Phase diagram of solutions of stiff-chain macromolecules:: A Monte Carlo simulation

The phase diagram of solutions of semiflexible macromolecules consisting of N=20 effective monomer units has been studied by means of grand canonical Monte Carlo computer simulation using the bond fluctuation model and the configurational bias scheme. Two different types of interactions were taken into account: an intramolecular potential controlling the chain stiffness and an attractive interaction between effective monomer units to model variable solvent quality. A very broad region of density from dilute solution to melt has been covered in the simulation. The phase diagram shows a strong increase of the density difference between isotropic dilute and nematic dense phases upon increasing attraction between monomer units (i. e., decreasing the temperature). We discuss methods of locating the isotropic-nematic transition point and the effects of the vicinity of the polymer-solvent critical point on the properties of the liquid crystalline transition. (C) 2003 American Institute of Physics.