Dopamine: promising building block for the conception of innovative polymer materials – DECIMAL

After synthesizing 3 functionalized chain transfer agent (gram scale), a large range of polymers (hydrophilic and hydrophobic) have been elaborated in a controlled fashion with low polydispersity indices. Coupling reaction between a catechol end-functionalized polymer and a boronic acid end-functionalized polymer leads to amphiphilic block copolymers, characterized by 1D and 2D NMR, cryo-TEM and dynamic light scattering.

During the first 18 months of the project, task 1 was fully achieved. It consisted on the synthesis of 3 functionalized chain transfer agents (CTA) bearing either a boronic acid or a catechol derivative. These CTAs were then used during the RAFT process to elaborate end functionalized polymers. At the early stage, only PNIPAM and PSty were considered in the project but it has been decided to extend the use of these CTA to other monomers in order to broaden the potential applications.

The task 2 of the ANR project consists on the coupling reaction between complementary end-functionalized polymers in order to obtain block copolymers having different properties. Firstly, as soon as optimal reaction conditions were found, different block copolymers were elaborated and characterized. Then, amphiphilic copolymers were introduced in aqueous medium in order to obtain a self-assembly. By Dynamic light Scattering and cryoTEM analyses, it has been stated that micelles were obtained with a diameter comprised between 100 and 300 nm, depending on the nature and the length of the polymers. In addition, Highly hydrophobic molecules could be encapsulated within the micelle core.

In the forthcoming works, a particular attention will be paid to the responsiveness of the multi-stimulabe micelles by applying clean stimuli such as electrochemistry, addition of sugar and UV light. We aim to prove that all of these stimuli can «break« the micelles allowing the release of the hydrophobic compound previously encapsulated (drug)

There is no paper published but 2 papers are currently in progress. 2 oral presentations and 1 poster were presented during conferences.

Polymer chemists are always pushing limits of creativity for complex macromolecular architectures in order to elaborate sophisticated materials with new and unique properties. It has led to the tremendous development of original polymer materials such as "smart materials", finding interesting applications in nanoscience and nanomedecine, for instance. Among all current employed strategies, well-defined polymer topologies are mainly obtained by using multiple successive synthetic and purification steps. Additionally, it is often observed that one strategy leads to only one polymer architecture.
Therefore, in this research programme, we aim to develop an innovative and powerful strategy for the elaboration of a wide range of polymer architectures from only one building block which is a derivative of catechol, i.e. dopamine. This bioinspired building block possesses the particularity of having different reaction sites, owing to orthogonal efficient reactions and gives the opportunity of plethora of functionalization combinations, thereby allowing the creation of a wide range of macromolecular architectures (block, cyclic, Y-shape, tadpole, biohydrid copolymers, etc.) with original properties. Among the intrinsic properties of the dopamine, it has the remarkable faculty to be easily incorporated in well-defined polymers designed by the Reversible Addition-Fragmentation chain Transfer (RAFT).
This challenging strategy would lead us to efficiently access to i) common, but very interesting, polymer architectures (homo- and block copolymers) and ii) very promising sophisticated architectures such as well-defined cyclic polymers.
Furthermore, all the foreseen coupling reactions (boronic acid/catechol and Michael addition) will be carried out in a simple, very efficient and “clean” manner, leading to the creation of covalent bonds in between the complementary macromolecules. Interestingly, part of these coupled copolymers will exhibit dynamic features originating in the reversibility of covalent bonds. In the framework of this project, new dynamic and stimulable polymer materials will be constructed such as micellar systems, able to respond to various clean and (bio)stimuli like electrochemistry, UV light and carbohydrates.
Moreover, we will exploit the remarkable adhesive properties of the catechol unit, known to strongly binds a wide range of substrates (silicon, titanium, gold and glass substrates for instance), to immobilize complex polymer structures (cyclic polymers), and then endowing surfaces with original properties, especially if cyclic thermostimulable polymers is immobilized.
In this challenging programme, we will demonstrate that the dopamine compound is arguably one of the most promising building blocks which allow for the design of a platform with original polymer architectures. Hence, we firmly believe that this project will have a strong impact in Polymer Chemistry field.
To accomplish this research programme, a consortium will be assembled combining skills and expertise on organic chemistry, controlled radical polymerizations, electrochemistry and surface chemistry.