Preparation And Characterization Of Hydrogels Based On 1,3-Dipolar Cycloaddition

The hydrogel is a kind of crosslinked polymeri c three-dimensional network that can store wate r and swelling but can not di ssolve in water. Due to its unique properi tie s and s tructure,hydrogel has a ttracte d more a nd more res earcher s’ attention and been applied in the fields of biological, me dical, daily l ife and so on. The properties and structures of hydrogels a re closel y linked to the method of prepa ring hydrogels, ther efore, it has been considered to be very important to develop new met hods to prepare hydrogels. Among them, preparing hydr ogels by alkyne- azide 1, 3-dipolar cycloaddition click reaction is an important method whic h has appe ared recently. The re action has some advantage s such as simple, mild conditions, no toxic and volatile solvent, etc. However, the cytotoxicity of residual Cu cat alyst bri ngs a pot ential limit ati on of the reaction when it is use d to synthesi ze and/or functionalize materials for biome dical applications. In this thesis, repl acing a lkyne by maleimide group, metal-free 1,3-dipol ar cycloaddition click rea cti on between azi de and maleimide modified polymers was us ed to prepare a series of hydrogels in water. The struc tures and pr operties of the hydrogels were primarily investi gati on. The details are as follows:(1) The copolymer( denoted as PHD) was prepared w ith 2-hydroxyethyl metha cryla te(HEMA) and N, N-dimethylacrylamide(DMA) as monomers, and the feedi ng molar ratios(HEMA:DMA) i s 1:10; the N- mal eoyl alanine(AMI) wa s synthesi zed by two- st ep r eaction,us ing alpha- al anine and maleic anhydride as raw materials. The pol ymeric dipolarophile was prepared by introducing AMI to the PHD, and the pol ymeric dipolar was prepa red by means of modifying the PHD with azidoacetic acid. Then the as-prepared polymeric dipolar and dipolarophil e wer e diss olved in water, the hydr ogels of di fferent concentrations were prepared in water t hrough catalyst-free 1, 3-di polar cycloaddition reaction. The pr oducts were cha racterized by GPC 、FTIR 、1HNMR、SEM 、TG and other instruments, it can be known t hatthe products all ha ve good stability, and the hydrogels have good channel network structure.The swell ing behavior and drug release behavior of the hydr ogel were also studied, a nd the results s how that the hydrogels have good abilities of swelling and dr ug-controlled release.(2) Three copolymers(de noted respectively as PT137, PT155, PT173) of HEMA, N-isopropyl acrylamide(NIPAM) and DMA we re prepar ed by controlling the feeding molar ratios(HEMA: NIPAM: DM A) to 1:3:7, 1:5:5, 1:7:3, r espect ivel y. The polymer ic dipolarophil es wer e prepared by introducing AMI t o the PT137, PT155, PT173, The polyme ric dipola r was prepared by modifyi ng the as-prepared PT137, PT155, PT173 with azidoace tic a cid. Afterward, t he above prepared polymeric dipolarophiles and polymer ic dipolar were dissolved in wat er, and the the rmosensitive hydrogels of different molar ratios were prepared through catalyst-fr ee 1, 3-dipolar cycloaddition reaction. Finally, the hydrogel micropheres were prepared by spray dryer. The products were characterized by GPC、 FTIR、1HNMR、SEM、TG a nd other instruments, and it can be known that t he products all have good s tabi lity, and t he thermosensi tive hydroge ls have good channel network structure. The s welli ng behavior of t he thermosensitive hydr ogels was mainly studied, and the r esults show that the hydrogels have good abilities of swe lling and thermos ensitivi l y.(3) The copolymers(denoted respectively a s PH137, PH155, PH173) of HEMA,4-vinyl pyridine(4-VP) and DMA were prepa red by controll ing the feeding molar ratios(HEMA: 4-VP: DMA) to 1:3:7, 1:5:5, 1:7:3, re spectively. The polymeri c dipolar ophiles were prepar ed by introducing AMI to the PH137, PH155, PH173; the polymeric dipolar polyme r was prepared modi fying the PT137, PT155, PT173 by azidoac eti c acid. Later, t he above prepared polymeric dipolarophiles and polymeric dipolar were dissolved in water, and the t hermo and pH se nsitive hydrogels of different mole ratios we r e prepared in water through ca talyst-fre e 1, 3-dipolar cycloaddition rea ction. The products were character ized by GPC 、FTIR、1HNMR、SEM、TG and other instruments, it can be known t hat the products all ha ve good stability, and the the rmo and pH sensitive hydrogels have good channel net work s truc ture. The swelling behav ior of the thermo and pH se nsit ive hydrogels was ma inly stu died,and the results show that t he hydrogels have good abilities of swe lling, thermo and pH s ensitivi l y.