Study On Preparation And Properties Of Thermo-sensitive Poly(N-isoproplyacrylamide) Based Microgel

A series of P(NIPAM-co-AMPS) binary copolymer microgels were prepared bysoap-free emulsion polymerization (SFEP) using N-isopropylacrylamide (NIPAM),2-acrylamido-2-methylpropane sulfonic acid(AMPS) as the monomers, N,N’-methylene-bis-acrylamide (MBA) as the cross-linker and ammonium persulfate (APS) as initiator. In thisformulation, a series of P(NIPAM-co-AMPS-co-NTBA) terpolymer microgels were preparedby the introduction of hydrophobic monomer N-tert-Butylacrylamide (NTBA). It was foundthat the microgel particle was uniform size, its morphology regular, and microgels had a goodtemperature and pH sensitivity, also had some salt tolerance.Studying the amount of cross-linker was used in binary copolymer microgels for TEManalysed, the results showed that the microgels had regular ball type structure. With theincrease of the amount of the cross-linker in the microgels, the particle size of the microgelreduced and tended to be more uniform. Resesched the microgel swelling and temperaturesensitive, it is found that the the microgel swelling rate and volume phase transitiontemperature (VPTT) decreasd with increasing amount of cross-linker in the microgel.Studying the impact of the amount of hydrophilic monomer AMPS in binary copolymermicrogels, reseached the various properties of the microgels, the results showed that theamount of the hydrophilic monomer AMPS increased in the microgels, so that the hydrophilicgroup increased in entire microgel, the water absorption of the microgels enhanced, promoteswelling rate increased; while enhancing the hydrogen bonding between the hydrophilicgroups in microgel and water molecules, resulting its VPTT rising; microgel pH sensitivityand salt tolerance enhanced with increasing of the amount of AMPS.Studying the impact of the amount of hydrophobic monomer NTBA in terpolymermicrogels, to analysis microgels performance, the results showed that, with increasing theamount of hydrophobic monomers NTBA in microgels, hydrophobicity of microgelsincreased, resulting in the swelling rate decreased. With the NTBA increasing, the VPTT ofmicrogels moved towards lower, and its range was widened.In the study of the drug load and the release, the drug loading of microgels related tohydrophilic and hydrophobic of microgels. The drug release rate and release time related tothe amount of monomer, the temperature, pH of the release medium and microgel state (dryor wet).