Surface chain dependent arrangement and self-assembly of polyhedral oligomeric silsesquioxane for supramolecular gels

Abstract In this study, a series of amino acid grafted inorganic/organic hybrid POSS (Cn@POSS) were designed and synthesized. In order to investigate the surface chain dependent arrangement and self-assembly of POSS in supramolecular self-assembly, the molecular stacking, gelation abilities, thermal stability, morphology and mechanical properties of Cn@POSS gels were evaluated. From the obtained self-assembly mechanism of hybrid POSS, we discovered that the arrangement of hybrid POSS regularly stacking on a hexagonal columnar pathway and assembled into fibrous networks to form the gel in colloid self-assembly. The peripheral segments on the surface of hybrid POSS in a loosely extended state instead the collapse which provide a better position for the closely stacking and oriented aggregation of POSS. As the hierarchical assembled fibrous network, the length of surface chain (LS) induced bending of assembled nano-fibers helps the efficient gelation by entanglement of surface chains, but weaken the self-recovery of gels. In contrast, in bulk self-assembly, the stacking of hybrid POSS were obviously affected and perturbed by the length of surface chain, with the shorter LS the closer packing of POSS. This fundamental research helps the understanding of hierarchical self-assembly behaviours of nano-building block POSS in supramolecular gels and inspire the discovering on the applications of POSS based organic-inorganic hybrid molecules in functional soft materials.