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Propriétés mécaniques et nanotribologiques de monocouches auto-assemblées de microgels de poly(NIPAM) cationique en milieux aqueux

Abstract : The aim of this project is to advance the knowledge and understanding of lubricating systems, whether synthetic or biological, in aqueous media. For this purpose, we develop self-assem-bled monolayer 2D-arrays of cationic pNIPAM thermosensitive microgels in order to study their mechanical and nanotribological properties. We establish several synthetic routes to modulate the microgel rigidity and study its effect on the tribological behaviour. We also look at the effect of the grafting nature of microgels on the substrate, by developing an innovative chemical coupling method, to compare the properties of physisorbed and chemisorbed mon-olayers. We probe the mechanical properties of the microgel layers in aqueous environment while varying the temperature, the nature of the grafting and the salts added to the system, primarily by using a Quartz Crystal Microbalance with Dissipation monitoring (QCM-D). The core of our study is performed using a modified Surface Forces Apparatus (SFA) which allows for tribological measurements, the results of which will be treated in two parts. First, we char-acterise the normal surface forces when compressing two surfaces decorated with the micro-gel layers. Second, we study the behaviour of these surfaces under compression and shear. We explore their lubricant properties and observe the appearance of a shear-induced velocity-dependent lift force, whose origin we seek to determine. We thus discovered a mechanism specific to a compliant substrate, decorated with discrete particles presenting a repulsive con-tact without friction at long range.
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https://tel.archives-ouvertes.fr/tel-02008351
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Submitted on : Tuesday, February 5, 2019 - 4:14:34 PM
Last modification on : Friday, October 23, 2020 - 4:37:55 PM
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  • HAL Id : tel-02008351, version 1

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Pierre Vialar. Propriétés mécaniques et nanotribologiques de monocouches auto-assemblées de microgels de poly(NIPAM) cationique en milieux aqueux. Polymères. Université de Bordeaux; Université de Montréal, 2018. Français. ⟨NNT : 2018BORD0225⟩. ⟨tel-02008351⟩

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