Preparation Of Antifreeze And Rewarming Gel And Its Application In Frostbite Dressing

The western and northern regions of China are mostly in the cold region,field training,construction and operation personnel due to long-term exposure to cold environment,vulnerable to frostbite,severe frostbite will also lead to disability,and even life-threatening.The key to field prevention and treatment of frostbite is to rewarm the wound as soon as possible,improve local blood circulation,and avoid further aggravation of frostbite.In recent years,hydrogels have become ideal medical dressings due to their good biocompatibility and expandable functionality.In view of the problems such as hydrogel being easy to freeze at low temperature,affecting the performance of dressing,and the photothermal conversion temperature is not mild and easy to cause secondary damage.Using physical and chemical cross-linking methods,a new gel network with antifreeze,photothermal rewarming and other properties was constructed,which can be developed into antifreeze medical gel dressings,which is expected to be used for emergency prevention and treatment of frostbite in the field in alpine areas.The main contents of this thesis research are as follows:（1）Preparation and performance study of PAM/CS/MXene/Betaine/Ag NPs antifreeze rewarming gel.The photothermal conversion material MXene and silver nanoparticles（Ag NPs）and the antifreeze material betaine（Betaine）are introduced in the gel network of acrylamide（AM）and chitosan（CS）,and PAM/CS/MXene/Betaine/Ag NPs composite gels are prepared by one-pot method and in situ reduction method.SEM,XRD and TEM demonstrate the successful preparation of MXene nanosheets.Antifreeze experiments showed that when Betaine was 5g,PAM/CS/MXene/Betaine5 gel could still maintain its soft gel properties at-24℃.Photothermal experiments show that MXene and Ag NPs can cooperate with photothermal,and the time required for PAM/CS/Betaine/MXene30/Ag NPs200 gel to reach a rewarming temperature of 40.5℃is 9min,after 30 min the temperature reaches 46.5℃,and the temperature differenceΔT is 23.5℃.（2）Preparation and performance study of PAM/CS/P-Py-DA/Gly antifreeze rewarming gel.Due to the high price of MXene,the preparation method is more complicated,which limits industrial application.The poly-pyrrole-dopamine（P-Py-DA）obtained by the polymerization of pyrrole and dopamine induced by Fe³⁺was introduced as photothermal conversion material,and glycerol（Gly）as antifreeze material and dispersant in the gel network of acrylamide（AM）and chitosan（CS）,and PAM/CS/P-Py-DA/Gly gel was prepared by one-pot method.FT-IR and SEM demonstrated the synthesis of P-Py-DA.Antifreeze experiments show that P-Py-DA polymer chain can also be used as a layer of gel network to improve its mechanical properties,PAM/CS/P-Py-DA/Gly12 gel has good flexibility at low temperature（-24℃）and room temperature（25℃）,and can be stretched to 4.2 times and 5.1 times the original length.Photothermal experiments showed that the time required for the PAM/CS/Gly/P-Py-DA30 gel to reach the rewarming temperature of 40.7℃was16 min,the temperature reached 42.6℃after 30 min,and the temperature differenceΔT was 18.4℃.（3）Preparation and performance study of PAM/PVP/MXene/Ch Cl antifreeze rewarming gel.Through the experiments in the first two chapters,it is found that the carbon-based photothermal conversion material MXene has better photothermal rewarming performance than the organic photothermal conversion material poly-pyrrole-dopamine（P-Py-DA）.The photothermal conversion material（MXene）and the antifreeze material choline chloride（Ch Cl）was introduced in the interpenetrating network of acrylamide（AM）and polyvinylpyrrolidone（PVP）.As a layer of gel network and a dispersant of MXene,PVP can effectively inhibit the agglomeration of MXene,and a pre-gel solution with good dispersibility can be obtained,and PAM/PVP/MXene/Ch Cl gel can be prepared by one-pot method.The antifreeze experiment showed that when Ch Cl was 4.0g,the deformation of the gel reached 75%,and the stress required at-24℃and 25℃was 0.553MPa and 0.462MPa,respectively,and the PAM/PVP/MXene/Ch Cl4 gel showed good flexibility at-24℃.Photothermal experiments showed that the time required for PAM/PVP/Ch Cl/MXene20 gel to reach a rewarming temperature of 40.4℃was 10 min,and the temperature reached 49.4℃after 30 min,and the temperature differenceΔT was 26.9℃.This thesis can provide reference for the application of antifreeze and photothermal rewarming gels in frostbite dressings.