化学力滴定技术:一种新的测定自组装膜表面解离常数的方法

Chemical force titration:a new approach for characterizing the surface dissociation properties of self assembled monolayers

本文介绍了一种新的测定自组装膜表面官能团解离常数的方法—化学力滴定技术。利用这种新方法，测定了自组装膜表面酸碱基团的解离常数。与接触角滴定相比，化学力滴定技术具有高度的空间局域性，反映了自组装膜表面官能团的局域解离性质。

Chemical force microscopy(CFM) was used to measure the adhesion force between ω mercaptoundecanol(HS (CH 2) 11 OH) self assembled monolayer(SAM) modified tip and ω mercaptoundecanoic acid (HS (CH 2) 10 COOH) SAM on gold (shortly OH/ COOH),HS (CH 2) 10 COOH SAM modified tip and HS (CH 2) 11 OH SAM on gold(shortly COOH/ OH),and HS (CH 2) 11 OH SAM modified tip and a silicon substrate functionalized with NH 2 groups (shortly OH/ NH 2) in phosphate buffer solutions.The force titration curves, the plots of adhesion force versus pH value of solution, were obtained. Form the force titration curve of OH/ COOH ( COOH/ OH) and OH/ NH 2 respectively,the dissociation constant pK 1/2 values of surface COOH and NH 2 groups were obtained. Comparing with the results obtained from the conventional contact angle titration, it shows that the force titration technique embodied highly local properties of the surface groups of SAM.