Three-dimensional analysis of membrane formation via thermally induced phase separation by dissipative particle dynamics simulation

The effects of polymer molecular weight (polymer chain length), polymer molecular weight distribution (polymer chain length distribution) and diluent structure on the membrane formation of polymer–diluent system via the thermally induced phase separation (TIPS) method were analyzed on the basis of a dissipative particle dynamics (DPD) simulation platform. The simulation platform was extended into three-dimensions (3-D) to make sure that the results were more comprehensive. The simulation results proved that both the polymer chain length and polymer chain length distribution had significant influences on the phase separation process. As the polymer chain length increased, phase separation rate first increased when the polymer chain was relatively short and then decreased when the polymer chain length was larger. In addition, as the chain length distribution got wider, the phase separation rate decreased gradually at the middle and last stages of the phase separation process. It was also demonstrated that the interaction between polymer and diluent could be regulated by changing the interaction of the polymer and diluent local part by the local modification on the diluent molecular structure, which was beneficial to the membrane preparation. The information obtained from this study is consistent with the experimental results in literatures, proving that the simulation method could be widely applied in dynamics analysis of the membrane formation process.