title: Phase behavior of block co-poly(ethylene oxide-butylene oxide), E18B9 in water, by small angle neutron scattering.
abstract: We present a small angle neutron scattering (SANS) study into the micellar structures of diblock copolymer E18B9 (where E denotes a ethylene oxide unit and B denotes a butylene oxide unit, 18 and 9 being the number of repeat units respectively) in aqueous solution over a range of five different concentrations (0.2, 1.0, 10.0, 20.0, and 40.0% (by mass fraction)) and eight temperatures (10 to 90 degrees C). The NG7 30 m SANS instrument provides a q range of 0.0009 to 0.5548 A(-1), thus probing the structure over a very broad length scale. At low temperature and low concentration, spherical micelles exist, elongating into worm-like structures at higher temperatures. This transition is observed by the scaling of the scattered intensity at low q and confirmed upon fitting to an appropriate model. Upon increasing concentration, the micelles pack into ordered arrays of either hexagonally packed rod-like micelles or lamellar sheets, again dependent on temperature. Both concentration and temperature effects of this block copolymer have been discussed.
authors.affiliation: Polymers Division, Stop 8542, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8542, USA. anorman1@umd.edu
authors.forename: Alexander I
authors.initials: AI
authors.lastname: Norman
authors.forename: Derek L
authors.initials: DL
authors.lastname: Ho
authors.forename: Alamgir
authors.initials: A
authors.lastname: Karim
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Amis