Dynamic Diels–Alder Cross-Linked Polyurethanes for High-Performance Selective Laser Sintered Elastomers

Selective laser sintering of elastomers has attracted increasing interest across both industrial and academic sectors. However, common elastomers such as TPU suffer from high melt viscosity and insufficient sintering. Polymer CANs offer a promising solution, yet dynamic elastomer powders with good sintering behavior and high performance remain scarce. In this work, we prepared dynamically cross-linked polyurethane elastomers (PUBFDA) by incorporating rigid furan-bismaleimide Diels–Alder (FBDA) adducts as dynamic cross-linking sites. By tuning the ratio of rigid and flexible chain extenders, an optimized balance among powder processability, mechanical strength, and dynamic reversibility was achieved. The introduction of reversible Diels–Alder (DA) bonds contributed to enhanced interlayer bonding, reduced mechanical anisotropy, and enabled effective post-treatment via thermal heating. Consequently, the as-fabricated dog-bone specimens exhibited a high tensile strength of 25.85 MPa, exceeding that of reported powder bed fusion printed TPUs. The tensile strength of the printed specimen reaches 70% of the value achieved by the hot-pressed material. Meanwhile, the Z-axis tensile strength reached 64.66% of the X-axis value, which is notably higher than that of conventional TPU (55.68%). This work provides a practical material design strategy for developing dynamic cross-linked polymers compatible with powder bed fusion additive manufacturing.