We report on two types of pH-triggered shape response in cubical hollow microcapsules. The cubical microcontainers were produced as poly(methacrylic acid)-based hydrogel (PMAA) replicas of cubical inorganic carbonate microparticles obtained from chemically cross-linked multilayers of hydrogen-bonded precursor films.  We found that while cubical (PMAA)20 capsules turned into spherical-like when transitioned from pH=3 to pH=8, cubical PMAA-poly(vinylpyrrolidone), (PMAA-PVPON)5, hydrogel cubical capsules retained their cubical shape and increased in size instead.  The decrease in cross-link density in the (PMAA-PVPON)5 hydrogel hollow microcontainers resulted in the increase in their swelling ratio.  The drastic difference in pH-triggered shape responses was rationalized through the difference in hydrogel rigidity expressed as the ratio of the polymer contour length between the neighboring cross-links to persistence polymer length.  We believe that our findings provide new prospects for developing polymeric materials with predictable shape and size-changing properties for controlled drug delivery and cellular uptake.

Cubical ultrathin hydrogel microcontainers: pH-triggered shape transitions

244th National Meeting (2012)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.