Nuraje Nurxat, Su Kai, Yang Nan-Loh, Matsui Hiroshi
Department of Chemistry, Hunter College and The Graduate Center, The City University of New York, 695 Park Avenue, New York, New York 10021, USA.
ACS Nano. 2008 Mar;2(3):502-6. doi: 10.1021/nn7001536.
Single crystalline nanoneedles of polyaniline (PANI) and polypyrrole (PPY) were synthesized using an interfacial polymerization for the first time. The interfacial crystallization of conductive polymers at the liquid/liquid interface allowed PANI and PPY polymers to form single crystalline nanocrystals in a rice-like shape in the dimensions of 63 nm x 12 nm for PANI and 70 nm x 20 nm for PPY. Those crystalline nanoneedles displayed a fast conductance switching in the time scale of milliseconds. An important growth condition necessary to yield highly crystalline conductive polymers was the extended crystallization time at the liquid/liquid interfaces to increase the degree of crystallization. As compared to other interfacial polymerization methods, lower concentrations of monomer and oxidant solutions were employed to further extend the crystallization time. While other interfacial growth of conducting polymers yielded noncrystalline polymer fibers, our interfacial method produced single crystalline nanocrystals of conductive polymers. We recently reported the liquid/liquid interfacial synthesis of conducting PEDOT nanocrystals; however, this liquid/liquid interfacial method needs to be extended to other conductive polymer nanocrystal syntheses in order to demonstrate that our technique could be applied as the general fabrication procedure for the single crystalline conducting polymer growth. In this report, we showed that the liquid/liquid interfacial crystallization could yield PANI nanocrystals and PPY nanocrystals, other important conductive polymers, in addition to PEDOT nanocrystals. The resulting crystalline polymers have a fast conductance switching time between the insulating and conducting states on the order of milliseconds. This technique will be useful to synthesize conducting polymers via oxidative coupling processes in a single crystal state, which is extremely difficult to achieve by other synthetic methods.
首次采用界面聚合法合成了聚苯胺（PANI）和聚吡咯（PPY）的单晶纳米针。导电聚合物在液/液界面处的界面结晶使得PANI和PPY聚合物形成了米状的单晶纳米晶体，PANI的尺寸为63 nm×12 nm，PPY的尺寸为70 nm×20 nm。这些结晶纳米针在毫秒时间尺度内显示出快速的电导切换。产生高度结晶导电聚合物所需的一个重要生长条件是在液/液界面处延长结晶时间以提高结晶度。与其他界面聚合法相比，采用了较低浓度的单体和氧化剂溶液来进一步延长结晶时间。虽然其他导电聚合物的界面生长产生的是非晶态聚合物纤维，但我们的界面法产生了导电聚合物的单晶纳米晶体。我们最近报道了导电聚3,4-乙撑二氧噻吩（PEDOT）纳米晶体的液/液界面合成；然而，这种液/液界面法需要扩展到其他导电聚合物纳米晶体的合成，以证明我们的技术可以作为单晶导电聚合物生长的通用制备方法。在本报告中，我们表明液/液界面结晶除了能产生PEDOT纳米晶体外，还能产生PANI纳米晶体和PPY纳米晶体，这两种都是其他重要的导电聚合物。所得的结晶聚合物在绝缘态和导电态之间的电导切换时间很快，在毫秒量级。该技术将有助于通过氧化偶联过程合成单晶态的导电聚合物，而这是其他合成方法极难实现的。
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