CE06 - Polymères, composites, physique et chimie de la matière molle

Borinic Vitrimers – aBOVE

Submission summary

Vitrimers are polymeric networks containing dynamic bonds such that their topology can rearrange without any loss of network integrity. Thanks to these chemical and structural characteristics, vitrimers undergo a very gradual Arrhenius like viscosity change when the material is both heated above its glass transition (Tg) or melting (Tm) temperature and the exchange reactions between dynamic bonds are fast. Under these conditions, vitrimers behave like viscoelastic liquids and can be processed, reshaped and repaired. At service temperature, the topology of the network is frozen, either by quenching the exchange reaction or the motion of polymer molecules through Tg or crystallization. Both catalysis and polymer functionality/topology can be used to manipulate the rate of exchange within vitrimers, thereby providing simple, yet efficient tools to adjust the transition temperature below which vitrimers behave like thermosets and above which they can be processed and recycled. However, to be processable with similar equipment and production rates as those employed for thermoplastics, an essential feature for their industrial development, vitrimers needs to present low viscosities at processing temperatures, which translates into very fast rates of exchange of their dynamic crosslinks. Therefore, dynamic crosslink is the pivotal element of vitrimers. A very significant advance was recently made in the field of vitrimers thanks to dioxaborolane metathesis. Indeed, dioxaborolane metathesis allowed to “uncorrelate” the exchange reaction from a specific polymer matrix, and therefore to apply a single chemistry to most of the significant polymer families. In striking contrast, other exchange chemistries used to prepare vitrimers are usually specific of a given polymer matrix, due to synthetic limitations or chemical incompatibilities.

In this context, borinic acids offer unique opportunities to design vitrimers with new properties, as they should combine the strength a boron chemistry, already exemplified with dioxaborolane vitrimers, with their specific attributes, such as their hydrolytic stability, which significantly differentiate them from boronic esters, their charged or neutral character, and the labile N-B coordination bond in the case of borinato derivatives. Yet, until recently, the structural diversity around the boron atom has been mostly limited to boronic acid derivatives RB(OR)2, partly due to the tedious preparation of borinic acid derivatives. However, it has been shown recently that amine borane complexes can be used to selectively prepare diarylborinic acids, in the absence of any residual boronic acid or triarylborane.

The aim of the aBOVE project is to design organo- and hydrosoluble vitrimers relying on borinic acid chemistry and to study them in bulk and in solution. This exchange chemistry was selected for its potential to give access to vitrimer (hydro)gels, an area still unexplored, as well as vinyl-based polyelectrolytes and ion conducting vitrimers. In the case of borinato derivatives, i.e. borinic acids complexed with amino alcohols, the possibility to use the labile N-B coordination bond to induce stimuli-triggered auto-vitrimerization of functional polymers will be explored. If successful, this approach will offer an innovative route to transform thermoplastics into vitrimers, without the need to add crosslinkers, reactive additives or catalyst to induce network formation. Therefore, the aBOVE project aims at merging fundamental and application oriented research, to develop new synthetic methodologies and innovative advanced vitrimers, with potential applications in the fields of injectable gels, adhesives, galenic, batteries, fuel cells and separation membranes.

Project coordination

Renaud NICOLAY (Chimie Moléculaire, Macromoléculaire, Matériaux)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

ISM Institut des Sciences Moléculaires
C3M Chimie Moléculaire, Macromoléculaire, Matériaux

Help of the ANR 393,791 euros
Beginning and duration of the scientific project: October 2019 - 48 Months

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