LAUSR

Shape memory polymers (SMPs) are one of the most typical intelligent materials. However, the precise regulation of the shape memory effect (SME) remains a critical challenge in the field. This study introduces a simple strategy for regulating the SME, employing crystalline thermoplastic polyurethane (CTPU) as the raw material and utilizing isophorone diisocyanate (IPDI) trimer to regulate both one-way SME (1W-SME) and two-way SME (2W-SME). Results showed that incorporation of IPDI-trimer induced a cross-linked network within CTPU. The tensile strength at break reached a maximum of 27.4 MPa, and the elongation at break remained relatively high (2484%) when the IPDI-trimer content was below 10wt%. The resulting cross-linked CTPU exhibited exceptional one-way shape memory performance, achieving a 99.9% recovery rate and 96.4% fixation rate. Notably, switchable 2W-SME emerged when IPDI-trimer concentrations exceeded 11wt%. This dual SME functionality, coupled with a 54.3% actuation magnitude, signified a significant advancement in SMPs capabilities. Systematic analysis reveals that shape memory activation originates from the synergistic effects of oriented crystalline domain melting and energy release within the cross-linked network under thermal stimuli. The precise control of 1W-SME and 2W-SME demonstrated in this study fundamentally arises from regulated crystallinity and cross-linking degree of CTPU. Owing to these enhanced integrated properties, these materials show great promise for diverse applications, particularly in smart sensors and intelligent robotics.