Interpenetrating polymer network for nanostructured coating – IPNanocoat

Wider research context: Thin films of polymers are increasingly developed for various biomedical or industrial applications. Polymer blends are often used to provide improved and versatile properties to the coating. However, 2D confinement may affect their miscibility behavior. To avoid phase separation over time in 3D blends and ensure stability to external stimuli, cross-linking of both polymers using two different pathways has been used leading to interpenetrating polymer networks (IPN). We propose to use the same concept in ultrathin films at the air-water interface, i.e. Langmuir films, leading to 2D-IPN nanocoating once transferred onto solid substrate.

Research questions: The aim of our proposal is to fundamentally understand how physico-chemical parameters and cross-linking reactions affect phase separation in polymer blends confined in 2D geometry in order to control the morphology and synthesize 2D-IPN nanocoating on demand.

Methods: In a first step, pressure-composition phase diagram will be studied for a large variety of polymer couples with different hydrophobicity, by combining pressure isotherms, morphology observations by Brewster angle microscopy and molecular level organization by sum frequency generation experiments. Modelling will be used to identify the key physico-chemical parameters. In a second step, we will focus on the miscibility regions of the phase diagrams to synthesize one-phase 2D-IPN and study the evolution of the morphology depending on reaction parameters. In a final step, the 2D-IPN will be evaluated as nanocoatings in terms of morphology, molecular scale organization and wetting properties, and compared to disordered IPN spin-coated films.

Level of originality: The scientific originality of the project first resides on the synthesis of one-phase 2D-IPN, since the mechanisms of phase separation in cross-linked polymer blends has not been addressed in 2D. By taking advantage of real-time monitoring by SFG of the reactions and modelling, the proposed strategy provides the possibility of investigating how the pressure – composition phase diagrams and morphologies are impacted during cross-linking of both polymers. For this, a screening of a broad diversity of 2D polymer blend Langmuir films is necessary as no detailed overview of the mixing behavior of polymers in 2D through the building of phase diagrams is present in the literature. Finally, by comparison with other thin film elaboration methods, stable and organized 2D nanocoatings with versatile properties should be obtained.

Primary researchers involved: The project gathers a complementary team including specialists of thermodynamic and morphology characterization of polymer Langmuir films (S. Cantin, A. El Haitami, CYU), modelling of polymer blends thermodynamic properties (E. Masnada, CYU) and sum frequency generation experiments at liquid and solid interfaces (E. Backus, UV).