PAMAM-Based Dendrimers with Different Alkyl Chains Self-Assemble on Silica Surfaces: Controllable Layer Structure and Molecular Aggregation

Abstract

Amphiphilic poly(amidoamine) (PAMAM) dendrimers are a well-known dendritic family due to their remarkable ability to self-assemble on solid surface. However, the relationship between molecular conformation (or adsorption kinetics) of a self-assembled layer and molecular amphiphilicity of such kind of dendrimer is still lacking, which limits the development of modulating self-assembling structures and surface functionality. With this in mind, we synthesized a series of amphiphilic PAMAM-based dendrimers, denoted as GC , with different alkyl chains ( n = 8, 12, and 16), and investigated the molecular aggregation on silica surfaces by means of quartz crystal microbalance with dissipation, atomic force microscopy, and contact angle. After rinsing, remaining adsorption amounts of GC were higher than those of GC at high concentrations, suggesting that GC adlayers were more stable due to the stronger intermolecular hydrophobic interactions, whereas it preferred to adopt the intramolecular hydrophobic interactions for GC, with low adsorption amounts and unstable adlayers. Bilayer-like structures were inferred in GC and GC adlayers with loose conformation, whereas monolayer structures were likely to exist in the sparse adsorption film of GC. Our results provided more detailed understanding of the effect of molecular structure on the self-assembled structures of amphiphilic dendrimers on solid surfaces, shedding light on the controlled microstructure and wettability of functional surface by modulating the length of hydrophobic chains of dendrimers and a potential application of dendrimer-substrate combinations.

In Situ Investigation on the Effect of Salinity and pH on the Asphaltene Desorption under Flowing Conditions

“…The changes in frequency (Δ f ) and dissipation (Δ D ) represent the adsorption mass and softness of the adsorption layer, respectively. Detailed principles on the QCM-D method are explained in detail in our previous study − and only a brief explanation is provided here. A negative decrease in the frequency indicates mass uptake, while an increase in the frequency indicates mass reduction.…”

Dendrimer‐Based Gold Nanostructures for SERS Detection of Pesticides in Water

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