title: Self-assembly of carbon nanotubes in polymer melts: simulation of structural and electrical behaviour by hybrid particle-field molecular dynamics.
abstract: Self-assembly processes of carbon nanotubes (CNTs) dispersed in different polymer phases have been investigated using a hybrid particle-field molecular dynamics technique (MD-SCF). This efficient computational method allowed simulations of large-scale systems (up to ∼1 500 000 particles) of flexible rod-like particles in different matrices made of bead spring chains on the millisecond time scale. The equilibrium morphologies obtained for longer CNTs are in good agreement with those proposed by several experimental studies that hypothesized a two level "multiscale" organization of CNT assemblies. In addition, the electrical properties of the assembled structures have been calculated using a resistor network approach. The calculated behaviour of the conductivities for longer CNTs is consistent with the power laws obtained by numerous experiments. In particular, according to the interpretation established by the systematic studies of Bauhofer and Kovacs, systems close to "statistical percolation" show exponents t ∼ 2 for the power law dependence of the electrical conductivity on the CNT fraction, and systems in which the CNTs reach equilibrium aggregation show exponents t close to 1.7 ("kinetic percolation"). The confinement effects on the assembled structures and their corresponding conductivity behaviour in a non-homogeneous matrix, such as the phase separating block copolymer melt, have also been simulated using different starting configurations. The simulations reported herein contribute to a microscopic interpretation of the literature results, and the proposed modelling procedure may contribute meaningfully to the rational design of strategies aimed at optimizing nanomaterials for improved electrical properties.
authors.affiliation: Institute of Nano-Photonics, School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Dipartimento di Chimica e Biologia and NANOMATES, Research Centre for NANOMAterials and nanoTEchnology at Università di Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy. gmilano@unisa.it.
authors.forename: Maksym
authors.initials: M
authors.lastname: Byshkin
authors.affiliation: Institute of Nano-Photonics, School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Cong
authors.affiliation: Department of Physics, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kawakatsu
authors.affiliation: Dipartimento di Ingegneria Industriale, Università di Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy.
authors.forename: Liberata
authors.initials: L
authors.lastname: Guadagno
authors.affiliation: Dipartimento di Chimica e Biologia and NANOMATES, Research Centre for NANOMAterials and nanoTEchnology at Università di Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy. gmilano@unisa.it.
authors.forename: Antonio
authors.initials: A
authors.lastname: De Nicola
authors.affiliation: Institute of Nano-Photonics, School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600, China.
authors.forename: Naisen
authors.initials: N
authors.lastname: Yu
authors.affiliation: Dipartimento di Chimica e Biologia and NANOMATES, Research Centre for NANOMAterials and nanoTEchnology at Università di Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy. gmilano@unisa.it and IMAST Scarl-Technological District in Polymer and Composite Engineering, P.le Fermi 1, 80055 Portici (NA), Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Milano
authors.affiliation: Institute of Nano-Photonics, School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Dong