ABC-Type, Bola-Form Giant Surfactants: Synthesis and Self-Assembly

Due to the fast phase separation kinetics and small feature size, the self-assembly of giant molecules has attracted lots of attention. However, there is not much study on multicomponent giant surfactants. In this work, through a modular synthetic strategy, different polyhedral oligomeric silsesquioxane (POSS)-based molecular nanoparticles are installed with diverse functionalities (hydrophobic octavinyl POSS (VPOSS), hydrophilic dihydroxyl-functionalized POSS (DPOSS), and omniphobic perfluoroalkyl-chain-functionalized POSS (FPOSS)) on the ends of one polystyrene (PS) chain to build up a series of triblock bola-form giant surfactants denoted as XPOSS-PSn-FPOSS (X represents V or D). The target molecules are prepared by a combination of atom transfer radical polymerization (ATRP), esterification, as well as Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and thiol-ene click reactions. These macromolecules are thoroughly characterized by combined technologies including nuclear magnetic resonance (NMR), size exclusion chromatography (SEC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry MALDI-TOF MS analyses. It is revealed by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) that VPOSS-PSn-FPOSS adopts a two-phase separation scenario where VPOSS and POSS are segregated in one phase. DPOSS-PSn-FPOSS with a third hydrophilic DPOSS shows a three-phase separation scenario, where highly ordered phase structures are difficult to develop owing to the competition of mutual phase separation processes and may be trapped in kinetically metastable states.

Automated summary

The self-assembly of giant molecules has attracted attention due to their fast phase separation kinetics and small feature size. However, there is not much study on multicomponent giant surfactants. In this work, a series of triblock bola-form giant surfactants with diverse functionalities were built through a modular synthetic strategy. These molecules were thoroughly characterized and it was revealed that they exhibit different phase separation scenarios.