Dynamic simulations of novel oligomers containing fluorinated segments
Şen, Ünal (2004) Dynamic simulations of novel oligomers containing fluorinated segments. [Thesis]
Nowadays, many fluorinated polymers are designed for novel applications. Computational studies are very important in understanding their properties from a theoretical point of view. In this thesis, we carry out computer simulations of linear and graft fluorinated polymers at the quantum level as well as the atomistic and mesoscopic scales. The semiempirical quantum mechanical approach can not optimize the structureof the polymers to their global minima of the potential energy surface and is not an appropriate method for conformational search analysis of the long chain polymers. On the other hand, it can be used to predict 13C chemical shifts and heats of formation. We performed MD simulations on bulk linear fluorinated polymers under external electric field to investigate the effects of strong electric field on the conformational properties of the polymers. Cyanide functional groups in the polymer are aligned along the applied electric field due to their polarity. A total alignment of the cyanide groups is observed only at electric fields on the order of 1011 V/m. We observe that polarization increases with increased electric field and density of the system. We also used two mesoscale simulation methods, Dissipative Particle Dynamics (DPD) and MesoDyn, to simulate the polymer-solvent mesophase morphologies of the graft and fluorinated polymers at different concentrations. It is observed that both polymers have spherical morphology in an aprotic solvent. Although DPD and MesoDyn use different approaches for the simulation of mesoscale structures, they give similar results and can be used interchangeably to predict three-dimensional phase behaviour. We predict that the wettability of the linear polymers should be higher than that of the graft, and this is in accordance with experimental findings on these systems.
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