Site-specific recognition of nanophase-separated surfaces of amphiphilic block copolymers by hydrophilic and hydrophobic gold nanoparticles.
Site-specific recognition of nanophase-separated surfaces of amphiphilic block copolymers by hydrophilic and hydrophobic gold nanoparticles.
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DOI：
10.1002/anie.200603516
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发表时间：
2007-02
影响因子：
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通讯作者：
Shigeru Watanabe;Ryutaro Fujiwara;M. Hada;Y. Okazaki;T. Iyoda
中科院分区：
文献类型：
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作者：
Shigeru Watanabe;Ryutaro Fujiwara;M. Hada;Y. Okazaki;T. Iyoda
有序的二维和三维均匀分布的纳米粒子阵列在纳米电子学、纳米光学、等离子体学等领域具有广泛的应用前景自组装和Langmuir-Blodgett技术等自下而上的制造技术已经得到了广泛的探索。最近，高度有序的纳米阵列已经成功地通过模板方法制造，使用天然纳米结构，如DNA，[4,5]细菌表层蛋白，[6,7]铁蛋白，[8]，[9]病毒，[10,11]和噬菌体这些方法提供了有吸引力的自下而上的制造方案，以产生规则的纳米尺度图案；然而，大多数自然模板需要繁琐的处理和准备。在这方面，人工纳米结构如纳米相分离嵌段共聚物具有明显的优势。特别是，提供垂直于衬底的圆柱形纳米畴的双嵌段共聚物薄膜是有吸引力的，因为它们产生的模板和掩模是可预测和可控的纳米级顺序。最近，Iyoda和同事们制备了两亲性二嵌段共聚物PEOm-b-PMA (Az) n,[13]，由亲水性聚乙烯氧化物（PEO）和疏水性聚甲基丙烯酸酯组成，具有偶氮苯基液晶侧链（PMA (Az)），在PMA （Az）基体中容易自组装成六边形填充的PEO圆柱体。在表面，每个PEO结构域都以圆形空心的形式被PMA （Az）矩阵包围。通过改变共聚物组分的相对体积分数，可以有规律地调整六边形对称排列的PEO结构域的周期结构。然而，为了使用这种PEOm-b-PMA (Az) n薄膜作为构建周期性纳米颗粒阵列的纳米模板，有必要阐明这些纳米相分离表面上位点特异性识别过程的基本特征。在此，我们报道了金纳米粒子在纳米相分离的PEOm-b-PMA (Az) n薄膜上的自组装。采用浸渍包膜的方法，考察了表面性质、金纳米粒子浓度、浸渍时间、分散介质组成等因素对纳米粒子的现场覆盖率和选择性的影响。用PEO高分子引发剂对11-[4-（4-丁基苯基偶氮）苯氧基]十一烷基甲基丙烯酸酯进行活性聚合，制备了两亲性嵌段共聚物（PEOm-b-PMA (Az) n）。[13b]采用3 wt%甲苯溶液将纳米相分离的PEOm-b-PMA (Az) n薄膜浇铸在硅片上，然后在110 - 1408℃真空退火24h。采用轻叩模式获得的AFM形貌图像表明，PEO114-b-PMA (Az) 48、PEO272-b-PMA (Az) 75和PEO454-b-PMA (Az) 152呈现六边形填充柱状形貌（图1）。直方图显示，PEO114-b-PMA (Az) 48的柱周期为（25.3 Æ 1.9） nm, peo277 -b- pma (Az) 75的柱周期为（40.6 Æ 2.0） nm, PEO454-b-PMA (Az) 152的柱周期为（45.2 Æ 2.5） nm。为了研究膜表面PEO和PMA （Az）结构域的位点特异性识别，制备了两种具有亲水性[14](1)和疏水性[15](2)表面的金纳米颗粒（方案1）。将纳米相分离的PEO272-b-PMA (Az) 75薄膜浸入0.1-0.25 wt%的1 (d=（2.35 Æ0）溶液中。35) nm，其中d=平均直径)在EtOH和2 （d=(2.17 Æ 0.40) nm）在Et2O中，亲水性和疏水性金纳米颗粒1和2分别选择性地组装在PEO和PMA （Az）结构域上（图2a和b）。在纳米相上组装的金纳米粒子的位点选择性（SPEO）。
Ordered two and three-dimensional arrays of uniformly distributed nanoparticles are attractive for applications in nanoelectronics,[1] nanooptics,[2] and plasmonics.[3] Bottom-up fabrication techniques such as self-assembly and Langmuir–Blodgett techniques have been extensively explored. More recently, highly ordered nanoarrays have been successfully fabricated by a template method that uses natural nanoarchitectures such as DNA,[4, 5] bacterial surface layer proteins,[6, 7] ferritin,[8] chaperonin,[9] viruses,[10, 11] and bacteriophages.[12] These methods provide attractive bottom-up fabrication schemes to produce regular nanoscale patterns; however, most natural templates require tedious handling and preparation. In this respect, artificial nanoarchitectures such as nanophase-separated block copolymers have distinctive advantages. In particular, diblock copolymer films that provide cylindrical nanodomains oriented perpendicular to the substrate are attractive because they produce templates and masks that are predicatable and controllable with nanoscale order. Recently, Iyoda and co-workers prepared amphiphilic diblock copolymers, PEOm-b-PMA (Az) n,[13] consisting of hydrophilic polyethylene oxide (PEO) and hydrophobic polymethacrylate with azobenzene-based liquid crystalline side-chains (PMA (Az)), which readily self-assemble into hexagonally packed PEO cylinders in a PMA (Az) matrix. At the surface, each PEO domain is in the form of a circular hollow surrounded by the PMA (Az) matrix. The periodic structure of PEO domains arranged with hexagonal symmetry is regularly tunable by changing the relative volume fractions of the copolymer components. However, to use such PEOm-b-PMA (Az) n films as nanotemplates for the construction of periodic nanoparticle arrays, it is necessary to elucidate fundamental features of site-specific recognition processes on these nanophase-separated surfaces. Herein, we report the self-assembly of gold nanoparticles on a nanophase-separated PEOm-b-PMA (Az) n film. The effects of the surface properties, concentration of gold nanoparticles, dipping time, and the composition of the dispersion medium on-site coverage and selectivity were investigated by a dip-coating method. Amphiphilic block copolymers (PEOm-b-PMA (Az) n) were prepared by a well-controlled living polymerization of 11-[4-(4-butylphenylazo) phenoxy] undecyl methacrylate by using PEO macroinitiators.[13b] The nanophase-separated PEOm-b-PMA (Az) n films were cast on a silicon wafer from 3 wt% toluene solution, followed by annealing at 110–1408C for 24h under vacuum. The AFM topography images obtained with the light tapping mode demonstrate that PEO114-b-PMA (Az) 48, PEO272-b-PMA (Az) 75, and PEO454-b-PMA (Az) 152 provided a hexagonally packed cylinder morphology (Figure1). Histograms show cylinder periods of (25.3 Æ 1.9) nm for PEO114-b-PMA (Az) 48,(40.6 Æ 2.0) nm for PEO272-b-PMA (Az) 75, and (45.2 Æ 2.5) nm for PEO454-b-PMA (Az) 152.To investigate site-specific recognition of PEO and PMA (Az) domains on the film surface, two kind of gold nanoparticles with hydrophilic [14](1) and hydrophobic [15] surfaces (2) were prepared (Scheme 1). When films of the nanophase-separated PEO272-b-PMA (Az) 75 were dipped into a 0.1–0.25 wt% solution of 1 (d=(2.35 Æ0. 35) nm, where d= mean diameter) in EtOH and of 2 (d=(2.17 Æ 0.40) nm) in Et2O for 10–60s, the hydrophilic and hydrophobic gold nanoparticles 1 and 2 selectively assembled on the PEO and PMA (Az) domains, respectively (Figure 2a and b). The site selectivity (SPEO) of gold nanoparticles assembled on the nanophase …