Study On The Properties Of PNIPAM - Cellulose Balls Synthesized By RAFT Polymerization

Regenerated cellulose porous spheres have larger specific surface area and higher porosity, and are hydrophilic and non-toxic, which have broad application prospects in the purification, adsorption and chromatography fields. Because of these advantages, porous cellulose microspheres could be used to control the release of drugs. In order to further improve the application performance of cellulose microspheres, thermosensitive PNIPAM was grafted onto cellulose microspheres by RAFT polymerization method, which made products thermosensitive and pH-sensitive.Reversible addition fragmentation chain transfer(RAFT) polymerization was a living controlled radical polymerization(CRP) technique, apart from RAFT CRP also included atom transfer radical polymerization(ATRP), nitroxide-mediated polymerization(NMP). A wide range of suitable monomers were suitable to RAFT polymerization, and reaction could conduct in mild conditions without the metal catalyst.4-cyano-4-ethyl-trithiopentanoic acid(CETP) was synthesized by ethyl mercaptan,carbon disulfide, 4-toluene-thionyl chloride(TsCl) and 4,4’-azobis(4-cyanopentanoic acid) and was used as chain transfer agents for next reversible addition-fragmentation chain transfer(RAFT) polymerizations. Poly(N-isopropylacrylamide)(PNIPAM) was grafted to cellulose microspheres via RAFT polymerizations, and PNIPAM-cellulose microspheres were produced. In this paper, temperature-sensitive and pH-sensitive PNIPAM-cellulose microspheres were produced with RAFT polymerization reaction,then ibuprofen was chose to test rates of dugs releasing from product at different temperatures and pH values.The grafting of PNIPAM to cellulose microspheres was confirmed by Dynamic Light Scattering(DLS), Fourier-transform infrared(FTIR) spectroscopy, scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray photon spectroscopy(XPS) analysis and thermo gravimetric analysis(TGA). The PNIPAM-cellulose microspheres with a diameter of 1.2-2 m were biocompatible and favorable to be utilized as drug carriers for controlling drug release. Ibuprofen was chosen as a model drug to test the drug loading and releasing properties of the PNIPAM-cellulose microspheres. It was found that the ibuprofen released from the microspheres at 25 oC was more rapidly than that at 38 oC, and it released morerapidly at pH 7.4 than that at pH 4.0. Providing the favorable thermosensitivity, the PNIPAM–cellulose microspheres are expected to be widely used as drug carriers for controlled drug release.