Full elastic constitutive relation of non-isotropic aligned-CNT/PDMS flexible nanocomposites.

The elastic response of vertically aligned-carbon nanotube/polydimethylsiloxane (A-CNT/PDMS) nanocomposites is presented in this study and related to the underlying aligned-CNT morphology. Multiwalled carbon nanotubes (MWCNTs) at 1% Vf are embedded in a flexible substrate of PDMS to create a flexible polymer nanocomposite (PNC). The PNC properties are evaluated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and tensile mechanical tests, and the full linearly elastic constitutive relation is established for such a PNC. The results suggest that the CNTs retain the alignment after wetting and curing of PDMS. PDMS is significantly modified by the reinforcing aligned-CNT fibers, demonstrating non-isotropic (as opposed to the isotropic neat PDMS) elastic properties all different from PDMS (Young's modulus of 0.8 MPa), including an anisotropy ratio of 4.8 and increases in the modulus of A-CNT/PDMS over PDMS by more than 900% and 100%, in the CNT longitudinal and transverse directions, respectively. This study reports the first full constitutive relation that may be useful in modeling PNCs as composites or as elements of hierarchical nanoengineered composites, particularly PDMS-CNT PNCs are envisioned as elements in biomedical devices such as pressure transducers and energy harvesters.

[1]  A John Hart,et al.  Fabrication and Characterization of Ultrahigh‐Volume‐ Fraction Aligned Carbon Nanotube–Polymer Composites , 2008, Advanced materials.

[2]  Goutam Koley,et al.  Miniaturized implantable pressure and oxygen sensors based on polydimethylsiloxane thin films. , 2009, Materials science & engineering. R, Reports : a review journal.

[3]  P. Ajayan,et al.  Synthesis and Characterization of Thickness-Aligned Carbon Nanotube−Polymer Composite Films , 2005 .

[4]  Otto Zhou,et al.  Deformation of carbon nanotubes in nanotube–polymer composites , 1999 .

[5]  Kee Suk Ryu,et al.  A modular microfluidic architecture for integrated biochemical analysis. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[6]  Jie Xiong,et al.  Polymer‐Embedded Carbon Nanotube Ribbons for Stretchable Conductors , 2010, Advanced materials.

[7]  Jin Zhai,et al.  Wetting and anti-wetting on aligned carbon nanotube films. , 2006, Soft matter.

[8]  P. Pissis,et al.  Glass transition and segmental dynamics in poly(dimethylsiloxane)/silica nanocomposites studied by various techniques , 2007 .

[9]  Robert H. Hauge,et al.  Crystallization and orientation studies in polypropylene/single wall carbon nanotube composite , 2003 .

[10]  P. Geerlings,et al.  Theoretical analysis of carbon nanotube wetting in polystyrene nanocomposites. , 2009, Physical chemistry chemical physics : PCCP.

[11]  Joost Conrad Lötters,et al.  Polydimethylsiloxane as an elastic material applied in a capacitive accelerometer , 1996 .

[12]  Z. Ren,et al.  Dispersion and alignment of carbon nanotubes in polycarbonate , 2003 .

[13]  D. Beebe,et al.  Three-dimensional micro-channel fabrication in polydimethylsiloxane (PDMS) elastomer , 2000, Journal of Microelectromechanical Systems.

[14]  Chunyu Li,et al.  Quantized molecular structural mechanics modeling for studying the specific heat of single-walled carbon nanotubes , 2005 .

[15]  Hui-Ming Cheng,et al.  Mechanical and electrical properties of a MWNT/epoxy composite , 2002 .

[16]  Yong-Jun Kim,et al.  Flexible wireless pressure sensor module , 2005 .

[17]  R. D. Bradshaw,et al.  Fiber waviness in nanotube-reinforced polymer composites—II: modeling via numerical approximation of the dilute strain concentration tensor , 2003, Composites Science and Technology.

[18]  K. Khanafer,et al.  Effects of strain rate, mixing ratio, and stress–strain definition on the mechanical behavior of the polydimethylsiloxane (PDMS) material as related to its biological applications , 2009, Biomedical microdevices.

[19]  J. Tour,et al.  Covalent Functionalization of Single-Walled Carbon Nanotubes for Materials Applications , 2004 .

[20]  J. Bernholc,et al.  Nanomechanics of carbon tubes: Instabilities beyond linear response. , 1996, Physical review letters.

[21]  Micah J. Green,et al.  NANOTUBES AS POLYMERS , 2009 .

[22]  Brian L. Wardle,et al.  Multifunctional properties of high volume fraction aligned carbon nanotube polymer composites with controlled morphology , 2009 .

[23]  T. Schmitz-Rode,et al.  Vascular capsule for telemetric monitoring of blood pressure. , 2003, RoFo : Fortschritte auf dem Gebiete der Rontgenstrahlen und der Nuklearmedizin.

[24]  A. Rinzler,et al.  ALIGNED SINGLE-WALL CARBON NANOTUBES IN COMPOSITES BY MELT PROCESSING METHODS , 2000 .

[25]  Z. Suo,et al.  Stretchable gold conductors on elastomeric substrates , 2003 .

[26]  K. R. Atkinson,et al.  The effect of carbon nanotube properties on the degree of dispersion and reinforcement of high density polyethylene , 2010 .

[27]  Frank T. Fisher,et al.  Fiber waviness in nanotube-reinforced polymer composites-I: Modulus predictions using effective nanotube properties , 2003 .

[28]  Brian L. Wardle,et al.  Flexible Pressure Sensors: Modeling and Experimental Characterization , 2012 .

[29]  Frank T. Fisher,et al.  Effects of nanotube waviness on the modulus of nanotube-reinforced polymers , 2002 .

[30]  Donald W. Brenner,et al.  The stress–strain behavior of polymer–nanotube composites from molecular dynamics simulation , 2003 .

[31]  James M. Tour,et al.  Materials Science: Nanotube composites , 2007, Nature.

[32]  R. Gorga,et al.  Morphological and mechanical properties of carbon nanotube/polymer composites via melt compounding , 2006 .

[33]  R. Superfine,et al.  Bending and buckling of carbon nanotubes under large strain , 1997, Nature.

[34]  I. Kinloch,et al.  Ultra-low electrical percolation threshold in carbon-nanotube-epoxy composites , 2003 .

[35]  Vincent Studer,et al.  Scaling properties of a low-actuation pressure microfluidic valve , 2004 .

[36]  P. Veltink,et al.  The mechanical properties of the rubber elastic polymer polydimethylsiloxane for sensor applications , 1997 .

[37]  Tsu-Wei Chou,et al.  Nanocomposites in context , 2005 .

[38]  Brian L. Wardle,et al.  Nanocomposite Flexible Pressure Sensor for Biomedical Applications , 2011 .

[39]  K. Begum,et al.  Prediction Models for the Elastic Modulus of Fiber-reinforced Polymer Composites: An Analysis , 2011 .

[40]  R. L. Shambaugh,et al.  Enhancing the strength of polypropylene fibers with carbon nanotubes , 2004 .

[41]  Brian L. Wardle,et al.  Fabrication of composite microstructures by capillarity-driven wetting of aligned carbon nanotubes with polymers , 2007 .

[42]  J. R. Raney,et al.  Synthesis and characterization of carbon nanotube-polymer multilayer structures. , 2011, ACS nano.

[43]  J. Lu,et al.  Elastic Properties of Carbon Nanotubes and Nanoropes , 1997, cond-mat/9704219.

[44]  Anastasios John Hart,et al.  Rapid growth and flow-mediated nucleation of millimeter-scale aligned carbon nanotube structures from a thin-film catalyst. , 2006, The journal of physical chemistry. B.

[45]  A. Slocum,et al.  Conductive Carbon Nanotube Composite Microprobes , 2008 .

[46]  A. Slocum,et al.  High-yield growth of vertically aligned carbon nanotubes on a continuously moving substrate , 2009, Nanotechnology.

[47]  Weileun Fang,et al.  Static and dynamic mechanical properties of polydimethylsiloxane/carbon nanotube nanocomposites , 2009 .

[48]  R. Andrews,et al.  Carbon nanotube polymer composites , 2004 .