Liquid–Solid Interfacial Fusion Assembly Enables Programmable Chain Density for Controlling Polymer–Mineral Interactions

Abstract Biomineralization offers key insights into nature’s design of hierarchical materials with exceptional properties. However, progress is hindered by limited molecular-level understanding of organic–inorganic interfacial interactions, particularly how organic matrix structure directs mineral formation and organization. Herein, we synthesize a series of poly(methacrylic acid)x-block-poly(benzyl methacrylate)y (Mx-By) nanoparticles with varying block lengths via polymerization-induced self-assembly, followed by their fusion onto mesoporous silica surfaces through liquid–solid interfacial fusion assembly. This approach yields silica-copolymer core–shell composite nanoparticles with tunable interfacial structures. We show that the packing density of copolymer chains on the fused layer is governed by the degree of polymerization of the hydrophobic block (By). This tunability provides a model platform to systematically investigate how surface chain density dictates polymer–mineral interactions. It is demonstrated that the surface chain density plays a decisive role in controlling the spatial distribution of guest species within mineral phases. We reveal the underlying mechanism behind this interesting phenomenon, which is widespread in natural biominerals. This work not only offers new insights into biomineralization but also provides new design rules for engineering composite crystals with tunable internal compositions and structures.