Lim Min Soo, Smiley Katelyn J, Gawalt Ellen S
Department of Chemistry, Slippery Rock University, Slippery Rock, PA 16057, USA.
Scanning. 2010 Sep-Oct;32(5):304-11. doi: 10.1002/sca.20192.
Stainless steel 316L is widely used as a biomedical implant material; however, there is concern about the corrosion of metallic implants in the physiological environment. The corrosion process can cause mechanical failure due to resulting cracks and cavities in the implant. Alkyl phosphonic acid forms a thin film by self-assembly on the stainless steel surface and this report conclusively shows that thermal treatment of the octadecylphosphonic acid (ODPA) film greatly enhances the stability of the ODPA molecules on the substrate surface. AFM images taken from the modified substrates revealed that thermally treated films remain intact after methanol, THF, and water flushes, whereas untreated films suffer substantial loss. Water contact angles also show that the hydrophobicity of thermally treated films does not diminish after being incubated in a dynamic flow of water for a 3-hour period, whereas the untreated film becomes increasingly hydrophilic due to loss of ODPA. IR spectra taken of both treated and untreated films after water and THF flushes show that the remaining film retains its initial crystallinity. A model is suggested to explain the stability of ODPA film enhanced by thermal treatment. An ODPA molecule is physisorbed to the surface weakly by hydrogen bonding. Heating drives away water molecules leading to the formation of strong monodentate or mixed mono/bi-dentate bonds of ODPA molecule to the surface.
不锈钢316L被广泛用作生物医学植入材料；然而，人们担心金属植入物在生理环境中的腐蚀问题。腐蚀过程会因植入物中产生的裂纹和空洞而导致机械故障。烷基膦酸通过自组装在不锈钢表面形成薄膜，本报告确凿地表明，对十八烷基膦酸（ODPA）薄膜进行热处理可大大提高ODPA分子在基底表面的稳定性。从改性基底获取的原子力显微镜（AFM）图像显示，经过热处理的薄膜在甲醇、四氢呋喃（THF）和水冲洗后仍保持完整，而未经处理的薄膜则有大量损失。水接触角也表明，经过热处理的薄膜在动态水流中孵育3小时后疏水性并未降低，而未经处理的薄膜由于ODPA的损失而变得越来越亲水。水和THF冲洗后处理和未处理薄膜的红外光谱表明，剩余薄膜保留了其初始结晶度。提出了一个模型来解释热处理增强ODPA薄膜稳定性的原因。一个ODPA分子通过氢键弱物理吸附在表面。加热驱走水分子，导致ODPA分子与表面形成强单齿或混合单齿/双齿键。
