等离子体对聚甲基丙烯酸甲酯改性效果持久性的研究

目的探讨等离子体处理聚甲基丙烯酸甲酯（PMMA）后的标本在空气中表面元素和湿润角的变化。方法将聚甲基丙烯酸甲酯制成2mm×10mm×10mm的试件70片。采用氧气离子体处理标本。将处理前、处理后即刻、空气中放置4d和6d的标本作光电子能谱分析。将氧气等离子体处理后的标本分成10组，每组6片，在空气中暴露时间从1d到10d，分别作湿润角测量。结果氧气等离子体处理后，聚甲基丙烯酸甲酯表面O／C（氧／碳）原子比，从0．289升至0．682，空气中放置4d后O／C原子比降至0．649，6d后为0．648。在空气中暴露最初4d，材料表面湿润角增大明显，即湿润性下降。但随着暴露时间的延长，其变化趋缓。结论氧气等离子体处理聚甲基丙烯酸甲酯标本后，在空气中暴露初期，处理效果快速下降。4d后表面O／C原子比和润湿角的变化趋缓，部分保留了氧气等离子体处理效果。

Durability of modification on plasma-treated polymethyl methacrylate surface

Objective To test change of chemical composition and wetting angles on O2-plasma-treated surface of PMMA after exposure to air. Methods Specimens were prepared from an acrylic resin denture material in the size of 2mm×10mm×10mm. 60w of power was imposed on the surface of experiment specimens for 4 min with O2-plasma. XPS studies were performed before and after exposure to air. Durability of wetting angles was tested after exposure to air（exposure time from 1 to 10 days）. Results After O2-plasma treatment,the O/C atomic ratios increased from 0.289 to 0.682. The O/C atomic ratios decreased from 0.682 to 0.649 and 0.648 at the fourth and sixth day after exposure to air respectively. Wetting angles on O2-plasma-treated surface of PMMA initially increased quickly and then leveled off after 4 days exposure. Conclusion Plasma modification exhibited time - dependent properties, but the effect of plasma surface treatment was partially retained.