Synthesis Of Hypercrosslinked Polystyrene Via Post-crosslinking By Dichloroalkane,Its Chlorination And Properties

Hypercrosslinked polystyrene(HCPS)resins are widely used in adsorption and separation because of their high specific surface area,large adsorption capacity,excellent swelling property,high mechanical strength and regeneration performance.In the industrial production of HCPS from polystyrene(PS)resins,the carcinogenic and highly dangerous chemical of chloromethyl methyl ether(CMME)needs to be used,which limits the production of HCPS from PS,and thus synthesis of HCPS from PS by using cheaper and low-toxic external cross-linkers are desirable for low cost and sustainable large-scale production.Therefore,cheap and readily available dichloroalkanes,e.g.dichloromethane(DCM),1,2-dichloroethane(DCE),were used as external cross-linkers to prepare HCPS resins in this dissertation.The main contents of this dissertation are shown as following:1.HCPS with the crosslinking bridge of methylene,which was denoted as PS-M,was prepared from PS resin via the Friedel-Crafts reaction by using DCM as external cross-linker and solvent,and using anhydrous Al Cl₃ as catalyst.Then HCPS with the crosslinking bridge of both methylene and 1,2-ethylene,which was denoted as PS-M-E,was prepared from PS-M via the Friedel-Crafts reaction by using DCE as external cross-linker and solvent,and using anhydrous Fe Cl₃ as catalyst.The results of surface area and porosity analysis showed that the specific surface area of PS,PS-M,and PS-M-E was 91 m²/g,641 m²/g,and 913m²/g respectively,pore volume of PS,PS-M,and PS-M-E was 0.48 cm³/g,0.80 cm³/g,and 0.98 cm³/g respectively.PS-M and PS-M-E displayed the high specific surface area characteristic of the HCPS resins.2.Static adsorption performance of PS-M and PS-M-E for phenol,salicylic acid,caprolactam,acetanilide,creatinine,and vitamin B12 in aqueous solution was investigated,and adsorption percentage of parathyroid hormone(PTH)and interleukin 6(IL-6)onto PS-M and PS-M-E from plasma was measured.The results showed that the adsorption performance of PS-M-E was better than that of PS-M because the specific surface area and pore volume of PS-M-E were higher than those of PS-M.Adsorption thermodynamic parameters were calculated from the adsorption isotherms of the six adsorbates onto PS-M and PS-M-E from aqueous solution,and the results showed that the adsorption process for organic compounds with lower relative molecular mass,including phenol,salicylic acid,caprolactam,acetanilide,and creatinine,was exothermic,spontaneous and entropy decreasing,whilst the adsorption process for vitamin B12,a compound with higher relative molecular mass,was endothermic,spontaneous and entropy increasing.The adsorption percentage of parathyroid hormone(PTH)and interleukin 6(IL-6)onto PS-M-E from plasma amounted to 84.00%and 39.06%,respectively,which implied that PS-M-E was a good candidate of polymeric adsorbent applied in hemoperfusion.3.In order to prepare HCPS with higher skeleton density so as to fit the demand of application,PS-M-E was reacted with chlorine generated in situ firstly,and then eliminated the chlorine bonded to saturated carbon with Na OH-ethanol solution,and thus obtained an aromatically chlorinated HCPS resin,which was denoted as PS-M-E-Cl.Chlorine content,skeleton density,moisture holding capacity,and surface area and porosity of PS-M-E-Cl were tested,and adsorption isotherms of phenol,salicylic acid,gallic acid onto PS-M-E-Cl from aqueous solution or sucrose solution were determined.The results showed that the chlorine content increased from1.53%of PS-M-E to 14.00%of PS-M-E-Cl,the skeleton density increased from 1.08 g/m L of PS-M-E to 1.31 g/m L of PS-M-E-Cl,which implied PS-M-E was chlorinated successfully and the resin with higher skeleton density was obtained.The specific surface area decreased from 913 m²/g of PS-M-E to 500 m²/g of PS-M-E-Cl,the pore volume decreased from0.98 cm³/g of PS-M-E to 0.63 cm³/g of PS-M-E-Cl,and the average pore diameter increased somewhat.The adsorption capacities of the three adsorbates on PS-M-E-Cl were all lower than the corresponding capacities on PS-M-E,but the capacities were high enough yet.PS-M-E-Cl displayed good adsorption performance for salicylic acid in sucrose solution,which implied that PS-M-E-Cl might be applied in decolorization of sugar juice.