Optimization of Lubrication Properties: Molecular Structure Design Strategies for Polyurethane Lubrication Materials

This study, focusing on the molecular structure design, successfully synthesized three distinct polyurethane (PU) elastomers, which were designated as PU1, PU2, and PU3. By manipulating the molecular architecture, the researchers aimed to develop materials with expected properties. These materials were designed by incorporating hydrogen bonds and rigid units. The primary goal was to unravel the effects of these structural elements on the mechanical and tribological characteristics of the PU elastomers, providing insights into how molecular design influences performance. A comprehensive array of characterization techniques was employed to analyze the synthesized PU elastomers. These techniques included Fourier-transform infrared spectroscopy (FTIR) to identify chemical bonds, universal testing machines for assessing mechanical properties, simultaneous thermal analyzers to evaluate thermal stability, friction and wear testing machines to measure tribological performance, and scanning electron microscopy (SEM) for observing surface morphology and details. Among the synthesized PU elastomers, PU1 exhibited superior mechanical properties. This was evident through various metrics that demonstrated its enhanced performance compared to PU2 and PU3. The tensile strength of PU1 was measured at 48.4±1.6 MPa, indicating its ability to with stand significant stress before failure. The elongation at break was 1 352.9±192.7%, show casing its remarkable flexibility. Additionally, the toughness, defined as the energy absorbed before fracturing, was 263.9 ± 40.9 MJ/m³. This mechanical superiority was primarily attributed to the hard domains within PU1. These hard domains were formed by the aggregation of hard segments through hydrogen bonds, which provided structural reinforcement and enhanced material strength. Furthermore, PU1 demonstrated outstanding tribological performance, particularly under conditions of water lubrication. It exhibited a friction coefficient of 0.014 and a wear rate of 5.45×10⁻⁶ mm³/(N·m). Specifically, the friction coefficient of PU1 was reduced by 52% and 70% compared to PU2 and PU3, respectively. Similarly, the wear rate of PU1 was decreased by 40% and 63% compared to PU2 and PU3, respectively. These reductions indicated a significant improvement in tribological performance. This superior performance was primarily attributed to the introduction of hydrogen bonds and rigid units into the molecular structure of PU1. These features endowed PU1 with optimal toughness, allowing it to absorb more energy during the friction process, thereby reducing wear and enhancing durability. Under shear stress, PU1 exhibited greater resistance to fracturing and damage compared to PU2 and PU3. This resistance reduced wear and improved the overall tribological performance of the material. The strategic introduction of rigid units alongside hydrogen bonding marked a pivotal advancement in the design of PU elastomers. This combination endowed the elastomers with an enhanced ability to with stand mechanical stresses and tribological challenges, thus broadening potential applications. In summary, this research had significantly improved the mechanical and tribological performances of PU elastomers through the optimization of molecular structure. This approach not only enhanced the material's properties but also introduced innovative strategies and perspectives for the design and development of high-performance polymers. By emphasizing structural design at the molecular level, the study opens new pathways for creating advanced materials that exhibit superior durability and efficiency.