Flow enabled self assembly of polymers

Abstract

Self-assembly of nanoscale materials to form intriguing structures has garnered considerable attention due to their potential applications in optical, electronic, magnetic and information storage devices. Among all the efforts to pattern functional polymers and nano materials, flow-enabled self-assembly (FESA) stands out as a lithography-free evaporation-induced self-assembly technique to construct large-scale 0D, 1D and 2D periodic structures in a simple, robust and cost effective manner. In the first part of the thesis, flow-enabled self-assembly of polystyrene is chosen as the model system, and systematic experiments have been conducted to reveal intrinsic and external variables that lead to 3 possible FESA patterns (i.e., coffee ring induced spoke pattern, fingering instability induced strip pattern, and their intermediate network-like structures). In the second part of the thesis, applications of FESA in patterning electrochromic polymers and fabricating PS-PMMA strips as etching mask of Si microchannels are demonstrated. Both applications convincingly illustrate the advantages of cost effective, large yield and flexible control of flow-enabled self-assembly.