Formation of a molecularly and mesoscopically ordered structure from cage siloxanes with a long alkyl chain and dimethylsilanol groups

Structural control of siloxane-based materials at multiple length scales is important for various applications. In this study, we report the controlled assembly of cage oligosiloxane building blocks by both intermolecular hydrogen bonding and hydrophobic interactions. A cage siloxane molecule modified with seven dimethylsilanol groups and an octadecyldimethylsilyl group was synthesized by stepwise silylation of double-four-ring (D4R) cage octasilicate anions. This molecule self-assembled to form a molecularly and mesoscopically ordered structure by solvent evaporation. Furthermore, the silanol groups in the assembled solids were cross-linked by silylation with dichlorodimethylsilane. This approach will allow for the creation of various hierarchically ordered siloxane-based materials by molecular design. Graphical Abstract: [Figure not available: see fulltext.]