Programmed Degradation of Hydrogels with a Double‐Locked Domain

The ability to control the degradation of a material is critical to various applications. The purpose of this study was to demonstrate a concept of controlling degradation by using a double‐locked domain (DLD). DLDs are molecular structures with two functional units that work cooperatively under environmental stimulation. One unit is triggered to transform without cleavage in the presence of the first stimulus, but this transformation enables the activation of the other unit for cleavage in the presence of the second stimulus. A DLD is presented that is activated to transform through intramolecular reconfiguration when exposed to light. After this transformation, the light‐triggered DLD can undergo rapid cleavage under acid treatment. When this DLD is used as the crosslinkers of hydrogels, hydrogels undergo rapid degradation after sequential exposure to light irradiation and acid treatment. Reversing the order of light irradiation and acid treatment or only using individual stimulation does not lead to comparable degradation. Thus, this study has successfully demonstrated the great potential of using DLDs to achieve programmable degradation of materials.     

Synthesis of Responsive Two‐Dimensional Polymers via Self‐Assembled DNA Networks

Despite a growing interest in two‐dimensional polymers, their rational synthesis remains a challenge. The solution‐phase synthesis of a two‐dimensional polymer is reported. A DNA‐based monomer self‐assembles into a supramolecular network, which is further converted into the covalently linked two‐dimensional polymer by anthracene dimerization. The polymers appear as uniform monolayers, as shown by AFM and TEM imaging. Furthermore, they exhibit a pronounced solvent responsivity. The results demonstrate the value of DNA‐controlled self‐assembly for the formation of two‐dimensional polymers in solution.