Nano Spray-Dried Block Copolymer Nanoparticles and Their Transformation into Hybrid and Inorganic Nanoparticles

Block copolymers (BCPs) self-assemble into highly ordered structures with periodicities of 5-50 nm. When BCP self-assembly is confined in macro and nano spheres various morphologies can be achieved by tailoring BCP chemical composition, solvent, and process parameters, making them attractive materials for applications like drug delivery and catalysis. So far, BCP NPs were mainly fabricated through emulsion-based methods. However, there is need to develop novel, potentially scalable, BCP NP fabrication methods which will enable new NP morphologies.
We present a new route for BCP NP fabrication through BCP confinement in sprayed nano-droplets using Nano Spray-Drying (NSD). PS-b-PMMA and PS-b-PVP were NSD from toluene and chloroform. SEM and TEM were used to study the effects of BCP chemistry, solvent, and NSD process parameters on BCP NP morphology. Following NSD, BCP NPs were suspended in non-solvents and solvent annealed with chloroform to tune internal NP morphology. Finally, hybrid organic-inorganic particles were created through Sequential Infiltration Synthesis (SIS), a method that enables growth of metal-oxides within polymers. Using SIS, alumina and zinc-oxide were selectively grown in BCP polar domains, transforming the BCP NP into hybrid or BCP-templated inorganic NPs.