Synthesis And Adsorption Studies Of Liquid Crystalline Poly (Ethyleneimine) Chelating Resins

Based on the review of the relationship between chemical structure and properties for polymer liquid crystallines and the recent research progress of liquid crystalline polymer with poly(ethyleneimine) as the main chain, six novel types of polymers with side-chain mesogenic groups and the methylene units as spacer were synthesized. All of the novel polymers(PN6 I , PN4 I , PN6II, PN4 II, PN6III, PN4III) were structurally characterized by !H NMR, IR spectra. The liquid crystalline properties of the polymers prepared were also investigated by differential scanning calorimetry(DSC), polarizing microscopy and X-ray measurement.4-hydroxy-4' -methoxybiphenyl, 4-hydroxybiphenyl , pentachlorophenol were used in this paper as mesogenic side groups and reacted with poly(ethyleneimine)(PEI), different reaction situation were tried. IR and 'H NMR were used to characterize the different structure, the branching degree of the mesogenic side groups on N-H units of PEI were also calculated from 'H NMR.DSC analyses show that with biphenyl as the mesogenic, the branched PEI shows bitropic phase behavior. While with the side groups of pentachlorophenol, the branched PEI shows no liquid crystalline properties. The heat flow of these polymers from liquid crystalline phase to isotropization is very high. Results also show that these polymers posses wide temperature range of liquid crystalline phase, which implied consequently better thermostability. The spacer influences the mesophase behaviour dramatically. The longer the spacer, the lower of the isotropisation transition temperature(Ti) is. The polarizing microscopy observed from the liquid crystalline indicate that the PN6 I polymer has the schlieren texture , PN4 I polymer overcome the transition from fan texture to schlieren texture, while PN6II is banded texture, PN4II is threaded texture. The four liquid crystalline polymer illustrate peaks at the 2 9 of about 20掳 in the X-raydiffraction and PN4 I illustrate peaks of about 2. which implying the exiting of smectic phase in PN4 I . The space(d) of the the mesogenic side units was also calculated from Bragg' s equation.PEI is outstanding for both the backbone of liquid crystalline polymer and a widely used chelating resins. PEI as chelating resins is short for its no shape and easy to flow. When PEI was branched with rigid side units, PEI posses hardness and shape, hard to flow. And most important is that a novel kind of liquid crystalline chelating resins was synthesized here. The adsorption properties for Hg(II), Cd(II), Co(II), Cu(II), Cr(III), Zn(II), Pb(II), Mg(II) and their absorptive selectivity, the influence of temperature and time during absorption were studied. Results show that the resins have excellent absorption and absorptive selectivity for Hg( II) and some absorption to Cd( II), Co( II), Cu( II), Zn( II), Pb( II) but poor absorption to Mg( II). The influence of temperature show that 20 掳C is a critical temperature to Cu( II). Higher or lower temperature cumbers the absorption. PN6 I and PN4 I posses a high absorption speed to ions but PN6III and PN4III a lowest absorption speed. In the coexist of Hg(II), Zn( II), Cr(III), Cu( II), Mg( II), the resins could selectively absorb Hg( II), and thus can be used for the waste water purify and protect the environment.