Facile Synthesis of Shape-Programmed Polymer Nanoparticles for Agile Manufacturing

Shape-programmed polymer nanoparticles (PNPs) represent a critical opportunity to advance research in small molecule drug delivery, self-assembly for soft robotics, and metamaterials with emergent properties. Extant techniques like emulsion polymerization commonly used to synthesize PNPs primarily produce particles that are spherically shaped. To achieve non-spherical PNPs, time-consuming solution-based protocols are commonly required, along with additional fabrication and purification steps. The limited selection of monomers, restricted by their solubility, leads to a narrow range of PNP shapes and chemistries, whose deployment is further hindered by the laborious and costly synthesis. Here we report the rapid synthesis of shape-programmed PNPs without the need for nano/microfabrication, enabled by two fresh strategies revolving around chemical vapor deposition (CVD) polymerization.<br/> <br/>The first strategy is a novel template- and solvent-free technique we recently developed, namely condensed droplet polymerization (CDP), which delivers unprecedented flexibility in PNP synthesis. With CDP, particle sizes and dimensions could be varied continuously, from sub-10 nm to above 1 µm. As a proof-of-principle, we demonstrated the synthesis of polymer nanodomes (hydrophilic, hydrophobic, cross-linked, fluorinated, biocompatible) within minutes (seconds for polymerization).<br/> <br/>The second strategy is to leverage structured liquids, such as liquid crystals, as templates for the polymerization with reactants, i.e., monomers and initiators, delivered with picomole precision in the vapor phase. The precise delivery of reactants allows polymerization to proceed without disturbing the dynamic structures of liquid templates. A variety of shapes, including nanospheres, domes, disks, and porous networks could thus be obtained using a single technique.<br/> <br/>These novel strategies build upon an existing manufacturing instrument, i.e., CVD, and hence can be scaled down for decentralized manufacturing, or scaled up for industrial production in semi-continuous roll-to-roll fashion. The ability to manufacture shape-programmed soft materials is critical for advancing a wide cross-section of applications ranging from soft robotics to tough yet injectable implants.