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J Phys Chem B. 2018 Jun 28;122(25):6648-6655. doi: 10.1021/acs.jpcb.8b02534. Epub 2018 Jun 20.

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

Author information

1
CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , P. R. China.
2
University of Chinese Academy of Sciences , Beijing 100049 , P. R. China.
3
Key Laboratory of Oilfield Chemistry , Research Institute of Petroleum Exploration and Development (RIPED), CNPC , Beijing 100083 , P. R. China.
4
Department of Chemistry and Chemical Engineering , Guangzhou University , Guangzhou 510006 , Guangdong , P. R. China.

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 G1C n, 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 G1C12 were higher than those of G1C8 at high concentrations, suggesting that G1C12 adlayers were more stable due to the stronger intermolecular hydrophobic interactions, whereas it preferred to adopt the intramolecular hydrophobic interactions for G1C16, with low adsorption amounts and unstable adlayers. Bilayer-like structures were inferred in G1C8 and G1C12 adlayers with loose conformation, whereas monolayer structures were likely to exist in the sparse adsorption film of G1C16. 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.

PMID:
29897753
DOI:
10.1021/acs.jpcb.8b02534

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