Polymer Grafted Nanoparticle Viscosity Modifiers

Abstract

AbstractIt is demonstrated that the addition of nanoparticles can decrease the viscosity of an entangled polymer matrix (plasticization). While there has been considerable effort in understanding the role of bare nanoparticles on viscosity, the corresponding study on grafted particles is nascent. Two nanometer radius zirconia fillers with a bimodal population of grafted PDMS is used. Two fillers are considered: one has grafted chains with a molecular weight, Mg, less than the entanglement M, Mg < Me(ZrO21k 10k), and the other filler has grafted chains M > Mc(the critical Me) (ZrO21k 36k). The ZrO21k 10k composites exhibit plasticization for large matrix molecular weight Mm. The ZrO21k 36k composites, in contrast, have Einstein‐like behavior. The plasticization effects are either due to: the small filler size relative to the tube diameter or an increase in chain mobility at the interface due to autophobic dewetting.