Because of its high melting temperature, chemical resistance, stiffness, and high compressive strength, isotactic polypropylene (iPP) foams will likely replace other thermoplastic foams in various applications. However, the foaming property of ordinary linear iPP is limited by its low melt strength (MS), which causes a cell elongation defect during cell growth. In a new methodology by Chen Chen et al. on page 961, a nucleophilic substitution reaction between the epoxy group of polypropylene-graft-glycidyl methacrylate (PP-g-GMA) and carboxyl groups of the oxidized carbon nanotubes (O-CNTs) is used to fabricate PP-g-CNT foam, which provides reinforcement, more uniform cellular structure, and enhanced thermo-mechanical properties to improve foaming ability. The cover image shows a micrograph of cryofractured PP-g-GMA.