Study On Synthesis And Performance Of LCST-type Backbone Hydrolyzable Polymer

In recent years,due to the easy control of temperature changes,thermo-responsive smart polymer materials can be conveniently used in various fields,and have been widely sought after by researchers at home and abroad.The research of thermo-responsive polymers has greatly promoted the development of medical smart materials,while also revealed some of the shortcomings of current research on such polymers.It is well known,the degradation rate of polymer materials in aqueous solution and the toxicity of degradation products are the key factors affecting their use in biomedical materials.However,from the current results reported,thermo-sensitive polymers are rarely degradable,which limits its application range.Therefore,designing and synthesizing thermo-sensitive responsive polymers with degradability and improving their safety as biomedical materials have become the mission of many researchers.In this paper,a new class of backbone-hydrolyzable polymers with tunable LCST behavior was prepared,the thermal response behavior and hydrolysis rate of such polymers were discussed in depth.main tasks as follows:The polymer prepared in the present invention has the advantages of simple synthesis method,tunable temperature sensitivity,mild hydrolysis condition and no cytotoxicity.Preparation of the target polymer poly(oligo(ethylene glycol)bis(glycidyl ether)-alt-ketoglutaric acid)s(PEmKs)by carboxylic acid-epoxy reaction(CAER)using oligo(ethylene glycol)bis(glycidyl ether)(EmBG)and 2-ketoglutaric acid(KGA)as raw material.Nuclear magnetic resonance(1H-NMR)and infrared visible light meter(FT-IR)demonstrated the successful preparation of PEmKs,Gel permeation chromatography(GPC)showed that the molecular weight distribution of this type of polymer was double-distributed.The thermo-responsive behavior of PEmKs aqueous solution was tested by a ultraviolet-visible spectrometer(UV-vis)and a nuclear magnetic resonance spectroscopy(1H-NMR).The results showed that PEmKs have tunable thermo-sensitive responsive behavior in aqueous solution,by changing the concentration of PEmKs and the ratio of two raw materials can make the aqueous polymer solution have excellent LCST reversible response behavior at 30?60 ?.PEmKs polymer can degrade itself in aqueous solution,the transmittance of aqueous solution increased from 2.4%to 97.5%;the pH value decreased from 3.45 to 1.20;the main peak of GPC spectrum decreases continuously,and the shoulder peak gradually moved toward low molecular weight;the ester bond proton peak in the 1H-NMR spectrum disappear.These data all demonstrated that PEmKs polymer can undergo autocatalytic hydrolysis in water,and elevated temperatures accelerate their rate of degradation.Cell viability tests demonstrated the good biosafety of this type polymers.Such stimuli-responsive polymers have tunable LCST temperature-sensitive behavior and controllable backbone degradation properties,and have potential applications in smart response materials,biomedical applications.