Structural transitions in polydiacetylene Langmuir films.
Polydiacetylene (PDA) Langmuir films (LFs) were investigated directly at the air/water interface using in situ synchrotron grazing incidence X-ray diffraction, and ex situ transmissison electron microscopy and diffraction. The films were compressed and polymerized on pure water. A crystallographic model describes the structures and phase transitions of the unpolymerized (monomer) film, via the metastable (blue phase), to the fully stable PDA red phase as a function of irradiation dose. The monomer-to-blue-to-red chromatic phase transitions are accompanied by changes in the in-plane crystal structure and pendant chains packing arrangement from arced alkyl chains (in the monomer and blue phases) to near-vertical closely packed chains in the red phase. Notably, the characteristic linear strand morphology of PDA films can be explained as a direct result of the marked decrease in spacing between adjacent polymer chains upon transition from the blue to the red phase.
Department of Materials Engineering, Ilse Katz Institute of Nanoscience and Nanotechnology, Beer-Sheva, Israel.
Yevgeniy
Y
Lifshitz
Yuval
Y
Golan
Oleg
O
Konovalov
Amir
A
Berman
D000388:Air; D003460:Crystallization; D018360:Crystallography, X-Ray / Q000379:methods; D008055:Lipids / Q000737:chemistry; D008567:Membranes, Artificial; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008956:Models, Chemical; D015394:Molecular Structure; D000078789:Polyacetylene Polymer; D011108:Polymers / Q000737:chemistry*; D053279:Polyynes / Q000737:chemistry*; D012997:Solvents; D013499:Surface Properties; D017356:Synchrotrons; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
D008055:Lipids; D008567:Membranes, Artificial; D000078789:Polyacetylene Polymer; D011108:Polymers; D012997:Solvents; D014867:Water; D053279:Polyynes; C082361:polydiacetylene