- Title
- Synthesis, optimisation and characterisation of thermoresponsive polymer brushes
- Creator
- Murdoch, Timothy J.; Johnson, Edwin; Edmondson, Steve; Wanless, Erica J.; Webber, Grant B.
- Relation
- Asia Pacific Confederation of Chemical Engineering Congress 2015 (APCChE 2015) incorporating CHEMECA 2015. Proceedings of the APCChE 2015 Congress incorporating CHEMECA 2015 (Melbourne, Vic. 27 September - 01 October, 2015) p. 1553-1564
- Relation
- ARC.DP110100041 http://purl.org/au-research/grants/arc/DP110100041
- Publisher
- Engineers Australia
- Resource Type
- conference paper
- Date
- 2015
- Description
- The use of polymer brushes, terminally grafted polymer films, is a common method for modifying interfacial properties on range of substrates. The use of stimulus-responsive monomers allows the formation of brushes that change their conformation and physicochemical properties due to changes in, for example, solution pH, salt concentration or nature, temperature and even exposure to light. Homo- and copolymer brushes of oligo(ethylene glycol) methacrylates are a relatively new class of these so-called "smart surfaces", whose thermoresponse can be finely tuned. Herein we detail the optimisation of the synthesis of homopolymer brushes of 2-2(-methoxyethoxy)ethyl methacrylate (MEO₂MA) and an oligo(ethylene glycol) methacrylate (OEGMA₃₀₀), and a statistical copolymer of 80:20 MEO₂MA:OEGMA (PPEGMA), by the activators continuously regenerated by electron transfer atom transfer radical polymerisation (ARGET ATRP) methodology. The thermoresponsive behaviour of the MEO₂MA homopolymer and PPEGMA copolymer brushes were confirmed by 'in situ' ellipsometry, which showed the range of temperatures over which the brushes changed conformation is substantially greater than their free polymer analogues. Ellipsometry measurements of the PPEGMA brush in 500 mM potassium acetate revealed the addition of electrolyte decreased the lower critical solution temperature (LCST). Atomic force microscopy measurements of the PPEGMA brush revealed that above the LCST the brush was initially compliant as it interacted with the approaching tip and the force rapidly increased near zero apparent separation. The different force-distance profile below the brush LCST demonstrates the dependence of brush conformation on temperature. Interestingly, lateral force measurements were distinctly different either side of the LCST. Above the LCST, where the brush is collapsed, the lateral force was significantly higher and exhibited a change in the applied load-lateral force relationship that indicates a load-induced change in conformation of the brush. This has implication for the use of these brush layers as, for example, bio-lubricants.
- Subject
- ellipsometry; polymer brush; atomic force microscopy; surface initiated polymerisation
- Identifier
- http://hdl.handle.net/1959.13/1324713
- Identifier
- uon:25103
- Identifier
- ISBN:9781922107473
- Language
- eng
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