Amino-functionalized SBA-15 immobilized NiBr2(PPh3)2 as a highly effective catalyst for ATRP of MMA

3-Aminopropyltriethoxysilane modified mesoporous SBA-15 was used to load the NiBr2(PPh3)2 as a heterogeneous catalyst for the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) when initiated by ethyl 2-bromoisobutyrate (EBriB) in toluene. Due to the Lewis acid sites formed by the surface silanol groups of the mesoporous material, some monomer conversions were much higher even than that catalyzed by the homogeneous catalyst NiBr2(PPh3)2 under the same reaction conditions while polydispersity indices (PDI) of the products still kept narrow (1.20–1.30). At the same time, the activity of the catalyst could be modulated by changing the quantity of the –NH2, SBA-15 and the free PPh3. In the recycling experiments, the recovered heterogeneous catalyst basically maintained its catalytic activity without any addition of new heterogeneous catalyst.

Graphical abstractThe immobilized –NH2, free PPh3 and the surface silanol groups on the mesoporous material SBA-15 influence ATRP of MMA collectively. This heterogeneous catalyst is even more effective than the homogeneous catalyst without additional Lewis acid.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► By immobilizing NiBr2(PPh3)2 on 3-aminopropyltriethoxysilane functionalized SBA-15 as heterogeneous catalyst, Ni(II) species are separated from polymerization product effectively. ► With the added free PPh3, this heterogeneous catalyst could make the supported ATRP of MMA more effective even than the corresponding homogeneous reaction without the Lewis acid. ► Quantity of free PPh3, –NH2 and SBA-15 could regulate the monomer conversion and PDI of the product together. ► In the recycling reactions, this heterogeneous catalyst could keep catalytic ability well.