The crystallization morphology and lamellae thickness of poly(ethylene oxide)-b-poly(-caprolactone) (PEO-b-PCL) under high pressure CO2 was studied by means of wide-angel X-ray diffraction (WAXD) and small-angel X-ray scattering (SAXS).For the sample of PEO0.5 k-b-PCL24.5 k

only PCL blocks crystallized under 1~3 MPa CO2 and the lamellae thickness of PCL segment decreased with increasing CO2 pressure.The melting behavior and isothermal crystallization kinetics were investigated by using high pressure differential scanning calorimetry (HP DSC).The results indicated that only the melting peak of PCL segments can be observed and the melting peaks widened with increasing pressure.The crystallinity degree (Xc) and melting temperature (Tm) of PEO-b-PCL decreased with increasing CO2 pressure.Xc of PCL in the sample decreased from 46.9% to 36.6% and Tm decreased from 54.5℃ to 47.2℃ under 0 MPa and 3 MPa respectively.The Avrami analysis was performed to obtain the kinetics parameters.The overall crystallization rate decreased with increasing pressure and the crystallization process was controlled by nucleation rate.The half crystallization time (t1/2) of the sample increased from 2.23 min at 0 MPa to 5.83 min at 3 MPa.The value of Avrami index n

is between 3.7 and 4.7

demonstrating a three-dimensional spherulitic growth in the process of isothermal crystallization.The decreasing crystallinity degree and crystallization rate illustrated that pressurized CO2 hindered the crystallization of PEO-b-PCL.