Polysilane Organogel with Hierarchical Structures Formed by Weak Intra-/Inter-chain Si/FC and van der Waals Interactions

Abstract

A semiflexible polysilane copolymer bearing 3,3,3-trifluoropropyl and n-decyl side chains formed an organogel in nonpolar organic solvents. Weak Si/FC interchain/intrachain interactions were formed between the Si main chain and fluoropropyl side chain, and acted as noncovalent crosslinks. Long alkyl (n-decyl) groups acted as solvophilic moieties that effectively absorbed and retained organic solvent molecules. Furthermore, the relatively rigid main chain was also important for the gelation ability of the material. The existence of Si/FC interchain interactions was first demonstrated by careful IR measurement and analysis using a model silane molecule. Hierarchical structures at the meso-and nano-scale levels were successfully characterized by AFM, cryo-HR-TEM, IR, and 19 F{ 29 Si}-NOE NMR experiments.

Helical Polymers: Synthesis, Structures, and Functions

“…A semiflexible polysilane copolymer bearing 3,3,3-trifluoropropyl and n-decyl side chains (73, Chart 10) forms an organogel in nonpolar organic solvents, 132 probably due to the weak C-F • • • Si intermolecular interactions between the Si main-chain and the fluoropropyl side chain, which act as noncovalent cross-links. In addition, the relatively rigid main-chain is also responsible for the gelation ability of the copolymer.…”

Controlling Anti-Penetration Performance by Post-Grafting of Fluorinated Alkyl Chains onto Polystyrene-block-poly(vinyl methyl siloxane)

“…Such interactions between silicon and fluorine were also reported in polysilanes. 44,45 The degree of chemical shifts mentioned above increases with the length of fluorinated alkyl chains, which implies that a longer fluorinated alkyl chain can result in stronger inter-and intrachain interactions because of the attraction between the atoms of fluorine and silicon.…”

Molecular origin for helical winding of fibrils formed by perfluorinated gelators

“…A similar effect of fluorinated chains was reported recently for achiral perfluoroalkaneamides. [13][14][15] The Chart 1 The molecular structure of RR-CF7. dependence of the sol-gel transition temperature on the concentration of a gelator was studied for acetonitrile gels.…”

“…Such weak non-covalent interactions are previously postulated for hierarchical structures in the case of fluorinated polysilane gelators. 14 The X-ray diffraction measurements on the powder sample of SS-CF7 showed the sharp peaks at 1.87 nm and 0.47 nm, which were assigned to the molecular length of CF7 and the intermolecular distance of stacked molecules, respectively (ESIw). The X-ray diffraction measurements on the gel samples are now under progress.…”