Study On Preparation Of Monodisperse Functional Polymer Microspheres By Solvothermal Precipitation Polymerization

Monodisperse functional polymeric microspheres are widely used in the fields of biomedicine,chromatographic analysis,adsorption separation,industrial catalysis and so on,due to their uniform particle size,functional groups,easy derivatization and stable physical properties.Among the strategies of preparation of micro-sized monodisperse polymeric microspheres,precipitation polymerization is a unique method without adding any surfactants or other additives,leading to a rapid process and pure microspheres with clean surfaces.However,in the traditional precipitation polymerization,the monomer loading is relatively low(generally lower than 5 wt%),and the yield of microspheres is also low(generally lower than 50 wt%),which is the main obstacle for scale-up preparation of microspheres by this method.In this dissertation,solvothermal precipitation polymerization is adorpted to fabricate various functional polymeric microspheres at high monomer loading.The specific research of this dissertation is as follows:1.Preparation of poly(methacrylic acid monomer-divinylbenzene)functional microspheres by solvothermal precipitation polymerization.Glycidyl methacrylate(GMA),lauryl methacrylate(LMA),methacrylic acid(MAA),hydroxyethyl methacrylate(HEMA)were used as functional monomer,and divinylbenzene(DVB)was used as crosslinker.The effects of reaction conditions including monomer type,monomer ratio and solvent composition on the morphologies of the functional microspheres were investigated.The results showed that when the monomer loading was 20 wt%,the particle size of the microspheres could be controlled between 2.422 ?m and 5.811 ?m,the yield of the microspheres was above 90%,and the polydispersity index of the microspheres was lower than 1.05.The copolymerizations of the functional monomers with DVB were confirmed by means of infrared spectroscopy,elemental analysis and energy spectrum.Based on the Flory-Huggins model and Hansen's three-dimensional solubility parameters,the polymer-solvent interaction parameters(Flory parameters,?s,p)were calculated.It was found that monodisperse microspheres were easily obtained when the values of ?s,p were between 1.15 and 1.33.2.Preparation of fluorine-containing functional microspheres by solvothermal precipitation polymerization.Trifluoroethyl methacrylate(TFEMA)or dodecafluoroheptyl methacrylate(DFHMA)was used as the functional monomer and divinylbenzene was used as the crosslinker.The effects of the amount of monomer loading and monomer-crosslinker ratio on the morphologies of the microspheres were investigated.The results showed that when the monomer loading was 15 wt% and the ratio of fluorine monomer to DVB was 10/90,the fluorine-containing microspheres could be obtained with narrow size-distribution.The microspheres were studied by scanning electron microscopy,infrared spectroscopy and contact angle test.Superhydrophobic surfaces fabricated by the self-assembly of the fluorine-containing microspheres by dip-coating method were found to show higher than 150 o of water contact.3.Preparation of polydivinylbenzene fluorescent nanoparticles by solvothermal precipitation polymerizaton.Divinylbenzene was used as monomer,azobisisobutyronitrile was used as initiator,and acetonitrile was used as solvent.The effects of the amount of initiator and the temperature of polymerization on the morphologies of the microspheres were investigated.Under the same conditions,the particle size of the obtained microspheres increased from 1.350 ?m to 1.572 ?m and then decreased to 17.7 nm with the initiator concentrations increased from 2 wt%(relative to monomer)to 80 wt%.When the polymerization temperature ranged from 85 °C to 200 °C,the particle size of the obtained PDVB microspheres was lower than 50 nm.In addition,all of the obtained PDVB microspheres showed fluorescence property.When the excitation wavelength was 336 nm,the microspheres showed the maxmimum emission wavelength at 400 nm-410 nm.