Macromolecules, Vol.48, No.19, 7320-7326, 2015
Linear Rheology of Supramolecular Polymers Center-Functionalized with Strong Stickers
We investigate the linear viscoelastic properties of a series of low polydispersity poly(n-butyl) acrylate chains center-functionalized with a triurea interacting moiety, able to self-associate by six hydrogen bonds. Depending on the molecular weight (M-n) of the side chains, the polymers can self-associate and form supramolecular structures in the melt state. For M-n < 40 kg/mol, the polymers form large bundles of parallel rods which relax stress as large colloidal objects. For M-n >= 40 kg/mol, the self-assembly of stickers form smaller and randomly oriented rods and the viscoelastic properties are mainly governed by the side chains relaxations, as observed for weak stickers. However, in both regimes, the side chains relax at short time scales, and then, the relaxation of fibrillar aggregates follow (by scission or diffusion process) at long time scales. The weak correlation between both relaxation modes makes the tuning of the linear viscoelastic properties relatively easy by varying independently the length of the side chains and the associating strength of the sticker. The good control of the molecular dynamics via the chemical structure makes the supramolecular center-functionalized polymers extremely interesting for materials applications where dissipative rheological behaviors are targeted over large frequencies ranges, such as vibration damping or adhesive applications.