Fitrilawati F, Renu R, Baskar C, Xu L G, Chan H S O, Valiyaveettil S, Tamada K, Knoll W
Departments of Chemistry and of Materials Science, National University of Singapore, 10 Science Drive 4, Singapore 117543.
Langmuir. 2005 Dec 20;21(26):12146-52. doi: 10.1021/la0505667.
Asymmetrically substituted poly(paraphenylene) (PhPPP) with hydrophilic and hydrophobic side chains was investigated. The polymer behavior at the air-water interface was studied on the basis of surface pressure-area (pi-A) isotherms and compression/expansion hysteresis measurements. PhPPP can form stable monolayers with an area per repeat unit of A=0.20+/-0.02 nm2 and a collapse pressure in the range of pi=25 mN/m. Then, Langmuir-Blodgett-Kuhn (LBK) films of PhPPP were prepared by horizontally and vertically transferring the Langmuir monolayers onto hydrophilic solid substrates at pi=12 mN/m. Cross-section analysis of the AFM tapping-mode topography images of a single transferred monolayer reveals a thickness of d0=0.9+/-0.1 nm. Taking into account the obtained monolayer thickness, curve-fitting calculations of angular scan data of LB monolayers measured using surface plasmon resonance (SPR) spectroscopy lead to a value for the refractive index of n=1.78+/-0.02 at lambda=632.8 nm. Next, the spontaneous formation of a PhPPP monolayer by adsorption from solution was studied ex situ by atomic force microscopy and UV-vis spectroscopy and in situ by using SPR spectroscopy. Stable self-assembled monolayers of PhPPP can be formed on hydrophilic surfaces with a thickness similar to that of the monolayer obtained using the LB method. The characterization results confirmed the amphiphilic character and the self-assembly properties of PhPPP, as well as the possibility of preparing homogeneous monolayer and multilayer films.
研究了具有亲水和疏水侧链的不对称取代聚对亚苯基（PhPPP）。基于表面压力-面积（π-A）等温线和压缩/膨胀滞后测量研究了该聚合物在气-水界面的行为。PhPPP可以形成稳定的单分子层，每个重复单元的面积为A = 0.20±0.02 nm²，崩溃压力在π = 25 mN/m范围内。然后，通过在π = 12 mN/m下将Langmuir单分子层水平和垂直转移到亲水性固体基板上，制备了PhPPP的Langmuir-Blodgett-Kuhn（LBK）膜。对单个转移单分子层的原子力显微镜轻敲模式形貌图像进行横截面分析，显示厚度d0 = 0.9±0.1 nm。考虑到获得的单分子层厚度，使用表面等离子体共振（SPR）光谱对LB单分子层的角度扫描数据进行曲线拟合计算，得出在λ = 632.8 nm时折射率n = 1.78±0.02的值。接下来，通过原子力显微镜和紫外-可见光谱对溶液吸附法原位自发形成PhPPP单分子层进行了非原位研究，并使用SPR光谱进行了原位研究。PhPPP可以在亲水性表面上形成稳定的自组装单分子层，其厚度与使用LB方法获得的单分子层相似。表征结果证实了PhPPP的两亲性和自组装特性，以及制备均匀单分子层和多层膜的可能性。
