Peripheral Groups of Polyhedral Oligomeric Silsequioxane (POSS) Core Based Dendrimers: Crucial Factor for Higher-level Supra-architecture Building
The role of peripheral groups (PGs) on dendrimer in spontaneously higher-level organization of hierarchically assembled nanofibers was investigated in a series of POSS based dendritic gelators (POSS-Lys-X, X: -Boc, -Cbz, -Fmoc, et. al). We demonstrate that the PGs not only affect the gelation ability in solution, but also the construction of orderly entangled fibrous supramolecular networks, eg. “loofah-like” networks. Attribute to the PGs (especially -Boc group) caused lower cooperative assembly, the steady state with lowest potential energy of gelators can be easily achieved by higher ordering the entanglement of nanofibers into superstructures. The -Boc group contained dendrimers show low molar enthalpy and molar entropy of gelation, which helps the construction of unique three-dimensional (3D) “loofah-like” superstructures. In constrast, the high cooperative assembly of the dendrimer (-Cbz as the PGs) promotes the gelator in a higher enthalpy gelation process, with normal fibrous network constructed. Hence, the PGs of POSS based dendrimers act as the crucial factor in controlling of the hierarchical self-assembly via a thermodynamics approach. This research presents new perspectives to explicate the relationships between PGs of dendrimer, supra-architectures and gel performances, which further guide the design of functional supramolecular materials via controllable self-assembly.