Coarse grained simulation of the aggregation and structure control of polyethylene nanocrystals

Abstract

Polyethylene (PE) telechelics with carboxylate functional groups at both ends have been shown to assemble into hexagonal nanocrystal platelets with a height defined by their chain length in basic CsOH-solution. In this coarse grained (CG) simulation study we show how properties of the functional groups alter the aggregation and crystallization behavior of those telechelics. Systematic variation of the parameters of the CG model showed that important factors which control nanoparticle stability and structure are the PE chain length and the hydrophilicity and the steric demand of the head groups. To characterize the aggregation process we analyzed the number and size of the obtained aggregates as well as intramolecular order and intermolecular alignment of the polymer chains. By comparison of CG and atomistic simulation data, it could be shown that atomistic simulations representing different chemical systems can be emulated with specific, different CG parameter sets. Thus, the results from the (generic) CG simulation models can be used to explain the effect of different head groups and different counterions on the aggregation of PE telechelics and the order of the obtained nanocrystals.

Understanding and Modeling Polymers: The Challenge of Multiple Scales

“…Such findings illustrate how mesoscale structure (entanglements) can have a profound effect on local structure (local packing), and vice versa, in polymers. The associated time scales can be very large, which offers unusually versatile opportunities to control local structure by processing (for example, in flow-induced crystallization − ) or by tiny chemical modifications. , On the other hand, the mesoscale structure and dynamics determines the elastic and plastic response of the materials to deformations , and the inhomogeneous stress fields in the materials, which in turn drive the large-scale structure formation and spherulite growth …”

“…The associated time scales can be very large, which offers unusually versatile opportunities to control local structure by processing 35 (for example, in flow-induced crystallization 36−40 ) or by tiny chemical modifications. 41,42 On the other hand, the mesoscale structure and dynamics determines the elastic and plastic response of the materials to deformations 43,44 and the inhomogeneous stress fields in the materials, which in turn drive the large-scale structure formation and spherulite growth. 45 The interplay of multiple scales also determines the structural and dynamic properties of other multiphase polymer materials 46 that are highly heterogeneous and filled by internal interfaces, such as polymer blends, 47,48 block copolymer melts and solutions, 49−52 or foams.…”

Editorial: Multiscale simulation methods for soft matter systems

“…The articles in this special issue illustrate the progress that has been made in the field of multiscale modelling of soft matter in recent years, as well as the many remaining challenges and open questions. They also demonstrate the potential of multiscale simulations for obtaining insights into complex systems and processes, such as nanoscale-segregated ionic liquids [17], high performance rubber materials [28], emergent properties of active or responsive colloids [11,23], or controlled nanoparticle growth [29,30].…”

Molecular dynamics simulation and non-isothermal crystallization kinetics of polyamide 4 and different bio-based polyamide blends

“…To study the molecular-level phase behaviors of blends with different biobased PA56 contents, Yan et al 31 established a coarse-grained (CG) model of a PA56/polyethylene terephthalate (PA56/PET) blend, wherein a group of atoms was modeled as a bead. 32,33 At the lowest PA56 content, the phases were partially miscible. As the PA56 content increased, the dispersed phase formed larger bundles, thereby forming a co-continuous morphology.…”