Thiol-Michael “click” chemistry: another efficient tool for head functionalization of giant surfactants

One of the challenges in the precise synthesis of giant surfactants lies in the homogenous functionalization of a head with bulky ligands. In this article, we report the use of thiol-Michael “click” chemistry as a facile, modular and robust approach to address this issue. A giant surfactant with acryloxyl-functionalized POSS (ACPOSS) head was conveniently constructed from commercially available acrylo POSS and polystyrene (PS). Functional thiols with different sizes, such as 2-mercaptoethanol, 1H,1H,2H,2H-perfluoro-1-decanethiol, 1-thio-β-D-glucose tetraacetate (sugar-SH), and 2-naphthalenethiol, were attached onto the head of the ACPOSS-PS conjugate by thiol-Michael and thiol–ene reactions. It was found that while both the methods offer a straightforward and highly efficient approach to prepare uniform and precise giant surfactants with small thiol ligands, only the former proceeds without apparent side reactions when large and bulky thiols, such as sugar-SH and 2-naphthalenethiol, are used. The former method also eliminates the need for UV irradiation or heat initiation. Therefore, the mild condition, high efficiency, and broad functional group tolerance of thiol-Michael chemistry should further expand the scope of POSS-based giant surfactants with unparalleled possibilities for head surface chemistry manipulation, which provides numerous opportunities for nanofabrication by the direct self-assembly of giant surfactants.