Organometallic-polypeptide Block Copolymers: Synthesis and Crystallization-driven Self-assembly in Aqueous Solutions...

The synthesis of polyferrocenyldimethylsilane-b-poly(L-glutamic acid) block copolymers was systematically explored. Rod-like and plate-like micelles were prepared from self-assembly of the block copolymers in aqueous solution with two different approaches. In a dissolution-dialysis approach, micelles were prepared by dissolving a block copolymer sample in excess aqueous base followed by the dialysis of the solution against water. The morphology of the resultant micelles showed composition dependence. The block copolymer sample with the lowest soluble block content formed rod-like micelles, while the other samples with higher soluble block content formed spherical micelles. In a THF-mediated approach, THF was added into a block copolymer solution, which was first prepared by the dissolution-dialysis approach, and then the THF was evaporated slowly. Plate-like micelles were obtained from all the block copolymer samples examined, and these had a broad range of soluble block content. The formation of these plate-like micelles was attributed to the crystallization of the PFDMS blocks in the presence of THF. A tendency of large platelet micelles evolving to thin filaments over time was observed. This change may have been driven by the increase in the corona-chain stretching energy as THF evaporated.