Stuttgart 2012 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 14: Poster 2: Biomolecules, Electronic Spectroscopy, Experimental Techniques, Quantum Chemistry, Various Topics

MO 14.25: Poster

Mittwoch, 14. März 2012, 16:30–19:00, Poster.IV

Raman Experimental Evidence for CTAB-Chain Bending within Clay – Generalized Concept of Conformation Reorganization in Long CH₂Chains Embedded within Modified Clay — •Patrice Donfack¹, Elena A. Sagitova^1,2, Kirill A. Prokhorov², Goulnara Yu. Nikolaeva², Viktor A. Gerasin³, Nadezhda D. Merekalova³, Evgeny M. Antipov³, Pavel P. Pashinin², and Arnulf Materny¹ — ¹Research Center of Functional Materials and Nanomolecular Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany — ²A.M. Prokhorov General Physics Institute of RAS, Moscow, Russia — ³A.V. Topchiev Institute of Petrochemical Synthesis of RAS, Moscow, Russia

We have studied the CH₂-chain bending in connection with the conformation reorganization and switching within long CH₂-chain molecules confined in modified clay interlayers. Besides different other observations, specifically Raman spectra give strong evidence for the bending within the galleries of clay modified by cetyltrimethylammonium bromide (CTAB)-chains; CTAB consists of single CH₂-chains. As also suggested by computational modeling, the CH₂-chain bending results in a splitting of the symmetric C-C stretching Raman mode into two subbands, indicating the coexistence of two nonequivalent (in length and terminal group) CH₂-chain trans-segments within the alkylammonium ion embedded in the clay interlayer space. The monitoring of modifier content-dependent interlayer conformational states is demonstrated. This is important for fabricating modified clays-based nanocomposites with desired properties in a tunable way.