Molecular design of polymer-filler interfaces in automotive tires

PART 1: NON-TECHNICAL SUMMARY The number of cars worldwide is expected to grow substantially over the next few decades, increasing the need for tires that are safer, more durable, and more energy efficient. Many modern tires include tiny silica particles that improve fuel efficiency and traction on wet roads. However, these particles do not yet strengthen rubber as effectively as traditional materials, limiting further improvements in tire performance. This project investigates the fundamental mechanisms that govern how rubber interacts with silica at very small scales. It focuses on the interface—the region where the rubber and particles meet—and examines how the materials are arranged, how they move, and how these factors influence overall tire performance. By understanding the relationships among structure, motion, and performance, the research aims to establish general design principles for improving tire materials. The work combines experiments, computational modeling, and advanced manufacturing approaches to better control and design this interface. These insights are expected to guide the development of next-generation tire materials with improved safety, durability, and energy efficiency. Such studies will also aid understanding of nanocomposites in general and all kinds of goods produced using such materials in advanced manufacturing. The project also supports education and workforce development through training opportunities at national laboratories for undergraduate and graduate students, international research experiences, and efforts to broaden participation in polymer science and engineering. PART 2: TECHNICAL SUMMARY Recently, silica (SiO₂) fillers have received significant attention due to their ability to enhance elastomer processability and reduce energy consumption. The central mechanism governing reinforcement of SiO₂-filled elastomers is the formation of bound rubber (BR) at the filler surface. BR interacts with the surrounding matrix polymer and, at high filler loadings, bridges adjacent particles to form a percolated filler network that provides large-scale reinforcement. It is hypothesized that the structure and dynamics of BR govern network formation, reinforcement, and failure mechanisms. The overarching goal of this project is to uncover BR-induced interfacial phenomena through integrated, multiscale experimental and computational approaches. The structure and dynamics of BR will be characterized using neutron scattering with isotope labeling, providing nanometer-scale structural resolution and dynamical information over timescales from picoseconds to approximately one microsecond. Coarse-grained molecular dynamics simulations will complement these experiments by linking molecular-level interactions to emergent network behavior and accessing interfacial details not directly observable experimentally. To probe the structure and dynamics of the filler network under driving conditions, in operando X-ray photon correlation spectroscopy will be performed during oscillatory loading. Polymer-grafted nanoparticle systems, in which polymer chains are covalently grafted to SiO₂ surfaces, will be used to isolate interfacial interactions and provide a comparison with conventional SiO₂-reinforced elastomers using silane coupling agents. These systems will be further leveraged using advanced manufacturing approaches to systematically control interfacial architecture and hierarchical assembly, enabling direct tests of structure–dynamics–property relationships. Collectively, these efforts will establish multiscale structure–dynamics–property relationships in model polymer nanocomposites and provide design principles for next-generation elastomeric materials for transportation applications. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2613946 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Tadanori Koga | Institution: SUNY at Stony Brook, STONY BROOK, NY | Award Amount: $478,536 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2613946 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2613946.html