Porosity‐controlled chitosan‐mesoporous silica composite membranes prepared using an ionic liquid Porogen: Implications for model drug transport

Abstract Chitosan (Chit)/mesoporous silica nanoparticle (MSN) composite membranes (Chit/MSN‐0–3) with hierarchically controlled meso‐ and macro‐porosity were prepared using a room‐temperature ionic liquid (RTIL), bmimBF4, as a liquid porogen and evaluated as a porous platform for model molecule transport. These membranes were formed by the self‐assembly of nanohybrid building blocks comprising negatively charged MSN cores and a positively charged Chit shell, while inter‐unit meso‐ and macro‐pores were introduced in a controllable manner by varying the porogen content. As the porogen amount increased, porosity increased from approximately 15.36% to approximately 64.49%, and the BET surface area increased from 168.35 to 354.59 m 2 g −1 , whereas the average mesopore diameter remained nearly constant (approximately 3.59–3.64 nm), accompanied by an increase in pore volume (approximately 0.057–0.256 cm 3 g −1 ). These structural features were characterized by N 2 adsorption (BET) and electron microscopy. Transport‐related performance was examined using bovine serum albumin (large, negatively charged) and cytochrome C (small, positively charged) as model proteins in both in vitro release tests and an ex vivo Franz diffusion cell setup. Overall, RTIL‐assisted pore engineering enabled a clear structure‐transport relationship and provided a tunable composite membrane platform for charge‐ and size‐dependent molecular loading and permeation.