Polymer crystallization under nano-confinement of droplets studied by molecular simulations.

Fabrication of polymer nano-crystals proceeds usually through hierarchical ordering of the different-scale structures. Nano-scale patterns are produced first, which serve as a spatial template for subsequent polymer crystallization under nano-confinement. We begin with a survey of the effects of nano-confinement on polymer crystallization, mainly on the basis of the knowledge obtained from molecular simulations. After that, we report dynamic Monte Carlo simulations of polymer crystallization confined in nano-droplets. We observed that the shape of droplets on a solid substrate appears as a pancake, and both initiation and development of crystallization are depressed with the decrease of droplet size. Surface-induced crystal nucleation guides the dominant edge-on crystal orientation at high temperatures; however, its contribution to nucleation rates is not much greater than crystal nucleation in the volume of the droplet. At low temperatures, edge-on crystals are frequent at both substrate/polymer and polymer/air interfaces. In conclusion, molecular simulations can shed light on the microscopic mechanisms of polymer crystallization under nano-confinement.