The wettability of polymeric carbon nitride (PCN) is an important surface chemical factor affecting its catalytic and separation performance. However, due to the amphipathic characteristics of hydrophilic/lipophilic and porous powder properties, the contact angle (CA) of PCN measured by the common sessile drop method will be interfered by the substrate, resulting in randomness of the results. Herein, the pristine PCNs obtained by thermal polycondensation of different precursors in air or nitrogen atmosphere were used as the wettability research object. The CA of the PCNs was measured by a modified sessile drop method after the traditional powders were replaced by pressed-tablet samples. The influence of sample mass and applied pressure on specific surface area, pore volume, surface morphology and CA of the pressed-tablet samples was investigated carefully, and the optimal experimental conditions were determined. When the sample mass was 0.15 g and the applied pressure was 10 MPa, the measured water CA of PCNs was between 27 ∼ 34°, and the diiodomethane CA is between 24 ∼ 29°. The measurement results showed considerable stability and reproducibility. This improved CA measurement method provides a simple and standardized way to accurately explore the surface chemistry of PCN, and has the potential to be applied to other hydrophilic and/or oleophilic porous powder materials.

中文翻译：

---

可靠测定聚合物氮化碳润湿性：用于压片样品的标准化座滴法


聚合物氮化碳 （PCN） 的润湿性是影响其催化和分离性能的重要表面化学因素。然而，由于亲水/亲油和多孔粉末特性的两亲特性，用普通无柄滴法测量的 PCN 的接触角 （CA） 会受到基材的干扰，导致结果的随机性。本文以不同前驱体在空气或氮气气氛中热缩聚得到的原始 PCN 为润湿性研究对象。在用压片样品代替传统粉末后，通过改进的无座滴法测量 PCN 的 CA。仔细研究了样品质量和施加压力对压片样品比表面积、孔体积、表面形貌和 CA 的影响，并确定了最佳实验条件。当样品质量为 0.15 g，施加压力为 10 MPa 时，PCN 的测得水 CA 在 27 ∼ 34° 之间，二碘甲烷 CA 在 24 ∼ 29° 之间。测量结果显示出相当的稳定性和重现性。这种改进的 CA 测量方法提供了一种简单且标准化的方法来准确探索 PCN 的表面化学性质，并有可能应用于其他亲水和/或亲油多孔粉末材料。