Wednesday April 10th, 2019

Thesis: Platform of supramolecular assemblies of hydrogen bonding synthetic copolymers

 POSITION FILLED

Titre du projet :

“Platform of supramolecular assemblies of hydrogen bonding synthetic copolymers”

 

 

Laboratory: Macromolecular Engineering and Architetures of the Institut Charles Gerhardt de Montpellier

Start Date: 1 October 2019

Supervisors: Vincent Ladmiral and Sylvain Catrouillet

Thesis Project

Amphiphilic block copolymers self-assemble in solution and form micelles composed of a solvophobic core and a solvophilic corona.[1] These self-assemblies are attracting major interest for their ability to form various morphologies (spheres, cylinders, vesicles, lamellae, Janus particles, etc…) and the possibility to vary their functionality. However, individual polymer chains (i.e. unimers) are generally unable to exchange between micelles. This is why these systems are often insensitive to external stimuli and are difficult to adapt.

A concept that resolves this issue consists in the use of hydrogen bonds as the driving force of the self-association instead of solvophobic interactions. Indeed, hydrogen bonds are dynamic and directional, endowing these objects with the ability to respond to stimuli, thus opening potential applications such as drug delivery[2] and the synthesis of functional materials with a controlled porosity.[3] In nature, hydrogen bonds are at the origin of secondary and tertiary structure of enzymes (proteins) and are also responsible for the double helix structure of DNA. Hydrogen bonds in DNA originate from the nucleobases [Cytosine (C), Guanine (G), Adenine (A), Thymine (T) (and Uracile for RNA)]. The co-assembly of complementary nucleobases is favored compared to other combinations (A–T > A–A, A–G or A–C for example in the case of Adenine). Furthermore the longer the DNA, the stronger the self-association between two DNA strands is. In a biomimetic approach, some research groups have investigated the synthesis of polymers functionalized by nucleobases.[4] These systems form supramolecular self-assemblies with an adaptable morphology.

These first studies give a proof-of-concept but do not precisely investigate the parameters influencing the co-assemblies and their limits. This project aims at studying the influence of parameters such as the polymer architecture, their topology, nature, composition, molar mass, dispersity as well as the nature of the solvent (especially in function of its ability to form hydrogen bonds), temperature, pH, ionic strength, on the supramolecular co-assemblies. In fine, the goal of the project will be to rationalize and optimize the design of the copolymers and the formulation required to obtain controllable and stimuli-responsive co-assemblies. Thus, an adaptable supramolecular platform made of synthetic hydrogen bonding polymers will be designed.

[1] Mai Y. and Eisenberg A., Chem. Soc. Rev. 2012, 41(18), 5969-5985.

[2] Ahmad Z., Shah A., Siddiq M., and Kraatz H.-B., RSC Advances 2014, 4(33), 17028-17038.

[3] Bagshaw S.A., Prouzet E., and Pinnavaia T.J., Science 1995, 269(5228), 1242-1244.

[4] Hua Z., Keogh R., Li Z., Wilks T.R., Chen G., and O’Reilly R.K., Macromolecules 2017, 50(9), 3662-3670.

Profile of the Candidate

The candidate should possess a Master’s degree or equivalent and have skills in organic and polymer synthesis. An interest for physico-chemical characterization of polymers would be appreciated.

Candidature

The candidates need to contact the thesis supervisors: Vincent Ladmiral (vincent.ladmiral@enscm.fr) and Sylvain Catrouillet (sylvain.catrouillet@umontpellier.fr).

Candidates must also apply on the following website before May 31: https://www.adum.fr/as/ed/voirproposition.pl?langue=fr&site=ed459&matricule_prop=25060

The application consists of a CV, a cover letter stating the applicant’s motivation to undertake the project, the grade cards for the Master studies up to the date of the application (combined into one pdf file). It is possible to include recommendation letters from one or two teachers of the Master’s program.

Location: Montpellier

Laboratory: IAM in the ICGM

Deadline: 31 May 2019

Begins: 1 October 2019