Formation of ordered two-dimensional polymer latticeworks with polygonal meshes by self-organized anisotropic mass transfer

This manuscript addresses the formation of self-assembled two-dimensional (2D) polymer latticeworks with multiple polygonal meshes packed in various ordered arrays. Firstly, ordered arrays of water droplets were formed in the hydrophilic regions of patterned self-assembled monolayers (SAMs) consisting of isolated hydrophilic circles surrounded by a continuous hydrophobic region. After dip-coating this water-patterned surface into a polymer solution in chloroform, dewetting of the polymer solution led to the formation of a crater-like porous polymer film. Next, the resulting polymer film with round pores arranged in a 2D ordered array was subjected to a thermal treatment carried out at a temperature higher than the glass-transition temperature (Tg) of the polymer. The thermal annealing process resulted in a morphological transformation from circular pores into polygonal meshes packed in either a similar or different ordered array. This morphological transition is self-organized, involving mass transfer, an anisotropic process, and is controlled by the minimization of the Gibbs free energy. An empirical equation was established to guide the experiments. Thus, the patterned features of the polymer meshes can be designed via the ordered arrays of the hydrophilic circles of the SAMs as well as by experimental parameters such as the concentration of the polymer solution. The formation of the polymer latticework with polygonal meshes reveals that self-organized mass transfer can be applied in micropatterning by elaborate experimental design.NRC publication: Ye