Study On Poly(Aryl Ether Nitrile)s Containing Phthalazinone Moieties And Their Sulfonation-modified Polymer Ultrafiltration Membranes

Poly(phthalazinone ether nitrile ketone) (PPENK) with high glass-transition temperature(260℃) and good solubility is a candidate for membrane materials because of its well membrane-forming ability, hydrofilicity, good mechanical performance and chemical stibility, which was synthesized from 4-(4-hydroxyphenyl) -l(2H)-phthalazinone(DHPZ), 4,4'- difluorobenzophenone (DFK), 2, 6-dicholobenzonitrile(DCBN) by poly-condensation in our laboratory.Flat-type PPENK ultrafiltration membranes with different pore size and pure water flux were prepared by traditional phase-inversion method with N-methyl-pyrrolidone as casting solvent, water as coagulant, PEG-400, ethylene glycol (EgOH), n-butonal (Bu-OH), ether, ethylene glycol monomethyl ether (EGME), Diethyleneglycol (DegOH) as organic non-solvent additives (NSA) and lithium nitrate as a inorganic solvents. The effects of these additives and their mixture on the performance of UF membranes were examined in terms of water flux, rejection and porosity et al. The results showed that the effect of NSA on the membrane performance was related not to the absolute content of NSA, but to the ratio of near-to-cloud-point, a. The compound additive mixed-up by LiNO3 and NSA lead to the changing of membrane structure from fingerlike to spongylike. In addition, effects of polymer content, coagulant bath temperature, evaporation (time, temperature) etc. on PPENK UF membrane performance were investigated in detail. At 0.1MPa, pure water flux of the prepared PPENK UF membranes was from 129 L.m-2.h-1 ~ 1083 L.m-2.h-1, rejection to clayton-yellow was from 24%~99%, mean pore size was from 33nm to 96nm. Defect-free PPENK UF membranes with high performance can be prepared with proper evaporation time/temperature (240~330s, 80~100℃) process. The PPENK UF membranes have good retention to several kinds of dyes such as Clayton Yellow (CY), Congo Red (CR), PASD-BF,PACOSD, PAGSD-2, PCSD-BK, the preliminary study shows greatpotential of membrane separation process in the field of refine dyes. The anti-fouling property of PPENK UF membrane to Bovine Serum Albumin (BSA) was also studied. As a result, PPENK membrane has better anti-fouling property than traditional polysulfone membranes because of its good hydrophilicity. Furthermore, thermostability of PPENK membrane was investigated. When operating temperature increased from 14°C to 97°C, flux increased by 1.6 times and the rejection to 0.2g/L PAGSD-2 dye solution had no obvious change (more than 99%).Poly(phthalazinone bisphenol ether nitrile)s (PPBEN) copolymerized from DHPZ, bisphenol (BPA) and DCBN is another high performance resin synthesized in our group, which is cheaper, has better tenacity than PPENK. PPBEN UF membranes were also prepared by phase inversion technique with NMP as solvent. The effects of polymer content, kinds and content of additives, coagulant bath temperature and evaporation were investigated systematically. At O.lMPa, PPBEN UF membranes had pure water flux 18.4 Lm"2h"1~292 Lm"2'h"\ rejection to PEG20000 reached 75%, retention to CY reached 96%.The relationship between four serials of copolymer molecular structure containing phthalazinone moieties and their membrane performance was studied. These four serials of copolymers are: PPBEN, synthesized from DHPZ, BPA and DCBN; PPBES, synthesized from DHPZ, BPA and dichlorodiphenyl sulfone (DCS); PPESK, synthesized from DHPZ, DCS and DFK; PPENK, synthesized from DHPZ, DCBN and DFK. Firstly, the solubility parameters (4p) of copolymers were calculated by group-donation method and water containing ratio of these copolymers were also detected. Secondly, Contact angles between UF membranes prepared from the copolymers and water were measured. Thirdly, the relationship between the UF performance and molecular structure of membrane material was studied. Finally, the effect of evaporation process in preparing UF membranes on the different copolymer UF membrane performance was investigated. The results show that the more the content of the phthalazinone moiety in the copolymer molecular structure, the larger of dsP the copolymer has, the smaller the contact angle between polymer UF membrane and water is, and the better the hydrophilicity of the UF membrane is. The defect-free polyarylethers containing phthalazinone moieties UF membranes with high performance can be prepared through high temperature evaporation processs.