Deprotection-Induced Micellization Of Glycopolymers: Control Of Kinetics And Morphologies

In recent years, self-assembly of block or graft copolymers with sugar-containing component has drawn great attention. We just reported that protectiondeprotection chemistry could initiate self-assembly of glycopolymers based on the high polarity change induced by the deprotection. Considering that the protection-deprotection is so common and its variety in glycochemistry, it is worth developing this finding into a new and general strategy of self-assembly of glyco-containing polymers. For this purpose, this article focuses on the kinetics and morphology control of the assemblies of glyco-block copolymers induced by the deprotection. Benzoyl (Bz) as the protective group was introduced, which has much lower deprotection rate than acetyl group (Ac) reported previously. Thus, the detailed kinetic study of the self-assembly of Bz copolymer by means of in situ light scattering and H-1 NMR, etc., became possible. The morphologies of all of the resultant assemblies were observed by cryo-TEM. Thus, we found that in the case of using an equivalent catalyst TBAOH, with the progress of deprotection of Bz, the copolymer follows three-stage assembly, i.e., fast initiation, steady growth, and then fission/reorganization into stable state. In most conditions, both Bz and Ac copolymers form stable vesicles, but the former is apparently larger than the latter. This is because that the slow deprotection of Bz makes the resultant assemblies assume structures closer to equilibrium, and the fast reaction of Ac makes the assemblies with more kinetic-trapped features.