Synthesis And Characterization On Medical Biodegradable Telechelic Copolymer

In this paper, a new biodegradable telechelic copolymer was firstly synthesized through orthogonal experiments, which included three steps:1) synthesis of PLGA, 2) synthesis of amino protecting polymer, 3) synthesis of amino telechelic copolymer. Meanwhile, the structure and thermal performance of telechelic copolymer was characterized by FT-IR、1H-NMR and DSC.At first, using glycolide and lactide as monomers, a series of PLGAs were obtained by the open-ring polymerization, orthogonal experiments were used to optimize the synthesis conditions of PLGA, and we also studied the effects of reaction parameters on the yield of product, these factors included:the ratio of raw material, the dosage of catalyst and co-initiator, and reaction time et al.The results showed that the relatively high yield can be acquired under the conditions of adding 130μL catalyst (stannous octanoate),284μL co-initiator(1, 4- butyl glycol),and the monomer (glycolide and lactide)ratio of 1:1,polymerization at 113℃and after 12 h ,the yield of product was reached to35%. Infrared spectrum and 1H-NMR results have proved that the product was the PLGA;the results of DSC showed that PLGAs were amorphous polymers, their glass transition temperature(Tg)decreased with the dosage of co-initiator increased.In addition, by using N1, N2-Bis(tert-butoxycarbonyl)-L-lysine(Di-Boc Lysine) as amino protecting reagent,PLGA as raw materials,amino protecting polymers were obtained by esterification reaction. Orthogonal experiments were used to determine the synthesis conditions of amino protecting polymer; we also discussed the effects of reaction parameters on the yield of product, these factors included:the ratio of raw material, the dosage of catalyst and coupling agent, and reaction time et al.The results showed that the relatively high yield can be acquired under the conditions of adding 0.2188 g coupling agent ( 1, 3-Diisopropylcarbodiimi ) and 0.164 g catalyst(4-dimethylaminopyridine 4-toluene sulfuric acid),and the raw material(PLGA and Di-Boc Lysine)ratio of 3:1,polymerization at 20~25℃, the yield of product was reached to 53.6%. Infrared spectrum and 1H-NMR results have indicated that the product was amino protecting polymer; the results of DSC showed that amino protecting polymers were also amorphous polymers. Compared with PLGA, its Tg rises somewhat, mainly due to the fact the flexibility of molecular chain is reduced.Finally, the amino telechelic copolymer has been obtained by taking off the amino protecting groups(Bis-(tert-butoxycarbonyl)).Meanwhile, we discussed the effects of reaction parameters on the yield of product, these factors included:the dosage of trifluoroacetic acid(TFA)and catalyst, reaction time and reaction temperature et al. The results showed that the relatively high yield can be acquired under the conditions of adding 3 mL TFA /g polymer, polymerization at 0℃and after 4 h, the yield of product can be reached to 52%. Infrared spectrum and 1H-NMR results have demonstrated that the products obtained were the telechelic copolymers; The DSC results showed that they were amorphous polymers, which make it possible to synthesize the biodegradable elastomers.