Electrical conductivity and Young's modulus of flexible nanocomposites made by metal-ion implantation of polydimethylsiloxane: The relationship between nanostructure and macroscopic properties

• Published in: Acta materialia Vol. 59; no. 2; pp. 830 - 840
• Main Authors: NIKLAUS, M, SHEA, H. R
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier 2011
• Subjects: Applied sciences; Exact sciences and technology; Implantation; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Micrographs; Modulus of elasticity; Nanocomposites; Other surface treatments; Production techniques; Resistivity; Silicone resins; Surface treatment; Titanium; Transmission electron microscopy; Volume fraction; Elastic constant; Dimethylsiloxane polymer; Elastic modulus; Ion implantation; Polymer matrix composites; Electrical conductivity; Electrical properties; Elasticity; Mechanical properties; Polymer; Nanostructure; Composite material; Surface treatment; Young modulus; Nanocomposite; Electro-active polymers; Nanostructured materials
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2010.10.030

The mechanical and electrical properties of nanocomposites created by gold and titanium implantation into polydimethysiloxane (PDMS) are reported for doses from 1015 to 5A-1016 at.cma degree 2, and for ion energies of 2.5, 5 and 10keV. Transmission electron microscopy (TEM) cross-section micrographs allowed detailed microstructural analysis of the implanted layers. Gold ions penetrate up to 30nm and form crystalline nanoparticles whose size increases with ion dose and energy. Titanium forms a nearly homogeneous amorphous composite with the PDMS up to 18nm thick. Using TEM micrographs, the metal volume fraction of the composite was accurately determined, allowing both electrical conductivity and Young's modulus to be plotted vs. the volume fraction, enabling quantitative use of percolation theory for nanocomposites <30nm thick. This allows the composite's Young's modulus and conductivity to be linked directly to the implantation parameters and volume fraction. Electrical and mechanical properties were measured on the same nanocomposite samples, and different percolation thresholds and exponents were found, showing that, while percolation explains both conduction and stiffness of the composite very well, the interaction between metal nanoparticles occurs differently in determining mechanical and electrical properties.