Dynamics of linear alternating polymer-nanoparticle hybrids

Compared with the linear viscoelastic properties of association polymers, the glassy dynamics of association polymers are much less understood. In this contribution, we study the influence of supramolecular structures on the structural relaxation and the glass transition of a new type of association polymers, the linear alternating polystyrene (PS)-polyhedral oligomeric silsesquioxane (POSS) hybrids (LAPH). The LAPH exhibits inter-connected flower-like micellar supramolecular structures. Broadband dielectric spectroscopy (BDS) and differential scanning calorimetry have been employed to probe the structural relaxation and the glass transition. The glass transition temperature of LAPH is comparable to the PS homopolymer with similar molecular weight of the PS block rather than the whole polymer hybrid chain. Moreover, the LAPH exhibits a much lower fragility index than the PS homopolymer. Since the nanoparticle-nanoparticle association time is much longer than the structural relaxation of the LAPH, one cannot explain the low fragility index of LAPH from the accessible configurational entropy. These observations suggest the supramolecular structures affect strongly the glass formation behaviors of LAPH.