Chemoluminescent molecules to quantify bond breakage and investigate fracture of elastomers

 

 

^a Laboratory of Soft Matter Science and Engineering, ESPCI ParisTech-UPMC-CNRS, Paris-F

^bDSM Research, Geleen, The Netherlands

^cInstitute for Complex Molecular Systems, Eindhoven - NL

University of Technology, Eindhoven - NL

 

We have recently shown¹ that very brittle and very elastic elastomers can be stiffened and toughened, while retaining elasticity and reversibility of the deformation, by using the interpenetrated networks concept developed for hydrogels^{2, 3}. The elastomers are prepared by sequential swelling and polymerization steps resulting in highly entangled networks combining a high modulus (3 MPa), fully reversible deformation (<3% of residual strain) and ahigh toughness (5 kJ/m²)¹.

The resulting materials have a population of elastic chains with a broad level of prestretching and hence failure strain. The main demonstrated toughening mechanism is the failure of the highly prestretched chains of the network polymerized first, which act as sacrificial bonds while the non prestretched network prevent macroscopic crack propagation.

We have developed a method, by incorporating chemoluminescent molecules⁴, to directly visualize how many and when bonds break. We will present quantitative analyses of the bond breakage during cycles in uniaxial extension and during crack propagation for simple networks, double networks and triple networks. The results will be used to gain insight on how soft elastic materials can be made tougher without being made viscoelastic.

1.     Ducrot, E.; Chen, Y.; Bulters, M.; Sijbesma, R. P.; Creton, C. Science 2014, 344, (6180), 186-189.

2.     Gong, J. P. Soft Matter 2010, 6, (12), 2583-2590.

3.     Webber, R. E.; Creton, C.; Brown, H. R.; Gong, J. P. Macromolecules 2007, 40, (8), 2919-2927.

4.     Chen, Y.; Spiering, A. J. H.; KarthikeyanS; Peters, G. W. M.; Meijer, E. W.; Sijbesma, R. P. Nat Chem 2012, 4, (7), 559-562.