硬 Pd 纳米棒在 CTAB 和 Pluronics 混合软表面活性剂中:无种子合成及其自组装。
Hard Pd Nanorods in the Soft Surfactant Mixture of CTAB and Pluronics: Seedless Synthesis and Their Self-Assembly.
机构信息
Department of Chemistry , Dong-A University , Busan 604-714 , South Korea.
Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095-1569 , United States.
出版信息
Langmuir. 2018 Apr 10;34(14):4271-4281. doi: 10.1021/acs.langmuir.8b00205. Epub 2018 Mar 27.
Seedless synthesis of Pd nanorods and their self-assembly into the layered smectic ordering are described. Aqueous Pluronic triblock copolymers (14.3-35.7%) are used as a soft template along with cetyltrimethylammonium bromide for inducing one-dimensional growth of Pd nanorods. Pluronic triblock copolymers are probably the most used polymer surfactants, and they are composed of poly(ethylene oxide) (PEO)-poly(propylene oxide) (PPO)-PEO triblocks. Neither pH adjustment nor AgNO and other additives, such as poly(vinyl pyrrolidone) and ethylene glycol, are required to obtain Pd nanorods. Sonochemical synthesis at 43 °C, followed by thermal annealing for 1 h at 65 °C produces Pd nanorods with the aspect ratio from 3.1 (17.9%, Pluronic L-64) to 6.7 (35.7%, Pluronic P-123). Two-dimensional self-assembly of the nanorods is observed, and both nematic ordering between the mesogens and smectic ordering between the layers is identified. Micellar hydrophobic PPO with hydrated PEO coronas are known to self-assemble into many crystalline orders, including cubic, hexagonal, lamellar, and inverse hexagonal mesophases, which extend into cylindrical micelles with increasing temperature. Relatively small size of Pluronic copolymers with regard to general polymers, but rather large size of their micelles and their tendency to organize into crystalline mesophases are thought to contribute to the anisotropic growth of Pd nanorods.
本文描述了无籽合成钯纳米棒及其自组装成层状近晶有序的过程。使用水相 Pluronic 嵌段共聚物(14.3%-35.7%)作为软模板,同时使用十六烷基三甲基溴化铵诱导钯纳米棒的一维生长。Pluronic 嵌段共聚物可能是最常用的聚合物表面活性剂,由聚(环氧乙烷)(PEO)-聚(环氧丙烷)(PPO)-PEO 三嵌段组成。既不需要调整 pH 值,也不需要添加 AgNO3 和其他添加剂,如聚乙烯吡咯烷酮和乙二醇,就可以得到钯纳米棒。在 43°C 下进行超声化学合成,然后在 65°C 下进行 1 小时热退火,得到的钯纳米棒的纵横比从 3.1(17.9%,Pluronic L-64)到 6.7(35.7%,Pluronic P-123)。观察到纳米棒的二维自组装,并且鉴定出介晶之间的向列有序和层之间的近晶有序。众所周知,具有水合 PEO 冠的亲脂性 PPO 胶束可以自组装成多种晶体有序,包括立方、六方、层状和反六方介相,随着温度的升高扩展成圆柱状胶束。Pluronic 共聚物的相对较小的尺寸,相对于一般聚合物,但其胶束的较大尺寸及其组织成结晶介相的倾向被认为有助于钯纳米棒的各向异性生长。