Equipe d`accueil / Hosting Team : Equipe Soft Polymer Networks

Equipe d'accueil / Hosting Team : Equipe Soft Polymer Networks
Site Web / Web site :http : https://www.ppmd.espci.fr/spip.php?rubrique10
Responsables du stage (encadrants) / Direct Supervisor : Costantino Creton, Pierre Millereau
Tél / Tel : 01 40 79 46 83
E-mail : [email protected], [email protected]
Période de stage / Internship period: janvier-juillet 2016
Gratification / Salary : ~546 Euros/mois
Possibilité de continuer en thèse : Oui
Background
Nominal stress (MPa)
Simple networks of elastomers have very poor mechanical properties. They are generally either stiff
and brittle, or soft and extensible depending on the amount of crosslinker. In partnership with DSM
research, we recently succeeded in combining the two kinds of networks into a bicontinuous
interpenetrated structure which is able to increase both stiffness and extensibility1 and results in
extremely tough unfilled elastomers: perfectly elastic at low and moderate strains but highly
dissipative at large strains, delaying crack propagation. The synthesis developed in the lab is carried
out with UV light and in multiple steps of free radical polymerization to obtain these bicontinuous and
interpenetrated networks. SN = 1step, DN = two steps, TN = 3 steps and QN = 4steps.
10
Such unique combination of properties for an unfilled
QN
elastomer is due to the existence, inside the material, of
TN
8
polymer chains with a multimodal level of prestretching.
6
4
Subject of the internship
QN
DN
The objective of this internship is to synthesize and
characterize new types of multiple networks with finely
tuned prestretching levels. Only a few systems have been
SN
0
made for the moment and many questions remain. In
1.0
1.5
2.0
2.5
3.0
Lambda
particular the influence of the transfer reactions occurring
during the different synthesis remains to be studied, and a solution to avoid it would be to use
methacylate monomers.
2
Also, preliminary experiments have been carried out on multiple networks with different monomers,
showing interesting properties that might be due to a local microphase separation. Further similar
networks will be synthesized during the internship. Once the synthesis is completed, several
characterizations of the mechanical properties will be carried out such as viscoelastic properties in
small and large strain, hysteresis due to damage and fracture toughness tests.
This internship is an opportunity to have a good insight in the physical chemistry of the materials.
Indeed the internship will combine the synthesis and the mechanical characterization of innovative
elastomers.
Qualité requises
Stage idéalement ciblé pour un master physico-chimie des matériaux ou SMNO
Références
1. Ducrot, E., Y. Chen, M. Bulters, R. P. Sijbesma and C. Creton (2014). "Toughening Elastomers
with Sacrificial Bonds and Watching them Break." Science 344(6180): 186-189.