Effects Of Side Group Shape And Topology On Temperature Response Properties Of LCST Polypeptides

Stimuli-responsive polymers are a class of polymeric materials that respond to external stimuli and are important in on-demand drug delivery,tissue generation and repair,bio-sensor,intelligent recoating,and artificial muscles.Which have reach value and application prospects.According to reports in the literature,temperature-responsive polymers are a hot issue in current research which has and the most in-depth understanding.According to reports in the literature,most of these materials are non-degradable polyolefin backbones,which limits their application in the field of biomaterials to a certain extent.Temperature-responsive polypeptides have a wide range of applications because of their good biocompatibility and unique secondary structure.According to many researches the properties of temperature-responsive polymers are closely related to the molecular weight and concentration of the polymer,the type of solvent,the hydrophilicity and composition of the pendant groups,etc.,but the effect of the shape and topology of the polymer on their temperature response properties is not clear.This paper focuses on the relationship between the molecular structure of the polymer and the temperature response properties of the temperature-responsive polypeptide with Y-shaped and linear side-group structures combined with the triblock topology system.In this paper,a series of nonionic oligoethylene glycol?OEG?-containing homopolymers are synthesized by acid chloride esterification,cyclization,ring-opening polymerization,addition reaction,nucleophilic substitution reaction,and the like.The triblock polymer gives a new temperature responsive polymer having an LCST type phase transition temperature in aqueous solution.1.?-?4-?3-chloropropoxycarbonyl?benzyl?-L-glutamate and ?-4-?allyloxycarbonyl?benzyl-_L glutamate were synthesized by unilateral esterification.-Glutamate,the two esters are cyclized to give the corresponding N-carbonyl anhydride?NCA?monomer.A novel linear polymorph and a Y-type polypeptide were prepared by two kinds of NCA ring-opening polymerization,nucleophilic substitution,and click chemistry.The structures of the intermediates and target products were characterized by ¹H NMR and FTIR.The phase transition of linear and Y-shaped polypeptides in deionized water and different salt solutions was studied by temperature-dependent ultraviolet-visible spectroscopy?UV-vis?.Studies have shown that when the polymer concentration and OEG length are the same,Y-shape of the side group structure can significantly improve the hydrophilicity of the polymer and increase the cloud point temperature of the polymer?26.1??.The solution phase transition temperature of the polymer increases with the increase of the length of the OEG and decreases the concentration of the cloud point..2.Using polyetheramine D-2000 as initiator to initiate ring-opening polymerization of two NCA monomers to obtain poly??-4-?allyloxycarbonyl?benzyl-L-glutamic acid?-PPG34-polymer(?-4-(allyloxycarbonyl and poly??-4-?3-chloropropoxycarbonyl?benzyl-L-glutamate?-PPG34-poly??-4-??-4?-?3-Chloropropoxycarbonyl?benzyl-_L-glutamate?Two polymers We used ¹H NMR,GPC and other instruments to characterize the molecular structure of two triblock polymers by UV-vis The results show that the two triblock polymers have a transition temperature of about 37? at concentrations of 5 mg.mL^-1 and 0.4 mg.mL^-1,respectively,and the polymer concentration is lower than that of the homopolymer.