Controlled Cross-linking Strategy for Formation of Hydrogels, Microgels and Nanogels

Hydrogels are a kind of unique cross-linking polymeric materials with three-dimensional networks. Various efforts have been devoted to manipulate the formation of functional hydrogels in situ and enrich the production of hydrogels, microgels and nanogels with improved modulation capacity. However, these methods always fail to tune the gel properties because of the difficulty in achieving the precise control of cross-linking extents once the gel formation is initiated. Therefore, the preparation of tailor-made hydrogels remains a great challenge. Herein, we summarize a controlled cross-linking strategy towards not only fabrication of hydrogels at nano-, micro-and macro-scales, but also achievement of controlled assembly of nanoparticles into multifunctional materials in macroscopic and microscopic scales. The strategy is conducted by controllably activating and terminating the disulfide reshuffling reactions of disulfide-linked core/shell materials with selective core/shell separation using system p H or UV triggers. So it provides a facile approach to producing hydrogels, hydrogel particles and nanoparticle aggregates with tunable structures and properties, opening up the design possibility, flexibility and complexity of hydrogels, microgels/nanogels and nanoparticle aggregates from nanoscopic components to macroscopic objects.