“…28,29 The common methods that are used to form hollow structures of HPPs are template, 1,[30][31][32] self-assembly, 33,34 and acid/ alkali swelling, 35 with different synthesis techniques such as suspension, dispersion, emulsion, and precipitation polymerization. Advanced methods for the preparation of hollow polymers that have been reported recently include urea treatment, 36 an in situ reduction method, 37,38 inverse mini-emulsion periphery RAFT polymerization (IMEPP), 39 and coaxial electrohydrodynamic and atomization (CEHDA). 40 Different types of materials, such as monomers, 41 block copolymers, 42 copolymers, 43 and inorganic nanoparticles, 44 have been used to synthesize HPPs.…”