Facile Fabrication of Ultrahigh‐Strength Closed‐Cell Polystyrene Foam via MIPE Templating

The development of lightweight and high‐strength polymer foams via a cost‐effective strategy has been important to advanced structural applications. Herein, a facile approach for fabricating ultrahigh‐strength closed‐cell polystyrene (PS) foams by medium internal phase emulsion (MIPE) templating is presented, in which the stable MIPE is obtained through a prepolymerization strategy. The critical roles of internal phase volume fraction, initiator content, surfactant content, and crosslinking degree in determining the porous morphology and resultant mechanical performances are investigated in detail. It is revealed that the synergistic effect of the highly crosslinked polymer matrix and the well‐defined closed‐cell structure provides exceptional mechanical properties for the foams. The highest compressive strength of 12.2 MPa at the low density of 293 kg·m ⁻³ of the obtained PS foam is achieved. In addition, the foam has good thermal stability and a low dielectric constant. As a result, the high‐performance closed‐cell PS foams prepared by an effective and economical pathway show significant potential as a competitive alternative to conventional high‐cost engineering foams in fields such as aerospace and functional structures.