This study investigates the regulation of hard segment cluster structures in high-performance poly(urethane-urea) elastomers. The elastomers were synthesized by reacting polycaprolactone diol (PCL diol) with hard segments (AD or DD) and chain extenders. The synthesis involved heating, purging, and polymerization under nitrogen atmosphere. The resulting elastomers were characterized using various techniques, including ATR-FTIR, NMR, DSC, WAXD, TGA, and DMA, to determine their chemical composition, thermal properties, and mechanical behavior. Tensile tests were conducted to evaluate the mechanical properties, including tensile strength, elongation, and fracture energy. The results showed that PCL-AD exhibited higher tensile strength and elongation compared to PCL-DD. Cyclic tensile tests demonstrated the elastomers' ability to recover their shape after deformation. Recycling tests indicated that the elastomers could be reprocessed into a solution and reformed into new elastomers. Degradation tests showed that the elastomers could be degraded in a lipase solution, with mass reduction over time. Molecular dynamics simulations and density functional theory calculations were used to study the hydrogen bonding and cluster structures of the hard segments. The simulations revealed that the longer alkyl chain in DD resulted in less aggregation of the hard segments compared to AD. The study highlights the importance of controlling the hard segment cluster structures to achieve high-performance elastomers with desirable mechanical and degradation properties.This study investigates the regulation of hard segment cluster structures in high-performance poly(urethane-urea) elastomers. The elastomers were synthesized by reacting polycaprolactone diol (PCL diol) with hard segments (AD or DD) and chain extenders. The synthesis involved heating, purging, and polymerization under nitrogen atmosphere. The resulting elastomers were characterized using various techniques, including ATR-FTIR, NMR, DSC, WAXD, TGA, and DMA, to determine their chemical composition, thermal properties, and mechanical behavior. Tensile tests were conducted to evaluate the mechanical properties, including tensile strength, elongation, and fracture energy. The results showed that PCL-AD exhibited higher tensile strength and elongation compared to PCL-DD. Cyclic tensile tests demonstrated the elastomers' ability to recover their shape after deformation. Recycling tests indicated that the elastomers could be reprocessed into a solution and reformed into new elastomers. Degradation tests showed that the elastomers could be degraded in a lipase solution, with mass reduction over time. Molecular dynamics simulations and density functional theory calculations were used to study the hydrogen bonding and cluster structures of the hard segments. The simulations revealed that the longer alkyl chain in DD resulted in less aggregation of the hard segments compared to AD. The study highlights the importance of controlling the hard segment cluster structures to achieve high-performance elastomers with desirable mechanical and degradation properties.