Morphology of block copolymer micelles formed via electrospray enabled interfacial instability

Elongated micelles may be preferred over spherical because of their increased loading capacity, differential mass transport and biodistribution. Although morphological transitions of block co-polymer (BCP) micelles have been extensively investigated in batch systems, research on continuous or semi-continuous scalable approaches such as flash nanoprecipitation and coaxial electrospray-enabled interfacial instability (Aero-IS) have primarily focused on producing spherical micelles. This paper investigates whether process changes intended to increase micelle production via Aero-IS also induce morphological transitions.

BCP micelles were synthesized from carboxylated polystyrene-block-poly(ethylene oxide) (PS-b-PEO) (PS 9.5 kDa:PEO 18.0 kDa) using Aero-IS. Volumetric flowrates, polymer concentrations, and emulsion temperature were varied to investigate their effect on the micelle production rate and resulting micelle structure, including transitions to worm-like micelles.

These findings report the first worm-like micelles formed via a scalable, interfacial instability approach. The morphological transitions obtained by increasing polymer concentration occurred at lower nominal values than in corresponding batch processes. Optimizing operating conditions also led to a 12-fold increase in micelle production rates over prior electrospray reports (Duong, 2014). Thus, the Aero-IS approach holds promise for scalable nanomanufacturing of worm-like micelles, potentially enabling applications in drug delivery, imaging, diagnostics, and separations.