PPP Micro-nanostructures Fabricated By Self-assembly And Their Performances

Due to their unique photoelectric properties and application in optoelectronic devices, conjugated polymers have received much attention. The stiff conjugated polymer, due to the poor solubility, are attached flexible side chains to achieve the high solubility in common solvents. The substituted poly(p-phenylene) is a typical aromatic representative of hairy-rod polymers, which are constituted of an aromatic backbone and flexible side chains. In this work, poly(2,5-dialkoxyphenylene)s was choose as the research object to investigate the self-assembly behaviors in different solvents. The observation of optical properties of polymer in different solvents can imply the changes of the polymer conformations, during the self-assembly process. The optical properties and assembly mechanism of the polymeric micro-nanostructure were studied by adjusting the solvent atmosphere, solvent and the concentrations of polymer solutions, which can be controlled to prepare different conjugated polymer micro-nanostructures.The solvent quality such as polarity, aromaticity and solubility parameter can govern the conjugation length, and adjust the extended, twist and shrinking polymer conformations. By the addition of the polar poor solvent such as alchol, the polymeric aggregates can be induced to form the colloidal particles and then precipitate. In addition, the nonpolar poor solvent such as hexane can interact with the flexible alkoxy side chains to form the three-dimensional networks and finally the sol formed in solvent. Therefore, the species and the proportion of the mixed solvents can be controllable to prepare the conjugated polymeric supermacromolecular architectures.The various morphologies of PPP were self-assembled from the solution in nonsolvent vapor atmospheres. From Hexane/good solvent systems, the sponge-like superstructures with irregular micron-sized caves can be obtained by air-drying. The polar nonsolvent MeOH vapor atmospheres in the solution can induce the hairy-rod polymer molecules to form nanofibers and then aggregate further flower-or coil-like microspheres. The good solvents adjust the shapes of nanopetals.In the different good solvent vapor atmospheres, the self-assembly behaviors of PPP were also studied. The well-defined 1D nanowires can be self-assembled from the dilute solutions. Therefore, the polymer morphologies in thin films strongly depend on the state of the solution and the film processing conditions, which change the optoelectronic properties of the films. The driving force of aggregation would be the side-chain entanglement and the intermolecular ?-? interactions, which are dependent on the polymer solution concentration. The vapor pressure and polarity of solvents are also responsible for the morphologies of polymer. The discussion of this study can develop the further application of conjugated polymer in optoelectronic devices and so on.