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Thixotropic Twin‐Dendritic Organogelators
Author(s) -
Percec Virgil,
Peterca Mihai,
Yurchenko Michael E.,
Rudick Jonathan G.,
Heiney Paul A.
Publication year - 2008
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.200701273
Subject(s) - thixotropy , hydrogen bond , chemical engineering , materials science , chemistry , polymer chemistry , molecule , organic chemistry , composite material , engineering
Twin‐dendritic organogelators have been prepared through selective functionalization of N ‐(3‐aminopropyl)‐1,3‐propanediamine (APPDA) with self‐assembling dendrons by using 1,1′‐carbonyldiimidazole (CDI). Subsequent modification of the APPDA linker provided an additional degree of structural diversity by which to tailor the gelator self‐assembly in bulk or in the gel state. These compounds are able to gel cyclohexane, toluene, n ‐butyl acetate, ethyl acetate, dichloromethane, and tetrahydrofuran. 3,4‐Disubstituted apical branching units provided the most efficient organogelators and show a propensity to form thixotropic gels, wherein the gel recovers its elasticity after being subjected to shear. Structural and retrostructural analysis of the twin‐dendritic organogelators reveals the bulk structural characteristics to be indicative of the subsequent gel properties. Diverse self‐organized arrays were identified in bulk and all are able to form gels, thus indicating the role of quasiequivalence in mediating self‐assembly in the gel state. Furthermore, we have found that porous columnar mesophases provide a strategy by which to prepare thixotropic gels. We demonstrate the importance of weak lateral hydrogen bonding within a column stratum versus hydrogen bonding along the length of the column for forming porous columnar mesophases and, by extension, thixotropic gels.