A simulation study on the effect of nanoparticle size on the glass transition temperature of polymer nanocomposites

RAA Khan and HK Qi and JH Huang and MB Luo, SOFT MATTER, 17, 8095-8104 (2021).

DOI: 10.1039/d1sm00843a

The effect of the size of nanoparticles, sigma(NP), on the glass transition temperature, T-g, of polymer nanocomposites is studied by using molecular dynamics simulations. The variation of T-g with sigma(NP) shows two distinct behaviours for polymer nanocomposites at low and high volume fractions of nanoparticles (f(NP)). At a low f(NP), T-g decays almost exponentially with sigma(NP), whereas at a high f(NP)T(g) shows a complex behaviour: it initially increases and then decreases with increasing sigma(NP). The decrease in T-g with sigma(NP) is due to the significant decrease of adsorbed polymer monomers, while the increase in T-g with sigma(NP) is attributed to the slower diffusion of larger nanoparticles. We have also investigated the diffusion and relaxation of polymer chains at a temperature above T-g for both low and high f(NP)s. The diffusion constant and relaxation time of polymer chains are highly consistent with the behaviour of T-g.

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