Study On Surface Modification Of Poly(ε-Caprolactone, PCL)

Poly-caprolactone(PCL) is a biodegradable biomaterial which is promising in the biomedical field such as tissue engineering and controlled drug delivery,duo to its good biocompatibility,degradability,and mechanical performance.However,the application of PCL was greatly confined by its poor surface hydrophilicity.The purpose of this thesis was to improve its surface performance,to increase its surface hydrophilicity,to improve cell affinity and anti-coagulantion performance.The following are the main experiments and results.1.The surface of PCL was firstly primed with Polyallylamine Hydrochloride(PAH), and then natural biomacromolecule Hyaluronic acid(HA) and Chitosan(CS) were coated to the surface of PCL in a Layer-by-Layer self-assembly manner. Unlike the previous reported method of aminolysis,the PAH priming can provide enough surface amine-groups for subsequent biomacromolecular self-assembly without hydrolysis of PCL chain.Thus the mechanical property of PCL substrate can be better maintained.2.ATR-FTIR,surface contact angle test and protein adsorption of PCL samples modified by PAH/HA and HA/CS self-assembly method were evaluated.FTIR results confirmed the success of the immobilization of both polyelectrolyte systems on PCL surface.The surface hydrophilicity of PCL samples were greatly improved by the polyelectrolytes.Surface contact angle goes down to around 55â–¡for PCL(HA/CS)n system and 45â–¡for PCL(PAH/HA)n system from about 85â–¡for neat PCL.Furthermore,the contact angle decreases with the increasing of the number of polyelectrolyte Layers.The type of charge of the surface polyelectrolytes plays an important role in protein adsorption behavior of the modified PCL samples.3.Heparin Sodium(HS) and Chitosan(CS) were immobilized on the surface of PCL with the same LBL technique.The success of this method was confirmed by ATR-FTIR test.The surface hydrophilicity of PCL samples was drastically improved by the immobilization of HS and CS.The PIEC culturing experiments indicated that the cell affinity of PCL samples was improved efficiently.The PIECs could be adhered and profilerated more efficiently on the modified PCL surface than on neat PCL surface.With the introduction of the natual anticoagulant HS,the modified PCL film showed greatly improved anti-coagulant performance when tested with fresh anti-coagulated human blood.4.Preliminary study was carried out to develop a straightforward and simple route to synthesize halogen-functionalized PCL through cationic copolymerization of PCL and epichlorohydrin,using boron trifluoride etherate as catalyst.The NMR and GPC results of the resulting polymer confirmed its structure as expected.