Molecular Dynamics Study of the Swelling of Poly(methyl methacrylate) in Supercritical Carbon Dioxide

Abstract

The swelling of a poly (methyl methacrylate) in supercritical carbon dioxide was studied by means of full atomistic classical molecular dynamics simulation. In order to characterize the polymer swelling, we calculated various properties related to the density, structure, and dynamics of polymer chains as a function of the simulation time, temperature, and pressure. In addition, we compared the properties of the macromolecular chains in supercritical CO2 with the properties of the corresponding bulk system at the same temperature and atmospheric pressure. It was shown that diffusion of CO2 molecules into the polymer led to a significant increase in the chain mobility and distances between them. Analysis of diffusion coefficients of CO2 molecules inside and outside the poly(methyl methacrylate) sample has shown that carbon dioxide actively interacts with the functional groups of poly (methyl methacrylate). Joint analysis of the radial distribution functions obtained from classical molecular dynamics and of the averaging interatomic distances from Car-Parrinello molecular dynamics allows us to make a conclusion about the possibility of formation of weak hydrogen bonds between the carbon dioxide oxygen atom and the hydrogen atoms of the polymer methyl groups.

Impregnation of Poly(methyl methacrylate) with Carbamazepine in Supercritical Carbon Dioxide: Molecular Dynamics Simulation

“…We tried to estimate the swelling degree as it is described in our previous work. 11 Namely, we used the relation: α = m ads /m 0 , where m 0 is the mass of the original polymer, and m ads is the mass of the solvent and solute adsorbed by the polymer. The more detailed procedure of the swelling degree calculation can be found in Supporting Information.…”

“…The MD simulations were conducted in GPU-accelerated GROMACS v5.0.7. 46 In our previous work, 11 we described the methodology of bulk PMMA simulation with the OPLSAA force field in detail. 47 By comparing the values of PMMA physical properties such as density, thermal expansion coefficient, and glass transition temperature calculated through simulation with the experimental ones, we concluded that the OPLSAA force field is suitable for PMMA modeling.…”

“…In the current study, we used the same Lennard-Jones (LJ) and partial atomic charge parameters as in. 11 For carbon dioxide, we used the model developed by Zhang and Duan. 48 The LJ and partial atomic charge parameters applied to CBZ as well as to PMMA are presented in Table S1 in Supporting Information.…”

Preparation of graphene/PMMA composites with assistance of ultrasonic wave under supercritical CO2 conditions

“…The coupling effect of carbon dioxide is also very important in this process. The coupling effect of carbon dioxide can provide MMA with a space where it can be fully dispersed and with a very small viscosity and great mobility, so that it can better absorb the energy generated by the ultrasonic cavitation and break the chemical bonds of the monomer molecules [38] .…”

Experimental and computational investigation of polylactic acid/silver‐NP nanocomposite with antimicrobial activity prepared by plasma in liquid

“…Along with experimental studies, simulation approaches are useful and powerful tools for investigating systems containing a polymer at the molecular level. [ 36 ] Recently, many studies have directed their attention toward the theoretical understanding of molecular aspects governing the self‐assembly of polymers on inorganic metal nanocrystals. [ 37,38 ]…”