Morphology model for polymer foams formed by thermally induced phase separation

Micro- and nano-structured polymer materials have wide application possibilities due to morphology-dependent thermal, acoustic, mechanical and physico-chemical properties. Rapid cooling of polymer dissolved in a suitable solvent can form a micro-structured material and this process is known as the thermally induced phase separation (TIPS). The result of TIPS is a porous material that has foamy or particulate morphologies with varying morphology characteristics, which strongly depend on the mechanism and dynamics of the material formation. We carried out experiments to obtain polymer materials by the TIPS method in dependence on the initial polymer concentration and quantitatively compared the resulting morphologies to the predictions of the Cahn-Hilliard model, which describes the dynamics of morphology evolution. The model predicts the correct type of morphology and cell size in dependence on the initial polymer concentration. Model results also explain the heterogeneity of the produced material. The quantitative understanding of polymer foam morphology evolution by TIPS opens a way for the prediction and control of morphologies of polymeric foams created by other routes involving phase separation. (C) 2015 Elsevier B.V. All rights reserved.