In order to improve the hydrophilicity of poly(lactic acid)

poly(ethylene glycol)-b-poly(L-lactic acid) diblock copolymers (PELA) with different relative molecular masses and compositions were synthesized by ring-opening polymerization of L-lactide (LLA) with Sn(Oct)2 as the catalyst and methoxy poly(ethylene glycol) (mPEG) as the initiator.The structure and properties were investigated by Fourier transform infrared spectroscopy

proton nuclear magnetic resonance

contact angle measurements and differential scanning calorimetry.Results indicated that the relative molecular mass of PELA could be controlled by adjusting the feed ratio of mPEG to LLA

and the hydrophilicity of PELA increased with the increase of amount and chain length of mPEG

but the values of Tg

Tcc

Tm of PELA decreased.Ultrafine fibrous PELA membranes were prepared by traditional electrospinning from a 0.2 g/mL PELA solution in a mixture of chloroform and N

N-dimethylformamide (90∶10

V/V)

and fibrous composite membranes with water-soluble poly(ethylene oxide) (PEO) as the core polymer were produced by emulsion electrospinning from a W/O emulsion solution of PEO/PELA in water/chloroform (E-PEO/PELA) and coaxial electrospinning from an aqueous PEO solution as the inner polymer solution and a PELA solution in 2

2

2-trifluoroethyl alcohol as the outer polymer solution (C-PEO/PELA)

respectively.Characterization by scanning electron microscope and transmission electron microscope verified the fine fiber morphology of the above three kinds of the obtained electrospun fibers.The hydrophilicity of the electrospun PELA membranes increased with their content of mPEG.Core/shell E-PEO/PELA and C-PEO/PELA fiber structures were obtained by both emulsion electrospinning and coaxial electrospinning

meanwhile their hydrophilicity was better than that of the electrospun PELA membrane because of the special core/shell fiber structure and PEO in the core.