Intercalation of dendrimers in the interlayer of hydrotalcite clay sheets

Abstract

IntroductionDendrimers [1] are highly branched macromolecules consisting of a multifunctional core, to which repeating units are sequentially covalently bonded to create a topologically regular structure. The resultant molecules present a well-defined number of terminal groups and a narrow molecular weight distribution that is truly monodisperse in most cases. Owing to their structural uniformity, dendrimers provide a valuable model for correlating the macromolecular structure to the technological function [2][3][4][5]. Thus, dendrimers have a wide range of applications, including drug delivery [6], catalysis, and sensors [7][8] in high-technology fields. The organization of dendrimers in monolayers results in materials that can be applied as devices [7][8][9][10] and scaffolds for posterior elaborations [11][12][13][14][15][16][17]. Moreover, stratumous-layered composites of a dendrimer and a linear polymer can be prepared by linking terminal groups of a dendrimer to functional groups of a polymer [12,13,16,[18][19][20].Double-layered hydroxides, also known as ionic clays, are important inorganic materials, and have deserved Progr Colloid Polym Sci (2004) Abstract Nanocomposites have been prepared through the intercalation of poly(amido amine) dendrimers with carboxylate terminals into hydrotalcite clays. The formation of nanocomposites by anion exchange during incubating at 70°C was investigated at various compositions with increasing dendrimer content in water and was assessed by Fourier transform IR absorption spectroscopy, X-ray diffraction, small-angle X-ray scattering, and elemental analysis. The dendrimer diffused into the clay galleries: the spacing between the clay layers (sheets) increased from its intrinsic value of 3.2 to 20-23 Å , and the mass fraction of the dendrimer in the composite was around 0.50 for mixing ratios (charge of clay to carboxylate of the dendrimer) higher than 1:2, indicating the saturated intercalation of the dendrimer in the clay. The dendrimers are densely packed with an ellipsoidal structure in the interlayer. At a mixing ratio of 1:8, there was excess adsorption of the dendrimer on the clay surface besides the intercalation and initial adsorption.

Electrochemistry at gold nanoparticles deposited on dendrimers assemblies adsorbed onto gold and platinum surfaces

“…van der Waals forces) [2,3]. Alternative methods rely on the use of either ordered templates [4][5][6][7][8] or a shell on nanoparticle [9][10][11][12][13][14][15][16]. Dendrimers-which are highly branched well-defined architectures of controlled molecular weight, topology, cavity size, and surface functionality [17][18][19][20][21][22][23][24][25] -have been used as shells, but their use as templates is scarcely reported, although it appears to be a promising strategy.…”

Facile exfoliation of rectorite nanoplatelets in soy protein matrix and reinforced bionanocomposites thereof

“…10 A great number of research has proven that the stronger interfacial bonding between the lamellae and matrix, and the homogeneous distribution of exfoliated lamella benefit higher mechanical strength. 1 To realize the exfoliation/delamination of layered silicates in com-posites, many strategies were submitted, such as organo-modification 11 and surface initiated polymerization 12 of layered silicates, polar group of polymer derivation 13 and compact polymer structure bearing multi polar groups (star, 14 dendritic, 15 and branched 16 structures).…”

Dendrimers and hyper-branched polymers interacting with clays: fruitful associations for functional materials

“…An increase of the hydrotalcite interlayer distance after the intercalation of the dendrimer was observed, from 3.20 to 25-28 Å. 31 These nanocomposites were then adsorbed on a Langmuir monolayer of arachidic acid at the air/water interface. 32 In a related example, the PAMAM dendrimers were used to protect silver nanoparticles, and this assembly was interacted with hydrotalcite.…”