The University of New Mexico/NSF Center for Micro-Engineered Materials, Chemical and Nuclear Engineering Department, Albuquerque, NM 87131, USA.
Chemistry. 2009 Oct 26;15(42):11128-33. doi: 10.1002/chem.200901786.
We report a new method in which spontaneous self-assembly is employed to synthesize monodisperse polymer nanoparticles with controlled size (<50 nm), shape, tunable functionality, and enhanced solvent and thermal stability. Cooperative noncovalent interactions, such as hydrogen bonding and aromatic pi-pi stacking, assist self-assembly of amphiphilic macromolecules (polystyrene-block-polyvinylpyridine, PS--PVP) and structure directing agents (SDAs) to form both spherical and anisotropic solid polymer nanoparticles with SDAs residing in the particle core surrounded by the polymers. Through detailed investigations by scanning electron microscopy and transmission electron microscopy (TEM), we have rationalized nanoparticle morphology evolution and dependence on factors such as SDA concentration and PVP size. By keeping the PS chain size constant, the particle morphology progresses from continuous films to spherical particles, and on to cylindrical nanowires or rods with increasing the PVP chain size. The final nanoparticles are very stable and can be redispersed in common solvents to form homogenous solutions and thin films of ordered nanoparticle arrays through solvent evaporation processes. These nanoparticles exhibit tunable fluorescent colors (or emissions) depending on the choices of the central SDAs. Our method is simple and general without requiring complicated synthetic chemistry, stabilizing surfactants, or annealing procedures (e.g., temperature or solvent annealing), making scalable synthesis feasible.
我们报告了一种新方法，该方法利用自发自组装来合成具有受控尺寸（<50nm）、形状、可调功能以及增强的溶剂和热稳定性的单分散聚合物纳米粒子。协同的非共价相互作用，如氢键和芳环π-π堆积，有助于两亲性大分子（聚苯乙烯嵌段-聚醋酸乙烯酯，PS-PVP）和结构导向剂（SDAs）的自组装，形成具有 SDA 位于聚合物包围的粒子核中的球形和各向异性固体聚合物纳米粒子。通过扫描电子显微镜和透射电子显微镜（TEM）的详细研究，我们已经合理化了纳米粒子形态的演变及其对 SDA 浓度和 PVP 尺寸等因素的依赖性。通过保持 PS 链大小不变，粒子形态从连续薄膜进展到球形颗粒，然后随着 PVP 链尺寸的增加，进展到圆柱纳米线或棒。最终的纳米粒子非常稳定，可以在常见溶剂中再分散，通过溶剂蒸发过程形成均匀溶液和有序纳米粒子阵列的薄膜。这些纳米粒子根据中心 SDA 的选择表现出可调谐的荧光颜色（或发射）。我们的方法简单且通用，不需要复杂的合成化学、稳定的表面活性剂或退火程序（例如温度或溶剂退火），使得可扩展的合成成为可能。
