Spontaneous Crystallization in Athermal Polymer Packings

International Journal of Molecular Sciences

Nikos Ch. Karayiannis¹  Katerina Foteinopoulou¹ 

[1] Institute of Optoelectronics and Microsystems (ISOM) and ETSII, Polytechnic University of Madrid (UPM), José Gutiérrez Abascal 2, 28006 Madrid, Spain;

关键词: polymer;    crystallization;    entropy;    phase transition;    Voronoi tesselation;    simulation;    Monte Carlo;    hard sphere;    random packing;    crystal morphology;   

DOI  :  10.3390/ijms14010332

来源: mdpi

【 摘 要 】

We review recent results from extensive simulations of the crystallization of athermal polymer packings. It is shown that above a certain packing density, and for sufficiently long simulations, all random assemblies of freely-jointed chains of tangent hard spheres of uniform size show a spontaneous transition into a crystalline phase. These polymer crystals adopt predominantly random hexagonal close packed morphologies. An analysis of the local environment around monomers based on the shape and size of the Voronoi polyhedra clearly shows that Voronoi cells become more spherical and more symmetric as the system transits to the ordered state. The change in the local environment leads to an increase in the monomer translational contribution to the entropy of the system, which acts as the driving force for the phase transition. A comparison of the crystallization of hard-sphere polymers and monomers highlights similarities and differences resulting from the constraints imposed by chain connectivity.

【 授权许可】

CC BY   
© 2013 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland.