Jang Han Gyeol, Jo Jun Young, Jung Unseok, Kim Young Nam, Jung Yong Chae, Lee Hunsu, Lee Doh C, Kim Jaewoo
Institute of Advanced Composite Materials, Korea Institute of Science and Technology (KIST), 92 Chudong-ro, Bongdong-eup, Wanju-gun, Jeollabuk-do 565-905, Korea.
Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea.
ACS Appl Mater Interfaces. 2024 Sep 4;16(35):46719-46727. doi: 10.1021/acsami.4c07977. Epub 2024 Aug 23.
Interfacial interactions between polymers and fillers play a crucial role in determining the performance of composite materials. In this study, mechano-responsive spiropyran (SP) beads, which exhibit fluorescence changes under stress, serve as force probes to evaluate force transfer efficiency across two types of interfaces: noncovalent and covalent. These interfaces are engineered by respectively employing physical blending and grafting polymerization to integrate hydroxyl SP beads with a polyurethane (PU) matrix. A custom-built in situ opto-mechanical setup quantitatively assesses force transfer by monitoring changes in fluorescence intensity and peak wavelength during specimen stretching. The analysis reveals that the covalent interface significantly outperforms the noncovalent interface, demonstrating a 100% improvement in force magnitude and transfer rate from the PU matrix to the SP beads. Direct observation of SP beads within the PU matrix during tension unveils that enhanced force transfer efficiency is closely linked to changes in the SP beads' aspect ratio. Fluorescence changes in SP beads are solely a function of aspect ratio, making them effective independent force probes.
聚合物与填料之间的界面相互作用在决定复合材料性能方面起着至关重要的作用。在本研究中，机械响应性螺吡喃（SP）微珠在应力作用下会发生荧光变化，用作力探针来评估两种类型界面（非共价和共价）上的力传递效率。这些界面分别通过物理共混和接枝聚合来构建，从而将羟基化SP微珠与聚氨酯（PU）基体结合在一起。定制的原位光机械装置通过监测试样拉伸过程中荧光强度和峰值波长的变化来定量评估力传递。分析表明，共价界面明显优于非共价界面，从PU基体到SP微珠的力大小和传递速率提高了100%。拉伸过程中对PU基体内SP微珠的直接观察表明，增强的力传递效率与SP微珠的纵横比变化密切相关。SP微珠的荧光变化仅是纵横比的函数，使其成为有效的独立力探针。
