Research on Syntheses of PU Microcapsule for Gene Engineering Cell

Polyurethane(PU) water solutions were synthesized by combining the prepolymerization,chain-extension,neutralization and dispersion-diffluence methods in one step.And PU microcapsules were synthesized with the coacervation phase separation method.The synthetic conditions of PU water solutions and PU microcapsules were investigated,including the effects of the kinds of diisocyanate,the feed ratios of toluene-2,4-diisocyanate(TDI) and polyethylene glycol(PEG),reaction temperature,reaction time and stirred velocity on the morphology of PU microcapsules.The PU microcapsules were synthesized with TDI,PEG,dimethylol propionic acid(DMPA) and triethylamine(TEA).The structure and morphology of the PU microcapsules were measured with infrared spectrum(IR),differential scanning calorimetry(DSC) and scanning electron microscope(SEM).The diameter of the globose PU microcapsules is 2 mm or so,the cavity diameter in the PU microcapsules is 50 to 500 μm,and the membrane orifice diameter of the PU microcapsules is 20 to 100 nm.Furtheremore,the optimal conditions of synthesizing the stable, good morphology and microphase separation structural PU microcapsules were given.These conditions are as follows: the prepolymerization,chain-extension and neutralization temperatures are 60,50 and 30℃ respectively,both the times of prepolymerization and chain-extension are 2 h,the stirring velocities of prepolymerization and chain-extension are 500 to 600 r/min,and the stirring velocity of dissolution is 700 to 800 r/min.