In-situ ZnO-mediated ZIF-8 growth on porous cellulose microspheres fabricated via membrane emulsification

In this study, porosity-controlled cellulose acetate microspheres were fabricated via membrane emulsification and  used as scaffolds for ZIF-8 growth through an in-situ seeding strategy. Zinc-based porogen was incorporated as a porogen to engineer internal and surface porosity, and this porogen was further exploited as a latent zinc source for ZIF-8 growth. The research analyzed how the initial porogen ratios influenced primary pore formation and how the rearrangement of polymer chains during alkaline removal of acetyl groups affected the final porosity, specific surface area, and the distribution of retained zinc species.

FTIR showed a residual acetyl signal after deacetylation, indicating that a fraction of Zn²⁺ stayed coordinated within the matrix rather than leaching out. This retained zinc serves as a local reservoir that, under the alkaline condition, partly converts to surface-bound ZnO. The ZnO acts as both nucleation seed and zinc source, localizing ZIF-8 growth at the particle surface and suppressing free crystal formation in solution to yield a uniform, well-adhered ZIF-8 layer. In this way, a single porogen governs porosity, cross-linking, and in-situ MOF seeding, giving cellulose@ZIF-8 microspheres with potential for adsorbents, catalysis, and encapsulation.