Preparation,Structure And Properties Of PNVCL-Based Temperature-responsive Nanomaterials

In this study,we prepared a stimulus-responsive nanofiber membrane using temperature-responsive poly（N-vinylcaprolactam）（PNVCL）as the main raw material and electrospinning technology.We investigated methods for adjusting the response threshold of the fiber membrane and developed a method for maintaining the morphology of water-soluble PNVCL fibers.We obtained temperature-pH-near-infrared（NIR）multi-responsive nanofibers for use in drug controlled release and pollutant adsorption.The main work and conclusions are as follows:（1）Regulation of the response threshold and morphology control of the nanofiber membrane.To address the disadvantage of PNVCL’s response threshold deviating from application requirements,we studied copolymer modification to adjust the threshold;to address the inability to maintain morphology at temperatures below the lower critical solution temperature（LCST）,we developed hydrogen bond crosslinking technology.Using N-vinylcaprolactam（NVCL）,methacrylic acid（MAA）,and N-tert-butylacrylamide（t BAM）as raw materials,we synthesized poly（NVCL-co-t BAM-co-MAA）.We studied the effect of different contents of each ligand on the LCST of the polymer and analyzed the polymer structure composition using infrared spectroscopy and nuclear magnetic hydrogen spectroscopy.The results showed that increasing the MAA content would increase the LCST of the polymer,while increasing the t BAM content would decrease the LCST of the polymer.Further adjustment of the feed ratio resulted in a polymer with an LCST of 36.6°C.The nanofiber membrane was prepared using electrospinning technology,and MAA formed hydrogen bonds with NVCL to maintain the fiber morphology of the fiber membrane.（2）To improve the active controlled release ability of PNVCL fibers,we synthesized Fe₃O₄ nanoparticle photothermal conversion agents（PTCA）,modified with oleic acid,and blended with poly（NVCL-co-t BAM-co-MAA）to obtain temperature-NIR responsive composite nanofiber membranes.Using isosorbide dinitrate（ISDN）as a model drug,we measured NIR-triggered ISDN controlled release under near-infrared（NIR）laser irradiation in simulated gastrointestinal drug delivery environments and studied drug release kinetics.The results showed that nanofibers can be used for controlled release in gastrointestinal and transdermal drug delivery.（3）The obtained pH-temperature responsive PNVCL nanofiber membrane was used to loadβ-cyclodextrin to improve separation performance.Acryloyl chloride was used to introduce double bonds into cyclodextrin matrix to synthesize poly（NVCL-co-β-CD-co-t BAM-co-MAA）,and we studied the effect of different contents of cyclodextrin on LCST of polymer.In 5 mg/L naphthol green B solution,the equilibrium adsorption capacity of this fiber membrane at 25°C was 18.48 mg/g;at 50°C,it increased to 21.56 mg/g;within initial20 minutes,adsorption reached 83.17%of equilibrium adsorption capacity.It then grew slowly and reached adsorption equilibrium in 60 minutes.