Preparation And Characterization Of Poly (Diol Citrate) Based Degradable Elastomer And Its Porous Scaffold

As a new kind of biomedical material,network-type polyester bio-elastomer,which has its own advantages of stable structure,excellent flexibility and machable mechanical properties to the soft tissue of the human body,now has become one of the hotspot fields that scientists concern.Citrate-based network-type polyester bioelastomer,synthesized by citric acid and diol monomers,has great potentials in tissue-engineered scaffold materials and drug-controlled release materials,making it gradually become one of the hot spots in this field.In this dissertation,poly(caprolactone diol-citric acid)(PCC)prepolymers were obtained by melt polycondensation of citric acid and polycaprolactone diol.And then,PCC prepolymers were thermally cured to get PCC elastomers.Next,the chitin nano-whiskers(CWs)were loaded into PCC matrix to improve the properities of PCC elastomers.Finally,porous scaffolds were fabricated by salt-leaching for potential use in tissue engineering.The main results are as follows:1.PCC bioelastomers were prepared by melt polycondensation.The ratio of polycaprolactone-diol and citric acid,and crosslinking temperature and time were investigated respectively.The structure and properties of PCC elastomer were characterized by FT-IR,1H-NMR,GPC,DMA,DSC and TGA,etc.The results showed that citric acid and polycaprolactone diol were successfully polymerized without any catalyst;the mechanical properties,hydrophilicity and degradation properties of the elastomers can be adjusted by adjusting the monomer molar ratio,the temperature and the time of the post-polymerization.When the monomer molar ratio is 1: 1,and the curing is carried out at 120? for 7 days,PCC elastomer has the best comprehensive performance.The elastomer has p H-responsive property and has potential application as a drug-controlled release material.2.The CW was introduced into PCC matrix to improve the properties of PCC elastomer.The structure and properties of CW/PCC nanocomposite elastomers were characterized by FT-IR,DMA,TGA,XRD,etc.The conclusions are as follows: CW and PCC prepolymer can form homogeneous dispersion in acetone,and after thermocuring,the CW/PCC nanocomposite elastomers with CW uniformly dispersing in PCC matrix were obtained.The introduction of the CW improved the hydrophilicity of the PCC elastomer,and reduced the swelling degree and the degradation rate of the PCC elastomer.The tensile strength and Young's modulus were enhanced.The existing of CW could improve the cytotoxicity of PCC elastomers.3.PCC and CW/PCC porous scaffolds were prepared by salt-leaching method.The structure and properties of the porous scaffolds were characterized and the following conclusions were reached: when the size of the pore-forming agent was 400 meshes and the mass ratio of prepolymer: porogen was 1: 6,the PCC porous scaffolds with the best performance can be obtained.The porous CW/PCC scaffolds showed reversible recovery from compression,and the maxium compression stress was 345 KPa;the porosity was measured as ~80%,water-absorbability was about 105%,and the CW content has little influence on the water absorption and porosity of porous scaffold.