Dispersing nanoparticles in a polymer matrix: are long, dense polymer tethers really necessary?

Dispersing nanoparticles in a polymer matrix is intrinsically challenging because of unfavorable entropic interactions between the matrix and the nanoparticle. Similar to suspensions of larger colloidal particles, it has been found that thermodynamically stable dispersions of nanoparticles can be achieved in polymer matrices when the nanoparticles are decorated with dense layers of polymer tethers whose molecular weight is comparable to or greater than that of the matrix. Utilizing molecular dynamics simulations, we demonstrate that, in contrast to larger colloidal particles, repulsive interactions between nanoparticles can be achieved with tethered polymers much shorter than the polymer matrix when relatively sparse grafting is employed.