Thermoreversible, epitaxial fcc<-->bcc transitions in block copolymer solutions.
Uncharged block copolymer micelles display thermoreversible transitions between close-packed and bcc lattices for a range of concentration, solvent selectivity, and copolymer composition. Using small-angle x-ray scattering on shear-oriented solutions, highly aligned fcc crystals are seen to transform epitaxially to bcc crystals, with fcc/bcc orientational relationships that are well established in martensitic transformations in metals. The transition is driven by decreasing solvent selectivity with increasing temperature, inducing solvent penetration of the micellar core.
Bang
Joona
J
Departments of Chemistry and Chemical Engineering & Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Lodge
Timothy P
TP
Wang
Xiaohui
X
Brinker
Kristin L
KL
Burghardt
Wesley R
WR