Use of nanotubes of natural halloysite as catalyst support in the atom transfer radical polymerization of methyl methacrylate

Nanotubes of natural halloysite (HNTs) were used as a solid support for the heterogeneous atom transfer polymerization of methyl methacrylate (MMA) into poly(methylmethacrylate) (PMMA) using adsorbed CuBr–[1,1,4,7,10,10-hexamethyltriethylenetetramine] (CuBr–HMTETA) and CuBr–[3-(2-aminoethylamino)propyltrimethoxysilane] (CuBr–AEAPTS) as catalysts. CuBr–AEAPTS supported on HNTs proved to mediate a living polymerization of MMA, demonstrated by (i) an increase in the number-average molecular weight (Mn) with the increase of conversion, (ii) relatively low polydispersity indexes (PDI), and (iii) linear first-order rate plots. The presence of HNTs had a strong effect on the polymerization rate.