Thermal Properties of Particle Brush Materials: Effect of Polymer Graft Architecture on the Glass Transition Temperature in Polymer‐Grafted Colloidal Systems

Abstract

SummaryThe governing parameters controlling the glass transition temperature of polymer‐grafted particle systems are analyzed for the particular case of polystyrene (PS)‐grafted silica colloids in the dense grafting limit. At a given degree of polymerization of surface‐grafted chains the glass transition temperature is found to increase as compared to linear chain polymers of equivalent degree of polymerization. The difference in the glass transition temperature between polymer‐grafted particle systems and their respective linear polymer analogs increases with decreasing degree of polymerization of surface‐grafted chains and levels off at similar plateau values for particle brushes of distinct particle core size. The trend toward increased glass transition temperature is interpreted as a consequence of the increased steric hindrance in polymer‐grafted particles that counteracts the relaxation of surface‐grafted polymer chains. The increase in glass transition temperature is shown to be approximately consistent with the chain conformational regimes that are predicted on the basis of a Daoud‐Cotton type scaling model.