Preparation And Characterization Of PLLGC/BMPLGA Composite Membrane

Degradable polymer poly(D,L-lactic-co-glycolide)(PLGA)is a good biomedical material,due to its excellent biocompatibility and biodegradability.However,its toughness is poor,which is not conducive to the formation and processing of polymer matrix.At the same time,the accumulation of acidic substances in the degradation process of PLGA matrix,which may result in non bacterial chronic inflammation at the implantation site.The flexible CL segment of poly(?-caprolactone)(PCL)has special carbon chain structure and excellent rheological properties,which can give good toughness andprocessability.The introduction of an acid anhydride group into the degradable PLGA matrix and the further introduction of a basic group such as an amine group,it would be expected to achieve regulation of the accumulation and degradation rate of the acidic degrading products in the polymer.In this paper,terpolymers(PLLGC)and grafting of butanediamine linked with poly(D,L-lactide-co-glycolide)of maleation(BMPLGA)were synthesized.Then PLLGC/BMPLGA composite porous membrane materials were prepared with good performance,which is expected to be applied in the field of biomedical materials.In this work the terpolymers(PLLGC)was prepared by ring-opening copolymerization with stannous octoate as catalyst from purified L-lactide,glycolide and?-caprolactone.The effects of catalyst dosage,reaction temperature,reaction time and reaction vacuum on the molecular weight and molecular weight distribution of the terpolymer were studied.The results showed that the weight average molecular mass of the PLLGC reached 12.4×10~4 Da when the molar ratio of monomer to catalyst was 2000,the reaction temperature 140°C,the reaction time 24 h and the reaction vacuum 5 Pa.The copolymer had a Tg about 35°C and no melting endotherm peak was observed;this indicated that PLLGC is an amorphous polymer.The MPLGA was synthesized by melt-copolymerization under high vacuum using purified D,L-lactide,glycolide and maleic anhydride as raws with stannous octoate as the catalyst.After dissolving the MPLGA in chloroform,BMPLGA was obtained through the further introduction of 1,4-butanediamine.The PLLGC/BMPLGA composite film was obtained by combining PLLGC with BMPLGA.The mechanical properties and hydrophilicity of these polymer membranes were investigated.The results showed that both the tensile strength and contact angle were PLLGC>PLLGC/BMPLGA>BMPLGA,indicating that PLLGC had excellent toughness and BMPLGA had good hydrophilicity.The PLLGC and PLLGC/BMPLGA porous membrane materials were prepared by sodium chloride particles as porogen(50,100 and 150?m)through solvent casting/particle leaching method.The pore size of the porous membrane materials increased with the increase of the particle size of the porogen,the number of micropores increased with the increase of the porogen amount,and the pore structure connectivity increased.But the tensile strength decreased with the increase amount of the porogen.Among them,the number of micropores of the PLLGC/BMPLGA composite porous membrane is more than that of the PLLGC porous membrane and its connectivity is better.Therefore,the pore structure of porous membrane materials can be controlled by changing the particle size and amount of the sodium chloride.The degradation experiments of PLLGC,PLLGC/BMPLGA smooth membranes and porous membranes(porogen particle size 100?m)were studied in vitro.The mass loss and water uptake of the two membranes materials gradually increasing with increasing degradation time;however the pH value decreased in the buffer solution.The surface of the PLLGC/BMPLGA composite membrane materials showed roughness and pores,while the PLLGC membrane was not obvious on 15th day.The surface of both membranes materials showed a large degree of roughness,and the number of pores increased and there were interconnected pores on 30th day.Among them,the composite film contained acid anhydride bond and amino groups,and the morphology of the material changed greatly,and the degradation was more obvious.Cells were cultured by direct contact with materials.The growth and proliferation of cells on polymer membrane materials were studied by observing cell morphology and CCK-8method.The results showed that with the increase of culture time,the cells on the material showed a tendency to proliferate,grew well and had no cytotoxicity,that is,good biocompatibility.