Bismaleimide based shape memory polymers: Correlation between chemical composition and mechanical properties

Shape memory polymers have attracted great interest for application in adaptive or morphing structures. In order to understand the origins of the mechanical performance and durability of these polymers, the chemical structure must be understood, which is often hindered by the proprietary nature of commercially available shape memory polymers and their additives. In the present study, a series of novel linear polyaspartimide-polyurea based polymers utilizing 4-4-bismaleimidodiphenylmethane and an aliphatic Jeffamine diamine are thermomechanically characterized as a function of chemical structure. A di-isocyanate resin is incorporated to create a thermosetting material with both improved toughness and variable cross-link densities. The thermal and mechanical properties are determined utilizing thermogravimetric analysis and dynamic mechanical analysis. In addition, the shape memory cycle with free recovery is conducted on these polymers. The thermomechanical and shape memory properties are analyzed to elucidate the correlation between the chemical composition and changes in the mechanical performance. With a thorough understanding of structure-property relationships, the chemical composition of these novel bismaleimide based shape memory polymers can be tailored to meet the desired mechanical performance requirements of aerospace applications.