Lamellar ordering in computer-simulated block copolymer melts by a variety of thermal treatments
M. Banaszak1 , S. Wołoszczuk1 , S. Jurga1 , T. Pakuła2
1 Institute of Physics, A. Mickiewicz University, ul. Umultowska 85, 61-614 Poznan, Poland
2 Max-Planck-Institute for Polymer Research, P.O. Box 3148, D-55021 Mainz, Germany
The Journal of Chemical Physics, 119(21), 11451-11457 (2003)
A lattice computer simulation of a symmetric A-B-A triblock copolymer melt is reported. This melt is quenched, in simulation, from an athermal state to 39 different temperatures using cooperative motion algorithm. Energy,specific heat, copolymer end-to-end distance, bridging fraction, lamellar spacing, concentration profiles, and microstructure visualizations are reported. The quenching simulation results are compared with those obtained by alternative thermal treatments, that is by slow heating and slow cooling. Quenches yield data consistent with theory and experiment, whereas slow cooling and slow heating results do not capture the expected behavior for the lamellar spacing and the bridging fraction. Finally, at very low temperatures, below the conventional order-disorder transition temperature, an additional ordering is recorded, from a conventional lamellar phase to a lamellar structure showing copolymer junction points condensed into a two-dimensional plane.