A new progress in adjusting the acid strength and acid density of solid acid has been achieved recently by the DICP research group led by Prof. Yang Qihua. The results “Polystyrene sulphonic acid resins with enhanced acid strength via macromolecular self-assembly within confined nanospace” were published in the recent issue of Nature Communications. (Doi: 10.1038/ncomms4170; http://www.nature.com/ncomms/2014/140127/ncomms4170/full/ncomms4170.html).
Tightening environmental legislation is driving the chemical industries to develop efficient solid acid catalysts to replace conventional mineral acids. However, the acid strength and acid density of the solid acids closely related to catalytic activity are still hard to be adjusted.
In previous studies, we have found that local concentration of molecular catalysts could be greatly enhanced by encapsulating them in a confined nanospace. Inspired by the above finding, we prepared a series of novel solid acids via confining sulfonated polystyrene within the silica hollow nanospheres. It was found that the acid strength and density of sulfonated polystyrene could be adjusted through their reversible morphology transformation from aggregation to swelling state within the confined nanospace. The novel hybrid solid acid catalyst with enhanced acid strength demonstrates superior activity and stability in a series of important acid-catalyzed reactions. The deep understanding of the self-assembly behavior of macromolecular within the confined nanospace may provide a new strategy to fabricate efficient hybrid solid acid catalysts for green chemical processes.
This work was supported by the National Natural Science Foundation of China. (by Zhang xiaomin)