Side chain vs main chain.: Who dominates? : a polyester-grafted poly(p-phenyleneethynylene) with two different morphologies

The well-defined mesoscopic structures formed by a polydisperse polyester-substituted poly(p-phenylenethynylene) (PPE) was demonstrated. The structure and the size of the observed features are governed by the interplay between the stacking of the backbone and the association of the side chains. The supramolecular assemblies of PPE were reported when cast from solutions onto silicon oxide wafers and their morphological evolution were followed with annealing into a thermodynamically stable state. Thin films of PPE were obtained by drop-casting onto or dipping silicon wafers into a 0.1 % solution of PPE in chloroform. The main chains in the annealed films and in the thermodynamic equilibrium,controls the morphology while in the kinetically trapped solution state of PPE, and the side chains force the main chains into softer spheres that appear as circles when probed by atomic force microscopy (AFM) using high tapping strengths.