Parents Raft Of Block Copolymer Synthesis And Performance Research

In this paper, a series of amphiphilic block copolymers, PSt-b-PSMA-b-PAA, were synthesized by the reverse addition-fragmentation chain transfer (RAFT) process using BDATC as linking agent. The structure and the performance of the polymer were determined by1H NMR, FTIR, DSC and TGA. The self-assembled micelles of PSt-b-PSMA-b-PAA were paepared in different solutions, and the self-assembly process and the morphology of the micelles were investigated by Zetasizer and Transmission electron microscopy (TEM). The results revealed that with the increase of the initial polymer solution concentration, the aggregations of micelles increased, the particle size increased. In DMF/H2O solutions, the aggregates adopted a spherical shape and their diameters are small; In THF/H2O solutions, rod-like aggregates could be found, and the diameters increased; When combined DMF and THF as the common solvent, rod aggregates were observed among the spheres. When the pH of the solutions decreased, micelles size decreased and the liquid turned turbid; When the pH increased, micelles size increased and it could be well dispersed. Additionally, the increase of hydro philic segments could also add the hydrophilicity of the aggregates and increase its size.An amphiphilic nano-fibers were prepared by electronspinning of solutions of PSt-b-PSMA-b-PAA. Then, the immobilized cross-linking fibers were obtained by reaction with ethanediamine. Polarization microscope and FTIR were used to characterize the morphology and structure of the pristine and modified nano-fibers. And the surface wettability of the fibers were determined by contact angle tester. Factors such as solvent, pH, temperature, length of the segments and so on could influence the surface wettability. Moreover, the surface could be reversibly turned between hydrophilic and hydrophobic with treatment with water and toluene.