The synthesis of PEG-PCL and the physicochemical properties of its self-assembled nanoparticles

In this paper, poly(caprolactone)-poly(ethylene glycol) (PEG-PCL) was synthesized by using potassium bis(trimethylsilyl)amide as a catalyst, ethylene oxide and c-caprolactone as a raw material. Then, amphiphilic block polymers PEG-PCL of different molecular weights were synthesized by this method. These were PEG2K-PCL2K, PEG5K-PCL2K and PEG5K-PCL5K. But this method is different from most literature reports, where the amphiphilic block copolymer PEG-PCL was synthesized by using fixed molecular weight polyethylene glycolmonomethyl ether (PEG) and c-caprolactone as raw materials, and stannous caprylate (Sn(Oct)2) as a catalyst. This paper introduces the detailed experimental procedures. The copolymers obtained were characterized by Fourier-transform infrared spectroscopy, gel permeation chromatography and hydrogen nuclear magnetic resonance. Using the method of dialysis, the amphiphilic blockcopolymer PEG-PCL was self-assembled in water to form polymer nanoparticles. The physicochemical properties of the polymer nanoparticles were characterized by dynamic laser scattering, scanning electron microscopy and Zeta potentiometer.