Breath figure templated self-assembly of porous diblock copolymer films.
Porous polyethylene oxide-b-polyfluorooctylmethacrylate (PEO-b-PFOMA) diblock copolymer films were drop cast onto substrates from Freon (1,1,2-trichlorotrifluoroethane) in a humid atmosphere. The pores in the films exhibit long range hexagonal order in some cases, depending on the PFOMA-to-PEO molecular weight ratio. Films with the best ordered pores were formed with PFOMA-to-PEO ratios of 70 kDa:2 kDa. The pores in the polymer films derive from water droplets that condense as Freon evaporates. The polymer stabilizes the water droplets, or "breath figures," which act as an immiscible template that molds the porous film. Increased polymer hydrophobicity reduces the water wettability of the air/Freon interface, which in turn decreases water droplet nucleation, thus influencing the final pore size and spatial order in the polymer films. We describe how water droplet nucleation influences the final pore size and packing order in the polymer films.
Saunders
Aaron E
AE
Department of Chemical Engineering, Texas Materials Institute, Center for Nano- and Molecular Science and Technology, University of Texas, Austin, Texas 78712, USA.
Dickson
Jasper L
JL
Shah
Parag S
PS
Lee
Min Young
MY
Lim
Kwon Taek
KT
Johnston
Keith P
KP
Korgel
Brian A
BA