Preparation And Application Of Crosslinked Microspheres Of Poly(N-vinylpyrrolidone-maleic Anhydride-divinylbenzene)

In this paper, two kinds of monodisperse polymer microspheres were prepared byprecipitation polymerization in a mixed solvent consists of acetone and F225, which is short for1,2-dichloro-1,1,3,3,3-pentafluoropropane. Maleic anhydride （MA）, N-vinylpyrrolidone（NVP）and cyclohexyl vinyl ether （CHVE） was adopted as monomers with divinylbenzene（DVB） asthe crosslinker. The introduction of CHVE could greatly decrease the crossliking degree of thequaternary P（MA-NVP-CHVE-DVB） microspheres to as low as14%. The stucture andmorphology of the microspheres was characterized by FT-IR, TGA and SEM.Effects of the solvents, monomer feed ratio and concentration of the different componentswere investigated during the preparation of P（MA-NVP-DVB） microspheres. The resultsshowed that solvent composed of aceton and F225was a relatively suitable medium for thesystem and only when the concentration of DVB was more than70%of the total monomer andthe feed ratio of MA and NVP over7:3as well as a tatol concentraion exceeded0.2mol/L couldwe achieve monodiperse polymer microspheres. Influence of the charge transfer complex（CTC）formed by MA and NVP was discussed. The particle size increased with an increasing initiatorconcentration and the largest size1.117μm reached at a concentration of2wt.%. As moreinitiator was added, the particle size decreaed and adhesion of microspheres start to emerge.The maximum polymer yield is up to77.58%with a MA content of27.33%.CHVE, which could copolymerized with MA well, was introduced to decease thecrosslinking of microspheres, thus making it propatable to take full use of the anhydride groupby expanding the internal space of the microspheres. Newly prepared quaternaryP（MA-NVP-CHVE-DVB） microspheres showed a relatively higher conversion and MAcontent than the the ternary microspheres. The particle size of the quaternary microspheresincreased along with the decreasing amout of DVB, which was against the rule of the ternarysystem. The largest diameter was1.30μm, which was reached at the lowest DVB concentrationof14mol%, indicating a more expansive internal structure of the quaternary microspheres. Thedegrade temperature of quaternary microspheres with21%crosslinking degree was225℃,reducing135℃compared with P（MA-NVP-DVB） microspheres as the different crosslinkingdegree. Amide type chelating resina was obatained by grafting ethylenediamine（EDA） to theanhydride group which widely distributed in P（MA-NVP-CHVE-DVB） microsphere. Resultsof such a amidation reaction showed that the highest conversion of EDA was80.2%and wouldbe achieved when the mole ratio of MA/EDA was1.5with a feed concentration of0.04mmol/mL after6h in acetone.We also studied the amide type chelating resin adsorption ability of metal ions. Thequaternary chelating resin performed a strong chelate adsorption capacity for metal ions as over70%of the Pb²⁺was adsorbed by the resin in2h, and the ion adsorption capacity of Pb²⁺reached280mg/g which is almost twice as much as that of ternary chelating resin.5.4wasproved to be the most suitable pH for the adsorption process of the quaternary chelating resin.