Miikkulainen Ville, Rasilainen Tiina, Puukilainen Esa, Suvanto Mika, Pakkanen Tapani A
Department of Chemistry, University of Joensuu, P.O. Box 111, FI-80101 Joensuu, Finland.
Langmuir. 2008 May 6;24(9):4473-7. doi: 10.1021/la800285s. Epub 2008 Mar 21.
The wetting properties of polypropylene (PP) surfaces were modified by adjusting the dimensions of the surface nanostructure. The nanostructures were generated by injection molding with nanoporous anodized aluminum oxide (AAO) as the mold insert. Atomic layer deposition (ALD) of molybdenum nitride film was used to control the pore diameters of the AAO inserts. The original 50-nm pore diameter of AAO was adjusted by depositing films of thickness 5, 10, and 15 nm on AAO. Bis(tert-butylimido)-bis(dimethylamido)molybdenum and ammonia were used as precursors in deposition. The resulting pore diameters in the nitride-coated AAO inserts were 40, 30, and 20 nm, respectively. Injection molding of PP was conducted with the coated inserts, as well as with the non-coated insert. Besides the pore diameter, the injection mold temperature was varied with temperatures of 50, 70, and 90 degrees C tested. Water contact angles of PP casts were measured and compared with theoretical contact angles calculated from Wenzel and Cassie-Baxter theories. The highest contact angle, 140 degrees , was observed for PP molded with the AAO mold insert with 30-nm pore diameter. The Cassie-Baxter theory showed better fit than the Wenzel theory to the experimental values. With the optimal AAO mask, the nanofeatures in the molded PP pieces were 100 nm high. In explanation of this finding, it is suggested that some sticking and stretching of the nanofeatures occurs during the molding. Increase in the mold temperature increased the contact angle.
通过调整表面纳米结构的尺寸来改变聚丙烯（PP）表面的润湿性。纳米结构是通过以纳米多孔阳极氧化铝（AAO）为模具镶件进行注塑成型产生的。采用氮化钼薄膜的原子层沉积（ALD）来控制AAO镶件的孔径。通过在AAO上沉积厚度为5、10和15 nm的薄膜来调整AAO原来50 nm的孔径。双（叔丁基亚氨基）双（二甲基氨基）钼和氨用作沉积的前驱体。在涂覆氮化膜的AAO镶件中得到的孔径分别为40、30和20 nm。使用涂覆的镶件以及未涂覆的镶件对PP进行注塑成型。除了孔径外，注塑模具温度在50、70和90℃下变化并进行测试。测量PP铸件的水接触角，并与根据Wenzel理论和Cassie - Baxter理论计算的理论接触角进行比较。对于用孔径为30 nm的AAO模具镶件成型的PP，观察到最高接触角为140°。Cassie - Baxter理论比Wenzel理论更符合实验值。使用最佳的AAO掩膜，成型PP片材中的纳米特征高度为100 nm。为解释这一发现，有人提出在成型过程中纳米特征会发生一些粘附和拉伸。模具温度升高会增加接触角。
