title: In Situ Formation of Dual-Phase Thermosensitive Ultrasmall Gold Nanoparticles.
abstract: A novel method for the in situ synthesis of dual-phase thermosensitive ultrasmall gold nanoparticles (USGNPs) with diameters in the range of 1-3 nm was developed by using poly(N-isopropylacrylamide)-block-poly(N-phenylethylenediamine methacrylamide) (PNIPAM-b-PNPEDMA) amphiphilic diblock copolymers as ligands. The PNPEDMA block promotes the in situ reduction of gold precursors to zero-valent gold and subsequently binds to the surface of gold nanoparticles, while PNIPAM acts as a stabilizing and thermosensitive block. The as-synthesized USGNPs stabilized by a thermosensitive PNIPAM layer exhibit a sharp, reversible, clear-opaque transition in aqueous solution between 30 and 38 °C. An unprecedented finding is that these USGNPs also show a reversible soluble-precipitate transition in nonpolar organic solvents such as chloroform at around 0 °C under acidic conditions.
authors.affiliation: School of Chemistry and Molecular Engineering, East China Normal University, 500 N, Dongchuan Road, Shanghai, 200241 (P. R. China).
authors.forename: Zidong
authors.initials: Z
authors.lastname: He
authors.affiliation: School of Chemistry and Molecular Engineering, East China Normal University, 500 N, Dongchuan Road, Shanghai, 200241 (P. R. China).
authors.forename: Aiqing
authors.initials: A
authors.lastname: Zhong
authors.affiliation: School of Chemistry and Molecular Engineering, East China Normal University, 500 N, Dongchuan Road, Shanghai, 200241 (P. R. China).
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Chemistry and Molecular Engineering, East China Normal University, 500 N, Dongchuan Road, Shanghai, 200241 (P. R. China).
authors.forename: Linfeng
authors.initials: L
authors.lastname: Xiong
authors.affiliation: School of Chemistry and Molecular Engineering, East China Normal University, 500 N, Dongchuan Road, Shanghai, 200241 (P. R. China).
authors.forename: Yang
authors.initials: Y
authors.lastname: Xu
authors.affiliation: School of Chemistry and Molecular Engineering, East China Normal University, 500 N, Dongchuan Road, Shanghai, 200241 (P. R. China).
authors.forename: Tianqi
authors.initials: T
authors.lastname: Wang
authors.affiliation: School of Chemistry and Molecular Engineering, East China Normal University, 500 N, Dongchuan Road, Shanghai, 200241 (P. R. China).
authors.forename: Minghong
authors.initials: M
authors.lastname: Zhou
authors.affiliation: School of Chemistry and Molecular Engineering, East China Normal University, 500 N, Dongchuan Road, Shanghai, 200241 (P. R. China). khuang@chem.ecnu.edu.cn.
authors.forename: Kun
authors.initials: K
authors.lastname: Huang
keywords: block copolymers; gold; nanoparticles; thermoresponsive materials