The Study Of Polymer Micelle By Single-Molecule Force Spectroscopy

For its special properties and potential application, polymer micelle has attracted the attention of many researchers. Although polymer micelle has been studied using many kinds of methods, there is no such a study to directly detect the micelle cohesion force. In this thesis, the atomic force microscopy (AFM)-based single molecule force spectroscopy (SMFS) will be employed to study the cohesion force of polystyrene-block-poly (N-(2-acryloyloxyethyl) pyrrolidone) (PS-b-PNAP) micelle. Because of its excellent sensitivity on tiny force, SMFS will play a key role on the study of polymer micelles.Firstly, the hydrophobic force of the PS block of copolymer of PS-b-PNAP is obtained by SMFS. And then, we study the micelle cohesion of PS-b-PNAP micelle force by the same method. We find that the hydrophobic force and micelle cohesion force is-85 pN and-66 pN, respectively. The difference between of the two forces is attributed the presence the hydrophilic PNAP block. It also suggests that two kinds of force are independent on the stretching velocity and the substrate species.For the next step, we study the micelle adsorption on PS film. The result suggests that the force of micelle adsorption on PS film (-100 pN) is higher than that on the common PS substrate. The structure of micelle may be destroyed by the higher adsorption force on the PS film. The force of 100 pN is the adsorption force of the single copolymer chain on the PS film. This thesis provides insight on the modification of material by polymer micelles.