Balance of Hydrophilicity and Hydrophobicity of Stimuli-Responsive Metallopolymer-Decorated Organic Particles

The controlled design of surfaces through functionalization enables a tailored design of material properties. Especially stimuli-responsive polymers are of significant interest in preparing so-called "smart surfaces". The living anionic polymerization offers the possibility of modifying surfaces through a grafting-from or grafting-to strategy. This study applied both synthesis strategies to functionalize porous polystyrene-based microparticles with the redox-responsive poly(vinyl ferrocene). The living character of the polymerization enabled the preparation of polymers with various chain lengths, and the application of both grafting strategies led to particles of different hydrophilicity. The synthesis and resulting particles were investigated and characterized by infrared spectroscopy, size-exclusion chromatography, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analyses. The influence of the molecular polymer brush structure with different chain lengths and hydrophilicity on the electrochemical addressability of the functionalized polystyrene particles was demonstrated by cyclic voltammetry measurements. The results of this study revealed fundamental characteristics of surface-immobilized ferrocene polymers, which are of interest for the design of electrochemically responsive materials for sensing and (selective) separation applications.