Abstract: Poly(lactic acid) macromonomer with a double bond at its end was synthesized by ring open polymerization of lactide catalyzed by stannous chloride in the presence of allyloxylethanol(AOE) as a co-initiator. Its molecular weight was decreased along with the adding amount of AOE. Initiated by an oxidation-reduction system, e.g. K₂S₂O₈ and Na₂SO₃, the poly(latic acid) macromonomers were copolymerized with divinylbenzene and methacrylic acid in a water-in-oil-in-water emulsion manner to produce hollow microspheres with a size of hundreds nanometers. Their hollow structure was confirmed by transmission electron microscopy. Infrared spectroscopy measurement shows that the remainings of the microspheres after tetrahydrofuran extraction, constituting roughly 20 of the sphere's mass, contained all the initial monomer components. This provides a new pathway for fabricating biodegradable hollow microspheres with rather smaller size, which may find diverse applications in the fields of drug delivery, tissue engineering and nanotechnology.

Key words: Emulsion polymerization, Polyl(lactic acid), Hollow microspheres