Coupling reaction of two kinds of molecular-weight controlled biodegradable polymers

Abstract

Poly(ε-caprolactone) (PCL) having controlled molecular weight was synthesized by ring opening polymerization of ε-caprolactone (CL) initiated by ethanol with stannous(II) octanoate or scandium(III) trifluoromethane sulfonate as a catalyst. The hydroxyl end group of the resulting polymer was converted to trimethylsiloxyl group by using hexamethyldisilazane. On the other hand, poly(vinyloxy-t-butyldimethylsilane) (PVOTBDMS) was obtained by aldol-type of group transfer polymerization. Under the presence of ZnBr2 or TiCl4 as the catalyst, the coupling reaction of above two precursor polymers was carried out so as to build PCL-block-PVOTBDMS with controlled molecular weight and narrow molecular weight distribution. The PCL-block-PVA as the final goal could be obtained by elimination of the silyl groups in the above block copolymer.