Accelerated Mapping of Polymer Self-Assembly with SAXS/SANS and the NIST Autonomous Formulation Laboratory

Understanding the self-assembly pathways of complex biological and synthetic polymer systems remains a central challenge in soft matter physics, particularly when dealing with multicomponent formulations relevant to biological and industrial applications. While scattering techniques at large user facilities like SAXS and SANS excel at characterizing model systems, mapping structure-property relationships in real-world polymer formulations has remained challenging due to their compositional complexity. Here we present recent advances in autonomous experimentation at the NIST Center for Neutron Research that enable rapid exploration of polymer phase space using closed-loop machine learning guidance. The Autonomous Formulation Laboratory (AFL) combines automated sample preparation with simultaneous SAXS/SANS characterization and complementary techniques including UV-vis spectroscopy and rheometry. We demonstrate the platform's capabilities through studies of surfactant-biopolymer complexation, where we map phase boundaries 25× faster than conventional approaches. By correlating structural evolution across multiple length scales with bulk properties, we reveal how local molecular interactions drive emergent assembly behavior. This work showcases how national user facilities can accelerate soft matter research through integration of autonomous methods with advanced characterization tools. The open AFL platform is becoming available to external users through the NCNR user program when our reactor restarts and through a series of external partnerships, enabling broad access to automated multimodal analysis of complex polymer and soft materials systems.