Amphiphilic Diblock Dendrimers: Synthesis and Incorporation in Langmuir and Langmuir−Blodgett Films
摘要:
A new dendron with peripheral long alkyl chains and containing five C-60 units in the branching shell has been prepared and attached to a Frechet-type dendron functionalized with ethylene glycol chains. The peripheral substitution of the resulting globular dendrimer with hydrophobic chains on one hemisphere and hydrophilic groups on the other provides the perfect hydrophobic/hydrophilic balance allowing the formation of stable Langmuir films. Furthermore, a perfect reversibility has been observed in successive compression/decompression cycles. The diblock structure of the dendrimer has been also crucial for the efficient transfer of the Langmuir films in order to obtain well-ordered multilayered Langmuir-Blodgett films. This approach appears particularly interesting since functional groups not well adapted for the preparation of Langmuir and Langmuir-Blodgett films such as fullerenes can be attached into the branching shell of the dendritic structure and, thus, efficiently incorporated in thin ordered films.
Highly soluble dendritic branches with fullerene subunits at the periphery and a carboxylic acid function at the focal point have been prepared by a convergent approach, using successive DCC-mediated esterifications followed by cleavage of a t-butyl ester moiety under acidic conditions. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.