Research On Synthesis And Properties Of HPG/PU Composite Microspheres

In this paper,the deprotonation reaction of guar gum(GG)was happened in alkaline solution.Then modified guar gum,hydroxypropyl guar gum,was synthesized by reacting with propylene oxide.And the reaction conditions were determined.The results showed that the concentration of sodium hydroxide was 0.03 mol/L,quaternization lasted for 30 minutes,the content of epoxy propane was 12mL,reaction responded for 26 hours,Modified guar gum with good properties could be prepared.Waterborne polyurethane(WPU)was prepared in the experiment.Through the method of di-n-Butylamine and acetone,it could be concluded that the conditions in prepolymerization and chain extension stage.It could be concluded the molecular weight of PEG,the polyurethane(PU)solution concentrations and the R value(n(IPDI):n(PEG))by observing the status of PU solution and balling condition.And its performance were measured.Results showed that the molecular weight of PEG(m(PEG))was 200,the PU solution concentrations were 40%,the R value was 4,prepolymerization temperature was 80,? prepolymerization time was 3 hours,chain extension temperature was 60 ?,chain extension time was 2.5 hours,WPU with better performance could be obtained.The solution was stable in alkaline and high speed centrifugation,but it was unstable in acidic environment;The diameter of the microspheres was mainly distributed between 2.6 and 2.69mm;Morphological analysis indicated that the number of pores was less,and the inner was solid,which was not conducive to drug release.HPG/PU composite microspheres were prepared,and the factors such as HPG content(w(HPG)),solid content and R value were tested.Result shows that w(HPG)was between 0.1%and 0.3%,m(PEG)was 200,the Pu solution concentrations were 40%,the R value was 4,the HPG/PU composite solution was clear.The diameter of the microspheres was mainly distributed between 3.31mm and 3.40mm;Morphological analysis indicated that when w(HPG)was 0.1%,the number of pores on the surface of the microspheres increased,and a large number of cavities were distributed near the surface of the sphere.The drug loading and release properties of HPG/PU composite microspheres were studied.The results showed that when w(HPG)was 0.1%,the drug loading and encapsulation efficiency of HPG/PU composite microspheres were better;The higher w(HPG),the worse properties of drug loading;The release rate of HPG/PU composite microspheres was faster in alkaline solution and slower in acidic solution.HPG/PU composite microspheres are expected to be used as carrier material for intestinal administration.This paper provides some research basis for the research of HPG/PU composites.