Influence of patch size and chemistry on the catalytic activity of patchy hybrid nonwovens
Christian Hils, Martin Dulle, Gabriel Sitaru, Stephan Gekle, Judith Schöbel, Andreas Frank, Markus Drechsler, Andreas Greiner, Holger Schmalz
Nanoscale Adv., 2020, DOI: 10.1039/c9na00607a
In this work, we provide a detailed study on the influence of patch size and chemistry on the catalytic activity of patchy hybrid nonwovens in the gold nanoparticle (Au NP) catalysed alcoholysis of dimethylphenylsilane in n-butanol. The nonwovens were produced by coaxial electrospinning, employing a polystyrene solution as core and a dispersion of spherical or worm-like patchy micelles with functional, amino group-bearing patches (dimethyl and diisopropyl amino groups, anchor groups for Au NP) as shell. Subsequent loading by dipping into a dispersion of preformed Au NPs yields the patchy hybrid nonwovens. In terms of NP stabilization, i.e., preventing agglomeration, worm-like micelles with poly(N,N-dimethylaminoethyl methacryl¬amide) (PDMA) patches are most efficient. Kinetic studies employing an extended 1st order kinetics model, which includes the observed induction periods, revealed a strong dependence on the accessibility of the Au NPs´ surface to the reactants. The accessibility is controlled by the swellability of the functional patches in n-butanol, which depends on both patch chemistry and size. As a result, significantly longer induction (tind) and reaction (tR) times were observed for the 1st catalysis cycles in comparison to the 10th cycles and nonwovens with more polar PDMA patches show a significantly lower tR in the 1st catalysis cycle. Thus, the unique patchy surface structure allows to tailor the properties of this “tea-bag”-like catalyst system in terms of NP stabilization and catalytic performance, which resulted in a significant reduction of tR to about 4 h for an optimized system.