rheological studies and seem to be related to the network reconstruction with reduced DA bonds after the first retro-DA reaction.
In conclusion, graphene incorporation into PUR-DA adhesives enhances thermal conduction, accelerates retro-DA kinetics, and enables cyclic recovery of mechanical properties. This represents a promising approach to optimise layer debonding for recyclable multilayer packaging.

The transport sector, particularly aeronautics, increasingly relies on adhesive bonding solutions, especially "smart" adhesives. To ensure bonded structures perform across a wide temperature range, specific polymer blend-based adhesives are formulated. The phase separation phenomenon in polymers often generates nanostructures, which can significantly enhance the physicochemical properties of adhesives. Block copolymer (BCP) self-assembly enables a variety of promising applications, from nanoporous membranes to nanoelectronic devices. Optimizing BCP ordering is crucial to improving its performance in different applications.
This presentation will focus on the structure-property relationships of adhesives with BCPs, analyzing how nanostructures influence final adhesive properties. The goal of this study is to investigate the structure of different adhesive blends incorporating additives, specifically a commercial triblock copolymer (PMMA-PBuA-PMMA) from Arkema, with and without ionic liquids. By examining the resulting 3D adhesive structure and the nanostructure of the BCP, we aim to identify various morphologies formed within different blends and analyze how different compositions impact the final structure. Functionally graded adhesives (FGAs), which exhibit spatially varying properties along the bondline, are of particular interest due to their potential to enhance joint toughness. A driven wedge test is used to assess these variations, comparing the energy dissipation of FGAs with homogeneously filled adhesives. Understanding the structure-property relationships in these materials is crucial for addressing key application challenges and optimizing adhesive performance in demanding environments.

A series of water-based reversible adhesives based on polymer-clay emulsion composites have been developed from formulations containing polyelectrolytes. Overall, these adhesive composites record better mechanical and rheological properties than their pristine counterparts and can be reversed in acidic or alkaline aqueous media. On the one hand, montmorillonite, a negatively charged clay, was incorporated into a polyanionic emulsion of poly(styrene-co-butyl acrylate) grafted with poly(acrylic acid). On the other hand, positively charged hydrotalcite was used to produce polycationic emulsion composites with chitosan as polyelectrolyte.
While emulsions without clays show good adhesion properties and are reversible at either acidic or alkaline conditions when one substrate is coated with the polyanionic formulation and other with the polycationic, the addition of clays improve those behaviours. Polyanionic emulsion composites are reversible under alkaline conditions with the adhesive completely detaching from the substrates, and polycationic composites are reversible under acidic conditions. Moreover, the adhesive strength increases with the presence of montmorillonite, with lap shear strengths of over 1 MPa. The presence of clays also enhances the viscosity of emulsion composites, particularly at low shear rate regimes, hence minimising sagging during application. The remarkable rheological and mechanical properties, coupled with the unique reversible behaviour of such emulsion composites make of these adhesives a notable alternative when the dismantling of products at their end-of-life is required.

Arylazoisoxazoles (AIZs) represent a promising class of photochromic units with enhanced isomerization properties if compared to conventional azobenzenes. Their integration into the polymeric architecture enables the development of dynamic materials capable of reversible structural and functional modifications upon light exposure.
In this work, we explore two distinct applications of AIZ-containing polymers: photoresponsive adhesives and micellar nanocarriers for controlled hydrophobic compound encapsulation and release.
AIZ-functionalized acrylate polymers exhibit dynamic, light-triggered adhesion changes.(1) The trans-cis photoisomerization of AIZ moieties directly modulates the adhesion strength, allowing for reversible bonding and debonding under UV and visible light without requiring thermal activation. If compared to azobenzene-based systems, these adhesives show faster switching times and reduced photothermal effects, making them highly suitable for reusable and reversible bonding applications.
In parallel, polymeric micelles incorporating AIZ-thymine derivatives were synthesized via polymerization-induced self-assembly (PISA), an attractive one-step method in which amphiphilic block copolymers self-assembly in aqueous media occurs during polymerization.(2) AIZ units were stably incorporated within the micellar core through supramolecular interactions, allowing light-induced modulation of hydrophobic cargo encapsulation and release. The reversible trans-cis transition of AIZ moieties alters the micelle polarity, facilitating the controlled uptake and release of guest molecules without structural degradation.
By combining light-responsiveness with tunable adhesion and supramolecular nanocarrier systems, AIZ-based polymers offer new avenues for dynamic materials, bridging the gap between smart adhesives and nanocarriers for biomedical applications. Their rapid response and versatility make them attractive candidates for the next-generation functional polymeric systems.

The development of environmentally friendly coatings from conventional solvent-borne systems has been going on for more than 20 years. Various homo and copolymers are currently used as coatings for paper in packaging application and polyurethane based solutions are largely used.
Amongst the desired properties, the following are very important: blocking resistance, low moisture vapour transmission rate (MVTR) and Oxygen transmission rate (OTR), easy processability and coatability, environmentally friendliness, recyclability of coated paperboard, non-toxicity for food application, low Tg for crack resistance at low temperatures [1]. One of the major drawbacks of polyurethane family lies in the use of toxic isocyanate-based starting materials. In the context of the REACH regulation, which places restrictions on the use of substances containing free isocyanates, it is now urgent to find greener routes to PUs (polyurethanes). For this reason non-isocyanate polyurethanes (NIPUs) based on the polyaddition of poly(cyclic carbonate)s to polyamines have emerged in the past decade as greener alternatives to conventional PUs, their industrial implementation is at an early stage of development [2]. In this study the authors work on the improvement of NIPUs properties as coating for paper based packaging starting from optimization of recipe and reactivity in NIPU synthesis and also by introduction of nanostructured fillers such as organically modified clay and POSS (Polyhedral oligomeric silsesquioxanes)[3] in order to improve gas barrier properties and mechanical properties of coating in a biobased solution for packaging application. Nanostructure in NIPU dispersion is also evaluated with Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM).

Several minerals are prevalent as cost-effective plastic fillers since they offer higher stiffness and heat deflection with lower thermal expansion and end-price. These key advantages accompany many problems like impact strength reduction and increase in brittleness. Some tailored applications require specific fillers such as calcium carbonate (CaCO₃) for breathable films or magnesium hydroxide for flame retardancy. In the same context, sodium sulfate (Na₂SO₄) has recently emerged as a plastic filler for translucent film applications due to its refractive index similarity with polyolefins. In this work, we examine two sodium sulfate fillers of different average particle size via twin-screw extrusion (TSE) compounding with varying polyethylene (PE) matrices in terms of additives, surfactants, and coupling agent. These 60wt%-filled compounds are thermally, optically, and rheologically tested to show the outcomes of adding these dispersant agents depending on the particle size. They are then used in 30wt% with a linear-low density PE (LLDPE) matrix in lab-scale blown film trials to check the validity of the blends. Mechanical testing on the films confirms the prior rheological conclusions related to the reinforcing effect, whereas optical testing verifies the “translucency” of some of the films. Dynamic mechanical analysis (DMA) is also used to scrutinize the thermal effect on the mechanical properties of each film. Finally, to validate this work, a traditional CaCO₃-PE compound is compared to the highest performing Na₂SO₄-PE composite where mechanical properties are analogous and haze properties of the Na₂SO₄-filled film are much superior.