polymer concentration and solvent variation correlation ... · scanning electron microscopy. e...

Research ArticlePolymer Concentration and Solvent Variation Correlationwith the Morphology and Water Filtration Analysis of PolyetherSulfone Microfiltration Membrane

Muhammad Azeem U R Alvi1 Muhammad Waqas Khalid1 Nasir M Ahmad 2

Muhammad Bilal K Niazi2 Muhammad Nabeel Anwar1 Mehwish Batool3

Waqas Cheema2 and Sikandar Rafiq 4

1School of Mechanical and Manufacturing Engineering Department of Biomedical Engineering and SciencesNational University Of Sciences and Technology Islamabad 44000 Pakistan2School of Chemical and Materials Engineering National University of Sciences and Technology Islamabad 44000 Pakistan3Department of Chemical Engineering COMSATS University Islamabad Lahore Campus 54000 Pakistan4Department of Chemical Polymer amp Composite Material Engineering University of Engineering amp TechnologyKala Shah Kaku Campus Pakistan

Correspondence should be addressed to Nasir M Ahmad nasirahmadscmenustedupk

Received 13 November 2018 Revised 22 January 2019 Accepted 28 January 2019 Published 3 March 2019

Academic Editor Haiqing Lin

Copyright copy 2019 Muhammad Azeem U R Alvi et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Microfiltration flat sheetmembranes of polyether sulfone (PES)were fabricated by incorporating varying concentrations of polymerand investigated the influence of substituting solvents The membranes were prepared via immersion precipitation methodDifferent solvents that included NMP (N-methyl-2-pyrrolidone) DMF (dimethylformamide) and THF (tetrahydrofuran) wereused to analyse their effect on the performance and morphology of the prepared membranes Two different coagulation bathtemperatures were used to investigate the kinetics of membrane formation and subsequent effect on membrane performanceThe maximum water flux of 141 mlcm2h was observed using 21 of PES concentration in NMP + THF cosolvent system Thehighest tensile strength of 2915 MPa was observed using membrane prepared with 21 PES concentration in NMP as solvent andcoagulation bath temperature of 25∘CThe highest hydraulic membrane resistance was reported for membrane prepared with 21PES concentration in NMP as solvent Moreover the lowest contact angle of 67∘ was observed for membrane prepared with 15 ofPES concentration in NMP as solvent with coagulation bath temperature of 28∘C Furthermore the Hansen solubility parameterwas used to study the effect on the thermodynamics of membrane formation and found to be in good correlation with experimentalobservation and approach in the present work

1 Introduction

Drinkable water resources are declining every year leadingto exploring viable options for water reusability to treatand purify it [1] Membrane technology is extensively usedworldwide among various techniques to purify water [2]Microfiltration membranes are considered economical forwater treatment to reduce themicrobial and colloidal sourcesin water [3] These membranes are pressure driven mem-branes and can also be used as pretreatment for reverse

osmosis and nanofiltration water purification processes [1 3]Microfiltration membranes typically have a pore size rangingfrom 01 to 10 120583m in size These membranes are able toseparate out bacteria and suspended particles [4] as well asmacromolecules with a molecular weight less than 100000gmole [5]

For the preparation of microfiltration membranes dif-ferent polymers are used commercially such as polyvinyli-dene fluoride polyvinyl alcohol chitosan polyvinyl chlo-ride polyacrylonitrile polypropylene polyvinyl alcohol

HindawiAdvances in Polymer TechnologyVolume 2019 Article ID 8074626 11 pageshttpsdoiorg10115520198074626

2 Advances in Polymer Technology

polyimide cellulose acetate and polyether sulfone (PES) [6]All these polymers are used for their various characteris-tics For a specific polymer to be useful it must possessvarious characteristics such as excellent high heat agingresistance good mechanical properties and environmentdurability [7] Polyethersulfone (PES) is one of the mostcommonly used polymers for fabrication of microfiltrationmembrane PES is an amorphous thermoplastic polymerand has the highest number of moieties in the polymerrepeating unit in the sulfone group Hence the PES isthe most hydrophilic in the sulfone group polymers [8]Moreover PES has high mechanical strength stability at pHfrom 2 to 13 and chemical resistance which makes it quitesuitable to be used as membrane material [9 10] PES issoluble in aprotic polar solvents such as dimethylformamide(DMF) N-Methyl-2-pyrrolidone (NMP) etc Furthermoretetrahydrofuran (THF) [11] is borderline aprotic polar sol-vent and used as a cosolvent with NMP as main solvent[12]

An important advantage of asymmetric membranes is adense skin layer with porous substructure Skin layer offersselectivity and permeability whereas the sublayer providesmechanical strength Asymmetric polymeric membranesformed by immersion precipitation method are based onliquid-liquid phase separation [13ndash17] It has been sug-gested that gelation is responsible for the formation of skinFurthermore porous sublayer is formed by liquid-liquidphase separation by growth and nucleation [13 15 18ndash22] Thermodynamics and kinetics of membrane formationplays vital role in the morphology and performance ofmembranes [23] Thermodynamics of membrane formationcan be studied by Hansen solubility parameters (HSP)[24] Thermodynamics require that the free energy of mix-ing must be zero or negative for the solution process tooccur at the same time The membrane formation dependson both solvent-nonsolvent and polymer-solvent demixing[25]

The kinetics of membrane formation can be controlledby temperature of coagulation bath [24] The parameterssuch as polymer concentration [26] solvent [27] coagu-lation bath [28] conditions for preparation [29] polymersolution temperature air moisture and evaporation timebefore the wet phase have significant impact on the mor-phology and properties of the prepared membranes [30]A change in one or more parameter leads to a change inthe properties of the membrane as discussed elsewhere [31ndash33]

In consideration of the above the present work is focusedon the investigation of effect of polymer concentration vari-ation and different solvents substitution in the dope solutionused for the performance of flat sheet microfiltration mem-branes The structure and properties such as tensile strengthflux contact angle and membrane hydraulic resistance ofprepared membranes are analysed and correlated with thecomposition and concentration of polymer solution More-over the Hansen solubility correlated parameters were usedto study the thermodynamics and kinetics of the membraneformation

2 Materials and Methods

21 Materials Polyethersulfone NMP DMF and THF werepurchased from Sigma Aldrich All the chemicals were usedwithout further purification Deionized water was used in thefabrication of membranes

22 Preparation of Membranes The flat sheet membraneswere prepared by phase inversion method using castingmachine Five different formulations were prepared as shownin Table 1 PES was dissolved in respective solvent and stirredfor 24 hoursTheprepared solutionswere casted at room tem-perature (23∘C) on nonwoven polypropylenepolyethylenefabric Novatexx 2471 (Freudenberg Germany) placed ona glass plate Solvent was applied on the support materialbefore casting the polymer solution on the support material[35] Casting was done by casting machine Then the castedfilm was immersed in coagulation bath (25∘C and 28∘C) for5 mins to let the demixing complete After the formationof membranes these were dried under ambient conditionsand kept for characterization testing [36 37] The graphicalabstract is shown in Figure 1

23 Membrane Hydraulic Resistance (MHR) The MHR isthe resistance of membrane to the feed flow MHR is theindication of tolerance of membrane towards pressure andwas calculated by [38]

119877119898 =119875119869119882

(1)

where119877119898 is themembrane resistance (KPaml-1cm2h1)119875 isthe transmembrane pressure (KPa) and 119869119882 is the water flux(ml cm-2h-1)

24 Fourier Transform Infrared Spectroscopy (FTIR) BrukerAlpha ATR spectrometer was used for IR characterizationof the membranes FTIR was carried out to investigate thechange in functional groups of formulated membranes usingdifferent solvents and variations in polymer concentrationAll the samples were tested in their natural state using ATRThe samples were cut into 1 x 05 cm in dimension and placedon the IR window

25 Contact Angle Analysis The contact angle was measuredby sessile drop measurement technique to determine theextent of hydrophilicity or hydrophobicity of the formulatedmembranes Typically 5120583L drop of distilled water was placedon the surface with a needle tip A magnified image of thedrop was then taken with a digital camera static contactangle of the droplet was calculated using ImageJ LBADSA(Low-Bond Axisymmetric Drop Shape Analysis) software indegrees The reported data was average of four determina-tions at different points on the prepared membrane and thenmean and standard deviation were calculated

26 Mechanical Testing Mechanical testing was carried outfor the preparedmembranes according to the standardASTM

Advances in Polymer Technology 3

Table 1 Composition of prepared membranes

Serial No Membrane Codes Polyether sulfone Concentration (Wt ) Solvents1 M1 15 NMP2 M2 18 NMP3 M3 21 NMP4 MS-1 21 DMF5 MS-2 21 70 NMP 30 THF

PES

+

O

S

n

NN

Dimethylformamide N-Methyl-2-pyrrolidoneO

O

O

O

O

Tetrahydrofuran

Hansen SolubilityParameters

PolymerSolution

Contact Angle

SEM

Filtration

Figure 1 Graphical abstract

D882 The tensile properties of the membranes were deter-mined using Trapezium-X Universal testing machine (AG-20KNXD Plus Shimadzu corporation Japan)Themaximumload limit was 20kNThe strain rate was 3mmsec The gaugelength of the samples was 2 cm while the total sample lengthwas 7 cm The width of the samples was 11 cm and thicknesswas 003 cm

All the samples were tested at room temperature Themechanical testing was performed to evaluate the effect ofpolymer concentration increment and solvent variation onthe prepared membranes

27 Scanning Electron Microscopy The topographical andcross-sectional morphologies of membranes were studied byscanning electron microscopy (JOEL JSM-6490A Analyticalscanning electron microscope Japan) Membranes were cutinto 025cm2 samples For cross-sectional morphology thesewere immersed in liquid nitrogen for approximately 60seconds to freeze After freezing themembranes were brokeninto smaller fragments to perform SEM of cross sectionThe samples were gold coated using JFC-1500 Ion sputteringunit

28 Pure Water Flux Filtration cell was used to test thepermeation characteristics of the fabricated membranes atdifferent pressures of 2666 3999 5332 6666 and 7999 kPafor determination of water flux For this purpose filtrationequipment was attached to a vacuum pump with adjustablepressure gauge to obtain desirable pressure to permeate thewater through the prepared porous membranes For eachexperiment 20 ml of water was taken in the fritted glassfunnel and then pressure was applied by the vacuum pumpto permeate the water through the membrane placed on glasssupport base Flux was calculated using the equation

119869 = 119907119886119905 (2)

where v is the volume of water a is the effective membranearea and t is the permeation time

29 Hansen Solubility Parameter (HSP) HSP is valuable inexplaining the influence of parameters such as polymersolvents and nonsolvent on membrane preparation Thethermodynamics and kinetics of the membrane fabricationmust be considered to explain the fabrication process and itsrelation to themembrane performanceThe thermodynamics


mainly depend on the chemical potential of the processparameters [39] Therefore the HSP can be an importanttool to discuss their influence on the membrane structureformation [40] The solubility parameter of polymer andsolvent by Hansen solubility parameter can be defined as

120575t = radic120575d2 + 120575p2 + 120575h2 (3)

where 120575119905 is Hansen solubility parameter 120575119889 is energy from thedispersion bonds 120575119901is energy from dipolar intermolecularforces and 120575ℎ is the energy from the hydrogen bonds

The polymer solvent interaction can be defined as

120575119901minus119904

= radic((120575119863119875 minus 120575119863119878)2 + (120575119875119875 minus 120575119875119878)2 + (120575119867119875 minus 120575119867119878)2(4)

Polymer and nonsolvent interaction is given by

120575119875minus119873119878

= radic(120575119863119875 minus 120575119863119873119878)2 + (120575119875119875 minus 120575119875119873119878)2 + (120575119867119875 minus 120575119867119873119878)2(5)

Solvent and nonsolvent is given by

120575119878minus119873119878


The calculations based on these relations can be used topredict and understand the membrane structure formation[41] The Hansen solubility parameter values of polymersolvent nonsolvent and their interaction with each other aregiven in Table 2

Fractional parameters were derived from the Hansenparameters using the equations

119891119889 =120575119863

(120575119863 + 120575119875 + 120575119867)(7)

119891119901 =120575119875

(120575119863 + 120575119875 + 120575119867)(8)

119891ℎ =120575119867

(120575119863 + 120575119875 + 120575119867)(9)

The sum of three fractional parameters remains equal to 1

119891119889 + 119891119901 + 119891ℎ = 1 0 (10)

3 Results and Discussion

31 Fourier Transform Infrared Spectroscopy The ATR-FTIRspectra of the formulated membranes are shown in Figure 2The strong peak of C6H6 benzene ring stretch at 1587 cm-1 isthe aromatic band of polyethersulfone [42]The sharp peak at1147 cm-1 is due to S=O group symmetric stretching vibration

[43] The peak at 1476 cm-1 is the representative band of C-S stretch [44] The peak around 1240 cm-1 is due to C=Cstretching [45]TheM1 M2 andM3membranes have shownno effect on FTIR spectra There is a difference in the spectraof membranes with solvent variation ie MS-1 and MS-2

Figure 2(b) has the spectra of polyethersulfonewithNMPDMF and cosolvent system of NMP+THF The shift at 2931cm-1 is due to symmetric methyl C-H bond stretching inmembrane with DMF [46] It is attributed to the presence ofresidual solvent [47] While the peaks in the region of 2839and 2931 cm-1 of membranes with cosolvent system are dueto the presence of C-H stretching vibrations of THF [48]

32 Morphological Analyses Scanning Electron Microscopy(SEM) was used to understand the effect of variability inpolymer and solvent substitution on the morphology of theprepared membranes Figure 3 represent the cross-sectionaland surface images of the membranes In membranes pre-pared with PES variation a marked difference between thestructures was observed The M1 membrane was found tobe more porous than M2 and M3 formulated membranesSimilarly the M1 membrane appeared to have thin structureswith cross-sectional length of 14898 120583m The support layerappears to be thinner than the others This can be attributedto the temperature of coagulation bath whereas a thickstructure of the membrane was observed in M3 membraneafter change in the thermodynamics of casting solution andcoagulation bath temperature

Similarly a change in structure was recorded when themembranes were prepared with solvent substitution In MS-1 membrane macrovoids were observed in the cross sectionThe underlying structure of the membrane can be attributedto high demixing rate of DMF [38 49] In MS-2 formulatedmembrane the active layer structure was found to be large Apersistent increase in flux rate was observed with increasingpressure for this membrane [50] In Figure 3(a) the structureof the membrane appears to be thin whereas in Figures 3(b)and 3(c) the thickness of the prepared membranes appears toincrease with increase in polymer concentrationThe surfaceimages of the membranes appear to be rough

33 Contact Angle Analysis The contact angle of the fab-ricated membranes was analysed using Low-Bond Axisym-metric Drop Shape Analysis (LBADSA) of surface contactangle of sessile drop based on Young-Laplace equation TheLBADSA offers first-order approximation solution to theYoung-Laplace equationThismethodwas used as a plugin onImageJ software [51] The capillary forces were the only driv-ing force for the small droplet Drop-base diameter definedthe spatial resolution of the sessile drop measurement

Figure 4 represents the contact angle of the fabricatedmembranes It was observed that with the membranes pre-pared by changing the concentration of polymer (M1 M2and M3 membranes) the surface became more hydrophobicas the concentration of polymer increased [52] This canbe attributed to the fact that the hydrophilicity of theformulatedmembrane depends on the pore size and porosityThe flux results clearly indicate the trend of hydrophilicity


Table 2 Hansen solubility parameter values of polymer solvent nonsolvent and their interaction [34]

S P NSDispersionParameter

(120575d) (MPa)05

PolarParameter

(120575p)(MPa)05

HydrogenBondingParameter

(120575h)(MPa)05

TotalSolubilityParameter(120575T)

(MPa)05

Polymer SolventInteraction(120575P-S)(MPa)05

Polymer-Non-SolventInteraction(120575P-NS)(MPa)05

Solvent-Non-Solvent

Interaction(120575S-NS)(MPa)05

NMP 180 123 72 229 296 - 3537DMF 174 137 113 248 420 - 3113THF 168 57 80 194 594 - 3583NMP +THF 2185 268 3538PES 196 108 92 2419 - - -WATER 156 160 423 478 - 3374 -

T

rans

mitt

ance

M3

M2

M1

3500 3000 2500 2000 1500 1000 500

Wavenumber (Cm-1)

C=C Stretch

S=Ostrectching

6（6 ring stretch

(a)

T

rans

mitt

ance

MS-2

MS-1

M3

C-H Stretching

C-H Stretch

3500

0

3000 2500 2000 1500 1000 500

Wavenumber (Cm-1)

(b)

Figure 2 ATR-FTIR spectra of membranes prepared by (a) polymer concentration variation and (b) membranes prepared by solventvariation

(a) (b) (c) (d)

(e)

microvoid

(f) (g)

Figure 3 SEM Images (a) M1 cross-sectional (b) M2 (c) M3 cross-sectional (d) M1 Surface (e) M3 Surface (f) MS-1 and (g) MS-2


M1 M2 M3 MS-1 MS-20

20

40

60

80

100

Con

tact

Ang

le (D

egre

es)

Membranes

Figure 4 Contact angle of formulated membranes analysed byImageJ Error bars represent standard deviation and five measure-ments were recorded for contact angle

M1M2M3

MS-1MS-2

30000 40000 50000 60000 70000 8000020000Transmembrane Pressure (Pa)

0

20

40

60

80

100

120

140

Wat

er F

lux

(mL

cm 2 h)

Figure 5 Water flux of membranes prepared by polymer concen-tration variation and solvent variation

in the formulated membranes [45] whereas the contactangle was observed to decrease with change of solvents informulated membranes (MS-1 and MS-2) as compared toM1 formulated membrane This can be explained by Hansensolubility parameters such as faster demixing rate in MS-1 which resulted in porous structure hence hydrophilicitywhereas inMS-2 the 120575P-S value dropped to 268MPa12Thisresulted in relatively less thermodynamically stable solutionand better demixing leading to porosity on surface [53]

34Water FluxAnalyses Thewater flux of all themembraneswas measured to determine their water permeability All themembranes were tested for water flux at different pressures

under steady state conditions The water flux has a directrelation to the porosity of the top layer including the numberof pores and their size [54] Figure 5 represents the purewater flux of the formulatedmembranes recorded at differentpressures with at least 4 determinations of each pressure

The M1 membrane had high values of water flux Resultswere supported by SEM analysis as seen in Figure 5 Thesublayer channels were smaller than the membrane withhighest level of PES ie M3 using NMP as solvent Theunderlying channel system aided the flow of water throughthe membrane at a faster rate Moreover the increase ofpressure also influenced the water flux However the per-meability of the membrane also increased due to underlyingmorphology of the membranes

Furthermore the pure water flux reduced with increasein concentration of polymer in prepared membranes It canbe attributed to increase in thickness and formation of denseskin layer with increase in polymer concentration Similarlythe productivity of the formulated membrane for liquidseparation also decreased [55] On the other hand the dilutepolymer solution formed a thin and porous skin layer withincreased values of flux at different pressures as evident fromSEM analyses

By increasing the concentration of polymer the viscosityof the polymer solution increased and the coagulationwas slowed down due to strong interaction of solvent andpolymer Moreover it also resulted in molecules aggregationof polymer because the interaction of polymer and water asnonsolvent was higher As a consequence it decreased thedissolving capacity of polymer for solvent [56] The mem-brane with high polymer concentration and high viscositycan slow down the diffusional exchange rate of NMP andwater in the sublayer structure of themembraneThis resultedin the slowdown of the precipitation rate at the sublayer level[57]

For M1 formulated membrane high flux rate wasobserved in membranes prepared with PES concentrationvariation This may be attributed to decrease in the thicknessof surface during polymer-rich phase [40]

Meanwhile in MS-1 formulated membrane the purewater flux was observed to be higher than the M3 membraneas the top skin of themembranewas even thinner SEM imageanalysis shows similar structureThis can be attributed to thevolatile nature of the THF During dry phase the THF onthe surface of the casted membrane was evaporated formingmore porous structure The MS-1 formulated membrane hadhigherwater flux values then theM3membraneThepresenceof DMF in the cast solution facilitated the formation of poreson themembrane surface After immersion in the nonsolventbath the formation of more porous structure was facilitated[35 40 58 59]

35 Mechanical Strength The tensile strengths of the formu-lated membranes with different concentrations and solventswere investigated Figure 6 represents the tensile strengthelongation at break and modulus of the formulated mem-branes As the concentration of polymer was increased thetensile strength of the membranes also improved This may


M1 M2 M3 MS-1 MS-2

30

20

10

0

Tens

ile S

treng

th (M

Pa)

129

086

043

000

Mod

ulus

(GPa

)

Membranes

64

48

32

16

0

Elon

gatio

n at

Bre

ak (

)

M1 M2 M3 MS-1 MS-2Membranes


Figure 6 Tensile strength elongation at break and modulus of prepared membranes

be due to the increase in the thickness of the top layerby enhancing the concentration of the polymer Meanwhilewith the membrane prepared by DMF as solvent the tensilestrength of the membrane decreased as compared to M3This can be attributed to the decrease in thickness of thetop layer of the membrane due to difference of hydrogenbonding value of 113 MPa12 resulting in faster diffusionrate of solvent into nonsolvent [38] However the tensilestrength increased when NMP+THF was used as a solventin formulated membrane as compared to DMF This can beassociated with miscibility of NMP with water There is areduction in thickness of membrane prepared by DMF andPES This can be explained by the fact that the transport ofNS in the polymer solutionwas slower than transport ofDMFinto water Results showed that the tensile strength is directlyproportional to the concentration of polymer in formulatedmembrane [60] According to Hansen solubility parameterthe solvent-nonsolvent interaction of 120575119863119872119865minus119882119860119879119864119877 is 3113MPa12 which is less than other solvents used The moremiscibility of DMF and nonsolvent allowed rapid demixingand disturbance in the thermodynamics of the stable castedsolution This resulted in formation of thin layer on top sub-sequently decreasing the tensile properties of the membrane[61]

36 Membrane Hydraulic Resistance (MHR) MHR isinversely proportional to the permeate flux of the membraneMHR was observed at five different pressures Figure 7shows the membrane hydraulic resistance of the formulated

0

2

4

2661 3998 5329 666 7997

Mem

bran

e Hyd

raul

ic R

esist

ance

(KPa

ml-1

cm2

h)

Transmembrane Pressure (KPa)

M1M2M3

MS-1MS-2

Figure 7 Membrane hydraulic resistance of prepared membranesmeasured at different pressures

membranes Membrane hydraulic resistance was measuredby the inverse of the slopes of the pure water flux againstpressure linear dependences MHR is used to determinethe intrinsic resistance of formulated membrane against thewater feed The results indicate that the M3 had the highestMHR measured at all the pressures It can be explainedby the fact that the MHR is inversely proportional to theflux and a lowest flux was recorded for M3 membrane at


00 01 02 03 04 05 06 07 08 09 10

00

01

02

03

04

05

06

07

08

09

1000

01

02

03

04

05

06

07

08

09

10

Polar Force fpHyd

roge

n Bon

ding

Forc

e f h

Dispersion Force fd

PES

Water

DMF

THF

NMPNMP+ THF

Figure 8 Teas graph of solubility parameter interaction of polymer solvent and nonsolvent

all the pressures Moreover the reason for low flux rate canbe attributed to the structure of the formulated membraneFor membranes prepared with solvent variation (MS-1 andMS-2) the MS-1 membrane was found to have good intrinsicresistance because of higher values of MHR calculated [38]

37 Correlation with Polymer Concentration Three mem-branes (M1 M2 and M3) were used to observe the influenceof polymer concentration NMP was used as a solvent (S) inthe formulations The pure water flux data of the membraneswas used to evaluate the effect of polymer concentrationon membranes performance [62] The M1 membrane hadthe highest flux values studied at various pressures As thepolymer concentration was increased the top layer of themembrane became less porous as indicated by SEM analysisMoreover the solution became thermodynamically stablewith increase in concentration of PES As a result the phaseseparation slowed down [63]

According to solubility parameter values the affinity ofNMP for nonsolvent (NS) was higher than the affinity ofPES for NS Therefore the difference in affinities resulted inthermodynamic instability and membrane of the type M1resulted in thinner upper surface as evident in SEM analysissubsequently more porous surface

The pore size of themembrane was reduced with increasein polymer concentration This resulted in low water per-meability through membrane The M3 membrane had thelowest pure water flux It can be explained by the fact thatthe phase separation of PES depends on the thermodynamicand kinetic factors of polymer solvent and nonsolvent In thefabrication of M1 and M2 the temperature of coagulant bathwas 28∘C whereasM3membranewas casted at a temperatureof 25∘C It was observed that the coagulant bath temperaturecontrols the S-NS phase of the membrane fabrication The

exchange of S-NS increased at 28∘C as previous findingssupport this temperature variation explanation [64] Thepolymer-solvent interaction value of 296 MPa12 suggestsbetter miscibility leading to delayed demixing of solvent innonsolvent The pores on upper surface of the membranedirectly affect the water permeation across the membrane[24]

38 Correlation with Solvent Variation The solvents vari-ation was investigated and compared with M3 membraneThe concentration of PES was kept constant at 21 TheM3 formulated membrane performance in terms of purewater flux was found to be the lowest among the other twoformulatedmembranesM1 andM2The temperature of waterbath used for all formulatedmembranes in this part was 25∘CIn this study the performance of MS-1 and MS-2 in terms ofpure water flux and contact angle was observed to improve

The kinetics of the phase inversion also influenced thefabrication of membranes and the interaction of solvents andnonsolvent during the wet phase which was the polymerpoor phase while the temperature of coagulation bath hadeffect on rapid and delayed demixing rates as both hadeffects on themorphology of the resultingmembranesWhenthe demixing rate was high the MS-1 membrane with thinskin layer was formed The reason for this can be explainedfrom the 120575S-NS value of 3113 MPa12 This can be attributedto high affinity of DMF towards NS (water) with stronghydrogen bonding parameter whereas the demixing rate wasslower in MS-1 membrane because of high value of 120575S-NSie 3538 MPa12 It is interesting to note that the 120575P-S valuefor cosolvent in MS-2 membrane decreased to 268 MPa12[24] Teas graph in Figure 8 was used to observe the relativepositions of polymer solvents and nonsolvent Teas graphprovides theoretical explanation of the solubility of polymer


solvent and nonsolvent with each other Teas graph translatespolar hydrogen and dispersion components into a two-dimensional graph [34]

4 Conclusions

Polyether sulfone microfiltration membranes were preparedby phase inversion method Moreover morphology andperformance were correlated with polymer and solvent vari-ation from the consideration of Hansen solubility param-eters The temperature of coagulation bath had effects onthe performance and morphology of prepared membranesIn polymer concentration correlation the concentrationincrease was found to have a negative effect with decreasingflux whereas positive effects of tensile strength enhance-ments were observed Moreover in solvent variations cor-relation the different demixing rate of solvents in non-solvent affected the performance of the membranes Theprepared membranes were investigated for their strengthcontact angle water permeability surface chemistry andmorphologyThermodynamics and kinetics of themembraneformation were also discussed For this purpose Hansensolubility parameters for the polymer solvent and nonsol-vent were calculated PES membrane prepared with 21polymer concentration in NMP solvent was observed toundergo relatively less phase separation hence resultingin less pores and less water flux Low concentration of15 PES in NMP resulted in relatively thin membrane butmore pores resulting in higher water permeation across themembrane The contact angle for the membrane preparedwith 15 PES concentration was the lowest while with 21PES concentration in NMP was found to exhibit the highestcontact angle The contact angle of membrane prepared with15 PES concentration in NMP was found to be closerto the membrane prepared with 21 PES in DMF withvalues of 67∘ and 68∘ respectively Moreover the membraneprepared with 21 PES concentration in NMP and THFcosolvent the contact angle was slightly higher than twoabovementioned membranes The water flux of membraneprepared with 21 PES concentration in NMP and THFcosolvent was the highest and in membrane prepared with21 PES concentration in NMP solvent the flux rate wasthe lowest recorded Furthermore the membrane hydraulicresistance of 21 PES concentration in NMP prepared mem-brane was observed to be the highest The tensile strengthof 21 PES concentration in DMF prepared membrane wasthe lowest and surprisingly the tensile strength of 21 PESconcentration in NMP and THF cosolvent was somewhatclosest to the 21 PES concentration in NMP preparedmembrane The results indicated that the membrane pre-pared by solvent mixture of NMP and THF had better waterflux performance and better strength as compared to othermembranes

Data Availability

Thedoc file data used to support the findings of this study areincluded within the article

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

The authors would like to thank School of Chemical andMaterial Engineering School of Mechanical and Manufac-turing Engineering NUST Islamabad and Chemical Engi-neering Department of COMSATS Lahore The authorswould like to thankMr ShamsDin (Late) andMr Zafar Iqbalof SCMENUST for facilitating the SEM analyses and contactanglemeasurements respectivelyThanks are due toDr TahirA Baig and Ms Shakira for allowing measuring pure waterflux in their lab Dr Nasir M Ahmad acknowledges thesupport of Higher Education Commission (HEC) NationalProgram for Universities (NRPU) Project nos 3526 and3620 for supporting the research work

References

[1] B VanDer Bruggen C Vandecasteele T VanGestelW Doyenand R Leysen ldquoA review of pressure-driven membrane pro-cesses in wastewater treatment and drinking water productionrdquoEnvironmental Progress vol 22 pp 46ndash56 2003

[2] S Rana U Nazar J Ali et al ldquoImproved antifouling potentialof polyether sulfone polymeric membrane containing silvernanoparticles self-cleaning membranesrdquo Environmental Tech-nology vol 39 no 11 pp 1413ndash1421 2018

[3] D Vial and G Doussau ldquoThe use of microfiltration mem-branes for seawater pre-treatment prior to reverse osmosismembranesrdquo Desalination vol 153 pp 141ndash147 2002

[4] R W Baker Membrane Technology and Applications 3rd edi-tion 2012

[5] W Sun J Liu H Chu and B Dong ldquoPretreatment and mem-brane hydrophilic modification to reduce membrane foulingrdquoMembranes (Basel) vol 3 no 3 pp 226ndash241 2013

[6] E A Moschou and N A Chaniotakis ldquoChapter 19 - Ion-partitioningmembranes as electroactive elements for the devel-opment of a novel cation-selective CHEMFET sensor systemrdquoinMembrane Science and Technology D Bhattacharyya and DA Butterfield Eds pp 393ndash413 Elsevier 2003

[7] I Munnawar S S Iqbal M N Anwar et al ldquoSynergistic effectof Chitosan-Zinc Oxide Hybrid Nanoparticles on antibiofoul-ing and water disinfection of mixed matrix polyethersulfonenanocomposite membranesrdquo Carbohydrate Polymers vol 175pp 661ndash670 2017

[8] Processing Guide for Polymer Membranes Solvay 2015[9] K Yadav K Morison andM P Staiger ldquoEffects of hypochlorite

treatment on the surface morphology and mechanical prop-erties of polyethersulfone ultrafiltration membranesrdquo PolymerDegradation and Stability vol 94 no 11 pp 1955ndash1961 2009

[10] B Pellegrin R Prulho A Rivaton et al ldquoMulti-scale analysisof hypochlorite induced PESPVP ultrafiltration membranesdegradationrdquo Journal of Membrane Science vol 447 pp 287ndash296 2013

[11] C M Hansen ldquo50 Years with solubility parametersmdashPast andfuturerdquo Progress in Organic Coatings vol 51 no 1 pp 77ndash842004


[12] Y S Kang B Jung and U Y Kim ldquoPolymeric dope solutionfor use in the preparation of an integrally skinned asymmetricmembranerdquo 1998 Google Patents

[13] V Laninovic ldquoRelationship between type of nonsolvent additiveand properties of polyethersulfone membranesrdquo Desalinationvol 186 pp 39ndash46 2005

[14] J Wijmans J Baaij and C Smolders ldquoThe mechanism offormation of microporous or skinned membranes produced byimmersion precipitationrdquo Journal of Membrane Science vol 14no 3 pp 263ndash274 1983

[15] D M Koenhen M H V Mulder and C A Smolders ldquoPhaseseparation phenomena during the formation of asymmetricmembranesrdquo Journal of Applied Polymer Science vol 21 no 1pp 199ndash215 1977

[16] H Bokhorst F W Altena and C A Smolders ldquoFormation ofasymmetric cellulose acetate membranesrdquoDesalination vol 38pp 349ndash360 1981

[17] P Van De Witte P J Dijkstra J W A Van Den Berg andJ Feijen ldquoPhase separation processes in polymer solutions inrelation to membrane formationrdquo Journal of Membrane Sciencevol 117 no 1 pp 1ndash31 1996

[18] M Ulbricht ldquoAdvanced functional polymer membranesrdquo Poly-mer vol 47 no 7 pp 2217ndash2262 2006

[19] H J Kim R K Tyagi A E Fouda andK Jonasson ldquoThekineticstudy for asymmetric membrane formation via phase-inversionprocessrdquo Journal of Applied Polymer Science vol 62 no 4 pp621ndash629 1996

[20] Q-Z Zheng P Wang Y-N Yang and D-J Cui ldquoThe relation-ship between porosity and kinetics parameter ofmembrane for-mation in PSF ultrafiltration membranerdquo Journal of MembraneScience vol 286 no 1-2 pp 7ndash11 2006

[21] M Amirilargani E Saljoughi T Mohammadi and M RMoghbeli ldquoEffects of coagulation bath temperature andpolyvinylpyrrolidone content on flat sheet asymmetricpolyethersulfone membranesrdquo Polymer Engineering amp Sciencevol 50 no 5 pp 885ndash893 2010

[22] I-C Kim H-G Yoon and K-H Lee ldquoFormation of integrallyskinned asymmetric polyetherimide nanofiltration membranesby phase inversion processrdquo Journal of Applied Polymer Sciencevol 84 no 6 pp 1300ndash1307 2002

[23] A C Sun W Kosar Y Zhang and X Feng ldquoA study ofthermodynamics and kinetics pertinent to formation of PVDFmembranes by phase inversionrdquoDesalination vol 309 pp 156ndash164 2013

[24] J Mulder Basic Principles of Membrane Technology SpringerScience amp Business Media 2012

[25] C A Smolders A J Reuvers R M Boom and I M WienkldquoMicrostructures in phase-inversion membranes Part 1 For-mation of macrovoidsrdquo Journal of Membrane Science vol 73no 2-3 pp 259ndash275 1992

[26] H Wood and J Wang ldquoThe effect of polyethersulfone con-centration on flat and hollow fiber membrane performancerdquoSeparation Science and Technology vol 28 no 15-16 pp 2297ndash2317 1993

[27] B K Chaturvedi A K Ghosh V Ramachandhran M KTrivedi M S Hanra and B M Misra ldquoPreparation Charac-terization and performance of polyethersulfone ultrafiltrationmembranesrdquo Desalination vol 133 no 1 pp 31ndash40 2001

[28] B Torrestiana-Sanchez R I Ortiz-Basurto and E Brito-De La Fuente ldquoEffect of nonsolvents on properties of spin-ning solutions and polyethersulfone hollow fiber ultrafiltration

membranesrdquo Journal of Membrane Science vol 152 no 1 pp19ndash28 1999

[29] J R Hwang S-H Koo J-H Kim A Higuchi and T-MTak ldquoEffects of casting solution composition on performanceof poly(ether sulfone) membranerdquo Journal of Applied PolymerScience vol 60 no 9 pp 1343ndash1348 1996

[30] A Rahimpour S SMadaeni andYMansourpanah ldquoHigh per-formance polyethersulfone UF membrane for manufacturingspiral wound module Preparation morphology performanceand chemical cleaningrdquo Polymers for Advanced Technologiesvol 18 no 5 pp 403ndash410 2007

[31] C Zhou Z Hou X Lu et al ldquoEffect of polyethersulfone molec-ular weight on structure and performance of ultrafiltrationmembranesrdquo Industrial amp Engineering Chemistry Research vol49 no 20 pp 9988ndash9997 2010

[32] T Miyano T Matsuura and S Sourirajan ldquoEffect ofpolyvinylpyrrolidone additive on the pore size and the poresize distribution of polyethersulfone (victrex) membranesrdquoChemical Engineering Communications vol 119 no 1 pp23ndash39 1993

[33] M Panar H H Hoehn and R R Hebert ldquoThe nature ofasymmetry in reverse osmosis membranesrdquo Macromoleculesvol 6 no 5 pp 777ndash780 1973

[34] C Hansen et al Hansen Solubility Parameters B Raton EdCRC Press 2007

[35] G R Guillen Y PanM Li and EMVHoek ldquoPreparation andcharacterization of membranes formed by nonsolvent inducedphase separation A reviewrdquo Industrial amp Engineering ChemistryResearch vol 50 no 7 pp 3798ndash3817 2011

[36] A Tabriz M A Ur Rehman Alvi M B Khan Niazi et alldquoQuaternized trimethyl functionalized chitosan based antifun-gal membranes for drinking water treatmentrdquo CarbohydratePolymers vol 207 pp 17ndash25 2019

[37] H T Bhatti et al ldquoGraphene oxide-PES-based mixed matrixmembranes for controllable antibacterial activity againstsalmonella typhi and water treatmentrdquo International Journal ofPolymer Science vol 2018 Article ID 7842148 12 pages 2018

[38] G Arthanareeswaran and V M Starov ldquoEffect of solventson performance of polyethersulfone ultrafiltration membranesInvestigation of metal ion separationsrdquo Desalination vol 267no 1 pp 57ndash63 2011

[39] P Van De Witte P J Dijkstra J W A Van Den Berg andJ Feijen ldquoPhase separation processes in polymer solutions inrelation to membrane formationrdquo Journal of Membrane Sciencevol 117 no 1-2 pp 1ndash31 1996

[40] Y L Thuyavan N Anantharaman G Arthanareeswaran andA F Ismail ldquoImpact of solvents and process conditions onthe formation of polyethersulfone membranes and its foulingbehavior in lakewater filtrationrdquo Journal of Chemical Technologyand Biotechnology vol 91 no 10 pp 2568ndash2581 2016

[41] P Vandezande X Li L E M Gevers and I F J Vankele-com ldquoHigh throughput study of phase inversion parametersfor polyimide-based SRNF membranesrdquo Journal of MembraneScience vol 330 no 1 pp 307ndash318 2009

[42] A Mushtaq H B Mukhtar and A M Shariff ldquoFTIR study ofenhanced polymeric blend membrane with aminesrdquo ResearchJournal of Applied Sciences Engineering amp Technology vol 7 no9 pp 1811ndash1820 2014


[43] V Vatanpour S S Madaeni R Moradian S Zinadini and BAstinchap ldquoFabrication and characterization of novel antifoul-ing nanofiltration membrane prepared from oxidized mul-tiwalled carbon nanotubepolyethersulfone nanocompositerdquoJournal ofMembrane Science vol 375 no 1-2 pp 284ndash294 2011

[44] E Arkhangelsky D Kuzmenko and V Gitis ldquoImpact of chem-ical cleaning on properties and functioning of polyethersulfonemembranesrdquo Journal of Membrane Science vol 305 no 1-2 pp176ndash184 2007

[45] H Susanto and M Ulbricht ldquoCharacteristics performanceand stability of polyethersulfone ultrafiltration membranesprepared by phase separation method using different macro-molecular additivesrdquo Journal of Membrane Science vol 327 no1-2 pp 125ndash135 2009

[46] N Biliskov and G Baranovic ldquoInfrared spectroscopy of liquidwaterndashNN-dimethylformamide mixturesrdquo Journal of Molecu-lar Liquids vol 144 no 3 pp 155ndash162 2009

[47] A Sharma et al ldquoFourier transform infrared spectral studyof NN

1015840

-dimethylformamide-water-rhodamine 6G mixturerdquoMolecular Physics vol 105 no 1 pp 117ndash123 2007

[48] J Stangret and T Gampe ldquoHydration of tetrahydrofuranderived from FTIR spectroscopyrdquo Journal of Molecular Struc-ture vol 734 no 1-3 pp 183ndash190 2005

[49] A Iqbal I Ani and R Rajput ldquoPerformance of microwavesynthesized dual solvent dope solution and lithium bromideadditives on poly(ethersulfone) membranesrdquo Journal of Chem-ical Technology and Biotechnology vol 87 no 2 pp 177ndash1882012

[50] M A Alaei Shahmirzadi et al ldquoTailoring PES nanofiltrationmembranes through systematic investigations of prominentdesign fabrication and operational parametersrdquo RSC Advancesvol 5 no 61 pp 49080ndash49097 2015

[51] A F Stalder et al ldquoLow-bond axisymmetric drop shapeanalysis for surface tension and contact angle measurementsof sessile dropsrdquo Colloids and Surfaces A Physicochemical andEngineering Aspects p 10 2010

[52] B Vatsha J C Ngila and R M Moutloali ldquoPrepara-tion of antifouling polyvinylpyrrolidone (PVP 40K) modifiedpolyethersulfone (PES) ultrafiltration (UF)membrane for waterpurificationrdquo Physics and Chemistry of the Earth Parts ABCvol 67-69 pp 125ndash131 2014

[53] M Omidvar et al ldquoPreparation and characterization ofpoly (ethersulfone) nanofiltration membranes for amoxicillinremoval from contaminated waterrdquo Journal of EnvironmentalHealth Science and Engineering vol 12 p 18 2014

[54] M-J Han and S-T Nam ldquoThermodynamic and rheologicalvariation in polysulfone solution by PVP and its effect inthe preparation of phase inversion membranerdquo Journal ofMembrane Science vol 202 pp 55ndash61 2002

[55] M I Mustaffar A F Ismail and R M Illias ldquoStudy on theeffect of polymer concentration on hollow fiber ultrafiltrationmembrane performance and morphologyrdquo p 12 2013

[56] K Kimmerle and H Strathmann ldquoAnalysis of the structure-determining process of phase inversion membranesrdquo Desalina-tion vol 79 no 2 pp 283ndash302 1990

[57] J-H Kim and K-H Lee ldquoEffect of PEG additive on membraneformation by phase inversionrdquo Journal of Membrane Sciencevol 138 no 2 pp 153ndash163 1998

[58] S Velu G Arthanareeswaran and L Muruganandam ldquoEffectof solvents on performance of polyethersulfone ultrafilterationmembranes for separation of metal ionsrdquo International Journalof Chemical and Analytical Science 2011

[59] Y LThuyavan et al ldquoPreparation and characterization of TiO2-sulfonated polymer embedded polyetherimide membranes foreffective desalination applicationrdquo Desalination vol 365 pp355ndash364 2015

[60] M G Buonomenna Advanced Materials for Membrane Prepa-ration 2012

[61] A Figoli et al ldquoTowards non-toxic solvents for membranepreparation A reviewrdquoGreenChemistry vol 16 no 9 pp 4034ndash4059 2014

[62] B Stefan B Marius and B Lidia ldquoInfluence of polymerconcentration on the permeation properties of nanofiltrationmembranesrdquoNew Technologies and Products in Machine Manu-facturing Technologies pp 227ndash232 2011

[63] J-F Li et al ldquoHydrophilic microporous PES membranes pre-pared by PESPEGDMAc casting solutionsrdquo Journal of AppliedPolymer Science vol 107 no 6 pp 4100ndash4108 2008

[64] C H Loh and RWang ldquoEffects of additives and coagulant tem-perature on fabrication of high performance PVDFPluronicF127 blend hollow fiber membranes via nonsolvent inducedphase separationrdquo Chinese Journal of Chemical Engineering vol20 no 1 pp 71ndash79 2012

CorrosionInternational Journal of

Hindawiwwwhindawicom Volume 2018

Advances in

Materials Science and EngineeringHindawiwwwhindawicom Volume 2018


Journal of

Chemistry

Analytical ChemistryInternational Journal of


ScienticaHindawiwwwhindawicom Volume 2018

Polymer ScienceInternational Journal of



Advances in Condensed Matter Physics


International Journal of

BiomaterialsHindawiwwwhindawicom

Journal ofEngineeringVolume 2018

Applied ChemistryJournal of


NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of


High Energy PhysicsAdvances in

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

TribologyAdvances in



ChemistryAdvances in


Advances inPhysical Chemistry


BioMed Research InternationalMaterials

Journal of


Na

nom

ate

ria

ls


Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom


polyimide cellulose acetate and polyether sulfone (PES) [6]All these polymers are used for their various characteris-tics For a specific polymer to be useful it must possessvarious characteristics such as excellent high heat agingresistance good mechanical properties and environmentdurability [7] Polyethersulfone (PES) is one of the mostcommonly used polymers for fabrication of microfiltrationmembrane PES is an amorphous thermoplastic polymerand has the highest number of moieties in the polymerrepeating unit in the sulfone group Hence the PES isthe most hydrophilic in the sulfone group polymers [8]Moreover PES has high mechanical strength stability at pHfrom 2 to 13 and chemical resistance which makes it quitesuitable to be used as membrane material [9 10] PES issoluble in aprotic polar solvents such as dimethylformamide(DMF) N-Methyl-2-pyrrolidone (NMP) etc Furthermoretetrahydrofuran (THF) [11] is borderline aprotic polar sol-vent and used as a cosolvent with NMP as main solvent[12]

An important advantage of asymmetric membranes is adense skin layer with porous substructure Skin layer offersselectivity and permeability whereas the sublayer providesmechanical strength Asymmetric polymeric membranesformed by immersion precipitation method are based onliquid-liquid phase separation [13ndash17] It has been sug-gested that gelation is responsible for the formation of skinFurthermore porous sublayer is formed by liquid-liquidphase separation by growth and nucleation [13 15 18ndash22] Thermodynamics and kinetics of membrane formationplays vital role in the morphology and performance ofmembranes [23] Thermodynamics of membrane formationcan be studied by Hansen solubility parameters (HSP)[24] Thermodynamics require that the free energy of mix-ing must be zero or negative for the solution process tooccur at the same time The membrane formation dependson both solvent-nonsolvent and polymer-solvent demixing[25]

The kinetics of membrane formation can be controlledby temperature of coagulation bath [24] The parameterssuch as polymer concentration [26] solvent [27] coagu-lation bath [28] conditions for preparation [29] polymersolution temperature air moisture and evaporation timebefore the wet phase have significant impact on the mor-phology and properties of the prepared membranes [30]A change in one or more parameter leads to a change inthe properties of the membrane as discussed elsewhere [31ndash33]

In consideration of the above the present work is focusedon the investigation of effect of polymer concentration vari-ation and different solvents substitution in the dope solutionused for the performance of flat sheet microfiltration mem-branes The structure and properties such as tensile strengthflux contact angle and membrane hydraulic resistance ofprepared membranes are analysed and correlated with thecomposition and concentration of polymer solution More-over the Hansen solubility correlated parameters were usedto study the thermodynamics and kinetics of the membraneformation

2 Materials and Methods

21 Materials Polyethersulfone NMP DMF and THF werepurchased from Sigma Aldrich All the chemicals were usedwithout further purification Deionized water was used in thefabrication of membranes

22 Preparation of Membranes The flat sheet membraneswere prepared by phase inversion method using castingmachine Five different formulations were prepared as shownin Table 1 PES was dissolved in respective solvent and stirredfor 24 hoursTheprepared solutionswere casted at room tem-perature (23∘C) on nonwoven polypropylenepolyethylenefabric Novatexx 2471 (Freudenberg Germany) placed ona glass plate Solvent was applied on the support materialbefore casting the polymer solution on the support material[35] Casting was done by casting machine Then the castedfilm was immersed in coagulation bath (25∘C and 28∘C) for5 mins to let the demixing complete After the formationof membranes these were dried under ambient conditionsand kept for characterization testing [36 37] The graphicalabstract is shown in Figure 1

23 Membrane Hydraulic Resistance (MHR) The MHR isthe resistance of membrane to the feed flow MHR is theindication of tolerance of membrane towards pressure andwas calculated by [38]

119877119898 =119875119869119882

(1)

where119877119898 is themembrane resistance (KPaml-1cm2h1)119875 isthe transmembrane pressure (KPa) and 119869119882 is the water flux(ml cm-2h-1)

24 Fourier Transform Infrared Spectroscopy (FTIR) BrukerAlpha ATR spectrometer was used for IR characterizationof the membranes FTIR was carried out to investigate thechange in functional groups of formulated membranes usingdifferent solvents and variations in polymer concentrationAll the samples were tested in their natural state using ATRThe samples were cut into 1 x 05 cm in dimension and placedon the IR window

25 Contact Angle Analysis The contact angle was measuredby sessile drop measurement technique to determine theextent of hydrophilicity or hydrophobicity of the formulatedmembranes Typically 5120583L drop of distilled water was placedon the surface with a needle tip A magnified image of thedrop was then taken with a digital camera static contactangle of the droplet was calculated using ImageJ LBADSA(Low-Bond Axisymmetric Drop Shape Analysis) software indegrees The reported data was average of four determina-tions at different points on the prepared membrane and thenmean and standard deviation were calculated

26 Mechanical Testing Mechanical testing was carried outfor the preparedmembranes according to the standardASTM




PES

+

O

S

n

NN


O

O

O

O

Tetrahydrofuran


PolymerSolution

Contact Angle

SEM

Filtration






119869 = 119907119886119905 (2)





120575t = radic120575d2 + 120575p2 + 120575h2 (3)



120575119901minus119904



120575119875minus119873119878



120575119878minus119873119878




119891119889 =120575119863

(120575119863 + 120575119875 + 120575119867)(7)

119891119901 =120575119875

(120575119863 + 120575119875 + 120575119867)(8)

119891ℎ =120575119867

(120575119863 + 120575119875 + 120575119867)(9)


119891119889 + 119891119901 + 119891ℎ = 1 0 (10)












(120575d) (MPa)05

PolarParameter

(120575p)(MPa)05


(120575h)(MPa)05


(MPa)05



Solvent-Non-Solvent



T

rans

mitt

ance

M3

M2

M1

3500 3000 2500 2000 1500 1000 500

Wavenumber (Cm-1)

C=C Stretch

S=Ostrectching

6（6 ring stretch

(a)

T

rans

mitt

ance

MS-2

MS-1

M3

C-H Stretching

C-H Stretch

3500

0

3000 2500 2000 1500 1000 500

Wavenumber (Cm-1)

(b)


(a) (b) (c) (d)

(e)

microvoid

(f) (g)



M1 M2 M3 MS-1 MS-20

20

40

60

80

100

Con

tact

Ang

le (D

egre

es)

Membranes


M1M2M3

MS-1MS-2


0

20

40

60

80

100

120

140

Wat

er F

lux

(mL

cm 2 h)












M1 M2 M3 MS-1 MS-2

30

20

10

0

Tens

ile S

treng

th (M

Pa)

129

086

043

000

Mod

ulus

(GPa

)

Membranes

64

48

32

16

0

Elon

gatio

n at

Bre

ak (

)






0

2

4

2661 3998 5329 666 7997

Mem

bran

e Hyd

raul

ic R

esist

ance

(KPa

ml-1

cm2

h)


M1M2M3

MS-1MS-2




00 01 02 03 04 05 06 07 08 09 10

00

01

02

03

04

05

06

07

08

09

1000

01

02

03

04

05

06

07

08

09

10

Polar Force fpHyd

roge

n Bon

ding

Forc

e f h

Dispersion Force fd

PES

Water

DMF

THF

NMPNMP+ THF











4 Conclusions


Data Availability




Acknowledgments


References



















































1015840





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls







PES

+

O

S

n

NN


O

O

O

O

Tetrahydrofuran


PolymerSolution

Contact Angle

SEM

Filtration






119869 = 119907119886119905 (2)





120575t = radic120575d2 + 120575p2 + 120575h2 (3)



120575119901minus119904



120575119875minus119873119878



120575119878minus119873119878




119891119889 =120575119863

(120575119863 + 120575119875 + 120575119867)(7)

119891119901 =120575119875

(120575119863 + 120575119875 + 120575119867)(8)

119891ℎ =120575119867

(120575119863 + 120575119875 + 120575119867)(9)


119891119889 + 119891119901 + 119891ℎ = 1 0 (10)












(120575d) (MPa)05

PolarParameter

(120575p)(MPa)05


(120575h)(MPa)05


(MPa)05



Solvent-Non-Solvent



T

rans

mitt

ance

M3

M2

M1

3500 3000 2500 2000 1500 1000 500

Wavenumber (Cm-1)

C=C Stretch

S=Ostrectching

6（6 ring stretch

(a)

T

rans

mitt

ance

MS-2

MS-1

M3

C-H Stretching

C-H Stretch

3500

0

3000 2500 2000 1500 1000 500

Wavenumber (Cm-1)

(b)


(a) (b) (c) (d)

(e)

microvoid

(f) (g)



M1 M2 M3 MS-1 MS-20

20

40

60

80

100

Con

tact

Ang

le (D

egre

es)

Membranes


M1M2M3

MS-1MS-2


0

20

40

60

80

100

120

140

Wat

er F

lux

(mL

cm 2 h)












M1 M2 M3 MS-1 MS-2

30

20

10

0

Tens

ile S

treng

th (M

Pa)

129

086

043

000

Mod

ulus

(GPa

)

Membranes

64

48

32

16

0

Elon

gatio

n at

Bre

ak (

)






0

2

4

2661 3998 5329 666 7997

Mem

bran

e Hyd

raul

ic R

esist

ance

(KPa

ml-1

cm2

h)


M1M2M3

MS-1MS-2




00 01 02 03 04 05 06 07 08 09 10

00

01

02

03

04

05

06

07

08

09

1000

01

02

03

04

05

06

07

08

09

10

Polar Force fpHyd

roge

n Bon

ding

Forc

e f h

Dispersion Force fd

PES

Water

DMF

THF

NMPNMP+ THF











4 Conclusions


Data Availability




Acknowledgments


References



















































1015840





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls






120575t = radic120575d2 + 120575p2 + 120575h2 (3)



120575119901minus119904



120575119875minus119873119878



120575119878minus119873119878




119891119889 =120575119863

(120575119863 + 120575119875 + 120575119867)(7)

119891119901 =120575119875

(120575119863 + 120575119875 + 120575119867)(8)

119891ℎ =120575119867

(120575119863 + 120575119875 + 120575119867)(9)


119891119889 + 119891119901 + 119891ℎ = 1 0 (10)












(120575d) (MPa)05

PolarParameter

(120575p)(MPa)05


(120575h)(MPa)05


(MPa)05



Solvent-Non-Solvent



T

rans

mitt

ance

M3

M2

M1

3500 3000 2500 2000 1500 1000 500

Wavenumber (Cm-1)

C=C Stretch

S=Ostrectching

6（6 ring stretch

(a)

T

rans

mitt

ance

MS-2

MS-1

M3

C-H Stretching

C-H Stretch

3500

0

3000 2500 2000 1500 1000 500

Wavenumber (Cm-1)

(b)


(a) (b) (c) (d)

(e)

microvoid

(f) (g)



M1 M2 M3 MS-1 MS-20

20

40

60

80

100

Con

tact

Ang

le (D

egre

es)

Membranes


M1M2M3

MS-1MS-2


0

20

40

60

80

100

120

140

Wat

er F

lux

(mL

cm 2 h)












M1 M2 M3 MS-1 MS-2

30

20

10

0

Tens

ile S

treng

th (M

Pa)

129

086

043

000

Mod

ulus

(GPa

)

Membranes

64

48

32

16

0

Elon

gatio

n at

Bre

ak (

)






0

2

4

2661 3998 5329 666 7997

Mem

bran

e Hyd

raul

ic R

esist

ance

(KPa

ml-1

cm2

h)


M1M2M3

MS-1MS-2




00 01 02 03 04 05 06 07 08 09 10

00

01

02

03

04

05

06

07

08

09

1000

01

02

03

04

05

06

07

08

09

10

Polar Force fpHyd

roge

n Bon

ding

Forc

e f h

Dispersion Force fd

PES

Water

DMF

THF

NMPNMP+ THF











4 Conclusions


Data Availability




Acknowledgments


References



















































1015840





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls







(120575d) (MPa)05

PolarParameter

(120575p)(MPa)05


(120575h)(MPa)05


(MPa)05



Solvent-Non-Solvent



T

rans

mitt

ance

M3

M2

M1

3500 3000 2500 2000 1500 1000 500

Wavenumber (Cm-1)

C=C Stretch

S=Ostrectching

6（6 ring stretch

(a)

T

rans

mitt

ance

MS-2

MS-1

M3

C-H Stretching

C-H Stretch

3500

0

3000 2500 2000 1500 1000 500

Wavenumber (Cm-1)

(b)


(a) (b) (c) (d)

(e)

microvoid

(f) (g)



M1 M2 M3 MS-1 MS-20

20

40

60

80

100

Con

tact

Ang

le (D

egre

es)

Membranes


M1M2M3

MS-1MS-2


0

20

40

60

80

100

120

140

Wat

er F

lux

(mL

cm 2 h)












M1 M2 M3 MS-1 MS-2

30

20

10

0

Tens

ile S

treng

th (M

Pa)

129

086

043

000

Mod

ulus

(GPa

)

Membranes

64

48

32

16

0

Elon

gatio

n at

Bre

ak (

)






0

2

4

2661 3998 5329 666 7997

Mem

bran

e Hyd

raul

ic R

esist

ance

(KPa

ml-1

cm2

h)


M1M2M3

MS-1MS-2




00 01 02 03 04 05 06 07 08 09 10

00

01

02

03

04

05

06

07

08

09

1000

01

02

03

04

05

06

07

08

09

10

Polar Force fpHyd

roge

n Bon

ding

Forc

e f h

Dispersion Force fd

PES

Water

DMF

THF

NMPNMP+ THF











4 Conclusions


Data Availability




Acknowledgments


References



















































1015840





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls





M1 M2 M3 MS-1 MS-20

20

40

60

80

100

Con

tact

Ang

le (D

egre

es)

Membranes


M1M2M3

MS-1MS-2


0

20

40

60

80

100

120

140

Wat

er F

lux

(mL

cm 2 h)












M1 M2 M3 MS-1 MS-2

30

20

10

0

Tens

ile S

treng

th (M

Pa)

129

086

043

000

Mod

ulus

(GPa

)

Membranes

64

48

32

16

0

Elon

gatio

n at

Bre

ak (

)






0

2

4

2661 3998 5329 666 7997

Mem

bran

e Hyd

raul

ic R

esist

ance

(KPa

ml-1

cm2

h)


M1M2M3

MS-1MS-2




00 01 02 03 04 05 06 07 08 09 10

00

01

02

03

04

05

06

07

08

09

1000

01

02

03

04

05

06

07

08

09

10

Polar Force fpHyd

roge

n Bon

ding

Forc

e f h

Dispersion Force fd

PES

Water

DMF

THF

NMPNMP+ THF











4 Conclusions


Data Availability




Acknowledgments


References



















































1015840





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls





M1 M2 M3 MS-1 MS-2

30

20

10

0

Tens

ile S

treng

th (M

Pa)

129

086

043

000

Mod

ulus

(GPa

)

Membranes

64

48

32

16

0

Elon

gatio

n at

Bre

ak (

)






0

2

4

2661 3998 5329 666 7997

Mem

bran

e Hyd

raul

ic R

esist

ance

(KPa

ml-1

cm2

h)


M1M2M3

MS-1MS-2




00 01 02 03 04 05 06 07 08 09 10

00

01

02

03

04

05

06

07

08

09

1000

01

02

03

04

05

06

07

08

09

10

Polar Force fpHyd

roge

n Bon

ding

Forc

e f h

Dispersion Force fd

PES

Water

DMF

THF

NMPNMP+ THF











4 Conclusions


Data Availability




Acknowledgments


References



















































1015840





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls





00 01 02 03 04 05 06 07 08 09 10

00

01

02

03

04

05

06

07

08

09

1000

01

02

03

04

05

06

07

08

09

10

Polar Force fpHyd

roge

n Bon

ding

Forc

e f h

Dispersion Force fd

PES

Water

DMF

THF

NMPNMP+ THF











4 Conclusions


Data Availability




Acknowledgments


References



















































1015840





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls






4 Conclusions


Data Availability




Acknowledgments


References



















































1015840





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls











































1015840





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls






Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls




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