The stability of radio-frequency plasma-treated polydimethylsiloxane surfaces
The stability of radio-frequency plasma-treated polydimethylsiloxane surfaces
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DOI：
10.1021/la0627720
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发表时间：
2007-03-13
期刊：
影响因子：
3.9
通讯作者：
Lindner, Erno
中科院分区：
文献类型：
--
作者：
Chen, I-Jane;Lindner, Erno
聚二甲基硅氧烷（PDMS）是一种广泛用于制造芯片实验室设备的材料。然而，PDMS的疏水性质在微流体系统中是一个缺点。为了将疏水性PDMS表面转化为亲水性，在150、300和500 mTorr压力下用射频（RF）空气等离子体处理30 min。表面处理后，将PDMS试样储存在空气、去离子水或0.14 M NaCl溶液中，温度为4 ℃、20 ℃和70 ℃。的PDMS表面的亲水性（润湿性）的变化，其次是接触角测量和傅里叶变换红外衰减全反射（FTIR-ATR）光谱作为时间的函数。作为RF等离子体处理的效果，在PDMS表面上测量的接触角从113 +/-4度下降到9 +/-3度。灭菌舱压力和处理时间对结果无影响或影响可忽略不计。然而，PDMS表面随着时间的推移逐渐失去其亲水性。该过程的速率受PDMS及其周围环境的介电常数差异的影响。在去离子水中低温时最小，在空气中高温时最大。显然，在等离子体处理过程中在PDMS表面上产生的OH基团在松弛过程中倾向于更亲水/更少疏水的环境。FTIR-ATR光谱信息和接触角数据之间的相关性支持这一解释。
Polydimethylsiloxane (PDMS) is a widely used material for manufacturing lab-on-chip devices. However, the hydrophobic nature of PDMS is a disadvantage in microfluidic systems. To transform the hydrophobic PDMS surface to hydrophilic, it was treated with radio-frequency (RF) air plasma at 150, 300, and 500 mTorr pressures for up to 30 min. Following the surface treatment, the PDMS specimens were stored in air, deionized water, or 0.14 M NaCl solution at 4 degrees C, 20 degrees C, and 70 degrees C. The change in the hydrophilicity (wettability) of the PDMS surfaces was followed by contact angle measurements and Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy as a function of time. As an effect of the RF plasma treatment, the contact angles measured on PDMS surfaces dropped from 113 +/- 4 degrees to 9 +/- 3 degrees. The chamber pressure and the treatment time had no or negligible effect on the results. However, the PDMS surface gradually lost its hydrophilic properties in time. The rate of this process is influenced by the difference in the dielectric constants of the PDMS and its ambient environment. It was the smallest at low temperatures in deionized water and largest at high temperatures in air. Apparently, the OH groups generated on the PDMS surface during the plasma treatment tended toward a more hydrophilic/less hydrophobic environment during the relaxation processes. The correlation between the FTIR-ATR spectral information and the contact angle data supports this interpretation.