Abstract
Dynamic structures containing polymers can behave as thermosets at room temperature while maintaining good mechanical properties, showing good reprocessability, repairability, and recyclability. In this work, alkyl diselenide is effectively used as a dynamic cross-linker for the design of self-healing poly(urea–urethane) elastomers, which show quantitative healing efficiency at room temperature, without the need for any catalysts or external interventions. Due to the combined action of the urea bond and amide bond, the material has better mechanical properties. We also compared the self-healing effect of alkyl diselenide-based polyurethanes and alkyl disulfide-based polyurethanes. The alkyl diselenide has been incorporated into polyurethane networks using a para-substituted amine diphenyl alkyl diselenide. The resulting materials not only exhibit faster self-healing properties than the corresponding disulfide-based materials, but also show the ability to be processed at temperatures as low as 60 °C.
Highlights
Thermosets are widely used in aerospace [1,2], the electronics industry [3], machinery and other fields [4,5,6] due to their network or body structure which results in good physical, mechanical and application properties [7,8]
Polyurethane with a diselenide dynamic bond was synthesized via a simple procedure according to Scheme 1
The diselenide-functionalized diamine product could be obtained with a high yield under mild conditions
Summary
Thermosets are widely used in aerospace [1,2], the electronics industry [3], machinery and other fields [4,5,6] due to their network or body structure which results in good physical, mechanical and application properties [7,8]. Polymers 2019, 11, 773 examples of reversible covalent chemistries used for the design of self-healing polymers The idea behind this is to reconnect the chemical cross-links which are broken when a material fractures, restoring the integrity of the material. Zhu et al demonstrated the ability of aromatic diselenide to exchange faster than aromatic disulfides on account of the barriers that are around 25–30 kJ/mol lower in the diselenide reaction [32], than in the disulfide reaction While these systems can have better healing efficiency and mechanical properties, there is still room for improvement, such as reduced healing time and improved mechanical properties. The present work reports the ability of diselenium alkyl systems to incorporate dynamic properties to cross-linked materials, and the ease of preparation from commercially available starting materials makes this system broadly applicable in a wide number of industrial sectors where poly(urea–urethane)s are already used. Alkyl diselenide has been compared to alkyl disulfide compounds, showing a better self-healing effect and healing efficiency can reach 100%. in a shorter time alkyl diselenide containing soft polyurethane thermosets are synthesized and their potential reprocessability and self-healing abilities are investigated
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