Abstract
Soluble starch polymers are shown to enhance the lubrication of ionic liquid-water solvent mixtures in low-pressure tribological contacts between hydrophobic substrates. A fraction of starch polymers become highly soluble in 1-ethyl-3-methylimidazolium acetate (EMIMAc)-water solvents with ionic liquid fraction ≥60 wt%. In 65 wt% EMIMAc, a small amount of soluble starch (0.33 wt%) reduces the boundary friction coefficient by up to a third in comparison to that of the solvent. This low-friction is associated with a nanometre thick film (ca. 2 nm) formed from the amylose fraction of the starch. In addition, under conditions where there is a mixture of insoluble starch particles and solubilised starch polymers, it is found that the presence of dissolved amylose enhances the lubrication of starch suspensions between roughened substrates. These findings open up the possibility of utilising starch biopolymers, as well as other hydrocolloids, for enhancing the performance of ionic liquid lubricants.
| Original language | English |
|---|---|
| Pages (from-to) | 507-516 |
| Number of pages | 10 |
| Journal | Carbohydrate Polymers |
| Volume | 133 |
| DOIs | |
| Publication status | Published - 1 Aug 2015 |
Bibliographical note
Publisher Copyright:© 2015 Elsevier Ltd. All rights reserved.
Funding
This work was performed in part at the Queensland node of the Australian National Fabrication Facility (ANNF-Q), a company established under the National Collaborative Research Infrastructure Strategy to provide nano- and micro-fabrication facilities for Australia’s researchers. The authors thank Ms Tracey Tra Mi Ho (University of South Australia) for assistance with ellipsometric measurements; Dr Sushil Dhital, Professor Michael Gidley, Dr Torsten Witt, and Dr Fred Warren (University of Queensland) are gratefully acknowledged for many helpful discussions. F. Xie and P.J. Halley wish to acknowledge the support of the Australian Research Council (ARC) for the research funding under the Discovery Project No. 120100344 . G.E. Yakubov and J.R. Stokes wish to acknowledge the support of the Australian Research Council (ARC) for funding to the ARC Centre of Excellence in Plant Cell Walls ( CE110001007 ).
| Funders | Funder number |
|---|---|
| ARC Centre of Excellence in Plant Cell Walls | CE110001007 |
| Australian Research Council | 120100344 |
Keywords
- Amylose
- Boundary friction
- Ionic liquid
- Lubrication
- Starch
- Suspension
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics
- Materials Chemistry