Single Copolymer Chain‐Templated Synthesis of Ultrasmall Symmetric and Asymmetric Silica‐Based Nanoparticles

Ultrasmall silica-based nanoparticles (SNPs) are attractive for application in many fields, but existing synthetic approaches show limited control over the size and morphology of these SNPs. This study describes a general single copolymer chain-mediated strategy for the scalable synthesis of highly monodispersed symmetric and asymmetric SNPs with sub-50 nm diameter. Random copolymers of poly(acrylic acid-r-styrene) intramolecularly collapse into ultrasmall single-chain nanoparticles and serve as seeds to template the hydrolysis of silica precursors to produce uniform SNPs. It is shown in experiments and simulations that the composition and random architecture of the copolymers are crucial to the formation of ultrasmall seeds and the uniform deposition of silica. Furthermore, tailoring the architecture of copolymers can be used to produce ultrasmall asymmetric Janus-like and dumbbell-like SNPs with well-defined polymer and silica domains. This study paves a new route to the scalable production of ultrasmall SNPs with tailored morphologies.