Preparation and action mechanism of inclusion complex of β-cyclodextrin and sulfurized isobutylene as additives in solution of polyethylene glycol-600

Abstract

The inclusion complex of β-cyclodextrin (β-CD) and sulfurized isobutylene (T321) was prepared with a co-precipitation method. The tribological properties of the complex with different concentrations were investigated by a four-ball tester in the solution of polyethylene glycol-600 (PEG-600). The experimental results suggest that the complex exhibits better anti-friction and anti-wear properties than β-CD under different load conditions. The tribo-system shows the least friction coefficient when the concentration of the complex is 0.8%. During the friction process, the complex was decomposed into various molecular fragments and the T321 molecules were released onto the friction interface to provide effective lubrication. The XPS analytical results on the worn surfaces reveal that sulfide film formed by the released T321 plays a major role, and the iron alkoxide and carbon deposition films formed by the β-CD fragments have better anti-friction effect on the sulfide film surface. The interactions of different films result in the formation of a mixed boundary lubrication film.

Semi-convertible Hydrogel Enabled Photoresponsive Lubrication

“…For supramolecular gelation, a-CDs assembled at the two ends of one PEG chain, and such complex domains aggregated with one from another a-CD/PEG chain to form the non-covalent physical crosslink. 41,42 a-CDs were not distributed along the whole PEG chain, which might be attributed to the PEG chain being so long that the assembly had already occurred before a-CDs included the middle of the PEG chain. When the hydrogel was irradiated by Vis, dissociated cis-AzoPB changed to its trans form, and the a-CD/PEG supramolecular network disassembled due to the competitive host-guest interaction brought by trans-AzoPB.…”