SF-PU composite hydrogel was prepared successfully by incorporating silk fibroin aqueous solution into polyurethane prepolymer (PU)which was synthesized using poly(ethylene glycol) (PEG)

poly-(polyethylene glycol) (PPG) and isophorone diisocyanate (IPDI) as the main materials.The structure and component of hydrogels as well as their interior morphology were characterized with the methods of ATR and SEM.Influences of hydrogels of different SF/PU and PEG/PPG proportions on their thermal properties and swelling behaviors were further investigated by means of DSC measurements and swelling tests

respectively.Results showed that the prepared composite SF-PU hydrogels have a kind of three-dimensional porous network structure.DSC curves of the hydrogels exhibited unique thermal properties

that the glass transition temperatures (Tg) and the crystallization changed lightly corresponding to the changed hydrogel compositions.Whats more

different composition hydrogels indicated similar excellent swelling dynamics and varied swelling ratios; the equilibrium swelling ratio (ESR) increased with the decrease of the SF content which could be seen as the cross-link agent; when the composition of hydrogel was SF/PU=1/25

PEG/PPG=2/1

the ESR could reach 440%.In the initial swelling stage

the hydrogels much fit the Fickian diffusion

while the Schott second-order kinetic equation was appropriate to describe the whole swelling process.All the above unique features of SF-PU composite hydrogels made them a promising material for the prosthetic disc nucleus in the future.