Li Hongbo, Liu Qingtao, Xu Miao, Bu Weifeng, Lin Xiankun, Wu Lixin, Shen Jiacong
Key Laboratory for Supramolecular Structure and Materials of Ministry of Education, Jilin University, Changchun, 130012, PRC.
J Phys Chem B. 2005 Feb 24;109(7):2855-61. doi: 10.1021/jp046816u.
In this paper, atomic force microscopy (AFM) has been used to investigate the morphology of monolayers of the amphiphilic rod-coil diblock molecule (EO7OPV) containing oligo(phenylene vinylene) dimer (OPV) and poly(ethylene oxide) (PEO) as well as the morphology of mixed monolayers of EO7OPV and palmitic acid (PA) deposited onto mica by the Langmuir-Blodgett technique. At surface pressures higher than 3 mN/m, EO7OPV forms regular-shaped aggregates with a monomolecular layer structure, where the hydrophilic PEO blocks are adsorbed onto the mica substrate and the hydrophobic OPV blocks form an ordered crystalline OPV layer on the top of the PEO layer through the strong pi-pi stacking interaction. In the mixed LB monolayers of EO7OPV and PA, the phase separation occurs. At a certain mixed ratio, EO7OPV molecules form rodlike domains with regular shape and uniform size at surface pressures higher than 3 mN/m. With the increase of the molar fraction of PA, the rodlike domains consisting of EO7OPV are elongated. The length of the rodlike domains can be tuned easily in a large range by altering the molar ratio of EO7OPV and PA. In addition, the rodlike domains are oriented to specific directions, corresponding to the directions of the potassium ion array on the mica surface having 6-fold symmetry. We demonstrate the possible formation mechanism and the elongation origin of rodlike domains in mixed LB monolayers and propose the two-step formation process of oriented rodlike domains deposited onto the mica substrate.
在本文中，原子力显微镜（AFM）被用于研究包含亚苯基乙烯基二聚体（OPV）和聚环氧乙烷（PEO）的两亲性棒-线圈二嵌段分子（EO7OPV）单层膜的形态，以及通过朗缪尔-布洛杰特技术沉积在云母上的EO7OPV与棕榈酸（PA）混合单层膜的形态。在高于3 mN/m的表面压力下，EO7OPV形成具有单分子层结构的规则形状聚集体，其中亲水性PEO嵌段吸附在云母基底上，疏水性OPV嵌段通过强π-π堆积相互作用在PEO层顶部形成有序的结晶OPV层。在EO7OPV与PA的混合LB单层膜中，发生相分离。在一定混合比例下，EO7OPV分子在高于3 mN/m的表面压力下形成形状规则、尺寸均匀的棒状畴。随着PA摩尔分数的增加，由EO7OPV组成的棒状畴被拉长。通过改变EO7OPV与PA的摩尔比，可以很容易地在很大范围内调节棒状畴的长度。此外，棒状畴沿特定方向取向，对应于云母表面具有六重对称性的钾离子阵列的方向。我们证明了混合LB单层膜中棒状畴的可能形成机制和伸长起源，并提出了沉积在云母基底上的取向棒状畴的两步形成过程。
