Recently, the development of advanced materials with superior properties and extended lifetime is a major requirement towards sustainability and economic aspects in material design. However, polymer materials, commonly thermosets, owning long-lasting properties and excellent mechanical/dimensional performance have restricted recycling capabilities due to the formation of permanent crosslinked networks that limit their potential for re-use. Thus, finding an approach for the design of material that combines mechanical robustness with an improved thermal (re)processability, mediated through a dynamic crosslinked network, is very important.<br/>In this study, the design of elastic dynamic polymer networks is introduced as a prominent approach to combine mechanical robustness and “on-demand” recyclability to the material. The uniqueness of these smart elastic vitrimers compared to the conventional vitrimer concept is providing comprehensive behavior to the resulted polymer networks, where the mechanical performance will be improved at higher temperatures due to restraining the malleability of vitrimer networks by introducing robust thermoset linkages. Mobility of crosslinked networks and recyclability of designed smart vitrimers will only be achieved by UV-irradiation of designed systems. The incorporation of disulfide bonds in the backbone chain allows malleability of the formed material at elevated temperature through dynamic exchange reactions of covalent bonds. To provide “on-demand” recyclability, photo-cleavable nitro-benzene moieties are introduced to the material. The resulted smart elastomers are responsive to UV-irradiation at the wavelength of 362 nm and lead to cleavage of the nitrobenzene moieties delivering nitroso compounds and bond breakage. Such behavior of smart elastomers provides several advantages over conventional vitrimers including thermal resistance, good elastic properties, and selective reprocessability. The formed dynamic crosslinked networks have shown good mechanical properties with the elongation at break up to 300% and ultimate tensile strength of 15 MPa. The crosslink density of the designed networks has a direct impact on the modulus and glass transition temperature of materials, which also affects their reprocessability behavior.<br/>The formed dynamic elastic networks have shown advanced performance and selective UV-response that make them prominent in various areas of applications including electronic devices, building materials, etc.

Elastic vitrimers with light triggered “lock and on” recyclability

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.