Polymer Thin Films

Block copolymer (BCP) research is an area which has been developed extensively over the past few years, due to its potential to form a variety of periodic structures by microphase separation. In addition, BCP films hold great potential for yielding periodic nanostructures in a large area. It is important to achieve well-ordered BCP nanopatterns for understanding the self-assembly behavior of BCPs and the factors influencing the phenomena. Therefore, our group is interested in investigating the kinetics & phase separation behavior of block copolymer self-assembly in confined systems.


The following topics are of current interest to our group.


A. Lattice transition of sphere forming block copolymer

B. Morphology transformation of block copolymer surface micells

A. Lattice Transition of Sphere Forming Block Copolymer

In sphere-forming block copolymers' self-assembly, their optimal packing structure is defined by the combination of entropic and enthalpic contributions, and these can be changed by controlling external environments like temperature, solvent quality, and else. We could observe the structural transition in BCP thin films under solvent annealing condition, and conduct in-depth analysis based on images.

B. Morphology Transformation of Block Copolymer Surface Micelles

Amphiphilic block copolymers (BCPs) can form 2-D confined micellar structures, called BCP surface micelles, through self-assembly at the air-water interface. These BCP surface micelles can transform into diverse nanostructures with direct immersion in specific solvents. To investigate this phenomena, we conduct experiments by controlling various experimental parameters, and further discuss how these parameters alter the rearrangement kinetics of the surface micelles. Based on the understanding of complex chain dynamics upon solvent immersion, our research provides a new strategy to fabricate a uniform array of diverse BCP nanopatterns.

C. Morphology Transformation of Metal-Infiltrated Block Copolymer Thin Films

Disordered structures in nanoscale have received increasing interest owing to their unique capability to localize wave-like quasiparticles – a renowned phenomenon known as Anderson localization. We present a methodology to construct such disordered structures by deliberately introducing controlled degree of defects into a single crystalline hexagonal array built on a sphere-forming block copolymer thin film. Various tunable parameters, including but not limited to relative ratio of different metal precursors incorporated into the core blocks, are proposed to broaden the spectrum of disorder. Our research potentially offers a platform for designing and engineering disordered systems which could mediate quasiparticle localization.

After the self-assembly of block copolymers, metals can be infiltrated into either of the two domains. These metal infiltrated structures can be transformed into various structures via thermal annealing. Depending on the original film's properties (e.g., defect density), the resulting films have different structures. We investigate the morphology alteration of such BCP films by gaining insight into the kinetics and thermodynamics of metal infiltrated BCP chains. Moreover, we seek for new avenues for the fabrication of nanodevices utilizing the large area production of such unique structures.