Aluminum- and calcium-incorporated MCM-41-type silica as supports for the immobilization of titanium(IV) isopropoxide in ring-opening polymerization of l-lactide and ε-caprolactone

Abstract

Aluminum- and calcium-incorporated MCM-41-type silica with various Al/Si and Ca/Si ratios were evaluated as catalytic supports for ring-opening polymerization (ROP) of l-lactide and ε-caprolactone. The catalytic centers were generated by grafting titanium(IV) isopropoxide onto the support. All prepared heterogeneous catalysts better restrained the ROP of lactide than the homogeneous analog, titanium(IV) isopropoxide. Compared to siliceous MCM-41, the incorporation of aluminum or calcium in MCM-41 framework improved the molecular weight of the polymers although it lessened the polymerization rate. The more acidic Al-MCM-41 support appeared to be more favorable than the more basic Ca-MCM-41 support for the ROP reactions. © 2013 Elsevier B.V.