A Green One-pot Synthesis of PDMS Bis-Macromonomers Using an Ecologic Catalyst (Maghnite-H+)

Abstract

PDMS bis-macromonomers bearing methyl methacrylate end groups is a material mainly used for making extended-wear contact lenses. Silicon-based materials give a good oxygen passage and methyl methacrylate has biocompatibility and mechanical properties of the elastomer. The present study shows the synthesis of this material. The polymerization of hexamethylcyclotrisiloxane (D3) catalyzed by Maghnite-H+ (Mag-H+), a montmorillonite sheet silicate clay exchanged with protons, an efficient catalyst for cationic polymerization of manyheterocyclic and vinylicmonomers. The structural compositions of “Maghnite” have already been determined. The effects of the amount of Mag-H+, temperature and the reaction time were studied. Moreover, we used a simple method, one step in solution to prepare Poly dimethyl siloxane (PDMS) and PDMS bis-macromonomers. The structure of the resulting products is characterized and established by 1H and 13C-NMR, where the methacrylate end groups are clearly visible. The presence of unsaturated end group was also determined by UV and FTIR analysis. The influence of the amount of methacrylic anhydride on monomer conversion was studied. The polymerization yield and the molecular weight of PDMS macromonomers depend on the amount of methacrylic anhydride used.