NZ767051B2 - Asymmetric composite membranes and modified substrates used in their preparation - Google Patents
Asymmetric composite membranes and modified substrates used in their preparation Download PDFInfo
- Publication number
- NZ767051B2 NZ767051B2 NZ767051A NZ76705119A NZ767051B2 NZ 767051 B2 NZ767051 B2 NZ 767051B2 NZ 767051 A NZ767051 A NZ 767051A NZ 76705119 A NZ76705119 A NZ 76705119A NZ 767051 B2 NZ767051 B2 NZ 767051B2
- Authority
- NZ
- New Zealand
- Prior art keywords
- poly
- polyolefin
- microporous sheet
- ethenol
- ethylene
- Prior art date
Links
- 239000012528 membrane Substances 0.000 title claims abstract description 74
- 239000002131 composite material Substances 0.000 title claims abstract description 49
- 239000000758 substrate Substances 0.000 title claims description 18
- 238000002360 preparation method Methods 0.000 title description 27
- -1 poly(ethenol) Polymers 0.000 claims abstract description 224
- 229920002451 polyvinyl alcohol Polymers 0.000 claims abstract description 61
- 229920000098 polyolefin Polymers 0.000 claims abstract description 52
- 239000003211 photoinitiator Substances 0.000 claims description 16
- 238000005406 washing Methods 0.000 claims description 16
- 239000006185 dispersion Substances 0.000 claims description 9
- 239000003125 aqueous solvent Substances 0.000 claims description 5
- 230000001678 irradiating Effects 0.000 claims description 5
- OVARTBFNCCXQKS-UHFFFAOYSA-N propan-2-one;hydrate Chemical group O.CC(C)=O OVARTBFNCCXQKS-UHFFFAOYSA-N 0.000 claims description 3
- 229920000642 polymer Polymers 0.000 abstract description 45
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 40
- 108090000623 proteins and genes Proteins 0.000 abstract description 20
- 102000004169 proteins and genes Human genes 0.000 abstract description 20
- 239000011780 sodium chloride Substances 0.000 abstract description 12
- 150000003839 salts Chemical class 0.000 abstract description 9
- 235000013361 beverage Nutrition 0.000 abstract description 3
- 239000000460 chlorine Substances 0.000 abstract description 3
- 229910052801 chlorine Inorganic materials 0.000 abstract description 3
- ZAMOUSCENKQFHK-UHFFFAOYSA-N chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 abstract description 3
- 235000013365 dairy product Nutrition 0.000 abstract description 3
- 235000013305 food Nutrition 0.000 abstract description 3
- 229920001112 grafted polyolefin Polymers 0.000 abstract description 2
- VMSBGXAJJLPWKV-UHFFFAOYSA-N 2-ethenylbenzenesulfonic acid Chemical compound OS(=O)(=O)C1=CC=CC=C1C=C VMSBGXAJJLPWKV-UHFFFAOYSA-N 0.000 abstract 2
- 238000000605 extraction Methods 0.000 abstract 2
- 238000011084 recovery Methods 0.000 abstract 2
- 239000000243 solution Substances 0.000 description 47
- CSCPPACGZOOCGX-UHFFFAOYSA-N acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 44
- 230000004907 flux Effects 0.000 description 24
- 239000002904 solvent Substances 0.000 description 21
- CHQMHPLRPQMAMX-UHFFFAOYSA-L Sodium persulfate Chemical compound [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 20
- 239000000178 monomer Substances 0.000 description 20
- 229920001155 polypropylene Polymers 0.000 description 18
- 235000018102 proteins Nutrition 0.000 description 18
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid Chemical compound OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 17
- RWCCWEUUXYIKHB-UHFFFAOYSA-N Benzophenone Chemical compound C=1C=CC=CC=1C(=O)C1=CC=CC=C1 RWCCWEUUXYIKHB-UHFFFAOYSA-N 0.000 description 16
- 239000007787 solid Substances 0.000 description 15
- 239000004372 Polyvinyl alcohol Substances 0.000 description 14
- 239000003999 initiator Substances 0.000 description 14
- 235000019422 polyvinyl alcohol Nutrition 0.000 description 14
- MAGFQRLKWCCTQJ-UHFFFAOYSA-N 4-ethenylbenzenesulfonic acid Chemical compound OS(=O)(=O)C1=CC=C(C=C)C=C1 MAGFQRLKWCCTQJ-UHFFFAOYSA-N 0.000 description 13
- 239000000203 mixture Substances 0.000 description 12
- 230000004048 modification Effects 0.000 description 11
- 238000006011 modification reaction Methods 0.000 description 11
- 210000004080 Milk Anatomy 0.000 description 10
- 238000000034 method Methods 0.000 description 10
- 235000013336 milk Nutrition 0.000 description 10
- 239000008267 milk Substances 0.000 description 10
- 238000007334 copolymerization reaction Methods 0.000 description 9
- 239000012224 working solution Substances 0.000 description 9
- 238000001157 Fourier transform infrared spectrum Methods 0.000 description 8
- 239000004698 Polyethylene (PE) Substances 0.000 description 8
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 8
- 239000012466 permeate Substances 0.000 description 8
- 229920000573 polyethylene Polymers 0.000 description 8
- 231100000489 sensitizer Toxicity 0.000 description 7
- ROOXNKNUYICQNP-UHFFFAOYSA-N Ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 6
- 239000008367 deionised water Substances 0.000 description 6
- 239000012153 distilled water Substances 0.000 description 6
- 238000001035 drying Methods 0.000 description 6
- 239000012071 phase Substances 0.000 description 6
- 241000668709 Dipterocarpus costatus Species 0.000 description 5
- 238000004132 cross linking Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- HRPVXLWXLXDGHG-UHFFFAOYSA-N acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 4
- 239000003153 chemical reaction reagent Substances 0.000 description 4
- 239000003431 cross linking reagent Substances 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 4
- 239000000835 fiber Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 159000000000 sodium salts Chemical class 0.000 description 4
- PPBRXRYQALVLMV-UHFFFAOYSA-N styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 4
- 239000008399 tap water Substances 0.000 description 4
- 235000020679 tap water Nutrition 0.000 description 4
- WOBHKFSMXKNTIM-UHFFFAOYSA-N 2-hydroxyethyl 2-methylacrylate Chemical compound CC(=C)C(=O)OCCO WOBHKFSMXKNTIM-UHFFFAOYSA-N 0.000 description 3
- WURBFLDFSFBTLW-UHFFFAOYSA-N Benzil Chemical compound C=1C=CC=CC=1C(=O)C(=O)C1=CC=CC=C1 WURBFLDFSFBTLW-UHFFFAOYSA-N 0.000 description 3
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 3
- 206010034972 Photosensitivity reaction Diseases 0.000 description 3
- 229920001748 Polybutylene Polymers 0.000 description 3
- 239000004743 Polypropylene Substances 0.000 description 3
- 239000004699 Ultra-high molecular weight polyethylene (UHMWPE) Substances 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 238000007792 addition Methods 0.000 description 3
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 3
- 239000003518 caustics Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 230000005670 electromagnetic radiation Effects 0.000 description 3
- 238000011010 flushing procedure Methods 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 229920000578 graft polymer Polymers 0.000 description 3
- 230000002209 hydrophobic Effects 0.000 description 3
- 239000004615 ingredient Substances 0.000 description 3
- CERQOIWHTDAKMF-UHFFFAOYSA-N methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 229920000139 polyethylene terephthalate Polymers 0.000 description 3
- 239000005020 polyethylene terephthalate Substances 0.000 description 3
- 238000002791 soaking Methods 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 description 3
- 235000008939 whole milk Nutrition 0.000 description 3
- MYRTYDVEIRVNKP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene Chemical compound C=CC1=CC=CC=C1C=C MYRTYDVEIRVNKP-UHFFFAOYSA-N 0.000 description 2
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 2
- KMNCBSZOIQAUFX-UHFFFAOYSA-N 2-ethoxy-1,2-diphenylethanone Chemical compound C=1C=CC=CC=1C(OCC)C(=O)C1=CC=CC=C1 KMNCBSZOIQAUFX-UHFFFAOYSA-N 0.000 description 2
- 229940044192 2-hydroxyethyl methacrylate Drugs 0.000 description 2
- VVQNEPGJFQJSBK-UHFFFAOYSA-N 2-methyl-2-propenoic acid methyl ester Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 2
- KFDVPJUYSDEJTH-UHFFFAOYSA-N 4-ethenylpyridine Chemical compound C=CC1=CC=NC=C1 KFDVPJUYSDEJTH-UHFFFAOYSA-N 0.000 description 2
- ISAOCJYIOMOJEB-UHFFFAOYSA-N Benzoin Chemical compound C=1C=CC=CC=1C(O)C(=O)C1=CC=CC=C1 ISAOCJYIOMOJEB-UHFFFAOYSA-N 0.000 description 2
- 229960002130 Benzoin Drugs 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium Ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- 240000008975 Styrax benzoin Species 0.000 description 2
- 235000000126 Styrax benzoin Nutrition 0.000 description 2
- 235000008411 Sumatra benzointree Nutrition 0.000 description 2
- ATMLPEJAVWINOF-UHFFFAOYSA-N acrylic acid acrylic acid Chemical compound OC(=O)C=C.OC(=O)C=C ATMLPEJAVWINOF-UHFFFAOYSA-N 0.000 description 2
- 230000001070 adhesive Effects 0.000 description 2
- 230000003466 anti-cipated Effects 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 2
- 239000012459 cleaning agent Substances 0.000 description 2
- 238000010924 continuous production Methods 0.000 description 2
- 229920001577 copolymer Polymers 0.000 description 2
- RTZKZFJDLAIYFH-UHFFFAOYSA-N diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 238000010559 graft polymerization reaction Methods 0.000 description 2
- 235000019382 gum benzoic Nutrition 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- 229920001684 low density polyethylene Polymers 0.000 description 2
- 239000004702 low-density polyethylene Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 125000005395 methacrylic acid group Chemical group 0.000 description 2
- YMWUJEATGCHHMB-UHFFFAOYSA-N methylene dichloride Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 2
- KWOLFJPFCHCOCG-UHFFFAOYSA-N methylphenylketone Chemical compound CC(=O)C1=CC=CC=C1 KWOLFJPFCHCOCG-UHFFFAOYSA-N 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- RPQRDASANLAFCM-UHFFFAOYSA-N oxiran-2-ylmethyl prop-2-enoate Chemical compound C=CC(=O)OCC1CO1 RPQRDASANLAFCM-UHFFFAOYSA-N 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 229920002530 poly[4-(4-benzoylphenoxy)phenol] polymer Polymers 0.000 description 2
- 229920001888 polyacrylic acid Polymers 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 2
- NFKAWBGFIMBUMB-UHFFFAOYSA-N 1-phenylpentan-2-one Chemical compound CCCC(=O)CC1=CC=CC=C1 NFKAWBGFIMBUMB-UHFFFAOYSA-N 0.000 description 1
- BJELTSYBAHKXRW-UHFFFAOYSA-N 2,4,6-tris(prop-2-enoxy)-1,3,5-triazine Chemical compound C=CCOC1=NC(OCC=C)=NC(OCC=C)=N1 BJELTSYBAHKXRW-UHFFFAOYSA-N 0.000 description 1
- XNLICIUVMPYHGG-UHFFFAOYSA-N 2-Pentanone Chemical compound CCCC(C)=O XNLICIUVMPYHGG-UHFFFAOYSA-N 0.000 description 1
- BSMGLVDZZMBWQB-UHFFFAOYSA-N 2-methyl-1-phenylpropan-1-one Chemical compound CC(C)C(=O)C1=CC=CC=C1 BSMGLVDZZMBWQB-UHFFFAOYSA-N 0.000 description 1
- HEOVGVNITGAUKL-UHFFFAOYSA-N 3-methyl-1-phenylbutan-1-one Chemical compound CC(C)CC(=O)C1=CC=CC=C1 HEOVGVNITGAUKL-UHFFFAOYSA-N 0.000 description 1
- RZVHIXYEVGDQDX-UHFFFAOYSA-N Anthraquinone Chemical compound C1=CC=C2C(=O)C3=CC=CC=C3C(=O)C2=C1 RZVHIXYEVGDQDX-UHFFFAOYSA-N 0.000 description 1
- 239000004342 Benzoyl peroxide Substances 0.000 description 1
- FFSAXUULYPJSKH-UHFFFAOYSA-N Butyrophenone Chemical compound CCCC(=O)C1=CC=CC=C1 FFSAXUULYPJSKH-UHFFFAOYSA-N 0.000 description 1
- 101700073334 CD59 Proteins 0.000 description 1
- YLQWCDOCJODRMT-UHFFFAOYSA-N Fluorenone Chemical compound C1=CC=C2C(=O)C3=CC=CC=C3C2=C1 YLQWCDOCJODRMT-UHFFFAOYSA-N 0.000 description 1
- VOZRXNHHFUQHIL-UHFFFAOYSA-N Glycidyl methacrylate Chemical compound CC(=C)C(=O)OCC1CO1 VOZRXNHHFUQHIL-UHFFFAOYSA-N 0.000 description 1
- 239000004831 Hot glue Substances 0.000 description 1
- OMPJBNCRMGITSC-UHFFFAOYSA-N Incidol Chemical compound C=1C=CC=CC=1C(=O)OOC(=O)C1=CC=CC=C1 OMPJBNCRMGITSC-UHFFFAOYSA-N 0.000 description 1
- 102100014837 MLIP Human genes 0.000 description 1
- 229920002845 Poly(methacrylic acid) Polymers 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- KRIOVPPHQSLHCZ-UHFFFAOYSA-N Propiophenone Chemical compound CCC(=O)C1=CC=CC=C1 KRIOVPPHQSLHCZ-UHFFFAOYSA-N 0.000 description 1
- UIERETOOQGIECD-ONEGZZNKSA-N Tiglic acid Chemical compound C\C=C(/C)C(O)=O UIERETOOQGIECD-ONEGZZNKSA-N 0.000 description 1
- 102000007544 Whey Proteins Human genes 0.000 description 1
- 108010046377 Whey Proteins Proteins 0.000 description 1
- 238000002835 absorbance Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000006399 behavior Effects 0.000 description 1
- 235000019400 benzoyl peroxide Nutrition 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 230000000875 corresponding Effects 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 238000004128 high performance liquid chromatography Methods 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009114 investigational therapy Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- KFZMGEQAYNKOFK-UHFFFAOYSA-N iso-propanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- HTEAGOMAXMOFFS-UHFFFAOYSA-N methyl 2-methylprop-2-enoate;prop-2-enoic acid Chemical compound OC(=O)C=C.COC(=O)C(C)=C HTEAGOMAXMOFFS-UHFFFAOYSA-N 0.000 description 1
- 230000003278 mimic Effects 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 230000001264 neutralization Effects 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N oxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 1
- 229920002492 poly(sulfones) Polymers 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000001846 repelling Effects 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- MNCGMVDMOKPCSQ-UHFFFAOYSA-M sodium;2-phenylethenesulfonate Chemical compound [Na+].[O-]S(=O)(=O)C=CC1=CC=CC=C1 MNCGMVDMOKPCSQ-UHFFFAOYSA-M 0.000 description 1
- 238000007614 solvation Methods 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N sulfonic acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- 125000000472 sulfonyl group Chemical group *S(*)(=O)=O 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
- 235000021119 whey protein Nutrition 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/02—Hydrophilization
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/30—Cross-linking
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/38—Graft polymerization
- B01D2323/385—Graft polymerization involving radiation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/40—Details relating to membrane preparation in-situ membrane formation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/02—Details relating to pores or porosity of the membranes
- B01D2325/022—Asymmetric membranes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/30—Chemical resistance
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0081—After-treatment of organic or inorganic membranes
- B01D67/0093—Chemical modification
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0081—After-treatment of organic or inorganic membranes
- B01D67/0095—Drying
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
- B01D69/125—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/26—Polyalkenes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/28—Polymers of vinyl aromatic compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/38—Polyalkenylalcohols; Polyalkenylesters; Polyalkenylethers; Polyalkenylaldehydes; Polyalkenylketones; Polyalkenylacetals; Polyalkenylketals
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/76—Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74
- B01D71/82—Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74 characterised by the presence of specified groups, e.g. introduced by chemical after-treatment
Abstract
Asymmetric composite membranes consisting of a film of partially cross-linked poly(ethenol) (polyvinyl alcohol (PVA)) adhered to a hydrophilicitized microporous sheet of grafted polyolefin are disclosed. The microporous sheet is made hydrophilic by grafting of the polyolefin, e.g. poly(ethylene), with a preformed polymer of ethenylbenzenesulfonic acid before adherence of the film of partially cross-linked poly(ethenol). The asymmetric composite membranes are chlorine tolerant with high levels of protein and salt rejection making them particularly suitable for use in the extraction or recovery of water from feed streams in the beverage and food industries, including dairy. th a preformed polymer of ethenylbenzenesulfonic acid before adherence of the film of partially cross-linked poly(ethenol). The asymmetric composite membranes are chlorine tolerant with high levels of protein and salt rejection making them particularly suitable for use in the extraction or recovery of water from feed streams in the beverage and food industries, including dairy.
Description
ASYMMETRIC COMPOSITE MEMBRANES AND MODIFIED SUBSTRATES
USED IN THEIR PREPARATION
FIELD OF INVENTION
The invention relates to a durable water permeable asymmetric composite
membrane with high levels of protein rejection, and substrates for use in
their preparation. In particular, the invention relates to a durable water
permeable asymmetric composite membrane consisting of a film of partially
cross-linked poly(ethenol) adhered to a hydrophilicitized microporous sheet
of poly(ethylene).
BACKGROUND ART
It is well-known to use grafting to modify the surface of films, sheets and
moulded objects formed from polyolefins. For example, the publication of
Tazuke and Kimura (1978) discloses photografting onto poly(propylene),
poly(ethylene) and several other polymer films using benzophenone as a
sensitizer. In this publication the choice of solvent and sensitizer was
noted to be very important.
The publication of Ang et al (1980) discloses an irradiation procedure
where the sensitizer is dissolved in the monomer solution and can be used
for the photosensitized copolymerization in high yields of styrene, 4-vinyl
pyridine and methyl methacrylate to poly(propylene). Again, this
publication notes that the reaction was found to be very specific to
certain types of sensitizers.
The publication of Ogiwara et al (1981) discloses the photografting on
poly(propylene) and low-density poly(ethylene) (LDPE) films on which
sensitizers were coated beforehand. The sensitizers coated on films enabled
vinyl monomers, such as methyl methacrylate, acrylic acid and methacrylic
acid to graft easily with high yields. The hydrophilic monomers acrylic
acid and methacrylic acid were conveniently grafted using them in aqueous
solution in a liquid phase system.
The publication of Allmer et al (1988) discloses the modification of
surfaces of LDPE, high-density poly(ethylene) (HDPE) and polystyrene by
grafting with acrylic acid. The grafting is performed in the vapor-phase
and increased the wettability of the polymer. It was observed that acetone
was able to initiate grafting and was found to promote and direct grafting
to the surface. The later publication of Allmer et al (1989) discloses the
grafting of the surface of LDPE with glycidyl acrylate and glycidyl
methacrylate by photoinitiation. Acetone and ethanol were used as solvents,
with acetone yielding slightly more grafting at the surface.
The publications of Yao and Ranby (1990a, 1990b and 1990c) disclose inter
alia a process for the continuous photoinitiated graft copolymerization of
acrylamide and acrylic acid onto the surface of HDPE tape film. The process
is performed under a nitrogen atmosphere using benzophenone as the
photoinitiator. It was noted that pre-soaking was very important for
efficient photographing within short irradiation times. The application of
this pre-soaking photografting method to poly(ethylene terephthalate) (PET)
was also disclosed. In this context acetone was found to be a somewhat
better solvent than methylethylketone and methylpropylketone. When applied
to a continuous process for the photochemically induced graft
polymerization of acrylamide and acrylic acid of poly(propylene) (PP) fibre
surface under a nitrogen atmosphere, optimal concentrations of monomer and
initiator in the pre-soaking solution were determined.
The publications of Kubota and Hata (1990a and 1990b) disclose an
investigation of the location of methacrylic acid chains introduced into
poly(ethylene) film by liquid and vapor-phase photografting and a
comparative examination of the photografting behaviours of benzil,
benzophenone and benzoin ethyl ether as sensitizers. In these latter
studies poly(methacrylic acid) was grafted onto initiator-coated LDPE film.
The publication of Edge et al (1993) discloses the photochemical grafting
of 2-hydroxyethyl methacrylate (HEMA) onto LDPE film. A solution phase
method is used to produce a material with increased wettability.
The publication of Singleton et al (1993) discloses a method of making a
polymeric sheet wettable by aqueous solvents and useful as an electrode
separator in an electrochemical device. The polymeric sheet is formed from
fibres which comprise poly(propylene) alone and is distinguished from a
membrane formed from a microporous polymer sheet.
The publication of Zhang and Ranby (1993) discloses the photochemically
induced graft copolymerisation of acrylamide onto the surface of PP film.
Acetone was shown to be the best solvent among the three aliphatic ketones
tested.
The publications of Yang and Ranby (1996a and 1996b) disclose factors
affecting the photografting process, including the role of far UV radiation
(200 to 300 nm). In these studies benzophenone was used as the
photoinitiator and LDPE film as the substrate. Added water was shown to
favour the photografting polymerisation of acrylic acid on the surface of
polyolefins, but acetone was shown to have a negative effect due to the
different solvation of poly(acrylic acid) (PAA).
The publication of Hirooka and Kawazu (1997) discloses alkaline separators
prepared from unsaturated carboxylic acid grafted poly(ethylene)-
poly(propylene) fibre sheets. Again, the sheets used as a substrate in
these studies are distinguished from a membrane formed from a microporous
polymer sheet.
The publication of Xu and Yang (2000) discloses a study on the mechanism of
vapor-phase photografting of acrylic acid onto LDPE.
The publication of Shentu et al (2002) discloses a study of the factors,
including the concentration of monomer, affecting photo-grafting on LDPE.
The publication of El Kholdi et al (2004) discloses a continuous process
for the graft polymerisation of acrylic acid from monomer solutions in
water onto LDPE. The publication of Bai et al (2011) discloses the
preparation of a hot melt adhesive of grafted low-density poly(ethylene)
(LDPE). The adhesive is prepared by surface UV photografting of acrylic
acid onto the LDPE with benzophenone as the photoinitiator.
The publication of Choi et al (2001) states that graft polymerisation is
considered as a general method for modifying the chemical and physical
properties of polymer materials.
The publication of Choi (2002) discloses a method for producing an acrylic
graft polymer on the surface of a polyolefin article comprising the steps
of immersing the article in a solution of an initiator in a volatile
solvent, allowing the solvent to evaporate, and then immersing the article
in a solution of an acrylic monomer before subjecting the article to
ultraviolet irradiation in air or an inert atmosphere. Acrylic acid is used
as the acrylic monomer in each one of the Examples disclosed in the
publication, although the use of equivalent amounts of methacrylic acid,
acrylamide and other acrylic monomers is anticipated.
The publication of Choi (2004) discloses the use of “ethylenically
unsaturated monomers” in graft polymerisation. These other monomers are
disclosed as monomers that are polymerizable by addition polymerisation to
a thermoplastic polymer and are hydrophilic as a consequence of containing
carboxyl (-COOH), hydroxyl (-OH), sulfonyl (SO ), sulfonic acid (-SO H) or
carbonyl (-CO) groups. No experimental results concerning the chemical and
physical properties of graft polymers prepared by a method using these
other monomers is disclosed.
The publication of Choi (2005) discloses a non-woven sheet of polyolefin
fibres where opposed surfaces of the sheet are hydrophilic as a consequence
of an acrylic graft polymerisation. The properties of the sheet are
asymmetric, the ion exchange coefficient of the two surfaces being
different. The method used to prepare these asymmetric acrylic graft
polymerised non-woven polyolefin sheets comprises the steps of immersing
the substrates in a solution of benzophenone (a photoinitiator), drying and
then immersing the substrate in a solution of acrylic acid prior to
subjecting to ultraviolet (UV) irradiation. The irradiation may be
performed when the surfaces are in contact with either air or an inert
atmosphere.
The publication of Gao et al (2013) discloses a method of preparing a
radiation cross-linked lithium-ion battery separator. In an example, a
porous polyethylene membrane is immersed in a solution of benzophenone and
triallyl cyanurate in dichloromethane. The immersed membrane is dried at
room temperature before being immersed in a water bath at 30°C and
irradiated on both sides using a high-pressure mercury lamp for three
minutes.
The publication of Jaber and Gjoka (2016) discloses the grafting of ultra-
high molecular weight polyethylene microporous membranes using monomers
having one or more anionic, cationic or neutral groups. The publication
states that the authors have discovered that molecules can be grafted on
the surface of an asymmetric, porous ultra-high molecular weight
polyethylene membrane using an ultraviolet radiation energy source. The
grafted membranes are proposed for use in removing charged contaminants
from liquids.
The objective of the majority of these prior art methods is to improve the
adhesion, biocompatibility, printability or wettability of the surface of a
substrate using photoinitiated polymerisation. These methods are to be
distinguished from the use of UV-initiated grafting with an exogenously
prepared preformed polymer to modify the permeability to water of a
hydrophobic microporous polyolefin substrate.
The publication of Bolto et al (2009) reviews what is disclosed in
publications concerning the cross-linking of poly(ethenol), i.e. PVA. These
publications include those concerning cross-linking methods and the
grafting of PVA onto support membranes, including porous hydrophobic
membranes such as poly(ethylene) and poly(propylene).
The publication of Linder et al (1988) discloses semipermeable composite
membranes comprising a film of modified PVA or PVA-copolymers on a porous
support. Suitable support materials are required to be water insoluble and
may be chosen, e.g. from polyacrylonitriles, polysulfones, polyamides,
polyolefins such as poly(ethylenes) and poly(propylenes), or cellulosics.
The publication of Exley (2016) discloses an asymmetric composite membrane
consisting of a film of cross-linked poly(ether ether ketone) adhered to a
sheet of grafted microporous poly(ethylene). The microporous poly(ethylene)
is obtained by photoinitiated grafting with an ethenyl monomer to provide a
hydrophilic sheet.
The publication of Craft et al (2017) discloses improvements in the
asymmetric composite membranes disclosed in the publication of Exley
(2016). The improved asymmetric composite membranes comprise of poly(vinyl
alcohol) polymer crosslinked with a crosslinking agent (such as divinyl
benzene) coated on a film of cross-linked poly(ether ether ketone) adhered
to a sheet of the grafted microporous poly(ethylene). The improvement is in
the selectivity of the asymmetric composite membrane obtained.
It is an object of the present invention to provide an asymmetric composite
membrane with improved levels of protein rejection while maintaining an
acceptable flux. It is an object of the present invention to provide a
method to preparing the asymmetric composite membrane. It is an object of
the present invention to provide a hydrophilicitized sheet of microporous
polyolefin particularly suited for use in the method of preparing the
asymmetric composite membrane. It is an object of the present invention to
provide asymmetric composite membranes and hydrophilicitized sheets of
microporous polyolefin adaptable for use in extracting or recovering water
from feed streams in the beverage and food processing industries, including
dairy. These objects are to be read in the alternative with the object at
least to provide a useful choice in the selection of such methods,
membranes and sheets.
STATEMENT OF INVENTION
In a first aspect the invention provides a hydrophilicitized microporous
sheet of polyolefin where the microporous polyolefin has been grafted with
a preformed poly(4-ethenyl benzene sulfonic acid).
Preferably, the polyolefin is selected from the group consisting of:
poly(ethylene), poly(propylene), poly(butylene) and poly(methylpentene).
More preferably, the polyolefin is poly(ethylene) or poly(propylene). Most
preferably, the polyolefin is poly(ethylene).
Preferably, the preformed poly(4-ethenyl benzene sulfonic acid) is
equivalent to that provided in the working solution prepared according to
Example 1.
In a second aspect the invention provides an asymmetric composite membrane
comprising a film of partially crosslinked poly(ethenol) adhered to a
hydrophilicitized microporous sheet of polyolefin where the polyolefin has
been grafted with a preformed poly(4-ethenyl benzene sulfonic acid) before
adherence of the film of partially crosslinked poly(ethenol).
Preferably, the partially crosslinked poly(ethenol) is crosslinked to a
degree in the range equivalent to that of the partially crosslinked
poly(ethenol) provided in Vial 2 of Example 8 to that of the partially
crosslinked poly(ethenol) provided in Vial 4 of Example 8. More preferably,
the partially crosslinked poly(ethenol) is crosslinked to a degree
substantially equivalent to that of the partially crosslinked poly(ethenol)
provided in Vial 3 of Example 8.
Preferably, the polyolefin is selected from the group consisting of:
poly(ethylene), poly(propylene), poly(butylene) and poly(methylpentene).
More preferably, the polyolefin is poly(ethylene) or poly(propylene). Most
preferably, the polyolefin is poly(ethylene).
In a preferred embodiment of the second aspect, the invention provides an
asymmetric composite membrane consisting essentially of a film of partially
crosslinked poly(ethenol) adhered to a hydrophilicitized microporous sheet
of poly(ethylene) where the polyolefin has been grafted with a preformed
poly(4-ethenyl benzene sulfonic acid) before adherence of the film of
partially crosslinked poly(ethenol).
In a most preferred embodiment of the second aspect, the invention provides
an asymmetric composite membrane consisting essentially of a film of
partially crosslinked poly(ethenol) adhered to a hydrophilicitized
microporous sheet of poly(ethylene) where the polyolefin has been grafted
with a preformed poly(4-ethenyl benzene sulfonic acid) equivalent to that
provided in the working solution prepared according to Example 1 before
adherence of the film of partially crosslinked poly(ethenol) and the
partially crosslinked poly(ethenol) is crosslinked to a degree
substantially equivalent to that of the partially crosslinked poly(ethenol)
provided in Vial 3 of Example 8.
An asymmetric composite membrane capable of providing at least 99.9% total
protein rejection at a flux of 5 LMH with milk as a feed stream is
provided.
In a third aspect the invention provides a method of preparing the
hydrophilicitized microporous sheet of polyolefin of the first aspect of
the invention comprising the steps of:
1. Contacting a microporous sheet of polyolefin with a dispersion
comprising a preformed poly(4-ethenylbenzenesulfonic acid) in an
aqueous solvent to provide a contacted microporous sheet;
2. Curing the contacted microporous sheet at a temperature and for a time
sufficient for at least a portion of the poly(4-ethenylbenzenesulfonic
acid) to be grafted onto the polyolefin substrate to provide a cured
microporous sheet; and then
3. Washing the cured microporous sheet to provide the hydrophilicitized
microporous sheet of polyolefin.
Preferably, the polyolefin is selected from the group consisting of:
poly(ethylene), poly(propylene), poly(butylene) and poly(methylpentene).
More preferably, the polyolefin is poly(ethylene) or poly(propylene). Most
preferably, the polyolefin is poly(ethylene).
Preferably, the aqueous solvent is acetone-water.
Preferably, the curing the contacted microporous sheet is by irradiating
with ultraviolet light at an intensity and at a temperature for a period of
time sufficient for at least a portion of the poly(4-ethenylbenzenesulfonic
acid) to be grafted onto the polyolefin.
Preferably, the irradiating is in the presence of a photoinitiator. More
preferably, the irradiating is in the presence of a photoinitiator selected
from the group consisting of: aceto-phenone, anthraquinone, benzoin,
benzoin ether, benzoin ethyl ether, benzil, benzil ketal, benzophenone,
benzoyl peroxide, n-butyl phenyl ketone, iso-butyl phenyl ketone,
fluorenone, propiophenone, n-propyl phenyl ketone and iso-propyl phenyl
ketone. Most preferably, the irradiating is in the presence of the
photoinitiator benzophenone.
Preferably, the ultraviolet light has a broad spectrum centred on 250 nm
and bandwidth limits of approximately 250 nm and 400 nm.
Preferably, the washing is with water.
In a preferred embodiment of the third aspect, the invention provides a
method of preparing a hydrophilicitized microporous sheet of poly(ethylene)
comprising the steps of:
1. Polymerising 4-ethenylbenzenesulfonic acid in the presence of a
radical initiator to provide a first dispersion in a first solvent of
a poly(4-ethenylbenzenesulfonic acid);
2. Contacting a microporous sheet of poly(ethylene) with a second
dispersion in a second solvent of the poly(4-ethenylbenzenesulfonic
acid) to provide a contacted microporous sheet of poly(ethylene);
3. Curing the contacted microporous sheet at a temperature and for a time
sufficient for at least a portion of the poly(4-ethenylbenzenesulfonic
acid) to be grafted onto the polyolefin substrate; and then
4. Washing the cured microporous sheet to provide the hydrophilicitized
microporous sheet of poly(ethylene),
where the first solvent is water and the second solvent is acetone-water.
The 4-ethenylbenzenesulfonic acid may be provided in the form of a salt,
e.g. as its sodium salt (SSS).
Preferably, the radical initiator is selected from the group consisting of:
ammonium persulfate and sodium persulfate. More preferably, the radical
initiator is sodium persulfate.
Preferably, the second solvent is 40 to 60% (v/v) acetone in water. Most
preferably, the second solvent is 50% (v/v) acetone in water.
The second dispersion may be prepared by adding acetone to the first
dispersion.
In a fourth aspect the invention provides a hydrophilicitized microporous
sheet of polyolefin prepared according to the method of the third aspect of
the invention.
In an unclaimed fifth aspect the invention provides a method of preparing
the asymmetric composite membrane of the second aspect of the invention,
comprising the steps of:
1. Contacting one side of the hydrophilicitized microporous sheet of the
first or fourth aspect of the invention with a solution in a first
solvent of partially cross-linked poly(ethenol) in the presence of a
radical initiator to provide a contacted sheet;
2. Drying the contacted sheet at a temperature and for a time sufficient
to allow the partially cross-linked poly(ethenol) to adhere to the one
side of the hydrophilicitized microporous sheet of polyolefin and
evaporate substantially all the solvent to provide a dried contacted
sheet; and then
3. Washing the dried contacted sheet in a second solvent to provide the
asymmetric composite membrane.
Preferably, the drying of the contacted sheet is by applying a positive
thermal gradient across the thickness of the sheet from the contacted one
side of the hydrophilicitized microporous sheet to the other side.
In the description and claims of this specification the following
abbreviations, acronyms, terms and phrases have the meaning provided:
“comprising” means “including”, “containing” or “characterized by” and does
not exclude any additional element, ingredient or step; “consisting of”
means excluding any element, ingredient or step not specified except for
impurities and other incidentals; “consisting essentially of” means
excluding any element, ingredient or step that is a material limitation;
“crosslinking agent” means a material that is incorporated into the
crosslinking bridge of a cross-linked polymer network; “flux” means the
rate (volume per unit of time) of permeate transported per unit of membrane
area; “graft polymer” means a polymer in which the linear main chain has
attached to it at various points side chains of a structure different from
the main chain; “homopolymer” means a polymer formed by the polymerization
of a single monomer; “hydrophilic” means having a tendency to mix with,
dissolve in, or be wetted by water and “hydrophilicity”,
“hydrophilicitized” and “hydrophilicitizing” have a corresponding meaning;
“microporous” means consisting of an essentially continuous matrix
structure containing substantially uniform small pores or channels
throughout the body of the substrate (such as may be manufactured using a
cast (wet) process technology) and specifically excludes a discontinuous
matrix of woven or non-woven fibres; “partially crosslinked” means that
only a portion of the available sites for cross-linking are utilised and
the cross-linking reaction has been limited by reagents, temperature or
period of time; “photoinitiator” means a photolabile compound which upon
irradiation forms a radical; “poly(ethanol)” and “polyvinyl alcohol” are
used synonymously; “post-treated polymer” means a polymer that is modified,
either partially or completely, after the basic polymer backbone has been
formed; “preformed” means formed beforehand, i.e. prior to treatment;
“PSSS” or “pSSS” denotes the product of the polymerization of SSS, i.e.
40 poly(4-ethenylbenzenesulfonic acid); “PVA” denotes poly(ethenol) (or
polyvinyl alcohol); “SSS” denotes sodium styrene sulfonate, i.e. the sodium
salt of 4-ethenylbenzenesulfonic acid; “UVA” means electromagnetic
radiation having wavelengths between 320 and 400 nm; “UVB” means
electromagnetic radiation having wavelengths between 290 and 320 nm; “UVC”
means electromagnetic radiation having wavelengths between 200 and 290 nm,
and “xPVA” denotes PVA that is at least partially crosslinked.
The terms “first”, “second”, “third”, etc. used with reference to elements,
features or integers of the subject matter defined in the Statement of
Invention and Claims, or when used with reference to alternative
embodiments of the invention are not intended to imply an order of
preference. The numbering of the Examples and the Comparative Examples (if
any) is not intended to mean any pair of Example and Comparative Example is
directly comparable. Where values are expressed to one or more decimal
places standard rounding applies. For example, 1.7 encompasses the range
1.650 recurring to 1.749 recurring. Where concentrations or ratios of
reagents or solvents are specified, the concentration or ratio specified is
the initial concentration or ratio of the reagents or solvents. References
to the use of 4-ethenylbenzenesulfonic acid encompass references to the use
of salts of the acid, including SSS. In the absence of further limitation
the use of plain bonds in the representations (if used) of the structures
of compounds encompasses the diastereoisomers, enantiomers and mixtures
thereof of the compounds.
The invention will now be described with reference to embodiments or
examples and the figures of the accompanying drawings pages.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1. FTIR spectra of the monomer 4-ethenylbenzenesulfonic acid (SSS)
and poly(4-ethenylbenzenesulfonic acid) (PSSS) prepared according to the
method described in Example 1 (water) and Example 2 (DMSO).
Figure 2. FTIR spectra recorded for poly(4-ethenylbenzenesulfonic
acid)(PSSS), the photoinitiator benzophenone (BP), no washing protocol (1),
washed with water at a temperature of 45 to 50°C before drying (2), washed
with acetone (3) and washed with water at a temperature of 45 to 50°C,
dried and then washed with acetone (4).
Figure 3. Photograph of vials containing partially crosslinked
poly(ethenol) (xPVA) prepared according the Example 8. From left to right:
Vial 1, Vial2, Vial 3 and Vial 4.
Figure 4. Flux (LMH)( ♦, broken line), total solids (%)( ▲, dotted line) and
protein rejection (%)( ■, solid line) of a sample of an asymmetric composite
membrane (030918Sii) prepared according to Example 9 during repeated clean-
in-place (C-i-P) protocols.
Figure 5. Pressure series testing (0 to 20 bar) of a sample (030918Siii) of
an asymmetric composite membrane prepared according to Example 9. Flux and
protein rejection with milk as the feed stream were measured.
Figure 6. Comparison of the FTIR spectra (full range) recorded for samples
(240818Si and 240818Sii) of an asymmetric composite membrane prepared
according to Example 9 and the poly(ethenol) (PVA) and cross-linked
poly(ethenol) (xPVA) used in their preparation.
Figure 7. Comparison of the FTIR spectra (stretch mode region) recorded for
samples (240818Si and 240818Sii) of an asymmetric composite membrane
prepared according to Example 9 and the poly(ethenol) (PVA) and cross-
linked poly(ethenol) (xPVA) used in their preparation.
Figure 8. Comparison of the FTIR spectra (finger print region) recorded for
samples (240818Si and 240818Sii) of an asymmetric composite membrane
prepared according to Example 9 and the poly(ethenol) (PVA) and cross-
linked poly(ethenol) (xPVA) used in their preparation.
Figure 9. Scanning electronmicrographs of the surface of samples of
asymmetric composite membrane prepared according to Example 9 before and
after being subjected to repeated clean-in-place (CIP) protocols.
DETAILED DESCRIPTION
The invention resides in part in the selection of a preformed polymer of 4-
ethenylbenzenesulfonic acid as the hydrophilicitizing agent used in the
preparation of hydrophilicitized polyolefin substrates. This part of the
invention is most advantageously applied to the hydrophilicitization of
preformed sheets of microporous poly(ethylene). Use of poly(4-
ethenylbenzenesulfonic acid) as the hydrophilicitizing agent has been found
to provide greater and more consistent hydrophilicitization of the
polyolefin substrate. This improvement is attributed at least in part to
the reduced number of side reactions that may occur when compared with use
of the monomer (cf. the method described in the publications of Exley
(2016) and Craft et al (2017)). It is also anticipated that the use
increases the likelihood of the preformed polymer grafting to the
polyolefin substrate at multiple sites. A structurally distinct form of
grafted polyolefin substrate may therefore be being obtained.
The improved performance of a hydrophilicitized sheet of microporous
poly(ethylene) prepared by the method of the present invention when
compared with that prepared by the method disclosed in the publications of
Exley (2016) and Craft et al (2017) is demonstrated by a higher flux with
water as the feed stream whilst retaining the desired durability including
tolerance to chlorine and other cleaning agents. The hydrophilicitized
sheets of microporous poly(ethylene) prepared by the method of the present
invention also “wet out” at pressures lower than those previously required.
The method of preparing the hydrophilicitized sheets of microporous
poly(ethylene) is also less wasteful of reagents, including the
photoinitiator, and eliminates the need for the exclusion of oxygen during
the preparation. The polymer of 4-ethenylbenzenesulfonic acid is
advantageously prepared as a dispersion (the ‘working solution’) that can
be used directly without the need to isolate the polymer. This advantage is
illustrated in the methods of the following Examples.
The invention also resides in part in the use of the hydrophilicitized
sheet of microporous polyolefin to prepare an asymmetric composite
membrane. Providing a hydrophilicitized, i.e. wettable, sheet of
microporous polyolefin facilitates the formation of the film of partially
cross-linked poly(ethenol) (xPVA) on the surface and adherence to that
surface. In contrast with the preparation of the asymmetric composite
membranes disclosed in the publication of Craft et al (2017) persulfate is
used as a cross-linking agent. The high levels of protein rejection
demonstrated for the asymmetric composite membranes is attributed in part
to the selection of this crosslinking agent. A porosity providing a size
exclusion reduced to an estimated 30 kDa from an estimated 160 kDa is
believed to be achieved (and is supported by the increased levels of total
protein rejection of greater than 99.9%).
When drying the hydrophilicitized microporous sheet of polyolefin contacted
with the dispersion in water of partially cross-linked poly(ethenol) (xPVA)
applying a positive thermal gradient across the thickness of the sheet from
the contacted side to the other side is also believed to assist in
maintaining porosity of the hydrophilicitized microporous sheet of
polyolefin and thereby provide an asymmetric composite membrane with higher
flux rates than might otherwise be achievable. In Example 9 the application
of a positive thermal gradient is a consequence of the sheet being
supported on a glass plate during the drying steps. The positive thermal
gradient is believed to limit the extent to which the dispersion in water
may permeate the pores of the hydrophilicitized microporous sheet.
The asymmetric composite membranes provided by the invention are therefore
further distinguished from other membranes, e.g. those suggested in the
publication of Linder et al (1988), where a superficial film of cross-
linked PVA or PVA-copolymer is proposed to be coated on a hydrophobic, i.e.
water repelling, sheet of microporous polyolefin.
MATERIALS AND METHODS
All microporous sheets used in the preparation of samples were prepared
from virgin poly(ethylene), i.e. poly(ethylene) of high purity.
FTIR
Spectra of the samples were recorded using a Thermo Electron Nicolet 8700
FTIR spectrometer equipped with a single bounce ATR and diamond crystal. An
average of 32 scans with a 4 cm resolution was taken for all samples.
Flux
Permeability was determined using a filter assembly (Sterlitech Corp.) by
measuring the flux with deionized water as the feed stream at various
pressures. Flux J was then graphed against effective pressure difference
across the membrane, p , and the slope of the permeability L .
eff p
� =
The samples were mounted in the filter assembly. Deionized water was fed
into the rig at 2.5 L min and 4 to 8 ºC. The time to collect a
predetermined volume of permeate was noted. The flux rate (J) was
calculated according to the following equation:
� =
� x �
where V is the permeate volume (L), t is the time (h) for the collection of
V and A is area of the sample (m ) which was determined to be 0.014 m .
Salt rejection
Rejection was measured using a 2 g/L solution in water of sodium chloride
with a feed pressure of 16 bar. The conductivities from the feed and
permeate were compared.
% � = 1 − × 100
where σ is the conductivity of permeate and σ is the conductivity of the
feed.
Total solids rejection
Rejection for whole milk samples was measured by pouring 20 mL of sample
from the feed in a petri dish and measuring the dry weight after 2 hours in
a 100 °C oven.
% � = 1 − × 100
where m is total milk solids in the permeate and m is the mass of milk
p,TS f,TS
total solids in the feed.
Protein concentrations
Total protein and total whey protein concentrations in permeate were
calculated on the basis of HPLC analysis with UV absorbance monitoring.
‘Clean-in-Place’ (CIP) protocol
To mimic commercial processing operations samples of the asymmetric
composite membrane was subjected to repeated in situ washing protocols) as
described in Craft et al (2017). The intermediate and subsequent flux
rates were determined to assess the likely durability of the membrane in
commercial processing operations. The in situ washing protocol was based
on that employed in a commercial processing operation but modified in
duration to compensate for the greater exposure of the membrane to the
cleaning agents (caustic and acid) in the filter assembly. Prior to the
washing steps the membrane was rinsed by circulating water at an initial
temperature of 65°C through the filter assembly for a period of three
minutes before draining the system.
The membrane was subjected to a first wash by circulating a 2% (w/v) sodium
hydroxide solution (“caustic wash”) through the filter assembly for a
period of five minutes before draining and flushing the system by
circulating water at an initial temperature of 65°C through the filter
assembly system for a period of five minutes. The membrane was subjected
to a second wash by circulating a 2% (w/w) nitric acid solution (“acid
wash”) through the filter assembly system for a period of ten minutes
before draining and flushing the system of circulating water at an initial
temperature of 65°C for a period of ten minutes. The membrane was subjected
to a third wash (a “caustic wash”) before flushing the system by
circulating water at an initial temperature of 65°C for a period of five
minutes before circulating chilled water for a period of five minutes to
cool the system. All rinsing and washing steps were performed with no
pressure recorded on the pressure gauge of the filter assembly.
Preparation of poly(4-ethenylbenzenesulfonic acid)
EXAMPLE 1
A quantity of 50 g of the monomer 4-ethenylbenzenesulfonic acid as its
sodium salt (SSS) was dissolved in a volume of 100 mL of distilled water to
provide a solution. A quantity of 0.5 g of the initiator sodium persulfate
(SPS) was then dissolved in the solution and the initiator-monomer mixture
heated with stirring at a temperature of 80 to 90°C for a time of about 20
minutes. A viscous solution was obtained having a total volume of about 125
mL. The viscous solution was diluted with the same volume of distilled
water to provide 250 mL of a working solution of poly(4-
ethenylbenzenesulfonic acid).
The polymer could be precipitated from this working solution by the
addition of an excess volume of acetone, followed by collection of the
precipitate by filtration through a Buchner funnel and then washing with
acetone to provide a light white solid that could be readily ground to a
powder using a pestle and mortar.
EXAMPLE 2
A quantity of 5 g of the monomer 4-ethenylbenzenesulfonic acid as its
sodium salt (SSS) was dissolved in a volume of 20 mL of dimethylsulfoxide
(DMSO) to provide a solution.
A quantity of 0.05 g of the initiator ammonium persulfate (APS) was then
dissolved in the solution and the initiator-monomer mixture heated with
stirring at a temperature of 80 to 90°C for a time of about 20 minutes. The
poly(4-ethenylbenzenesulfonic acid) was precipitated from the cooled
solution by addition of an excess volume of acetone, collected by
filtration through a Buchner funnel and washed with acetone to provide the
same light white solid that could be readily ground to a powder obtainable
in Example 1.
The Fourier transform infrared (FTIR) spectra of the powder obtained by the
methods of preparation described in Example 1 (PSSS from water) and Example
2 (PSSS from DMSO) are compared with that of the FTIR spectrum of the
monomer 4-ethenylbenzenesulfonic acid (SSS) in Figure 1. A comparison of
the spectra was consistent with the polymerisation of the monomer in both
methods of preparation. The polymer prepared by the method described in
Example 1, i.e. the working solution, was used as the hydrophilicitizing
agent in the preparation of hydrophilicitized sheets of microporous
poly(ethylene) according to the following examples.
Preparation of hydrophilicitized sheets of microporous poly(ethylene)
EXAMPLE 3
A volume of 6 mL of the working solution obtained according to Example 1
was mixed with a volume of 5 mL of distilled water in a vial to provide a
volume of initial solution containing 1.2 g of poly(4-
ethenylbenzenesulfonic acid)(pSSS). A volume of 10 mL acetone was added to
the volume of initial solution and allowed to become transparent before
adding and dissolving in the solution a quantity of 0.2 g of the
photoinitiator benzophenone to provide a hydrophilicitizing mixture. The
surface of a sheet of microporous poly(ethylene)(TARGRAY™ wet process
polyethylene separators, item no. SW320H (Targray, Kirkland QC, Canada))
dimensioned (13.5 cm x 18.5 cm) to fit the filter assembly (Sterlitech
Corp.) was contacted with the hydrophilicitizing mixture and irradiated
with ultraviolet (UV) light (broad spectrum centred on 320 nm) for a period
of time of 2 minutes. The irradiated contacted sheets were then washed with
cold tap water before being placed in a water bath maintained at a
temperature of 45 to 50°C for a time of about 5 minutes. The washed sheets
were then air dried before testing or use in the preparation of an
asymmetric composite membrane.
EXAMPLE 4
The method of preparation described in Example 3 was repeated with the
volume of initial solution containing 1.7 g of poly(4-
ethenylbenzenesulfonic acid). This quantity of the polymer was close to the
maximum that could be dissolved in the solvent system used.
EXAMPLE 5
A one step method of preparation including the monomer 4-
ethenylbenzenesulfonic acid was evaluated.
A volume of 3 mL of the working solution obtained according to Example 1
was mixed with a volume of 8 mL of distilled water and a quantity of 0.6 g
of the monomer 4-ethenylbenzenesulfonic acid in a vial to provide a volume
of initial solution containing 0.6 g of poly(4-ethenylbenzenesulfonic
acid). A volume of 10 mL acetone was added to the volume of this initial
solution and allowed to become transparent before adding a quantity of 0.4
g of the photoinitiator benzophenone to provide a hydrophilicitizing
mixture.
The surface of a sheet of microporous poly(ethylene)(TARGRAY™ wet process
polyethylene separators, item no. SW320H (Targray, Kirkland QC, Canada))
dimensioned (13.5 cm x 18.5 cm) to fit the filter assembly (Sterlitech
Corp.) was contacted with the hydrophilicitizing mixture and irradiated
with UV light (broad spectrum centred on 350 nm) for a period of time of 2
minutes before being washed with cold tap water and placed in a water bath
maintained at a temperature of 45 to 50°C for about 5 minutes and then air
dried.
EXAMPLE 6
A two-step method of preparation using only the monomer 4-
ethenylbenzenesulfonic acid in the first of the two steps was evaluated.
In the first step a volume of 10 mL of distilled water followed by a volume
of 10 mL of acetone was added to a foil wrapped vial containing a quantity
of 2.4 g of the monomer and a quantity of 0.4 g of the photoinitiator
benzophenone and the mixture shaken until all solids had dissolved. The
surface of a sheet of microporous poly(ethylene)(TARGRAY™ wet process
polyethylene separators, item no. SW320H (Targray, Kirkland QC, Canada))
dimensioned (13.5 cm x 18.5 cm) to fit the filter assembly of a test rig
(Sterlitech Corp.) was contacted with the mixture and irradiated with
ultraviolet (UV) light (broad spectrum centred on 350 nm) before washing
with cold tap water and placing in a water bath maintained at a temperature
of 45 to 50°C for a time of 5 minutes before being air dried.
In the second step a volume of 6 mL of the working solution obtained
according to Example 1 was mixed with a volume of 5 mL of distilled water
in a vial to provide a volume of initial solution containing 1.2 g of
poly(4-ethenylbenzenesulfonic acid). A volume of 10 mL acetone was added to
the volume of initial solution and allowed to become transparent before
adding and dissolving in the solution a quantity of 0.2 of the
photoinitiator benzophenone to provide a hydrophilicitizing mixture. The
surface of the air dried sheet obtained according to the first step was
contacted with the hydrophilicitizing mixture and irradiated with UV light
(broad spectrum centered on 350 nm) for a period of time of 2 minutes
before washing with cold tap water and placing in a water bath maintained
at a temperature of 45 to 50°C for a period of time of about 5 minutes and
then air dried.
Observations
Grafting of the preformed poly(4-ethenylbenzenesulfonic acid) onto the
sheet of microporous poly(ethylene) according to the methods of preparation
described in Example 3, Example 4, Example 5 and Example 6 was confirmed by
washing in acetone (solvent for the photoinitiator benzophenone) and water
(solvent for poly(4-ethenylbenzenesulfonic acid)). Four washing protocols
(1, 2, 3 and 4) were adopted and the FTIR spectra recorded for samples of
hydrophilicitized sheets of microporous poly(ethylene) prepared according
to the method described in Example 3 following application of these washing
protocols are presented in Figure 2.
Preparation of asymmetric composite membrane
EXAMPLE 7
A series of preliminary experiments were performed to evaluate methods of
preparing a film of cross-linked poly(ethenol) (xPVA) on a surface. A
solution of the radical initiator sodium persulfate (SPS) was prepared by
adding a quantity of 0.2 g of SPS to a volume consisting of 10 mL deionised
water and 10 mL acetone. The solution of radical initiator was applied onto
the surface of each of three glass plates (Plate 1, Plate 2 and Plate 3).
Plate 2 and Plate 3 were transferred to an oven and dried at a temperature
of 60°C until all solvent had evaporated to leave a thin layer of the
initiator deposited on the surface. Solutions of poly(ethenol) (PVA) were
prepared at a concentration of 1% (w/v) in either dimethyl sulfoxide (DMSO)
or deionised water. The solution of poly(ethenol) (PVA) in DMSO was sprayed
onto the wet surface of Plate 1 and the plate then transferred to an oven
and dried at a temperature of 60°C. The solution of poly(ethenol)(PVA) in
DMSO was also sprayed onto the dry surface of Plate 2 and the plate then
transferred to an oven and dried at a temperature of 60°C. The solution of
poly(ethenol) in deionised water was sprayed onto the dry surface of Plate
3 and the plate then transferred to an oven and dried at a temperature of
60°C. The desired film of cross-linked poly(ethenol) was not formed on
Plate 1. The failure attributed to the presence of acetone causing the
polymer to crash out of solution. The film formed on Plate 2 was too
frangible to be useful as a rejection layer of an asymmetric composite
membrane. A clear, peelable film formed on the surface of Plate 3. The film
was not brittle and this method of preparation was adopted for use in the
preparation of the asymmetric composite membrane.
EXAMPLE 8
A series of preliminary experiments were performed to evaluate methods of
preparing a film of partially cross-linked poly(ethenol) (xPVA) and thereby
control the properties of the rejection layer of the asymmetric composite
membrane. Volumes of 10 mL of a 1% (w/v) solution of poly(ethenol)(PVA) in
deionised water containing a quantity of 0.1 g of SPS were dispensed into
each four vials (Vial 1, Vial 2, Vial 3 and Vial 4). The solution in each
vial was heated to a temperature of 75°C and maintained at this temperature
with stirring until the following observations were made (and the vials
then cooled):
• A yellow solid crashed out of solution (Vial 1; 3 to 4
minutes)
• A cloudy white solution with some precipitation formed (Vial
2, around 3 minutes)
• A cloudy white solution formed (Vial 3; 1.5 to 2 minutes)
• A cloudy solution started to form (Vial 4; 10 to 20 seconds)
The observations are also presented in Figure 3. The method of preparing
partially cross-linked poly(ethenol) according to that formed in Vial 3 was
adapted for use in the preparation of the membrane.
EXAMPLE 9
A volume of 20 mL of the solution of the radical initiator sodium
persulfate (SPS) was prepared according to Example 7. A volume of the
solution of partially cross-linked poly(ethenol) (xPVA) was prepared
according to Example 8 (Vial 3).
The solution of the radical initiator was applied to one surface of a
hydrophilicitized sheet of microporous poly(ethylene) prepared according to
Example 3. The sheet was then placed on a glass plate and transferred to an
oven and dried at a temperature of 60°C. The solution of partially cross-
linked poly(ethenol) was applied to the same surface of the dried sheet and
the sheet then returned to the oven and dried at 60°C. The dried membrane
was then washed with cool water and air dried before evaluation for flux,
total solids and salts rejection with different feed streams (water and
milk).
Evaluation of samples of asymmetric composite membrane
Replicate samples (240818Si, 240818Sii, 240818Siii, 030918Si, 030918Sii,
030918Siii) of membrane prepared according to Example 9 were evaluated. The
results of this evaluation are summarised in Table 1. Following an initial
wetting with 20% (v/v) isopropanol in water, fluxes in the range 7.8 to
.9 litres per square meter per hour (LMH) were obtainable for a feed
stream of water at a pressure of 10 bar. Similar, if not slightly greater
fluxes were obtained for a solution of salts with salt rejection in excess
of 20%. For a feed stream of whole milk, fluxes were reduced but provided
in excess of 50% total solids rejection and well in excess of greater than
99% protein rejection.
Initial Salt Salt Milk Total solids Protein
Sample flux flux rejection flux rejection rejection
(LMH) (LMH) (%) (LMH) (%) (%)
.9 at 11.7 at
240818Si 20.3 - -
bar 10 bar
7.8 at 10 10.7 at
240818Sii 21.3 - -
bar 10 bar
8.9 at 10 10.3 at 4.5 at
240818Siii 28.4 63.0 99.95
bar 10 bar 10 bar
2.1 at 5 1.3 at
030918Si - - - 99.83
bar 10 bar
0.7 at
030918Sii - - - 62.4 99.99
bar
0.6 at
030918Siii - - - 55.7 100.00
bar
Table 1. Evaluation of samples of asymmetric composite membrane prepared
according to Example 9. The sample (240818Siii) demonstrating the highest
salt rejection was also evaluated along with two other samples (030918Sii
and 030918Siii) for total solids and protein rejection with milk as a feed
stream.
One of the samples (030918Sii) was further evaluated for its tolerance to
clean-in-place (CIP) protocols. One of the samples (030918Siii) was also
further evaluated in a pressure series test to see how the flux and protein
rejection were affected. The results of these further evaluations are
summarised in Tables 2 and 3 and Figures 4 and 5.
Number Milk flux Total solids Protein
of CIPs (LMH) rejection (%) rejection (%)
0 0.7 62.4 99.99
1 2.3 55.9 99.94
2 2.0 - 99.94
3 4.7 50.7 99.93
4 5.0 46.3 99.88
5.7 42.0 99.84
5.7 49.0 99.87
Table 2. Flux, total solids and protein rejection of a sample of an
asymmetric composite membrane (030918Sii) prepared according to Example 9
during repeated clean-in-place (CIP) protocols.
Milk flux Protein
Pressure
(LMH) rejection (%)
0 - 99.99
0.6 99.94
3.3 99.94
5.1 99.93
7.1 99.88
Table 3. Pressure series testing (0 to 20 bar) of a sample (030918Siii) of
an asymmetric composite membrane prepared according to Example 9. Flux and
protein rejection with milk as the feed stream were measured.
Although the invention has been described with reference to embodiments or
examples it should be appreciated that variations and modifications may be
made to these embodiments or examples without departing from the scope of
the invention. Where known equivalents exist to specific elements,
features or integers, such equivalents are incorporated as if specifically
referred to in this specification. In particular, variations and
modifications to the embodiments or examples that include elements,
features or integers disclosed in and selected from the referenced
publications are within the scope of the invention unless specifically
disclaimed. The advantages provided by the invention and discussed in the
description may be provided in the alternative or in combination in these
different embodiments of the invention.
INDUSTRIAL APPLICABILITY
A durable asymmetric composite membrane with high levels of protein
rejection whilst maintaining a high flux with feed streams such as whole
milk is provided.
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Claims (9)
1. ) A microporous sheet of polyolefin grafted with a preformed poly(4- ethenyl benzene sulfonic acid).
2. ) The microporous sheet of claim 1 where the polyolefin is poly(ethylene).
3. ) An asymmetric composite membrane comprising a film of partially crosslinked poly(ethenol) adhered to one side of a microporous sheet of polyolefin grafted with a preformed poly(4-ethenyl benzene sulfonic acid).
4. ) The asymmetric composite membrane of claim 3 where the polyolefin is poly(ethylene).
5. ) A method of preparing a hydrophilicitized microporous sheet of polyolefin comprising the steps of: a) Contacting a microporous sheet of polyolefin with a dispersion comprising a preformed poly(4-ethenylbenzenesulfonic acid) in an aqueous solvent to provide a contacted microporous sheet; b) Curing the contacted microporous sheet at a temperature and for a time sufficient for at least a portion of the poly(4- ethenylbenzenesulfonic acid) to be grafted onto the polyolefin substrate to provide a cured microporous sheet; and then c) Washing the cured microporous sheet to provide the hydrophilicitized microporous sheet of polyolefin.
6. ) The method of claim 5 where the polyolefin is is poly(ethylene).
7. ) The method of claim 5 or 6 where the aqueous solvent is acetone-water.
8. ) The method of any one of claims 5 to 7 where the curing the contacted microporous sheet is by irradiating with ultraviolet light in the presence of a photoinitiator.
9. ) A hydrophilicitized microporous sheet of polyolefin prepared according to the method of any one of claims 5 to 8.
Applications Claiming Priority (3)
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AU2018901072A AU2018901072A0 (en) | 2018-03-30 | Modified polymers | |
AU2018901072 | 2018-03-30 | ||
PCT/IB2019/052649 WO2019186518A1 (en) | 2018-03-30 | 2019-04-01 | Asymmetric composite membranes and modified substrates used in their preparation |
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NZ767051B2 true NZ767051B2 (en) | 2022-02-01 |
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