Design,Synthesis And Properties Of Medical Polyurethane Adhesives

In recent years,the development of medical adhesives that can replace sutures has become one of the research hotspots in the field of biomedical materials.However,challenge lies in developing surgical adhesives with strong adhesion in wet tissue,controlled degradation,mechanical properties and excellent biocompatibility.Inspired by natural plants and marine organisms,this paper utilizes molecular structures of castor oil and dopamine,combined with the characteristics of polyurethane segments,to prepare a new bio-based polyurethane bioadhesive modified by castor oil and dopamine.Physical and chemical properties,and biological properties of the prepared adhesives were studied in detail.（1）An isocyanate-terminated polyurethane adhesive（PU-PEG-CO-X）having different castor oil contents were synthesized.When the amount of castor oil accounted for 3%,6%,9%and 12%of the total solid mass,the isocyanate-terminated polyurethane adhesives were synthesized respectively,and their drying,mechanical and biological properties were studied.The results showed that there existed a suitable castor oil concentration for optimal comprehensive performances of the adhesives.Surface curing time of the polyurethane system increased with the increase of the amount of castor oil,while actual curing time of the system reduced significantly.DSC analysis showed that glass transition temperature（T_g）of the polymer system increased steadily as the castor oil content increased.When the dosage of castor oil is 6 wt%,the shear strength,adhesion strength,biodegradation rate,protein adsorption behavior and biocompatibility of the adhesives obtained are the best.Especially,its protein adsorption amount can be as low as 29.6±9.5μg BSA/cm².（2）A dopamine-terminated castor oil-based polyurethane adhesive was designed and synthesized.The urea bond was formed by-NH₂ and-NCO between the polyurethane adhesive in the above（1）and dopamine,thus catechol structures were introduced into the polymer,and phenolic hydroxyl terminated polyurethane adhesives（COGlu-CO-X）were successfully prepared.The results showed that under the premise of complete capping of dopamine,properties of COGlu-CO-X with different castor oil content showed significant differences,in which the gelation（curing）time of the adhesives decreased with the increase of castor oil concentration,while the swelling ratio and T_g of the adhesives films increased gradually.The mechanical strength of COGlu-CO-X indicated that the introduction of the catechol unit of dopamine enhances the adhesion of the adhesive to wet tissue,and the higher the catechol content was,the greater the adhesion was.In addition,the system’s biodegradation rate,protein adsorption capacity and cytotoxicity were maintained at a low level.Based on various results,COGlu-CO-9%shows the best performances.It has shorter gel time（229 s）,lowest swelling rate（53.8±3.5%）and protein adsorption amount（166±21μg BSA/cm²）and higher mechanical strengths（all above 40.0 kPa）,indicating its suitability in application.