Synthetic translocation membranes from hierarchical assemblies of block copolymers – TRANSPOLYMEM

The scientific program is structured in a multidisciplinary way from the design of molecular precursor to the membrane filtration. The first scientific task is devoted to the design and synthesis of the molecular precursors (monomers, micelle linkers and polymerization control agent) as well as the polymers (homo- and copolymers). The second task is focused on the preparation of the membranes. The membranes are prepared from the polymer precursors prepared in the task 1. A hierarchical self-assembly from polymers to micelles, and micelles to assembled membrane is carried-out in situ from a controlled evaporation of the solvent. A post-modification is also explored in order to modulate the mechanical properties, the surface chemistry and thus the overall dynamism of the membrane. The third task is devoted to a full characterization of the membrane. A first part consists in acquiring the “classical” experimental data of the membranes, such as pore size and pore size distribution, thickness, local and global morphologies. The second part enables to establish mathematical models on the basis on hypothetical behaviors and their validation through the simulation of data such as the membrane flux against the time of filtration. The confrontation between theory and experience enhances our comprehension of the membrane dynamic and its translocation mechanism. The fourth task is devoted to the study of the translocation of nano-objects through the membranes. After a selection of the best suited nano-objects, their translocation through the prepared membranes is studied during filtration experiments. The translocated objects are analyzed in terms of size and size distribution change in order to understand this new transport mechanism.

-Preparation of dynamic membranes, based on research using supramolecular chemistry.
-Understanding of the mechanisms for the preparation of membranes with an original approach to follow-up key steps in solution and in the solid state.
-Preparation of new membranes by a mixture of MOF particles and polymers for applications in gas separation.

It is expected a new type of filtration mechanism, bioinspired from the biological membrane translocation, able to compete with the best commercial systems, especially in the scope of bioseparation of biological products to purify a target used in biotechnologies.

1. Stimuli Responsive Nanostructured Porous Network from Triblock Copolymer Self-assemblies, Polymer Chemistry, 2015, 6, 2023 – 2028.
2. MOF-mixed matrix membranes: precise dispersion of MOF particles with better compatibility via a particle fusion approach for enhanced gas separation properties, Journal of Membrane Science, 2015, 492, 21-31.
3. Filtration Membranes from Self-assembled Block Copolymers- A review on recent progress, European Physical Journal Special Topics, accepted

Dynamic polymeric materials represent a novel and rapidly evolving class of bio-inspired materials that holds huge potential for biological and non-biological applications. Here, we propose the preparation of translocation membranes, which albeit simpler in structure behaves similarly to lipid bilayer membranes. Our preliminary findings show a clear correlation between the interactions of nano-objects with membrane, nano-particle geometry, concentration, driving force and nano-particle size for an effective translocation across a synthetic membrane. We anticipate this work to be an important contribution not only towards the development and functioning of intelligent bio-inspired materials but also for better understanding of transport mechanism of matter across biological membranes.
In this proposal, the novelty comes from the dynamic formation and closure of pores across a polymer membrane, triggered by the contact between the membrane surface and a targeted object. An ultra-fast and highly selective filtration of nano-objects is expected in order to purify bio-products and synthetic particles. The membrane will be prepared from a hierarchical self-assembly of block copolymers. Block copolymers with two or three blocks will be synthesized in order to carry all the information required to prepare the final membrane, i.e. the block incompatibility to prepare micelles under selective solvent conditions, and the appropriate chemistry to link the frozen micelles together with a mechanical stability high enough to sustain a water pressure during filtration. The final membrane will be a micelle assembly with reversible inter-micelle links able to be broken and reformed under controlled conditions. This dynamism will be implemented by the introduction of functional groups on the copolymer backbone, able to reversible assembly, known as dynamic chemistry. Here we propose to explore ambient temperature Diels-Alder reaction, supramolecular chemistry, trithiocarbonate UV rearrangement and the reversible formation of boroxine. Through these 4 examples of dynamic chemistry, we will be able to prepare various dynamic membranes based on micelles reversibly linked together. Those dynamic membranes will be then subjected to water flow and some nano-objects like nanoparticles will be introduced for their filtration. The water will be able to cross the membrane through the space left between the micelles but the nano-object size will be large enough to avoid this convective transport. Those objects will impact the membrane surface and should enable the mechanical separation of micelles in order to create a temporary pore. The pore created, the object will then diffuse slowly inside the membrane, pushed by the water flow, and escape the membrane on the other side. The pore will then close rapidly and the reversible chemistry will ensure the reformation of the micelle links. It is proposed here to identify the key parameters of the membrane and the translocated objects in order to understand the translocation mechanism. Moreover, the prepared translocation membranes will be used as a medium to design nano-objects with a large variety of shapes (cubes, spheroids, rods, wires) thanks to the control of the translocation mechanism. It is expected a new type of filtration mechanism, bioinspired from the biological membrane translocation, able to compete with the best commercial systems, especially in the scope of bioseparation of biological products to purify a target used in biotechnologies.