Nowadays the utilization of plastics is indispensable in daily life and there are growing concerns about the accumulation of plastic waste in the environment as well as the exhaustion of a range of natural resources. In terms of polymer recycling, thermoplastic materials like PET can be recycled efficiently by repeat melt processing, while this is not possible for cross-linked thermosets like polyurethanes. For an efficient recycling of appliances that have been assembled by means of adhesives a chemical debonding strategy is necessary to allow their disassembly.<br/>Polyurethanes are one of the main classes of polymers with a wide range of applications. They are existing in various forms and due to the different types of monomers and linkages in the cured product, chemical recycling of them is more difficult than that of simple thermoplastic polymers and is currently not practiced. One of the important areas of PUs utilization is in adhesives. It is of utmost importance to develop adhesives that provide strong bonding when required, but which can be easily debonded after the device’s lifetime has come to an end to facilitate the separation and replacement as well as subsequent recycling of components. The possibility of adding an acid-triggered debonding on demand mechanism into PU based adhesives and formulations would be of huge benefit for industrial applications. In this communication, we have shown that bio-derived HMF-glycerol acetal diols can be incorporated into polyurethanes as part of the polyol segment (Figure 1). Using a bio-derived polyether polyol, two types of PUs were synthesized and films containing 5 and 10% of acetal diol were produced. Acidic treatment of the PU films led to very fast hydrolysis and dissolution of all urea cross-linked films. These results demonstrate that HMF-glycerol acetal diol can be used as an acid-labile degradation trigger in PU formulations.

HMF-glycerol acetals as additives for the debonding of polyurethane adhesives

ACS Spring Meeting 2021

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