Nie Run-Pan, Huang Hua-Dong, Yan Ding-Xiang, Jia Li-Chuan, Lei Jun, Li Zhong-Ming
College of Carbon Neutrality Future Technology, Sichuan University, Chengdu 610065, China.
College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China.
ACS Appl Mater Interfaces. 2025 Jan 15;17(2):3982-3994. doi: 10.1021/acsami.4c19128. Epub 2025 Jan 6.
The ongoing soft actuation has accentuated the demand for dielectric elastomers (DEs) capable of large deformation to replace the traditional rigid mechanical apparatus. However, the low actuation strain of DEs considerably limits their practical applications. This work developed high-performance polyurethane-urea (PUU) elastomers featuring large actuation strains utilizing an approach of kinetic control over the microphase separation structure during the fabrication process. Additionally, disulfide (DS) bonds were incorporated as dynamic chemical linkages to effectively heal the mechanical damage in the resulting elastomer (PUUDS). Alteration in processing conditions creates notable differences in the rate of phase separation among the multiphase materials. A faster phase separation rate is associated with a reduced degree of microphase separation, increased spacing within hard domains, a higher proportion of disordered hydrogen bonds, and hydrogen bonding index. These changes synergistically improved the electromechanical properties of the PUUDS elastomers, thereby enhancing their actuation performance. The sample processed under the fastest phase separation condition showed the lowest Young's modulus and a pronounced dielectric response at low frequencies. The electrostriction effect accounts for 89% of the total electromechanical coupling, achieving a significant reduction in the driving voltage during actuation. The maximum actuation strain recorded was 21.6% at an electric field of 45 MV/m. Benefiting from the fully reversible dynamic network, the damaged PUUDS elastomer can be healed and restored to its original elongation at break after 3 h at room temperature. Practical application was demonstrated through the development of a miniature butterfly model constructed from a single-layer PUUDS elastomer, showcasing potential applications in soft robotics. These findings highlight the critical role of kinetic control in optimizing the performance of advanced DEs.
持续的软驱动突出了对能够大变形的介电弹性体（DEs）的需求，以取代传统的刚性机械装置。然而，DEs的低驱动应变极大地限制了它们的实际应用。这项工作开发了具有大驱动应变的高性能聚氨酯脲（PUU）弹性体，采用了在制造过程中对微相分离结构进行动力学控制的方法。此外，引入二硫键（DS）作为动态化学连接，以有效修复所得弹性体（PUUDS）中的机械损伤。加工条件的改变会导致多相材料之间相分离速率的显著差异。较快的相分离速率与微相分离程度降低、硬域内间距增加、无序氢键比例较高以及氢键指数有关。这些变化协同改善了PUUDS弹性体的机电性能，从而提高了它们的驱动性能。在最快相分离条件下加工的样品显示出最低的杨氏模量和低频下明显的介电响应。电致伸缩效应占总机电耦合的89%，在驱动过程中实现了驱动电压的显著降低。在45 MV/m的电场下记录到的最大驱动应变为21.6%。受益于完全可逆的动态网络，受损的PUUDS弹性体在室温下放置3小时后可以愈合并恢复到其原始的断裂伸长率。通过开发由单层PUUDS弹性体制成的微型蝴蝶模型展示了实际应用，展示了在软机器人领域的潜在应用。这些发现突出了动力学控制在优化先进DEs性能方面的关键作用。
