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Publication Citation: Monolayer Formation of PBLG-PEO Block Copolymers at the Air-Water Interface

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Author(s): Y Park; Y W. Choi; SK Park; C S. Cho; Michael J. Fasolka; Daeson Sohn;
Title: Monolayer Formation of PBLG-PEO Block Copolymers at the Air-Water Interface
Published: November 11, 2004
Abstract: Physicochemical properties of PBLG (poly(gamma-benzyl-L-glutamate))-PEO (poly(ethylene oxide)) diblock copolymers composed of PBLG as the hydrophobic rod component and PEO as the hydrophilic component were investigated at the air-water interface. Surface pressure-area isotherms obtained by the Wilhelmy plate method provide several variables such as molecular size, compressibility of PEO, and the free energy change of the PBLG-PEO block copolymer. GE-1 (M-w of PBLG:PEO = 103,700:12,000), with a relatively longer rod, has negative temperature effects and GE-3 (M-w of PBLG:PEO = 8400:12,000), with a relatively shorter rod, shows a positive temperature effect because of the large entropy loss.These competitions were based on the block size of PBLG and PEO and were affected by various microstructures of the PBLG-PEO diblock copolymer. Monolayer aggregations transferred onto mica from the air-water interface were analyzed with AFM. AFM images of GE-1 monolayers show cylindrical micelles, but the self-assembled structure has many large domains. The monolayer of GE-2 (M-w of PBLG:PEO = 39,800:12,000), which has a medium size rod, forms a spherical structure at the air-water interface. Monolayers of GE-3, with a short rod length, form bilayer structures. These results demonstrate that the microstructures of PBLG-PEO diblock copolymers are related to free energy changes between rod and coil blocks.
Conference: Journal of Colloid and Interface Science
Proceedings: 283 (2)
Pages: 7 pp.
Dates: March 15-16, 2005
Keywords: block copolymer;compressibility;Langmuir-Blodgett;PBLG-PEO;surface pressure
Research Areas:
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