One-Pot Template-Free Synthesis of Monodisperse Hollow Hydrogel Microspheres and their Resulting Properties

摘要

Monodisperse poly(methacrylic acid/ethyleneglycoldimethacrylate) (MAA/EGDMA) hollow microcapsules, which exhibit pH-responsive behavior, are prepared by diffusion of cationic surfactants and hydrophobic interaction. During the association of the negatively charged hydrogel microspheres and an oppositely charged surfactant (cetyltrimethylammonium bromide, CTA(+)B), the hydrophobic polymer-surfactant complexes that form are separated from the internal water; consequently, a hollow structure can be formed. Confocal laser scanning microscopy, UV spectroscopy and zeta potential are employed to study the formation of the hollow structure during the diffusion of the cationic surfactant. The controlled release behavior of methylene blue as a model drug from the as-prepared poly(MAA/EGDMA) microcapsules with a hollow structure is investigated under different pH conditions. The hollow structure can be retained, even during repetitive pH changes. Hollow hydrogel microcapsules are formed by a facile and rapid method. The electrostatic attraction and hydrophobic interaction between the negatively charged hydrogel networks and cationic surfactant causes the rapid formation of the hollow structure of the poly(MAA/EGDMA) microspheres with a low crosslinking density. In addition, the shell thickness can be adjusted by changing the degree of crosslinking. The as-prepared hollow poly(MAA/EGDMA) microcapsules show good structural stability and pH-responsive release properties.