Formation of Novel Nanoparticle Morphologies Using Homopolymer / Block Copolymer Blends in Flash NanoPrecipitation (FNP)

Abstract

Flash NanoPrecipitation (FNP), a rapid nanoparticle precipitation mechanism, was used for the first time to make nanoparticles out of blends of block copolymers and homopolymers. When pure block copolymer was used, lamellar nanoparticles consisting of concentric shells were observed, with some disorder at the center of the particles. Block copolymer of a high molecular weight resulted in kinetic trapping of the lamellae in a non-concentric pattern. In blends consisting of low molecular weight block copolymer and low molecular weight homopolymer, swollen lamellar and disorganized morphologies were observed. When the homopolymer was of a high molecular weight, disorganized Janus, lamellar Janus, and lamellar multi-faced morphologies were observed. In blends using high molecular weight block copolymer, the resulting particles had a continuous homopolymer phase containing small lamellar micelles. Finally, small amounts of copolymer added to a system containing two homopolymers resulted in Janus particles with a smooth gradient from one polymer to the other, with the copolymer acting as a surfactant. Some of these morphologies had previously been fabricated using other methods; however, it is advantageous to be able to synthesize them using FNP, which is a faster and simpler technique. Other morphologies produced here are novel particle types that have never before been reported in the literature.