Prompt Description

The M-WPU composite film exhibits both high tensile strength and high elongation at break, benefiting from the multi-level energy dissipation biomimetic composite system with sea cucumber-inspired multiple hydrogen bonds and disulfide bond exchange synergy. The MXene content has a significant regulatory effect on the dynamic three-dimensional network structure of the M-WPU composite film. At low MXene content (≤4 wt%), MXene acts as a rigid filler, and the OH on the MXene surface and the C=O of the WPU matrix can form stronger hydrogen bond cross-linking points, making the cross-linking network denser and reducing the chain segment movement ability, resulting in an increase in the tensile strength and a decrease in the elongation at break of the M-WPU composite film. At high MXene content (>4 wt%), the hydrogen bonding between MXene sheets is enhanced, resulting in agglomeration and stress concentration defects. At the same time, the agglomerates hinder the ordered arrangement of hard segments, reduce the crystallinity, and reduce the effective cross-linking density. Therefore, the tensile strength decreases, the chain segment movement is blocked by the MXene agglomerates, and the crack is more likely to propagate, and the elongation at break also decreases significantly. As the MXene content increases, the glass transition temperature (Tg) corresponding to the peak of the loss factor (tanδ) decreases slightly and the storage modulus (E′) decreases synchronously at low MXene content (0-6 wt%). At 8 wt%, both increase sharply, and at 10 wt%, they fall back again, showing a "decrease-increase-decrease" unconventional evolution law (Figure 2 c-d), which can be explained by the "dilution-anchoring-agglomeration" competition mechanism: MXene<6 wt%: The sheets are sparsely dispersed, and the hydrogen bonds formed with WPU weaken chain entanglement and produce a plasticizing effect, increasing the chain segment mobility, resulting in a decrease in Tg and E′; MXene=8 wt%: Reaching the percolation threshold, the sheets are lapped into a three-dimensional rigid skeleton, and a large number of hydrogen bonds anchor the soft segments to increase the chain segment movement energy barrier, and the stress transfer efficiency is improved, and Tg and E′ reach the peak value simultaneously; MXene=10 wt%: The agglomeration of the sheets leads to a decrease in the effective interface area and hydrogen bond density, and the integrity of the rigid network is destroyed, and Tg and E′ fall back. Based on the above content, generate a schematic diagram of the interaction interface between MXene filler and wpu matrix.