Synthesis And Property Research Of Star-shaped Polycation Based On Polycaprolactone

Poly(ε-caprolactone) has great potential application in biomedical materials due to its good biocompatibility. However, the higher hydrophobicity and the lack of functional groups limit it’s further application. Therefore, the modification of the poly(ε-caprolactone) by introducting functional groups has become the research hotspot. In this paper, star-shaped4-arm poly(ethylene glycol)-b-poly(ε-caprolactone-co-γ-amino-ε-caprolactone) was synthesized based on the advantage of star-shaped polymer and cationic caprolactone. The polymer was synthesized through ring-open polymerization of CL and CABCL monomers by4-arm PEG as initiator.The main contents of this paper are summarized below:(1) A series of4-arm poly(ethylene glycol)-b-poly(ε-caprolactone-co-γ-amino-ε-caprolactone)(4-arm PEG-b-P(CL-co-ACL)) copolymers with different chemical composition were synthesized by a ring opening copolymerization of CL and CABCL initiated with the hydroxyl group of4-arm PEG using stannous octoate as the catalyst, followed by the removal of the protected groups. The structure, relative molecular weight and molecular weight distribution of the copolymers were confirmed by1H NMR, FT-IR and GPC, respectively. Differential scanning calorimetry (DSC) and Wide Angle X-ray diffraction (WAXD) were used to study the thermal properties and crystallinity of the copolymers.(2) Dynamic light scattering (DLS), pyrene fluorescence test and pH trition test were used to analyze the solution properties of polymers. The results demonstrated that the polymer could form micelle by4-arm PEG as shell and P(CL-co-ACL) as core and the micelle has pH responsiveness. The morphology of the micelle was spherical by transmission electron microscope (TEM). The cytotoxicity of the micelles at different concertation were measured by MTT assayand the result proved that this polymer was nontoxic even at the concentration of1000mg·L-1and had promoted cell proliferation.(3) The temperature sensitive properties of the hydrogel was analysed by differential scanning calorimetry (DSC), rotational rheometer and vial inversion test. The mechanism from micelle to hydrogel was observed by atomic force microscope (AFM). The internal space structure of the hydrogel was observed by scanning electron microscope (SEM). These results proved that the4-arm PEG-b-P(CL-co-ACL) polymer could form hydrogel with temperature sensitive ability at high concentration.