Polystyrenes with Hydrophilic End Groups: Synthesis, Characterization, and Effects on the Self-Assembly of Breath Figure Arrays

We report the synthesis and characterization of a series of hydroxyl-end-functionalized polystyrenes (PS-OH) and the formation of patterned porous films. The polymers were synthesized by chain end reaction of polystyrene having a bromide end group (PS-Br) with hydramines including ethanolamine, diethanol amine, 2-amino-1,3-propanediol, and 2-(2-aminoethoxy) ethanol. The polymers were characterized by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), and differential scanning calorimetry (DSC). It was found that the end groups can influence the glass transition temperature (T-g) of the polystyrenes. The. polymers with different end groups were then used to prepare honeycomb-patterned porous films by the breath figure method. Results reveal that the subtle chain-end modification leads to a dramatic change in the morphology of the films. Honeycomb films with large area ordered structure can be easily prepared from PS-OH. Effects of the end groups as well as blending PS- OH with PS-Br on the surface pore diameter, pore center distance, and the hierarchical structure were studied in detail. As supported by the results of polymer hydrophilicity, in situ observation of the film formation process, as well as the chain mobility, the film structure is supposed to be mainly determined by the precipitation of polystyrene at the solution/water droplet interface and the interfacial activity enhanced by the end groups.