Azimi Mohammadyousef, Asselin Edouard
Department of Materials Engineering, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
ACS Appl Mater Interfaces. 2022 Jan 19;14(2):3601-3609. doi: 10.1021/acsami.1c23703. Epub 2022 Jan 5.
Polyolefins have had limited application in advanced technologies due to their low surface energy, hydrophobicity, and weak interfacial adhesion with polar coatings. Herein, we propose the use of transition metals at their lowest oxidation state and inorganic peroxides to improve the functionality, surface free energy, hydrophilicity, and adhesion properties of high-density polyethylene (HDPE). Among the nine combinations of transition metals and peroxides used in this study, the combination of Co(II) and peroxymonosulfate (PMS) peroxide was the most effective for surface modification of HDPE, followed closely by the combination of Ru(III) and PMS. After chemical treatment, HDPE's surface functionality, composition, and energy were analyzed via Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and contact angle measurements. Hydroxyl, carbonyl, and carboxylic acid functional groups were detected on the surface, which explained the improved hydrophilicity of the modified HDPE surface; the contact angle of HDPE with DI water decreased from 94.31 to 51.95° after surface treatment. To investigate the effect of HDPE's surface functionality on its interfacial properties, its adhesion to a commercial epoxy coating was measured via pull-off strength test according to ASTM D54541. After only 20 min of surface treatment with Co(II)/PMS solution, the adhesion strength at the interface of HDPE and the epoxy coating increased by 193%, confirming the importance of polyolefins' surface functionality on their interfacial adhesion properties. The method outlined herein can improve HDPE's surface functionality by introducing sulfate radicals. It improves HDPE's hydrophilicity and adhesion properties without requiring strong acids or time-consuming pre- or post-treatment processes. This process has the potential to increase the use of polyolefins in various industries, such as for protective coatings, high performance lithium-ion battery separators, and acoustic sensors.
由于聚烯烃表面能低、具有疏水性且与极性涂层的界面附着力较弱，其在先进技术中的应用受到限制。在此，我们提出使用处于最低氧化态的过渡金属和无机过氧化物来改善高密度聚乙烯（HDPE）的功能、表面自由能、亲水性和粘附性能。在本研究中使用的九种过渡金属与过氧化物的组合中，Co(II)与过一硫酸（PMS）过氧化物的组合对HDPE的表面改性最为有效，紧随其后的是Ru(III)与PMS的组合。化学处理后，通过傅里叶变换红外光谱、X射线光电子能谱和接触角测量对HDPE的表面功能、组成和能量进行了分析。在表面检测到了羟基、羰基和羧酸官能团，这解释了改性HDPE表面亲水性的提高；表面处理后，HDPE与去离子水的接触角从94.31°降至51.95°。为了研究HDPE表面功能对其界面性能的影响，根据ASTM D54541通过拉开强度试验测量了其与商业环氧涂层的附着力。仅用Co(II)/PMS溶液进行20分钟的表面处理后，HDPE与环氧涂层界面处 的附着力强度提高了193%，证实了聚烯烃表面功能对其界面粘附性能的重要性。本文概述的方法可通过引入硫酸根自由基来改善HDPE的表面功能。它无需强酸或耗时的预处理或后处理过程即可提高HDPE的亲水性和粘附性能。该工艺有可能增加聚烯烃在各种行业中的应用，例如用于防护涂层、高性能锂离子电池隔膜和声传感器。
