Synthesis And Characterization Of Polypeptoid Temperaturesensitive Materials With Three Keys In The Side Chain

The stimuli-responsive polypeptiods have drawn extensive attention because of their promising applications in biotechnology considering their biocompatibility and biodegradability.we reported a facile and efficient approach to prepare a class of temperature responsive,REDOX responsiveness and pH responsive multiple responsive temperature-sensitive polypeptoid materials by ring-opening polymerization?ROP?and post-modification strategy use polyethylene glycol?peg?or other thiol reagents,and explores a variety of factors affect the performance of polypeptoid solution,the thesis mainly includes the following content:1.we reported a facile and efficient approach to prepare a class of temperature-sensitive polypeptoid material by ring-opening polymerization?ROP?and post-modification strategy,the introduction of oligomeric ethylene glycol?OEG?bring out the polypeptoid material temperature responsiveness.The temperature response of the polypeptoids is characterized by us,we found that the temperature response behavior of the polypeptiod is completely reversible and has an adjustable phase transition temperature.In addition,we also studied the influence of polymerization degree and salt content on cloud point.It is found that as the polymerization degree increases,the cloud point of the polymer increases,and the salt content has little effect on the cloud point,which may be due to the non-electrolyte properties of the polypeptiod.2.The oxidative reducibility of the thermal-responsive polypeptoid was studied by using hydrogen peroxide and thioglycolic acid.The oxidation of thioether side-chain to sulfoxide or sulfone increases water solubility,which leading to cloud point elevation until thermal-responsive behavior is lost.The partially oxidized sulfoxide polymers can be reversed to thio-ethers by reduction and exhibit thermal-responsive behavior again,indicating that the degree of redox reaction of the side chain thioether group has great influence on the water solubility and cloud point of OEG-grafted poly?N-propargylglycine??PNPG-g-EGx?.We systematically studied the cloud point and found that the chemical structure is an important factor to cloud point.For a systematic study of the OEG-grafted side chain on physical properties of the polypeptoid,we synthesised a series of peptoids with OEG modified,by ring-opening polymerization?ROP?and Thiol-ene"click chemistry"reaction.We demonstrated that in addition to the degree of polymerization,concentration,ionic strength and other factors,the cloud point of peptoid can also be adjusted by changing the number of OEG grafts and the degree of oxidation-reduction of the side chain.We further prepared mPEG₄₄-b-?PNPG-g-EG₂?diblock copolymer using mPEG₄₄-NH₂ as macroinitiator,which can undergo reversible thermal gelation and reactive oxygen species?ROS?-dependent physical degradation,allowing new capabilities to construct multi-responsive injectable hydrogels.In addition,we used trimercaptopropionic acid as a thiol to synthesize pH-dependent temperature-responsive polypeptoid.We found that this kind of pepoid has the opposite phase transition behavior as the oligomeric PEG-modified ploypeptoid on the side chain.