Jang, Han Gyeol Jo, Jun Young Jung, Unseok Kim, Young Nam Jung, Yong Chae Lee, Hunsu Lee, Doh C. Kim, Jaewoo 2024-09-14T06:00:23Z 2024-09-14T06:00:23Z 2024-09-13 2024-09 1944-8244 https://pubs.kist.re.kr/handle/201004/150574 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. English American Chemical Society Revealing the Filler-Matrix Interfacial Interactions: Real-Time Observation with Mechano-Responsive Spiropyran Microbeads Article 10.1021/acsami.4c07977 1 ACS Applied Materials & Interfaces, v.16, no.35, pp.46719 - 46727 ACS Applied Materials & Interfaces 16 35 46719 46727 N scie scopus 001298220800001 2-s2.0-85201858674 Nanoscience & Nanotechnology Materials Science, Multidisciplinary Science & Technology - Other Topics Materials Science Article COVALENT BONDS POLYMER POLYPROPYLENE ACTIVATION ADHESION spiropyran force transfer interface in situ measurements mechanophore