CENTRALE LYON - PhD 3D-AFM study of the organization of polymer brushes at Liquid / Solid inter[...]

Organisation/Company Ecole Centrale de Lyon Research Field Chemistry Physics Researcher Profile First Stage Researcher (R1) Positions Master Positions Application Deadline 10 Apr 2026 - 12:00 (Europe/Paris) Country France Type of Contract Permanent Job Status Full-time Hours Per Week 35 Offer Starting Date 1 Oct 2026 Is the job funded through the EU Research Framework Programme? Not funded by a EU programme Is the Job related to staff position within a Research Infrastructure? No

Offer Description

The deposition of polymer brushes on solid surfaces creates versatile platforms for a wide variety of practical applications in the fields of biomedicine, nanotechnology, catalysis, photovoltaic devices, water conversion, as well as certain functions designed to reduce energy costs. Depending on the chemical composition of the polymers and the associated liquid environment, polymer brushes can be adapted to a specific application (1).

In our study, we are particularly interested in biocompatible polyelectrolyte polymers that have the ability to stretch or collapse depending on external stimuli (pH, ionic strength, temperature, etc.) (2). In biomedicine, by choosing their functional groups and modifying the pH or ionic strength, it is possible to promote the adhesion of species present in the target solution, such as proteins, to create a highly sensitive biosensor (Figure 1a).

Conversely, non-specific protein adsorption can interfere with the functioning of the bioactive surface, in the case of medical implants, and in this case a polymer brush capable of repelling unwanted entities in the physiological environment will be chosen (3,4). By grafting these brushes onto two surfaces, it is possible, depending on the experimental conditions, to promote sliding between the surfaces in contact and thus minimize friction and damage to the surfaces for improved energy efficiency (5,6).

To characterize these different polymer brushes, atomic force microscopy (AFM) is used, which in its spectroscopic mode allows the measurement of interaction forces between its tip and the grafted polymer brush. The force curves provide information on the influence of the liquid (ionic strength, pH, hydrophobicity, viscosity, etc.) on the conformation of the polymers.

The LTDS and INL laboratories and their representatives Frédéric Dubreuil and Magali Phaner have been working together since 2021 on the implementation of an innovative technique called 3D-AFM (the only one of its kind in France) that makes it possible to characterize liquid/solid interfaces at the nanometric scale by studying the behavior of the liquid and its ions based on force measurements (7). In a first thesis, the technique was developed and has proved its value in the study of polymer brushes on a gold substrate (8).

The objective of the thesis is to study a new system composed of polymer brushes onto a silicon substrate in order to determine the organization of the solvation layers and the elongation or not of the polymer brushes. This study will be performed with various polymer lengths and charges, grafting densities. The impact of the solutions in their composition, pH and ionic strength as well as the chaotropic character of the salt will be considered. One can thus choose the ideal solution to enable an antibacterial effect (antifouling) of polymers for applications in nanomedicine (Figure 1a) or an anti-friction effect of polymers deposited on two contacting surfaces for applications in tribology (Figure 1b).

Scientific environment:The PhD student will be supervised by Prof Magali Phaner-Goutorbe at the INL lab and by Dr Fréderic Dubreuil at the LTDS lab, both specialists of AFM since several years in the field of biology and tribology (8).INL The Chemistry and Nanobiotechnology group is conducting interdisciplinary research activities focusing on coupling micro/nanotechnology and molecular biology for biology, health care and environmental applications.LTDS The ComPETe group is working on the knowledge of all elementary friction phenomena and is focused on the usage of nanoparticle, lubricant additives, tribochemistry at the local scale to reduce friction and wear in the contact area. Scientific collaborations with other labs will be developed for comparison with other techniques and computer IRIS Lab for analyses of the 3D mapping by IA models

References(1) A. Kiełbasa, K. Kowalczyk, K. Chajec-Gierczak, J. Bała and S. Zapotoczny, Applications of surface-grafted polymer brushes with variousarchitectures, Polym Adv Technol. 2024; 35: e6397. DOI: /pat.6397(2) L. A. Smook, A. Dahlin, K. Schroën, and S. de Beer, Responsive Polyelectrolyte Brushes in Applications: Functions, Stimuli, and DesignConsiderations, Adv. Mater. 2025, 37, e09580 DOI: /adma. (3) M. Aghajani & F. Esmaeili, Anti-biofouling assembly strategies for protein & cell repellent surfaces: a mini-review(2021): Anti-biofouling assembly strategies for protein & cell repellent surfaces: a mini-review, Journal of Biomaterials Science, PolymerEdition, DOI: / (4) X. Song et al, « Design, preparation, and characterization of lubrificating polymer brushes for biomedical applications » ActaBiomaterialia , DOI: /j.actbio (5) P. Mocny and H.A. Klok, Tribology of surface-grafted polymer brushes, Mol. Syst. Des. Eng., 2016, 1, 141, DOI /C5ME00010F(6) S. Watson, M. Nie, L. Wang and K. Strokes, Challenges and developments of self-assembled monolayers and polymer brushes as a greenlubrication solution for tribological applications, RSC Adv., 2015,5, , DOI: /c5ra17468f(7) T. Fukuma, R. Garcia, Atomic- and Molecular-Resolution Mapping of Solid-Liquid Interfaces by 3D Atomic Force Microscopy, ACS Nano,2018, 12, , DOI: /acsnano.8b07216(8) Dahlia Saad, PhD from Ecole Centrale de Lyon, “What happens at the nanometric scale at the liquid/solid interface? Implementationof an Atomic Force Microscope for 3D-AFM imaging of liquid/solid interface: Application to Biosensors and Tribology “, defended2025/12/05

Where to apply

E-mail

Requirements

Research Field Chemistry Education Level Master Degree or equivalent

Research Field Physics Education Level Master Degree or equivalent

Skills/Qualifications

Candidate skills:The PhD candidate should ideally have a background in physics and in physical chemistry of surfaces and some knowledge in classical AFM. The candidate must have a strong taste for experimental work (sample preparation, characterization) but also for data analysis via the development of codes using high programming languages like Python or Matlab environment. Knowledge for programming (python) would be a plus for the force curves interpretation since some codes have been developed for the 3D -AFM data analysis. Also, the candidate must be able to work at the interface between physics, chemistry, mechanics and biology. However, no specific skills are required in biology.Firstly, the master's student will be introduced to the classic AFM mode of imaging in air and liquids and then he/she will work on the polymer brushes in liquid. In parallel, knowledges on the mechanical and chemical forces involved in these experiments will be given to the candidate to facilitate the work in curves interpretation.