Study on Porous Polymeric Membrane: Formation,Characterization and Performance

Study on Porous Polymeric Membrane:

Formation,Characterization and Performance

著者 上出 健二

journal or

publication title

博士学位論文要旨 論文内容の要旨および論文審査 結果の要旨／金沢大学大学院自然科学研究科

number 平成2年6月

page range 155‑161 year 1990‑02‑01

URL http://hdl.handle.net/2297/33170

氏 名 上 出 健 二

学 位 の 種 類 学 位 記 番 号 学位授与の日付 学位授与の要件 学 位 授 与 の 題 目

論 文 審 査 委 員

学 術 博 士 学博乙第8号 平成2年3月25日

論文博士（学位規則第5条第2項）

STUDYONPOROUSPOLYMERICMENBRANE

（高分子多孔膜に関する研究）

‑Fonnation,CharacterizationandPerformance‑

（−膜形成，キャラクタリゼーシヨン機能一）

( 主 査 ） 須 賀 操 平 ( 副 査 ） 石 田 真 一 郎 ( 副 査 ） 中 島 正 ( 副 査 ） 中 本 義 章 ( 副 査 ） 長 田 勇

学 位 論 文 要 旨

Recently,polymermembraneareattractingakeenattentionasprecisemedia ofseparatingmaterials.Theseparationofmaterialsbymeansofpolymermem‑

branescanbereadilycarriedoutwithoutanyphasechangeatroomtemperature usingacompactapparatus,whichcanbeoperatedwitharelativelysmall amountofenergyconsumptionascomparedwithotherconventionalmethods.

Amongnumerousmethodsproposedhithertoforforpreparationofpolymeric membranethesolventcastmethodisamethodofvasttechnologicalimportance, becausethismethodisoverwhelminglythemostpopularizedone,whichenables ustoproducemembranewithawiderangeofmeanporesize.

Figurelshowscorrelationshipsbetweencastingconditionsandperformanceof membranespreparedbythesolventcastingmethod.Itishighlyexpectedthat theperformanceofamembraneispredominantlygovernedbyporecharacteris‑

ticsandsupermolecularstructures,whichareformedthroughphaseseparation phenomenaofcastingsolutions,andthephaseseparationisunquestionably controlledbythecastingconditions.Then,therewillbestrongandlinearrela‑

tions:castingconditions=poreorstructurefOrmation=poreandsuper‑

molecularcharacteristics=performanceofmembrane.Ifwecouldestablished

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theserelationsveryquantitatively,wecoulddesignandproduceeffectivelymem‑

branewithdesiredperformances.

a) ^{− −}

「ー一・一ーー.､‑.‑ー一一一一−−．−．ーーー..１１１１ 一一一ー一一一−ｌｌＩＩ1 CasCing

Conditlon

P◎rcF｡〜虫rl◎n

byPhaseSePa茜■上1．、

b) PoreCharacEcrAst1cs

⑥gP⑥r◎uユHEmbrane

Perfomanごe

､ビHe画brane

L−−−−−‑一−‑.−二一一一一−．．−−−−−−−.̲」

Fig.1CoITelationsbetweencastingconditionandperformance.

Theanotherstartedhisresearchonsyntheticmembraneinmidl960's,paying systematicefforts(1)togetabetterandquntitativeunderstandingofthetheo‑

reticalbackgroundofporefonnation,(2)todevelopetechniquesforporechar‑

acterizationofthepolymermembranes,especiallyhavingthemeanporesizeof lO〜102nm,whicharewidelyusedasconnnerciallyavailableseparationmedia ofultrafiltrationandmicrofiltrationprocess,and(3)tostudytheseparationof gasmixtureandliquidmixturesbyporouspolymericmembraneonmolecular basis,includingitsapplicationtomedicalfieldasartificialkidney.

Themembraneformationinthecastingprocesswasshowntobeexplainedas thephaseseparationphennomenaofpolymersolutionsandthemorphology,in

Primdry 毒amry

蓼

灘

ｒ︲ｎ夕碓︑〃

ｖＪｕグー勿尉

ク

錫 ^汐汐汐

〃

〃

〃

Fig.2Schematicrepresentationoftheformationofporesofinthecastingprocess.

咽囲

oEMembrane

Casting

Condition

particular,shapeofpore,isgovernedbytherelativedifferencebetweenthepoly‑

merconcentrationatmembraneformingstepvpoandthecriticalsolutionconcen‑

tratiOnVpc(Fig.2):IfVpo<Vpc,thePOreiSnOnCirCUlarandifVpo>Vpc,thePOreiS circular.Intheformercase,theparticle(i.e.,apolymer.richphase)growth conceptwasproposed:Nucleationandgrowthofnucleitotheprimaryparticles andtheiramalgamationtoyieldthesecondaryparticleswithalmostthesame radius.Formationofporesbycontactofthesecondaryparticles.Thetheory wasconfirmedwiththeexperiments.Theporecharacteristicswasdemonstrat‑

edtobecontrolledbytheradiusofthesecondaryparticlesS2andthetwophase volumeratioR.

logN(7)=log2M[S22(1+r)]+log{γ−{1‑(I/ps/pp)113}S2]

+["S2‑1+(1/Ps",)'/3]21og[r/(1+r)] (1)

TheporesizedistributionN(r)(r,theradiusofpore)isgivenbyeq(1)．Here Nistheporedensity,x=N､/N(N､,totalnumberofparticleperunitsurface), V,polymervolumefractionofthepolymer‑richphase,psandpp,thedensityof thepolymer.richphaseandthepolymer.

Inthisway,nowwecandesignthecastingconditionsgivingmembranewith desiredporecharateristics(Chapter2).

Inceahter3,itwasdemonstratedforregeneratedcellulosemembranefrom cellulosecuprammonium‑acetonesolutionandcelluloseacetatemambranethe existenceofmulti‑layerstructuresinthemembranesmadebythesolvent‑casting method.Forthispurpose,atechniqueforevaluatingtheporeradius(r)distri‑

butionN(r)ofthehypotheticalinnerlayersofthemembranesparalleltoand apartfromthesurfacewasdeveloped.Themorphologicalchangewiththe thicknessdirection,asobservedbyelectronmicroscopywasreasonablyex‑

plainedforthesemembranesbychangeinthepolymerconcentrationwiththe thicknessdirection.

ArigoroustheoryofestimatingtheporesizedistributionN(r)ofstraight‑

throughcylindricallyandtruncated‑conicallyporousmembranefrommercury intrusion(MI),bubblepressure‑fluidpermeability(BP),ultrafiltration‑

permselectivity(UP)andgaspelmeability(GP)methodswereproposed.The physicalmeaningsofthevariousmeanporesize,determinedbyMI,nowrate, GP,UPandsurfaceareamethods,wereclarifiedfortheabovemembranes.

ExperimentalapparatusforMI,BP,UP,andGPweredesignedandconstructed.

Electronmicrographic(EM)methodwasalsoproposedwiththehelpofster‑

eologyforestimatingtheporecharacteristicsofporouspolymericmembrane havingtheporediameterlargerthanlOnmandthismethodwasmodifiedfor

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hollowfibermembrane(i.e.,aslantslicedthinsectional(ASTS)method).N(r) evaluatedbyvariousmethodswerecomparedfOrapolycarbonatemembranes withstraight‑throughporesandcelluloseacetatemembranes.

ThemeanporeradiievaluatedbyVariousmethodsweresuccessfUllycompar‑

ed.Atheorybasedontheparticlegrowthconceptwaspresentedtoestimate theprobabilitiesoffindingisolated(Pi),semi‑open(Ps)andthrough(Pf)pores intheporouspolymericmembranes,whicharecomposedofsmallparticles(Fig.

3).ThetheoreticalrelationsbetweenP,,Ps,P#andthestructuralparameters werederivedanditbecamepossibletoestimateP,,Ps,P!fromtheporosity(Pr)

data

J ￨ i

−4弓一2S2

Fig.3Schemaofamembranestructurecomposedofsecondary(O)andvacant (O)particles:i,sandtstandforisolated‑,semi‑open‑andthrough‑

pores,respecttively.

Chapter4dealswiththeporouspolymericmembranesaseffectiveseparation mediaforgasmixturesandliquidmixtures.Atheoryofgaspermeation throughporouspolymericmembraneswiththemeanporelargerthanlOnmwas presented，Inthetheory,inadditiontodissolution/diffusion(D)now,viscous (H)flow,slip(Sp)now,freemolecular(F)nowandsurfacediffusion(S)flow, proposedsofarindependentlyforthreedimensionalporousmedia,aconceptof anewflow(VFnow)wasintroduced:Itwasshownexperimentallythatina singleporeHflowandFflowdonotappearintheparallelcombination,butin agivenporeVnowiscombinedwithFnowinseriescombinationandinthis casetheoverallflowforthegivenholeisdefinedasVFflow(Fig.4).The theorycouldexplaintheappearanceofaminimuminthepenneabilitycoeffi‑

CientP(P!,P2)VS.aVeragePreS‑0 sureP(=(PI+P2)/2)plots

obtainedinl930sbyAzumiongas

flowinaglasscapillary.Thethe‑'く oryforasingleholewasgenerall‑

izedtomembranewiththeporesize d

0 入 I 〃 ‐ 入 氾 distributionandgasnowthrough

r

membranewasclassifiedintosix

Fi9.4Gaspenneationmechanisms:AｪTows categolies,dependingontherelative

indicatethenowdirection.

magnitudeofthemaximumandmini‑

mumporesizesandthemeanfree pathAatinletandoutletofthepore.

Theexperimentaldataongaspermeationthroughvariousmembraneswith straight‑throughporeswereanalyzedbasedonthetheory.

Theauthorobservedthesignificantdifferencebetweenmeasuredandcalcu‑

latedgaspermeabilitycoefficientsP(P,,P2)forpolymericmembranedominat‑

edbyfreemolecularflow(Fig.5).Inordertoexplainthisdifference,thesur‑

facediffusionflowwastakenintoaccountandequationforP(P,,P2)inthe caseFandSnowoccurconcurrentlywasderivedforaporousmembranehav‑

ingawideporesizedistribution,assumingthatthetotalgasfluxisthesumof thenuxesthroughtheindividualpores・ThecalculatedvaluesofP(P,,P2)for apolycarbonatemembranehavingstraight‑throughporesagreedwiththeexperi‑

mentalvalues.

ｓロ匡実Ｌｑ０Ｓｇ＆ 0

m111rppdn!(･C)

Fig.5Boilingpointdependenceof(P(0,0)‑P,,)/P(0,0)ofpolycafbonatemem. braneNuO.03forvariousgases:

P(0,0)="_P8.132→Olim̲P(P1,P2);PF,permeability

coefficientoffreemolecularnow;O,oIganicgas;O,moxganicgas.

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錘篭程

ｑＧＣ−■口の■甲ｒヰーデや◇ず雷雨︑哩一︒︑鮭澪賛ぃ一

●●︒●●今寺・・拳奉雲琵蚕蕊一議蕊 ・町ｇＧｇ●■０■函４−．︲ＧｊＣ必鈩︐︒．００︒︒︒︒︒．●募瑚●品︑●妬・神鰯斗織聯幟榊識糊一︒．・・・・謬・・蕊粥・謂領塊早︑Ｇ壇■・■６︒●■●●毎参・・認識鍵鍵

■烏屯将叩︑拍銘︒鐸琿矛牛・︾．︒零

Agenraltheoryforexplainingtheseparationofparticlesinsolutionby ultrafiltrationwithapolymericmembrane(inthecaseofparallelfiltration)was proposedasanextensionofFerry'sandRenkins'stheories.Innewtheory,four factorswereconsidered:(1)thesievingeffectduetocollisionbetweenparticles inthefiltrandwiththeporewallortheporeedgeofthemembrane(thesteric factor),(2)viscousinteractionbetweentheparticleandtheporewall(thevis‑

cousfactor),(3)thehydrodynamiceffectontheparticle(thefractionationfac‑

tor),and(4)intermolecularforcesbetweentheparticleandthemembrane(the intennolecularfactor).Notethat(1)onlywasconsideredinFerTy'stheory, and(1)and(2)weretakenintoaccountinRebkins'theory・TheratioW.(a)of theparticleconcentrationinthefiltratetothatofthefiltrand(a,radiusofparti‑ cle)isexpressedasafUnctionofparticlesize,filtrationconditionsincludingthe flowrate(shearrate)ofthefiltrand,andthemolecularcharacteristics(N(r) andporosity)．Thevalidityoftheproposedtheorywasconfirmedbytheexper‑

iment.

Asanexampleofhigh‑gradeapplicationofliquidseparationbymembraneto medicalfield,afiltration.typeartificialkidney(AK)usingporouspolymeric membranewasstudiedinaverysystematicwayinordertodiscloseitsfUnda‑

mentalfunctionsaskidney(Chapter5).Ultrafiltration‑typeartificialkidney (UAK)wasstudiedusingporouscelluloseacetatemembrane.Inourfiltration‑

typeAk,itwasconfirmedthat(1)notraceinthemembranedissolvesinthe

blood,(2)optimumporesizeliesbetweenO.06〜0.1"m(60〜100nm),(3)any pyrogenicmaterialsarenotcontaminatedwiththemembreneand(4)theblood

III)Akweredesignedandconstructedandusedforin.vitroexamination.The threeunsolvedproblemsremainedwerealsodiscussed.Atheorywasproposed forevaluatingtheultrafiltrationvolume(UFV)duringtimet(v'(t))invivoof AKfiPomthedataofthehematocritinvitroH｡andUFVinvitro(v(t))andthe hematocritinvivoH6,undertheconditions:thepressuredifferenceinvitro4P

=thatinvivo4P'andthefiltrationareainvitroS=thatinvivoS′・The experimentsverifiedtheusefulnessofthemethodproposed.

ThemarginalabilitywasestimatedonaultrafiltrationtypeAK(MarkII).

MarkllhavingeffectivefiltrationareaoflOOcm2showed40%inultrafiltration rateofwaterandonly4.3%inuricacidexcretionascomparedwithahuman kidney・Markllhadtosomeextentpermselectivitywithrespecttomolecular sizeandthiskindofpennselectivitycanbeexplainedbytheflowfr･actionation hypothesis.Asphysiologysuggests,theonlyremedytothisunavoidablein‑

balanceofexclusionofwaterandthewastematerials,observedinMarkll,is additionofotherfunctionalitytosimpleultrafiltration‑typeAK(i.e.,multi‑

functionalAK).

論文審査の結果の要旨

当該学位論文について，平成元年12月5日に第1回審査委員会を，また12月18日に口 頭発表会および第2回審査委員会を開催して次の審査結果を得た。

近年高分子多孔膜は，エネルギー消費量が少ない物質分離の精密な媒体として注目を 集めている。多くの高分子膜の製造法の中で，溶媒キャスト法は広範囲の孔径の膜を作 成できる点で重要であるにも関わらず，研究が少なかった。本論文ではこの点に着目し，

(1)孔形成の理論的基礎,(2)高分子膜の孔の特性化,(3)これらの膜の医療分野への高度利 用化，特に人工腎臓膜の試作などの研究を広範囲に行った。

この結果，高分子多孔膜の膜形成から孔構造の評価法，気体や液体の膜分離及び人工 腎臓に至るまで系統的に研究し，粒子成長膜の多層構造,VFながれ,分別因子，ろ過型 人工腎臓など多くの新しい概念や理論を提案した。これらの多くは現在定説となりつつ ある。

以上の結果は理論的にも優れた論文であり，また実用の腎臓透析膜の高性能化に寄与 したもので，工業的にも価値が高く，博士論文に値すると判定する。

以上を総合して，申請者上出健二氏は学術博士の学位を受ける資格を有すると判定す

る。

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