title: Organic/Metallic nanohybrids based on amphiphilic dumbbell-shaped dendrimers.
abstract: In this study, we synthesized a series of amphiphilic dumbbell-shaped dendrimers through the addition reactions of a hydrophilic poly(oxyalkylene) with hydrophobic dendrons based on 4-isocyanate-4'-(3,3-dimethyl-2,4-dioxo-azetidine)diphenylmethane with different numbers of branching generations. The addition reaction of azetidine-2,4-diones of dendrons to amines of poly(oxyalkylene) was proceeded by stirring the reactants in dry tetrahydrofuran (THF) under nitrogen at 60 °C. In aqueous media, the dumbbell-shaped dendrimers self-assembled into micelles with their hydrophobic dendrons in the core and their hydrophilic poly(oxyalkylene) segments forming loops in the corona shell. Employing the unique self-assembled micelle structures as templates for subsequent chemical reduction of the Ag(+) ions, we generated new types of organic/metallic [silver nanoparticle (AgNP)] nanohybrid clusters. The long poly(oxyalkylene) loops that extended into the aqueous phase complexed with the Ag(+) ions, providing the suspension with steric stabilization to prevent the AgNPs from collision and flocculation. After reduction, the AgNPs were present in a homogeneous distribution in the round dendrimer micelle-stabilized nanoclusters. The diameter of each AgNP was less than 10 nm; the diameter of each round nanocluster was in the range of 50-200 nm. The encapsulation efficiency of the AgNPs in micelles was about 54-69% for the dumbbell-shaped dendrimer based organic/AgNP nanohybrid.
authors.affiliation: Department of Chemical Engineering, National Chung Hsing University, Taichung 402, Taiwan.
authors.forename: Shi-Min
authors.initials: SM
authors.lastname: Shau
authors.forename: Chia-Cheng
authors.initials: CC
authors.lastname: Chang
authors.forename: Chia-Hao
authors.initials: CH
authors.lastname: Lo
authors.forename: Yi-Chu
authors.initials: YC
authors.lastname: Chen
authors.forename: Tzong-Yuan
authors.initials: TY
authors.lastname: Juang
authors.forename: Shenghong A
authors.initials: SA
authors.lastname: Dai
authors.forename: Rong-Ho
authors.initials: RH
authors.lastname: Lee
authors.forename: Ru-Jong
authors.initials: RJ
authors.lastname: Jeng