智能高分子调控纳米金低聚体组装及其宏观阵列的构建与高效SERS性能研究

Surface enhanced Raman scattering (SERS) technology has been widely applied in various important fields such as food safety and environmental monitoring. However, there are still some significant defects in sensitivity and reproducibility, which restrict severely development of SERS technology. High-efficiency SERS-active materials are need urgently to achieve a breakthrough in SERS performances. This research project integrates stimuli responsive polymers with anisotropic Janus gold nanoparticle (AuNP) to precisely control the microscopic self-assembly and macroscopic distribution of AuNP assembly. The AuNP is tuned subtly to assemble into high SERS-active oligomers and further arrange uniformly in a large scale, improving remarkably the sensitivity and reproducibility of SERS detection. In micro-levels, Janus AuNPs with different surface divisions are synthesized and modified subsequently by smart polymers brushes. The stimuli responses of smart polymers are employed to regulate the reversible assembly of Janus AuNP, forming AuNP oligomers in a high yield and adjusting precisely nanoparticle numbers in the oligomers. The realization of this partial work will resolve the problems of low-efficiency and poor regulation in traditional methods. In macro-levels, the assembled AuNP oligomers are tuned to assemble into macroscopic two-dimensional oligomer arrays at liquid/liquid interface, allowing the “hotspots” in the oligomers distribute densely and uniformly in a large-scale area. The achievement of this work will not only receive outstanding SERS-active materials with high sensitivity and high reproducibility, but also suggest a new way for exploring novel nanosensors with high performance.

表面增强拉曼散射（SERS）技术在食品安全、环境监测等重大领域已得到广泛应用，然而在灵敏度和重现性方面仍存在明显不足，严重限制了其发展，急需在高效基底材料方面做出突破。本项目拟结合智能高分子和各向异性Janus纳米金，从微观和宏观两个角度入手，精确调控纳米金自组装形成高效SERS活性的低聚体，并实现低聚体宏观均匀分布，从而大幅提高SERS灵敏度和重现性。微观上，利用智能高分子调节纳米金表面不同化学分区的比例，制备裸露不同表面积的Janus纳米金，进而调控其定向自组装，实现高产率可控制备纳米金低聚体以及精确调控低聚体中粒子数目，从而解决以往高分子制备低聚体产率低、难以精确可逆调控的问题；宏观上，利用界面组装调控纳米金低聚体宏观二维有序排列，构建大面积均匀分布的低聚体阵列，实现“热点”高密度、宏观均匀分布，从而获得高灵敏、高重现性SERS基底，同时为开发新型高效纳米传感器件提供一种新的途径。

作为重要的拉曼检测基底材料，如何精确调控纳米金组装体中粒子间隙及大面积有序组装，对于提高拉曼检测的灵敏度和稳定性具有重要意义。本项目利用智能高分子诱导不对称式或对称式金纳米粒子有序组装形成低聚体，并借助界面组装和界面反应等方法，制备大面积紧密有序排列的纳米金二维薄膜，从而获得具有高效拉曼增强效率及检测稳定性的新型纳米金材料。主要研究内容：（1）不对称金纳米粒子的制备及低聚体可控组装。首先，系统研究了不对称纳米金粒子的制备方法。重点分析两种配体（聚丙烯酸（PAA）/巯基苯乙酸（MPA））的比例、纳米金与配体比例、纳米金尺寸等因素对合成不对称纳米金/SiO2复合粒子的影响。研究发现，PAA/MPA摩尔比在1:15和1:1之间，纳米金与配体PAA的摩尔比为0.01，纳米金尺寸30-40 nm，不对称复合粒子的产率最高。其次，利用可见光和紫外光诱导不对称粒子表面偶氮苯与环糊精基团之间的超分子作用，调控纳米金可逆自组装形成二聚体等低聚体；此外，利用光敏螺吡喃高分子刷和聚乙二醇分子刷调控对称式纳米金可逆组装形成低聚体，实现了光诱导调节纳米金拉曼信号增强的开启和关闭。（2）界面诱导纳米金宏观大面积二维组装。利用油/水或空气/水界面组装及界面反应，成功制备一种纳米金紧密排列的宏观二维自支撑薄膜，调节粒子间隙缩小至0.5 nm，极大的提高了拉曼检测的灵敏度（信号增强因子10^8）和信号稳定性（波动小于5.6%）。（3）纳米金/碳纳米管复合薄膜的制备及其功能化应用。首先，以CNT薄膜作为界面反应器，利用界面组装和原位界面反应，诱导超小尺寸纳米金大面积有序紧密排列，制备宏观二维纳米金/CNT复合薄膜，具有高效的醇氧化反应催化性能；其次，将自支撑纳米金宏观二维薄膜界面转移到CNT薄膜表面，形成双层复合分离薄膜，实现大通量分离和净化油污废水，快速催化分解亚甲基蓝污染物（效率达到99%）。已发表相关研究论文5篇，授权发明专利一项，参加2017年全国高分子学术论文报告会，获得优秀墙报奖，培养毕业硕士研究生2名。