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Supramolecular Self‐Organization of “Janus‐like” Diblock Codendrimers: Synthesis, Thermal Behavior, and Phase Structure Modeling
Author(s) -
Bury Izabela,
Heinrich Benoît,
Bourgogne Cyril,
Guillon Daniel,
Donnio Bertrand
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200600449
Subject(s) - supramolecular chemistry , thermotropic crystal , materials science , crystallography , amphiphile , hydrogen bond , differential scanning calorimetry , mesophase , phase (matter) , molecule , liquid crystal , chemistry , polymer , copolymer , organic chemistry , crystal structure , liquid crystalline , physics , optoelectronics , composite material , thermodynamics
We report on the design and synthesis of three series of segmented amphiphilic block codendrimers, and on their self‐organizing behavior in liquid‐crystalline mesophases. Connecting two prefunctionalized monodendrons, each differing in their chemical constitution and generation number, yielded these diblock supermolecules. One wedge of the codendrimer was made hydrophobic, and is based on a branched poly(benzyl ether) monodendron functionalized at the periphery by lipophilic aliphatic fragments (also known as Percec dendrons). The other segment was made hydrophilic by the grafting of hydroxyl‐containing moieties onto the focal functions of the former dendrons. Both types of dendrons were prepared independently by convergent methods and then joined in the ultimate stage of the synthetic procedure by cross‐coupling reactions. In this way, the proportion of the dendritic blocks was varied independently to allow control of the hydrophilic/hydrophobic balance (HHB), the hydrogen‐bonding ability, and consequently the capacity to tune the mesomorphic properties of the resulting “superamphiphiles” was anticipated. Essentially all the dendritic compounds display a thermotropic mesomorphism directly at or near room temperature as determined by using X‐ray diffraction, polarized optical microscopy, and differential scanning calorimetry. The nature and the supramolecular organization of the mesophases, namely columnar and cubic phases, are correlated to the size of the respective block monodendrons and the chemical structures of the dendromesogens. The molecular organization within the cubic phases can be geometrically described and well understood by the space‐filling polyhedron model.