Preparation And Controlled Release Of Functional Polyurethane Microspheres

In this paper, a series of Na-CMC polyurethane microspheres were prepared withisophorone diisocyanate(IPDI) and polyethylene glycol(PEG) and Carboxymethyl-cellulose sodium(Na-CMC) as main materials, dimethylolpropionic acid(DMPA) and1,4–butanediol(BDO) as chain extender, dibutyltin dilaurate(DBTDL) as catalyst,triethylamine (TEA) as neutralizer by four steps of prepolymerization, chain-extention,neutralization and emulsification. The experimental parameters for preparation ofmicrospheres were optimized through the orthogonal experimental design which setparticle size as evaluation index. The influence of R (nNCO/nOH) value, content of Na-CMCand DMPA and BDO, reaction temperature and time, PEG molecular weight andemulsifying time on the property of Na-CMC polyurethane microspheres and emulsionwas researched. The microspheres were characterized by FTIR, TG, DSC and SEM.Then with ibuprofen as the simulating medicine, Na-CMC polyurethanemicrospheres encapsulating drugs were prepared with optimum experimental parameters.The influence of content of drugs on drug loadings, encapsulation efficiency, welling rateand stability were discussed. The release performance and mechanism under different pHwere researched in phosphate buffer.The results indicated that when the molar ratio of isocyanate and hydroxyl is3, thequality ratio of Na-CMC and PEG is0.15, DMPA content is3%, the reaction temperatureis90℃, reaction time is3h, the preparation of waterborne polyurethane emulsion hasgood appearance and microspheres particle size are small. According to the FTIR analysis,the Na-CMC has been successfully introduced to the polyurethane Molecular chain. Wecan observe that microspheres has good spherical structure through optical microscopeand electron microscope. Thermal performance test show that the preparation of Na-CMCpolyurethane microsphere has good thermal stability, heating weightlessness is less than2%in the300℃. The drug loadings and encapsulation efficiency of Na-CMCpolyurethane microspheres increases with the increase of the content of ibuprofen, whenthe amount is about50%of the wall material quality, they are the best. Na-CMC polyurethane microspheres are pH responsive, the drug release rate under different pHvalue are different, which related to the substitution degree of carboxymethyl cellulosesodium. Na-CMC polyurethane microsphere has good storage stability, the influence oftemperature on the release rate and release quantity is small, in addition, Na-CMCpolyurethane microsphere are degradable.