Controlling the extent of nanoparticle occlusion within calcite crystals via surface chemistry engineering

Directly occluding polymer nanoparticles into growing host crystals provides a versatile pathway for synthesizing polymer-inorganic composite crystals, where guest nanoparticles are distributed within the crystal matrix. However, systematically controlling the extent of nanoparticle occlusion within a host crystal remains a significant challenge. In this study, we employ a one-step, soap-free emulsion polymerization method to synthesize polyethyleneimine-functionalized poly(tert‑butyl methacrylate) (PtBMA/PEI) nanoparticles. These cationic nanoparticles are subsequently modified using formaldehyde to systematically tune the content of surface amine group via the Eschweiler-Clarke reaction. This approach yields a series of model nanoparticles that allow us to investigate how surface chemistry influences the extent of nanoparticle occlusion within calcite crystals. Our findings reveal that the extent of nanoparticle occlusion within calcite crystals is proportional to the surface amine group content. This study offers a new design rule for creating composite crystals with tailored compositions through a nanoparticle occlusion strategy.