Synthesis, assembly, and cross-linking of polymer amphiphiles in situ: polyurethane–polylactide core–shell particles

Abstract

Core–shell polymeric particles consisting of biodegradable polylactide (PLA) arms emanating from a crosslinked polyurethane (PU) core were prepared in situ by a polymerization induced phase separation strategy. Sub-micron sized particles were spawned in dilute solution during polyurethane formation with simultaneous incorporation of end-functional PLA macromonomers. The inherent incompatibility of PU with PLA was shown to induce micelle formation during core-crosslinking. The versatility of this method with respect to size characteristics was demonstrated by employing a variety of PLA–PU ratios. Electron microscopy was used to visualize the particle dispersions in organic solvents. The average size characteristics were measured by dynamic light scattering. Collectively, the initial ratio of PU precursor to PLA as well as the PLA chain length were shown to influence the resulting particle size characteristics. This simple preparation method combined with a biodegradable, biocompatible shell should be amenable to further functionalization and it carries the potential to encapsulate components intended for drug delivery, for example.