Thermomechanical properties of mineralized nitrogen-doped carbon nanotube/polymer nanocomposites by molecular dynamics simulations

In this paper, we investigate thermomechanical characteristics of silica-mineralized nitrogen-doped carbon nanotube (SC-NCNT)-reinforced poly (methyl methacrylate) (PMMA) nanocomposites for the first time by molecular dynamics simulations. An in-situ mineralization algorithm is employed for the mineralization of the silica layer where the thickness is determined from an atomic stress calculation. Young's modulus, shear modulus, and yield strength of SC-NCNT/PMMA systems are compared with those of nitrogen-doped carbon nanotube(NCNT)/PMMA and carbon nanotube (CNT)/PMMA systems at various filler weight percentage (wt%). Compared with the reinforcing effect of CNTs, SC-NCNT fillers revealed a superior reinforcing effect in the transverse direction. Additionally, the glass transition temperature (T-g) of nanocomposites at different filler wt% is studied. Both the SC-NCNT/PMMA and the CNT/PMMA system show a T-g decrease according to the filler wt% where the former decreases only 6 K and the latter decreases 31 K at 3 wt%. The enhanced thermomechanical properties of the SC-NCNT/PMMA system are attributed to the improved interfacial interaction between the silica layer and the PMMA matrix. Since thermomechanical properties of SC-NCNT/PMMA nanocomposites have not been studied since the discovery of the SC-NCNT filler, our simulation study can be a good guide for experimental researches on the thermomechanical behavior of mineralized CNTs.