Effects Of Dispersion And Orientation Of Nanorods On Electrical Networks Of Block Copolymer Nanocomposites

The incorporation of nanorods into block copolymer matrices can result in polymer nanocomposite materials with desirable electrical properties.However,until now,there have been no suitable conductive mechanisms and models to illustrate the behaviors of conductive composites.Meanwhile,the characterization of conductive networks that are constructed by conductive nanofillers in polymers are very difficult.In this article,the selective dispersion of conductive nanorods in incompatible block copolymers was investigated by the method of molecular dynamics simulation.The morphological structures in conductive composites,the orientation and distribution of nanorods,and the conductive properties of the system are critically concerned.The main works are summarized as follows:1.The influence of nanorod—polymer interaction ?bn on conductive properties is investigated.The result shows that the morphological structures can be changed with the increase of ?bn:sea-island structure,diphase dendritic cluster structure,branched worm-like micelle structure,and segment level tight bridging structure,and the probability of the system is first increased and then decreased.Meanwhile,the final probability can be also influenced by the orientation of anisotropic nanorods in the system.a slight uniaxial orientation is also beneficial to the conductive network.2.The effect of aspect ratio of nanorods on the electrical properties of diblock copolymer nanocomposites is investigated.With the increase of the aspect ratio of nanorods,the range of ?bn corresponding to the sea-island structure narrows down and that corresponding to the branched worm-like micelle structure broadens,leading to the conductive probability in a system with relatively large aspect ratio tends to arrive the peak point more quickly.3.The effect of block stiffness of copolymers on the electrical properties of diblock copolymer nanocomposites is investigated.The result shows that the increase of rigid portion in copolymers destroys the conductive networks in nanocomposites,leading to the decrease of probbility.4.The effect of external tensile force on the electrical properties of diblock copolymer nanocomposites is investigated.Result reveals that the external tensile force obviously induces the orientation of nanorods and destroys the conductive networks along the three-dimensional direction,which decreased the probability of the system.Meanwhile,the orientation degree of nanorods in nanocomposites have a decisive effect on the probability in the stretching direction,and a higher orientation degree induced a higher production on the orientation direction.To sum up,in the article,the effects of nanorod—polymer interaction,aspect ratio of nanorods,block stiffness,and external tensile force on the microstructure and electrical properties of diblock copolymer nanocomposites have been investigated using molecular dynamics simulation.An open-and-shut structure-property relationship with diagrams is built up.ihis Study provides a theoretical guidance to design the polymer nanocomposites with a low conductive percolation threshold.