Dendromesogens: Liquid Crystal Organizations of Poly(amidoamine) Dendrimers versus Starburst Structures

Abstract

A new series of liquid crystalline poly(amidoamine) (PAMAM) dendrimers is described. These dendrimers are made by attaching to the 0-, 1-, 2-, 3-, and 4-generation of PAMAM-terminal promesogenic units that carry two decyloxy chains in the 3- and 4-positions of their peripheral aromatic ring. X-ray diffraction studies show that all the compounds display a hexagonal columnar mesophase. A high density of aliphatic chains imposes a curved interface with the promesogenic units that forces the molecules to adopt a radial conformation, and therefore, the columnar structure. A model for the supramolecular organization of the different generations within the columnar mesophase is proposed based on the variation of some of the structural parameters.

Polyisobutylene-based polyurethanes: VII. structure/property investigations for medical applications

“…The peak in the 12–25° range, associated with first neighbor distances, is due to overlapping contributions from domains formed by various segments (i.e., soft and hard), and the peak in the 34–48° range, associated with second neighbor distances, is due to amorphous domains or higher order reflections for small crystalline domains. The unannealed sample shows a broad peak averaging lateral distances in the 14–22° range suggesting incompletely segregated individual segments.…”

Connector type‐controlled mesophase structures in poly(propyl ether imine) dendritic liquid crystals of identical dendrimer generations

“…There were no differences in the mesophase structures of dendritic LCs arising from these two different types of dendrimer cores. Higher densities of aliphatic chains at the peripheries induced a curved and radial arrangement of the mesogenic moieties, leading to stacking of the molecules and formation of a columnar mesomorphism . In another study, a hexagonal columnar mesomorphism was observed with third and fourth generation PPI and PAMAM dendrimers, peripherally functionalized with mesogenic groups.…”

Formation of nanogel aggregates by an amphiphilic cholesteryl‐poly(amidoamine) dendrimer in aqueous media

“…Reported examples of such ordered aggregation include unimolecular micelles, spherical aggregates with bilayered vesicular structure, and supramolecular liquid crystals. [17][18][19][20][21][22] Although studies on aggregates based on the coreshell-structured amphiphiles have been progressing, we are aware of only a few instances of studies on the aggregation characteristics of amphiphilic dendrimers that have a few hydrophobic groups attached at their peripheries. Menger et al 23 have modified a generation-4 amine-terminated polyamidoamine dendrimer with varying numbers of alkyl chains and further investigated their behavior in aqueous solutions.…”