Self-assembly of supra-amphiphiles building block fabricated by β-cyclodextrin and adamantane-based ionic liquid

A new adamantane-based ionic liquid, (11-(((-adamantane-1-carbonyl)oxy)undecyl)-1-methylimidazol-3-ium bromide (AD-C₁₁im), was synthesized from 1-adamantanecarboxylic acid and observed that it can aggregate into micelles in aqueous solution. A number of experiments were conducted to understand the self-assembly of supra-amphiphiles building block fabricated by β-cyclodextrin (β-CD) and adamantane-based ionic liquid at diverse molar ratios. Studies revealed that host-guest interaction between the adamantane group and β-CD occurred and AD-C₁₁im@1β-CD building block formed when same amount β-CD was added. Then the micelles aggregates formed by AD-C₁₁im only turned into spherical vesicles, which was confirmed by AFM, DLS and TEM. Besides, according to the results of AFM, it can be confirmed that the vesicles were monolayer structure. When double amount β-CD was added, both the adamantane group and the hydrophobic chain were encapsulated by β-CD and AD-C₁₁im@2β-CD building block formed. Thus the aggregations changed from vesicles to net-like nanofiber, which was observed by TEM. When the β-CD concentration increased to 40 mM, the formation of light blue hydrogel was observed during the self-assembling process of AD-C₁₁im@2β-CD building block.