Tunable Triple-Shape Memory Materials from Crystalline Micellar Networks Embedded in Epoxy Matrices

Owing to their ability to undergo programmable shape transformations, multiple-shape memory materials are emerging as key candidates for next-generation high-tech applications, ranging from soft robotics to adaptive devices. Despite their potential, achieving systems with multiple, well-defined switching transitions remains challenging due to the stringent requirements of material architecture. In this work, we demonstrate a simple and versatile approach to create triple-shape memory systems through elongated crystalline micelles that percolate to form a three-dimensional network within a cross-linked polymer matrix. This hierarchical architecture enables two distinct, thermally activated switching transitions─the melting of the crystalline network and the glass transition of the matrix─offering precise control over shape programming and recovery. The elongated micelles were obtained through crystallization-driven self-assembly (CDSA) of a poly(ethylene-block-ethylene oxide) (PE-b-PEO) diblock copolymer in an epoxy monomer based on diglycidyl ether of bisphenol A (DGEBA). The exceptionally high aspect ratio of these nanostructures facilitates their percolation, leading to the formation of a micellar network that immobilizes the epoxy monomer as a physical gel. Subsequent photopolymerization of the epoxy monomer at room temperature allowed us to obtain the cross-linked matrix while preserving the structure of the micellar network. By adjustment of the PE-b-PEO content, the relative position of the two thermal transitions can be effectively tuned, resulting in materials with distinct triple-shape memory performances. The origin of these differences is discussed in light of in situ small- and wide-angle X-ray scattering (SAXS and WAXS) results.