Modified chemistry of siloxanes under tensile stress: interaction with environment.
We present first principles molecular dynamics simulations of stretched siloxane oligomers in an environment representative of that present in single molecule atomic force microscopy experiments. We determine that the solvent used (hexamethyldisiloxane) does not influence the stretching of the siloxane in the high force regime or the rupture process, but trace amounts of water can induce rupture before the maximum siloxane extension has been attained. This would result in a significantly lower rupture force. The simulations show that the rupture of a covalent bond through a reaction with a molecule from the environment, which would not normally occur between the species when the polymer is not stressed, is possible, opening a route to mechanically induced chemical reactions. The attack of the normally hydrophobic siloxane by water when it is stretched has wider implications for the material failure under tensile stress, where trace amounts of water could induce tearing of the material.
Lupton
Elizabeth M
EM
Department of Chemistry and Biochemistry, and Center for Nanoscience, Ludwig Maximilians University Munich, Butenandtstr. 5-13, Haus E, 81377 Munich, Germany.
Achenbach
Frank
F
Weis
Johann
J
Bräuchle
Christoph
C
Frank
Irmgard
I
D008422:Materials Testing / Q000379:methods*; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D015394:Molecular Structure; D012821:Silanes / Q000737:chemistry; D012833:Siloxanes / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013718:Tensile Strength
D012821:Silanes; D012833:Siloxanes; D012997:Solvents; C520781:hexamethyldisilane