Activity: Talk or presentation › Talk or presentation at a conference
Dynamic covalent chemistries have been widely used to create reversibly crosslinked polymer networks that show improved (re)processability compared to permanently crosslinked networks. Accurate knowledge through modelling of reaction kinetics and thermodynamics allows simulating the structure development during synthesis and processing. Relating the material properties to their structure further allows simulating the property build-up during network polymerization. The effect of the choice of dynamically reversible chemistry, monomer architecture and composition on the resulting viscoelastic properties can be predicted, facilitating the design and optimization of the functional properties in view of intended applications and to tailor the processability of the reversible polymer networks. In dissociative networks, the crosslink density of the polymer network decreases with increasing time and intensity of the adequate stimulus, such as heat or light, resulting in a dramatic change in the viscoelastic behaviour. In contrast, associative networks do not show a net change in network connectivity. The rate at which a certain functional group can exchange bonds with existing covalent bonds changes upon the increase of the stimulus intensity. Dynamic covalent chemistries have also become very popular to create self-healing materials that are able to reform broken covalent bonds to recover their functional properties, increasing the service lifetime of structures and systems. The thermoreversible Diels-Alder reaction between furan and maleimide is the most widely studied dynamic covalent chemistry. Heating the thermally reversible polymer networks shifts the reaction equilibrium towards the gradual breaking of the cycloadduct crosslinks, eventually leading to degelation of the network structure. This reversible gel transition was employed to create compliant components for a self-healing soft robotic gripper via casting, moulding and additive manufacturing.