Preparation Of Hydrophilic/Hydrophobic Porous Materials

In recent years, porous materials are becoming widely used and much attention has been focused on them. In this article, our aim was to synthesize a novel porous material which had the ability to adapt environment automatically. This kind of material can adjust the humidity of environment so as to be used in special fields.As a sample work, polystyrene (PS) and polyacrylamide (PAM) were selected as the hydrophobic and hydrophilic polymers, respectively. An open-celled PS matrix was first prepared by verse concentrated emulsion polymerization (W/O). Then the porous matrix was impregnated in AM solution which subjected to polymerize in the cells and intercellular pores. Because of the volume contraction during polymerization, some free space existed in the PS/PAM composite.Scanning Electron Microscopy (SEM) was used to study the morphology of the composite. The results showed that PAM was penetrated in the cells and intercellular pores of PS matrix, and the pore size was increased as the increasing of AM concentration. The porosity and the pore size distribution were recorded by Mercury Intrusion Porosimetry (MIP). As the increasing of volume fraction of the concentrated emulsion, the porosity was increased. Two kinds of pores existed in the composite, and the pore size of the large one and the small one are 10μm and 3μm, respectively. Water absorption and vapor permeation were both investigated in this work, and the results showed the similar trend. With the increasing of AM concentration, the water absorption was decreased and much more time was needed to make the composite become close-celled in vapor. In the inverse situation, the results turned out to be opposite.