Characterization methods of polymer core–shell particles

The design and synthesis of various polymer core–shell particles result from their distinct characteristics, which combine the properties of two or more components into one material. Many accessible synthetic strategies for obtaining polymer core–shell particles lead to the formation of particles for which the internal morphology differs from the ideal core–shell structure. Understanding the precise morphology characteristics is important for mechanistic studies of particle formation, which ultimately results in the design of particles for specific structures and properties. The detailed characteristics of complex polymer particle structures are complicated and require more than one method. This review focuses on imaging methods such as transmission electron microscopy (TEM), cryo-TEM, scanning transmission electron microscopy (STEM) and confocal fluorescence microscopy that reveal the radial redistribution of the components and methods for the quantitative analysis of individual phases (core, shell and interfacial layer), such as small-angle X-ray scattering (SAXS), small-angle neutron scattering (SANS), differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR). Methods that can determine the surface composition and makeup of the character of interfacial layer (gradient or containing small domains, etc.) were also reviewed.