Computational Simulation Study On Tailoring The Mechanical Properties Of Elastomer Nanocomposites Via Interfacial Engineering

Based on the mechanical reinforcement of elastomers and their composites,we discussed the mechanism of the molecular structure of the materials on the mechanical properties of the system by using the coarse-grained molecular dynamics simulation.Focusing on the mechanically interlocked structure and the bimodal distribution grafted chains structure elastomer nanocomposites,the main contents are:(1)The mechanically interlocked structure elastomer nanocomposites.We successfully constructed the elastomer nanocomposites with the mechanically interlocked structure,composed of two ends functionalized chains grafted on the surface of the same nanoparticles to form a ring structure,and then let the free matrix chains penetrate into the rings and tightly entangle with them to form an interlocked structure.By adjusting the stiffness of the matrix chains and the structure of the grafted rings,the ideal structure state of the matrix chains penetrating into the grafted rings and entangling with them was obtained,and the structure can exist stably during the stretching process.At the same time,we found that the mechanically interlocked structure can not only enhance the interfacial interaction between the graft chains and the matrix chains,but also promote the entanglement between the matrix chains and increase the interaction strength between the matrix chains and the matrix chains,and then significantly improved the tensile mechanical properties of elastomer composites.In particular,compared with the traditional linear grafted composites,the tensile properties of the mechanically interlocked system improved by about 770%,showing a significant mechanical reinforcement effect,which provided a new idea for designing and fabricating new elastomer nanocomposites with excellent mechanical properties.(2)The bimodal distribution grafted chains structure elastomer nanocomposites.We uniformly grafted polymer chains of different lengths on the surface of each nanoparticle,and then mixed them uniformly with the matrix chains.It was found that when the total number of the grafted chain beads fixed,with the increase of the length of the grafted long chains,the grafting density and the steric resistance of the grafted chains decreased,resulting in the poor dispersion of the nanoparticles,but the mechanical properties were similar.The unimodal distribution and bimodal distribution grafted chains with the same total number of grafted beads had the same contribution to the interface interaction of the system and showed the similar mechanical properties.Therefore,we think that the mechanical properties of the system are closely related to the total number of the grafted beads,or the synergistic effect between the length and density of the grafted chains lead to no significant difference in the mechanical properties of the system.In addition,under the condition of constant graft density,with the increase of the length of the grafted long chains,the dispersion of nanoparticles is better,the ductility of polymer chains is better,the system expands,the density of polymer network decreases,and the total non-bond interaction decreases,resulting in the monotonous decrease of the tensile mechanical properties.This work will provide theoretical support for the controlofthe mechanical properties of elastomer composites.