F.C. Robles Hernández

Photomechanical response of composites based on PDMS and carbon soot nanoparticles under IR laser irradiation

We demonstrate a new type of smart composite based on carbon soot nanoparticles (CSP) and Poly(dimethylsiloxane). The addition of CSP in this polymeric matrix yields a composite with photomechanical response triggered by IR laser irradiation. The load capacity of this optically driven material ranged between 10 and 16 kPa depending on the CSP concentration in the composites. These photomechanical actuation features promises a good alternative for low-cost smart composite materials for photonic applications such as optically reconfigurable surfaces and optical actuating-sensing devices.

HRTEM low dose: the unfold of the morphed graphene, from amorphous carbon to morphed graphenes

AbstractWe present experimental evidence under low-dose conditions transmission electron microscopy for the unfolding of the evolving changes in carbon soot during mechanical milling. The milled soot shows evolving changes as a function of the milling severity or time. Those changes are responsible for the transformation from amorphous carbon to graphenes, graphitic carbon, and highly ordered structures such as morphed graphenes, namely Rh6 and Rh6-II. The morphed graphenes are corrugated layers of carbon with cross-linked covalently nature and sp2- or sp3-type allotropes. Electron microscopy and numerical simulations are excellent complementary tools to identify those phases. Furthermore, the TEAM 05 microscope is an outstanding tool to resolve the microstructure and prevent any damage to the sample. Other characterization techniques such as XRD, Raman, and XPS fade to convey a true identification of those phases because the samples are usually blends or mixes of the mentioned phases.

Electron Microscopy of Morphed Graphene Nanostructures Synthesized by Mechanical Milling

There are many carbon nanostructures (CN’s) and most likely graphene and diamond are still the most interesting due to its physical properties. Synthesis of CN’s is made via diverse methods including vapor deposition, exfoliation (graphene) or the use of high pressure and temperature (diamond). Thus it is interesting to investigate a purely mechanical, simple and room temperature procedure to synthesize CN’s. This investigation deals with the products of mechanically milling carbon soot at room temperature that has rendered a different C allotrope herein identified as morphed graphene. Identification of a new allotrope is quite complicated due to the wide variety of known carbon phases and the pronounce effects of even subtle morphology changes as in the twisted layer graphene. Nevertheless different forms of evidence have been shown that lead to conclude that the product of the synthesis procedure in use (mechanical milling) indeed delivers a new allotrope [1]. Starting with carbon soot, milling develops a variety of phases ranging from graphene (single, double-layered) to diamond. Similar phases have been previously proposed from theoretical considerations and numerical calculations [2]. In this work, medium dose electron microscopy is used to an in-depth characterization of the product phases and especially this newly found allotrope known as Rh6 and Rh6-II having a pure sp2 bonding.