## 1 Introduction
ZnO NPs coated with 0.1 wt% MPS (wt/wt MPS/ZnO colloid) were not miscible in styrene (St) emulsion and, hence, the PS core coated with ZnO NPs as Pickering-like particles were produced. The higher MPS content of 0.6-2 wt%, improving the compatibility between MPS-ZnO NPs and St, caused the encapsulation of ZnO in PS particles [13]. Using potassium persulfate (KPS) as an initiator, 70-96% of ZnO was entrapped in poly (styrene-\(\infty\)-methyl methacrylate) (P(St/MMA)) particles by the co-encapsulation of MPS-ZnO NPs and oil soluble organic sunscreen [14]. Up to 95% of the ZnO in the PS particles was attained when using APTES as the surface coupling agent and hexadecane (HD) as the hydrophobe [9]. The ZnO-embedded P(St/MMA) particles, using an azobisisobutyonitrile (AIBN) initiator and stearic-modified ZnO for the fabrication of multi-phase core materials, were also reported [15]. The size ratio of the ZnO NPs to the MMA/butyl acrylate monomers droplet affected their distribution and provided a composite copolymer with different morphologies [16]. The role of these parameters on the resulting morphologies often related to the chemical compatibility and site of polymerization [11; 12; 16]. What should be emphasized, such as kinetic and thermodynamic contributions, are not stated. Moreover, the role of crosslinking agent, e.g., divinyl benzene (DVB), on the ZPPs structure is less mentioned despite of the fact that DVB contributed to the rate of polymerization and affected the morphology of magnetic polymeric (MP) NPs [17]. MNPs were completely incorporated into PS or PMMA/DVB/acrylic acid (AA) due to the high viscosity caused from the presence of DVB inside the particle, which retained the MNPs from moving outward. By using the soap-free seeded EP with the Fe\({}_{3}\)O\({}_{4}\) colloidal nanocrystal clusters as the seed,the morphology of the composite PS microspheres could be controlled from raspberry- and flower-like shapes to eccentric structures by adjusting the feeding weight ratio of the seed to the St monomer and varying the amount of DVB. Crosslinked MPS-Fe\({}_{3}\)O\({}_{4}\)@PS microspheres showed much more intact and smooth polymer layers with an increased DVB feeding amount. Recently, in the preparation of hollow magnetic polymeric particles (HoMPs) via the one-pot mini-EP, the location of OA-MNPs at the inner shell and void interface and in the shell layer was designed by adjusting the ratio of MMA/DVB, which caused the difference in polymerization kinetics and phase separation [18]. Since the polymerization took place when oligoradicals, generated in the continuous phase, entered the droplets consisting of OA-MNPs, MMA/DVB, and HD, varying the ratio of MMA/DVB, it altered the polarity of polymer the shell, which affected the partitioning of OA-MNPs at different locations in the final particle, i.e., the MNPs-rich at the inner wall and at the shell. Herein, we reported a facile and direct method that can kinetically control the morphologies of ZPPs from Pickering-like to occluded-typed (core-shell) via the use of mini-EP of P(St/AA) using a KPS initiator. ZnO NPs, prepared via the co-precipitation method, were stabilized with OA and the effects of synthesis parameters, i.e., the amount of SDS surfactant, KPS initiator, and DVB crosslinking agent, on size and morphologies of ZPPs were elucidated using transmission electron microscopy and field emission scanning electron microscopy. The effect of a more hydrophilic monomer, i.e., MMA, in the presence of various amounts of DVB, on the morphological transition of ZPPs was also investigated. Based on the chemical parameters (e.g., surface chemistry and chemical reactivity) and the physical results (e.g., particle size and morphology), the formation mechanism of ZPPs was proposed. The UV shielding performance of polyvinyl alcohol (PVA) films containing core-shell, Pickering-like, and hollow ZPPs was evaluated by UV-visible spectroscopy.