High-performance nanostructured shape-memory polymer blends developed via solid-state mixing

Multiple-shape memory polymers (MSMPs) require hierarchical architectures capable of efficiently storing and releasing elastic energy through distinct permanent and switching domains. In this work, we test the hypothesis that nanoscale homogeneous polymer blends possessing molecular-level heterogeneity—created via solid-state mixing—can achieve high-efficiency dual- and triple-shape memory effects through the cooperative action of crystalline domains and polymer–polymer interphases, even without chemical crosslinking. To verify this hypothesis, semicrystalline–semicrystalline (PBT/PLA), semicrystalline–amorphous (PBT/PETG), and fully amorphous (ABS/a-PET) polymer blends were prepared by conventional melt mixing and by high-pressure torsion (HPT) solid-state mixing, and their shape-memory behaviour was systematically compared. Solid-state mixed blends form a single nanoscale homogeneous amorphous phase while retaining molecular-level heterogeneity, resulting in a broadened glass-transition interval. The HPT-processed PBT/PLA and PBT/PETG blends exhibit outstanding dual- and triple-shape memory performance, with shape fixity ratios R f ≈ 95–96% and recovery ratios R r ≈ 90–94%, showing negligible degradation (