Take a sneak peek at the new NIST.gov and let us know what you think!
(Please note: some content may not be complete on the beta site.).
NIST Authors in Bold
|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|
|Dates:||March 15-16, 2005|
|Keywords:||block copolymer,compressibility,Langmuir-Blodgett,PBLG-PEO,surface pressure|
|PDF version:||Click here to retrieve PDF version of paper (484KB)|