Distortion of surfactant lamellar phases induced by surface roughness

• Self-assembly is a characteristic property of soft matter and understanding the factors which assist or perturb this process is of a great importance in many biological and industrial processes.  Amphiphiles self-assemble and order into a variety of structures including well-ordered lamellar phases.  The present work uses neutron reflectometry to explore the effects of both interface roughness and temperature on the lamellar-phase structure of a non-ionic surfactant at a solid/liquid interface.  The structure of concentrated solutions of tetraethyleneglycol dodecyl ether has been compared against a smooth surface and one with a roughness of the order of the lamellar spacing.  The results showed that the surfactant forms a well-order and aligned structure at smooth surface that extends to a depth of micrometers from the interface.  Increasing the temperature of the sample and subsequent cooling helped the alignment and increased the number of oriented layers at the surface.  The same sample formed a significantly less aligned structure at a rough surface that did not align to same extent after heating.  The perturbation of the structure caused by thermal fluctuations was found to be much less than that imposed by a small surface roughness. Keywords

Subject headings

NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

Keyword

Roughness

thermal fluctuations

disorder

neutron reflectometry

nonionic surfactant

Publication and Content Type

ref (subject category)

art (subject category)