Thermophysical properties of graphene reinforced with polymethyl methacrylate nanoparticles for technological applications: a molecular model

Abstract

Context

“Nanostructure of graphene-reinforced with polymethyl methacrylate” (PMMA-G), and vice versa, is investigated using its molecular structure, in the present work. The PMMA-G nanostructure was constructed by bonding PMMA with graphene nanosheet in a sense to get three different configurations. Each configuration consisted of polymeric structures with three degrees of polymerization (such as monomers, dimers, and trimers polymers, respectively). The results obtained make this new PMMA-G material more reliable and useful for several important technological applications, such as the construction of devices for hydrogen storage, batteries, super-capacitors, sensors and solar cells, and dental materials, among others. The PMMA reinforcement with graphene favors its thermal stability maintaining greater dimensional stability against thermal variations (minimal deformation); this is crucial for electronic devices and for packaging systems that undergo repeated thermal cycles during their manufacture, and also they are good thermal insulators. For microelectronic devices, such as chips and sensors, with low thermal expansion coefficients, it may prevent unwanted deformation. The PMMA density increases when it is reinforced with graphene, the polymers tend to be stiffer and stronger, important for applications where greater structural strength is required, and also become less soluble in solvents than pure PMMA and more resistant to the action of chemicals. Comparing a common polyvinyl chloride (PVC) material with the PMMA-G polymer, we found more advantages, such as the PMMA-G is less expensive, it has improved aesthetics, it is less rigid, it has more stable color, and it is less prone to keeping microorganisms alive, among others advantages.

Methods

Materials Studio (MS) software is used as the best and most reliable computational tool in the sense of analyzing some thermophysical properties of graphene reinforced with polymethyl methacrylate nanoparticles. The most stable PMMA nanostructures, graphene and PMMA-G, were obtained by applying density functional theory methods implemented by a DMol³ computational code under the MS software. The Synthia computational code, also under MS software, which is based on connectivity indices methods derived from graph theory combined with geometric variables, was also applied, to each polymerized structure, obtaining some of the important thermophysical properties; i.e., Van der Waals volume, molar volume, coefficient of volumetric thermal expansion, density, solid phase molar heat capacity at constant pressure, thermal conductivity, glass transition temperature, secondary relaxation temperature, and half decomposition temperature. The best-used hardware was a T7500 Dell Workstation, with 3.47 GHz Quad-Core Processors, 96 Gb RAM memory, and a perpetual MS software license.