Micelle-Mediated PbBr₂ Complexation: Influence of Block Copolymer Architecture and Mixing Conditions

Block copolymer micelles mediate PbBr₂ complexation through two distinct pathways: an architecture-dependent interfacial process under static conditions and a shear-dominated mechanism under dynamic mixing. This study reveals how the polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) asymmetry governs the chain adsorption conformations (trains, loops, and tails) on PbBr₂ surfaces and its complexation outcome. Under static conditions, the process is kinetically limited by micellar diffusion. Upon reaching the PbBr₂ surface, the strong pyridine-Pb²⁺ coordination induces a restructuring of the micelle core. For asymmetric PS-b-P2VP with long P2VP blocks, a thin PS shell allows the P2VP core to deform and spread onto the surface, creating a large adsorption footprint. The long-tethered P2VP chains form multiple train-loop segments, maximizing the number of coordination sites per micelles and enabling efficient PbBr₂ dissociation into [PbBr₃]^- complexes. Conversely, the thick PS shells of symmetric copolymers act as a steric barrier. This shield prevents interfacial restructuring and hinders complexation. Dynamic mixing introduces an energy-driven mechanism that circumvents these architectural constraints. Shear forces simultaneously fragment PbBr₂ monoliths into nanoparticles, accelerating complexation independently of copolymer architecture. UV-vis and dynamic light scattering (DLS) analyses show that micelle dimensions and chain conformations dictate the efficiency of PbBr₂ complexation. By correlating micelle architecture with mixing conditions, this work establishes key design principles for PbBr₂ complexation. We reveal a critical mechanistic switch. Under static conditions, the process is architecture-dependent. In contrast, dynamic mixing creates a shear-dominated, architecture-independent process. This finding provides fundamental insight into controlling lead halide precursor solutions.