Speaker
Description
Polymers bearing stimuli-induced reversible chemical bonds and physical interactions have drawn increasing interest for smart materials in different fields of material science addressing daily life applications, i.e. fiber reinforced plastics (FRP). To achieve good mechanical stabilities thermosetting polymer matrices are required for FRPs yielding composite materials that , once produced, can no longer be modified or reshaped again. This determines the choice of industrial production processes and much more important complicates and limits the repair and the recycling of the composite materials. Recyclability and product life extension must now be considered when planning and manufacturing with these materials
Against this background, the dynamic covalent chemistry represent a promising approach as synthetic concept facilitating the access to three-dimensional networked composites that can be (re)shaped under certain conditions.
This contribution elucidates the impact of a solvent-free environment and processing conditions, e.g. temperature and reaction time on the covalent adapt network (CAN) formation by a reversible crosslinking between a bistriketone as a crosslinking molecule and multifunctional poly(ε-caprolactone) (PCL) based polyester polyols. Mild processing results polymer networks based on hemiketal/ketone equilibrium with properties typical for dissociative networks including dissolution in presence of water or elevated temperature and self-healing properties. Further thermal treatment of the polymer entails changes in swelling and solubility properties. Constant glass transition temperatures of the differently treated polymers indicated a steady overall network density, but changes in the nature of the network structure due to rearrangement. By varying the number of OH-groups, molar mass and stoichiometric ratio of the polyester polyol and the crosslinking molecule, respectively, material properties can be adjusted. This approach gives access to reversibly crosslinked polymers varying in their responsiveness and overall mechanical properties that can be used as matrix in FRP.
This research was funded by Bundesministerium für Bildung und Forschung, grant number 03XP0001.
| Speaker Country | Germany |
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