Self‐Assembled Designer Polymersomes of In Situ Hybrid Nanocomposites from Copolymers of Polystyrene and Poly (Acrylic Acid) with Functionalized‐Kaolinite for pH‐Induced Delivery

Abstract

Self-assembled vesicles of polymer clay nanocomposites (PCN) with functionalized Kaolinite (m-Kaol) nanoparticles and polystyrene (PS) with stimuli-sensitive release properties are interesting for chemotherapy. Modifying the vesicle corona by incorporating ionizable groups in the polymer chain can impart defined pH-sensitivity. In this study, in situ PCN with various compositions of m-Kaol with styrene and anionic acrylic acid were synthesized and characterized. PCN formed with 60:40 molar ratio of the monomers with m-Kaol showed self-assembly in THF into giant vesicles of 1.5–3.0 µm diameter and wall thickness of 50–70 nm, attributed to the functionalization-induced bilayer assembly of the delaminated, m-Kaol, Janus nanoparticles by hydrogen bonding involving terminal ─OH groups along the core and stabilized by the π─π interactions of the phenyl moiety along the periphery. Aliphatic rhodamine dye-encapsulated vesicles showed no release in pH 4.0 indicating the hydrogen bonded carboxyl groups in the corona. Sustained delivery was observed at pH 7.4, attributed to the limited deprotonation leading to diffusion-controlled release. The vesicles eroded completely at pH 9.0 due to the collapse of the hydrogen bonding. The results showed prospects for applications of these rigid, designer hybrid vesicles which are nontoxic and cost-effective as pH-sensitive delivery systems in the gastrointestinal tract or as scaffolds for topical delivery.