Synthesis, Preparation, Structure And Properties Of Degradable Polyester Bioelastomers

Biomedical materials or biomaterials are ones which can be planted in bodies and be joined with tissues and organs together. With the development of material science and biomedicine, biomaterials have been applied to varied biomedical fields such as common medical instruments, functional artificial organs, orthopedic materials and modern medical equipments. Today, people hope the materials planted in body are only acted as temporary substitution, and can be degraded and absorbed with the regeneration of tissues and organs to weaken the longer bad effect on bodies; so degradable biomedical polymers are greatly concerned by the researchers.Polyester bioelastomers, a kind of novel biomaterials, not only own good biocompatibility and biodegradability like traditional linear polyesters such as PLA and PGA, but also possess the stability of structure, good flexibility and advantage of modulus matching with soft tissues. Presently, they have been paid attention to at a full scale by many scientists.In this paper, biodegradable thermoplastic poly(glycerol-co-sebacate) ester (TM-PGS) and thermoset poly(glycerol-co-sebacate-co-citrate) ester elastomers have been successfully prepared by the environment-friendly condensation polymerization, and their composition, structure and properties have also been studied systemically. Finally, the elementary evaluation tests of cell toxicity were carried out.The main research content and achievements are shown as follows:(1) Biodegradable and thermal-moldable TM-PGS polyester elastomers have been successfully prepared by one-step method. As a result, firstly they have more sols with the content of 69～85% and lower gel crosslinking density with the swelling degree of 2700～5200%; secondly they own many hydroxyl groups in the chains which promote the formation of strong hydrogen bonding; thirdly they display micro-phase separation structure originating from crystal and non-crystal regions; fourthly by controlling the molar ratio of monomers, adjustable mechanical properties( tensile strength of 0.1～0.7MPa, elastic modulus of 0.05～0.7MPa, elongation at break of 12～115%), good hydrophilicity(water contact angle of 45～57°) and low water-uptake(3～8%) can be gained; fifthly after 7.5 day degradation, their mass loss can reach above 30%, and the rate of degradation is influenced by the sol content, crosslinking density, branching degree of sols, hydrogen bonding between gels and sols etc.; finally they are desired to be used as drug delivery carrier, hemostasis agent, bone wax, scaffold material, anti-adhesion film after operation etc. All these have not been found to be reported.(2) Biodegradable and thermal-moldable TM-PGS polyester elastomers have been successfully prepared by two-step method, first synthesize prepolymers, and then crosslink them by adding monomers again. As a result, firstly they have more sols with the content of 61～63% and lower gel crosslinking density with the swelling degree of 2000～2600%; secondly they own many hydroxyl groups in the chains which promote the formation of strong hydrogen bonding; thirdly they display micro-phase separation structure originating from crystal and non-crystal regions; fourthly by controlling the molecular weight of prepolymers, adjustable mechanical properties( tensile strength of 0.4～0.7MPa, elastic modulus of 0.3～0.7MPa, elongation at break of 100～260%), good hydrophilicity(water contact angle of 34～44°) and low water-uptake(1～9%) can be gained; fifthly, after 28 day degradation, their mass loss can reach above 30%, and the rate of degradation is influenced by the sol content and molecular weight, crosslinking density, hydrophilicity and water-uptake, hydrogen bonding between gels and sols etc.; finally they are desired to be used as drug delivery carrier, hemostasis agent, bone wax, scaffold material, anti-adhesion film after operation etc. All these have not been found to be reported.(3) TM-PGS elastomers prepared by one-step and two-step show thermoplastic property, which is because: more sols with the content of above 60%; lower crosslinking density; more reversible hydrogen bonding which contributes to the materials' crosslinking; existence of crystal regions; residual sebacic acid probably as plasticizers.(4) Biodegradable and thermoset PGSC polyester elastomers have been successfully prepared by two-step method, first synthesize prepolymers, and then extend chain and crosslink them by adding citric monomers. As a result, firstly they have lower sols with the content of 7～30% and higher gel crosslinking density with the swelling degree of 200～570%; secondly they own many hydroxyl groups in the chains which promote the formation of strong hydrogen bonding; thirdly they display amorphous structure and no crystals; fourthly by controlling the dosage of citric acid and shaping time, adjustable mechanical properties( tensile strength of 0.4～1.46MPa, elastic modulus of 0.45～3.26MPa, elongation at break of 51～171%), certain hydrophilicity(water contact angle of 70～85°) and low water-uptake(8～14%) can be gained; fifthly, after 28 day degradation, their mass loss only reach 25%, but during degradation they can absorb much water above 200%; finally, they are desired to be used as drug delivery carrier, scaffold material, anti-adhesion film after operation etc. All these have not been found to be reported.