Research Of Synthesis And Properties Of Polyurethane Mrcrosphere Modified With Polylactic Acid

The best conditions of synthesizing PLA were optimized by orthogonal experiments and the properties of PLA were tested. FTIR indicated that C-O-C asymmetry stretching vibration located at 1210-1160 cm-1, C-O-C symmetry stretching vibration located at 1100 cm-1, C-O-C stretching vibration absorption located at 1760 cm-1, and proved the synthesized polymer is PLA. GPC experiments were carried out, and the results showed the molecular weight is 420 and the mass distribution is narrow. The optimal conditions to synthesize PLA were lactic acid(LA) of 30ml, catalyzer of 0.5% and reaction temperature of 130-135℃, reaction time is an important factor influencing PLA molecular weight, and different PLA molecular weight can be prepared by controlling the reaction time.The optimal conditions to synthesize PU microspheres were -OH/-NCO=1/4, IPDI, 40% polyurethane aqueous and 8% calcium chloride solution. FTIR indicated that there are hydrogen bonds forming in the polyurethane synthesis, and the appropriate cross-link time of microsphere is 5-6h.Polyurethane (PU) latex was prepared by self-emulsifying using PEG, PLA, IPDI, DMPA and TEA, and then PU microspheres were got by calcium ion cross-linking. Latex particle diameter increased with PEG molecular weight increased, and it increased first then decreased with PEG content decreased. The PU mainly has amorphous structure, and the amorphous structure decreased with PEG molecular weight and PEG content increased. Latex particle diameter would increase when PLA molecular weight and content increased. The swell rate of PU microsphere decreased as a result of higher molecular weight of PLA which made PU have higher hydrophobicity, and the degradation rate increase with PLA molecular weight and PLA content increase. The amorphous structure of PU increased with PLA molecular weight, and decreased with PLA content increase.Amorphology observation indicated that the surface of PU microsphere was smooth, microsphere shape was round. There are many holes and some cavums in microsphere' surface and interior. The PU microspheres modified with PLA possess excellent blood and cell compatibility. They suit to be used as drug-loaded materials. DS-PU microspheres were prepared with DS as model drug. FTIR analysis showed that DS had been embeded into PU microspheres. The encapsulation ratio of PU microspheres presented increasing first then decreasing tendency and drug-loading rate increased and then balance with the increase of the drug concentration. The study of drug-releasing indicated that the PU microsphere can delay the releasing behavior of DS, and extend the half life of drug.