Statistical Mechanics of Braiding

In this thesis we developed a coarse-grained model based on Brownian Dynamics which allowed us to simulate the formation of two-strands braids. The statics of the buckling transition was deeply investigated confirming previous results obtained via a statistical-mechanical model. Furthermore we observed that the origin of this transition isn’ t necessarily related to plectonemic nucleation, but it can be due also to a solenoidal phase arising when the pulling force is large enough. We then studied the equilibrium dynamics and the statistics of plectonemic domains in strands with both homogeneous and heterogeneous stiffness. The latter case is represented by chains containing little fully flexible regions that thoroughly change the time evolution of plectonemes, whose end-loops often coincide with these local kinks.