High-Performance Poly(urethane-urea) Elastomers via Soft–Hard Domain Optimization

Elastomeric materials hold broad potential, but developing multifunctional elastomers combining high strength, transparency, fluorescence, and shape memory remains challenging. This study synthesized a high-performance polyurethane elastomer (IPDI-SPU) via two-step polymerization using polycarbonate diol (PCDL), isophorone diisocyanate (IPDI), and adipic dihydrazide (ADH). The IPDI molecular structure contained a rigid cyclohexane ring and a side methyl group (−CH3), whose pronounced steric hindrance and low symmetry effectively inhibited the close packing of hard segments, promoting the formation of uniformly distributed and smaller hard microdomains, thereby significantly enhancing the stress transfer efficiency of the material. Moreover, the rigid cyclic structure of IPDI strengthened the polymer network by increasing its three-dimensional cross-linking density, further imparting the material with superior mechanical properties. Extensive hydrogen bonding from acylsemicarbazide (ASC) and carbamate groups, along with pronounced microphase separation, further enhanced performance. The IPDI-SPU achieved a tensile strength of 69.6 MPa, elongation of 478%, and toughness of 122.1 MJ/m3. A 0.15 g sample supported 38 kg without fracture. It also exhibited 98% visible light transmittance (0.8 mm thickness), shape memory, and blue-green fluorescence. Ionic liquid modification improved strain sensitivity, enabling flexible sensor applications. With its unique combination of strength, transparency, and functionality, IPDI-SPU shows promise for transparent protective materials, high-load structural components, and wearable electronics.