Abstract A polyphosphoester (PPE) with phenyl phosphate groups separated by precisely 20 CH2 groups in its backbone was dissolved in chloroform and spread on the water surface of a Langmuir trough. The surface pressure vs area per monomer unit (π-A) Langmuir isotherm together with epifluorescence and Brewster angle microscopy suggested that some crystallization occurred already at zero surface pressure immediately after solvent evaporation of the spread polymer solution. The extended plateau region of the Langmuir isotherm in the range of π ≈ 4.5 mN m−1 corresponds to the 2D crystallization of most polymer chains. Brewster angle and epifluorescence microscopy show that during the crystallization of PPE in the Langmuir film single crystal like hexagonal entities are formed with lateral dimensions of up to 20 µm. These entities break upon compression beyond the limiting area per monomer unit which leads to a decrease of the elasticity modulus of the Langmuir film. The morphology of the single crystals and their failure upon compression are also observed in Langmuir-Blodgett films by atomic force microscopy. The thickness of the crystals is about 2.5 nm at the end of the plateau range and reaches 3.0 nm upon further compression. The polymer crystallization on the water surface is also confirmed by infrared reflection absorption spectroscopy.

中文翻译：

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多磷酸酯在空气-水界面结晶

摘要 将主链上由精确的 20 个 CH2 基团隔开的磷酸苯酯（PPE）溶解在氯仿中并铺展在朗缪尔槽的水面上。表面压力与每个单体单元的面积 (π-A) 朗缪尔等温线以及落射荧光和布鲁斯特角显微镜一起表明，在扩散的聚合物溶液的溶剂蒸发后，在零表面压力下立即发生了一些结晶。Langmuir 等温线在 π ≈ 4.5 mN m-1 范围内的扩展平台区对应于大多数聚合物链的二维结晶。布鲁斯特角和落射荧光显微镜表明，在朗缪尔膜中 PPE 的结晶过程中，形成了六边形实体的单晶，横向尺寸高达 20 µm。这些实体在压缩超过每个单体单元的限制面积时破裂，这导致朗缪尔膜的弹性模量降低。在 Langmuir-Blodgett 薄膜中也通过原子力显微镜观察到单晶的形态和它们在压缩时的失效。在平台范围的末端，晶体的厚度约为 2.5 nm，在进一步压缩时达到 3.0 nm。红外反射吸收光谱也证实了水表面的聚合物结晶。在平台范围的末端为 5 nm，在进一步压缩时达到 3.0 nm。红外反射吸收光谱也证实了水表面的聚合物结晶。在平台范围的末端为 5 nm，在进一步压缩时达到 3.0 nm。红外反射吸收光谱也证实了水表面的聚合物结晶。