What is the role of PEO chains in the assembly of core-corona supraparticles in aqueous dispersions?

Abstract

Hypothesis The assembly of core-corona supraparticles in aqueous dispersions has been regularly assisted by auxiliary monomers/oligomers which modify the individual particles with, e.g., surface grafting of polyethylene oxide (PEO) chains or other hydrophilic monomers. However, this modification complicates the preparation and purification procedures and increases potential upscaling efforts. Hybrid polymer-silica core-corona supracolloids could be more simply assembled if the PEO chains from surfactants, typically used by default as polymer stabilizers, concomitantly act as assembly promotors. The supracolloids assembly could therefore be more easily achieved without requiring particles functionalization or post-purification steps. Methods The self-assembly of supracolloidal particles prepared with PEO-surfactant stabilized (Triton X-405) and/or PEO-grafted polymer particles is compared to differentiate the roles of the PEO chains in the assembly of core-corona supraparticles. Using time-resolved dynamic light scattering (DLS) and cryogenic transmission electron microscopy(cryo-TEM), the effect of concentration of PEO chains (from surfactant) on the kinetics and dynamics of supracolloids assembly is investigated. Self-consistent field (SCF) lattice theory was used to numerically study the distribution of PEO chains at the interfaces present in the supracolloidal dispersions. Findings The PEO based surfactant can be used as assembly promoter of core-corona hybrid supracolloids due to its amphiphilic nature and via establishing hydrophobic interactions. The concentration of the PEO surfactant, and especially the PEO chains distribution over the different interfaces, crucially affect the supracolloids assembly. A simplified pathway for preparing hybrid supracolloidal particles with a well-controlled corona coverage over polymer cores is presented.