Research Article Interaction between Aqueous Solutions of...

Research ArticleInteraction between Aqueous Solutions of HydrophobicallyAssociating Polyacrylamide and Dodecyl Dimethyl Betaine

Zhongbin Ye12 Guangfan Guo3 Hong Chen1 and Zheng Shu3

1 State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu Sichuan 610500 China

2 School of Chemistry and Chemical Engineering Southwest Petroleum University Chengdu Sichuan 610500 China3 School of Petroleum Engineering Southwest Petroleum University Chengdu Sichuan 610500 China

Correspondence should be addressed to Guangfan Guo 383821889qqcom

Received 5 November 2013 Revised 1 January 2014 Accepted 8 January 2014 Published 23 February 2014

Academic Editor Shin-ichi Yusa

Copyright copy 2014 Zhongbin Ye et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The interaction between hydrophobically associating polyacrylamide (HAPAM) and dodecyl dimethyl betaine (BS-12) is studiedthrough surface tension interfacial tension (IFT) apparent viscosity aggregation behavior andmicroscopic morphologies Resultsshow that surface and interface properties of BS-12 are largely affected by HAPAM BS-12 critical micelle concentrations areincreased with the increment of polymer concentrations Abilities of reduced air-water surface tension and oil-water interfacialtension are dropped The oil-water interfacial tension to reach minimum time is increased HAPAM can form network structuresin the aqueous solutionMixedmicelles are formedby the interaction betweenBS-12micelles andhydrophobic groups ofHAPAMinaqueous solution and self-assembly behavior of HAPAM is affected With the increment of surfactant concentrations the apparentviscosity apparent weight average molecular weights (119872

119908119886) root mean square radius of gyration (⟨119877

119892⟩) and hydrodynamic radius

of HAPAM increase first and then decline Moreover microscopic morphologies of the mixed system are formed from relativelyloose network structures to dense network structures and then become looser network structures and the part of network structuresfracture

1 Introduction

Water-soluble polymers modified with a small amount ofhydrophobic groups (lt2 mole fraction) have become ofgreat interest in recent years They have broad applicationprospects such as oil exploration paint mineral separa-tion and cosmetic and pharmaceutical preparations et al[1ndash4] Hydrophobically associating polymer molecules inaqueous solution three-dimensional network structures areformed through the intermolecular interaction Thereforehydrophobicallymodified polymers have the good increasingviscosity heat resistance salt resistance and shear resistanceand so on [5ndash7] and they have a good application prospect

Polymer-surfactantmixed system is a kind of very impor-tant soft substance Usually adding surfactants into polymersolutions the dosage of polymers or surfactants can bereduced and solution performances are improved [8ndash10]Themixed system has many unique properties for example the

system viscosity interfacial adsorption solubilization drugdelivery and so on So the study of polymer-surfactant mixedsystem is that people are very interested in research subjects[11ndash14] In recent years the interaction between hydrophobi-cally associating polyacrylamide (HAPAM) and surfactant isstudied by some scholars [15ndash18] These studies find that thesystem can form mixed micelles and rheological propertiesof polymer solutions can be changed to a great extentThe interaction between polymer and surfactant is mainlydecided by the polymer hydrophobicity and the surfactantstructure Betaine is a main type of zwitterionic surfactantIt shows characteristics of different ionic surfactant underdifferent conditions owing to having anionic and cationicgroups at the same time Now the interaction betweenHAPAM and betaine surfactants is very little researched [19]In this paper the interaction of hydrophobically associatingpolyacrylamide (HAPAM) and dodecyl dimethyl betaineis studied Expecting polymer-surfactant mixed system has

Hindawi Publishing CorporationJournal of ChemistryVolume 2014 Article ID 932082 8 pageshttpdxdoiorg1011552014932082

2 Journal of Chemistry

CH NCl

CH2 CH3

CH3

CH3

(CH2)17H2C+

minus

Figure 1 Molecular structure of 18-alkyl-dimethyl diallyl ammo-nium chloride (C

18DMAAC)

good application prospects in washing textile daily chemicaland oil field development and so on

2 Experiment

21 Materials and Instruments Acrylamide (AM) acrylicacid (AA) anhydrous sodium carbonate (Na

2CO3) potas-

sium persulfate (K2S2O8) and sodium hydrogen sulfite

(NaHSO3) were provided by Chengdu Kelong Chemical

Reagents Corporation China and all drugs were analyt-ical pure 18-Alkyl-dimethyl diallyl ammonium chloride(C18DMAAC its molecular structure be shown in Figure 1)

and dodecyl dimethyl betaine (BS-12) were supplied bySouthwest Petroleum University TX-500C full range ten-siometer was purchased from the United States BowingIndustry Corporation Brookfield DV-III viscometer waspurchased from the United States Brookfield InstrumentCorporation BI-200SM dynamicstatic wide angle laserlight scattering apparatus was purchased from the UnitedStates Brooke Haven Instrument Corporation NanoscopeIIIa atomic force microscope was purchased from the UnitedStates Digital Instrument Corporation

22 Synthesis of Hydrophobically Associating PolyacrylamideHydrophobically associating polyacrylamide (HAPAM) syn-thesis is as follows 80 g distilled water 149 g acrylamide(AM) 5 g sodium acrylate (acrylic acid and anhydroussodium carbonate) and 01 g 18-alkyl-dimethyl diallyl ammo-nium chloride (C

18DMAAC) were added into a three-necked

flask according to the literature [20] Adjusting the pH valueof the system was 60-70 and potassium persulfatesodiumhydrogen sulfite redox (003ndash005) were added The solu-tion was mixed and then bubbled with nitrogen for 30minto displace dissolved oxygen then quickly capped The poly-merization was carried out at 50∘C for 24 h Products wereprecipitated and purified by ethanol to remove unreactedmonomers and oligomers and then were baked in a vacuumdrying oven at the 50∘C to constant quality The polymermolecular structure was shown in Figure 2 and characteristicparameters were shown in Table 1

23 Solution Preparation The aqueous solutions (5000 ppm)of surfactant and polymer were always freshly prepared usinga mechanical stirrer for 8ndash10 h to form a consistent homo-geneous solution at a low rotation per minute Appropriatequantity of zwitterionic surfactants and hydrophobicallyassociating polymers were dissolved carefully in distilledwater for about 40min [21 22]

NO Na

CH CH2 CH CH2 CH CH2

CH2

NH2 CH3

CH3

CH3

(CH2)17

Cl

x y zC = OC = O

+ +minusminus

Figure 2 Molecular structure of hydrophobically associating poly-acrylamide (HAPAM) (theoretical mole percents of 119909 119910 and 119911wereabout 797 202 and 01 resp)

24 Measurement of Surface Tension and Interfacial TensionIn polymer-surfactant mixed systems polymer concentra-tions were 500 1000 1500 and 2000 ppm respectivelyand BS-12 concentrations were 10ndash2000 ppm The surfactantsolutionwith or withoutHAPAMas outer-phase was injectedinto the glass tube and 2 120583L air or oil as inner-phase wasput into the middle of the tube Then the tube was envelopedwith the plastic cover and put into the apparatus measuringthe surface tension or interfacial tension at a temperature of25∘C [3] In surface tension experiment the outer-phase waspolymer-surfactant mixed system and the inner-phase wasair Surface tensions of polymer-surfactant mixed systemswere measured at a rotating velocity of 6000 rpm whensurface tension reached a minimum value and stopped thetest In interfacial tension (IFT) experiment the outer-phasewas polymer-surfactant mixed system and the inner-phasewas dodecane Interfacial tensions of mixed systems weremeasured at a rotating velocity of 5000 rpm when interfacialtension reached a minimum value and stopped the test Indynamic interfacial tension (DIFT) experiment surfactantconcentration was selected to make oil-water interfacialtension minimum in different polymer concentrations andthen interfacial tensions of themixed systemas time changingwere measured a at a rotating velocity of 5000 rpm

25 Measurement of Apparent Viscosity In polymer-surfact-ant mixed systems the polymer concentration was 1500 ppmand BS-12 concentrations were 10ndash2000 ppm The viscositiesof polymer-surfactant mixed systems were measured byBrookfield DV-III viscometer with a shearing rate of 734 sminus1and at a temperature of 25∘C

26 Laser Light Scattering Experiment The diluted polymer-surfactant mixed system was dusted and filtered by theMillipore Corporation production of the disposable filterwith a 08120583mapertureThefiltratewas collected in the samplepool In the laser light scattering experiment toluene as astandard solution the laser wavelength was 532 nm and themeasured temperature was 25∘C [23 24]

According to the light scattering theory [25ndash27] weightaverage molecular weight (119872

119908) and root mean square radius

of gyration (⟨119877119892⟩) of polymers were measured by static light

Journal of Chemistry 3

Table 1 Characteristic parameters of hydrophobically associating polyacrylamide (HAPAM)

Sample Molecular weight Degree ofhydrolysis ()

Critical associationconcentration (ppm) Polydispersity index

HAPAM 6000000 250 800 146

scattering For high molecular weight polymers the lightscattering of polymer dilute solution can be expressed as

(119870119862

119877VV (119902))

12

asymp (1

119872119882

)

12

(1 +1

6⟨1198772

119892⟩ 1199022

)

times (1 + 1198602119872119908119862)

(1)

where 119870 = 41205872

1198992

0(119889119899119889119862)

2

(1198731205824

0) 119870 was associated with

the constant of solvent nature and incident light frequency1198990was the refractive index of solution 119862 was the solution

concentration ppm119877VV(119902)was the solvent effect of scatteringintensity for different angles 120582

0was the incident light wave-

length 120582 was the wavelength of incident light in solution120582 = 120582

01198990 119889119899119889119862was the refractive index increment and the

ratio of solution refractive index and concentration ppm119873was theAvogadro constant ⟨119877

119892⟩was rootmean square radius

of gyration and the chain quality centre to each chain segmentaverage of squared distance When the scattering angles were120579 rarr 0 and concentrations were 119862 rarr 0 some parameterswere obtained such as ⟨119877

119892⟩ and119872

119908by extrapolation [28 29]

Hydrodynamic radius ⟨119877ℎ⟩ of polymer molecules under

different surfactant concentrationswasmeasured by dynamiclight scattering (DLS) [24] In the dynamic light scatteringmeasurements were the light intensity-light intensity timerelated spectroscopy

119866(2)

(120591) = 119860 sdot (1 + 120573 sdot10038161003816100381610038161003816119892(1)

(120591)10038161003816100381610038161003816

2

) (2)

where119866(2)(120591)was the autocorrelation function of light inten-sity 119860 was the baseline of the autocorrelation function 120573was the experimental constant of constraint signal noise ratioassociated with the measuring experimental device 119892(1)(120591)was autocorrelation function of electric field Its relationshipwith the line width distribution 119866(Γ) is as follows

119892(1)

(120591) = int

infin

0

119866 (Γ) exp (minusΓ120591) 119889Γ (3)

If the relaxation is caused entirely by diffusion under theconditions of 119862 rarr 0 and 119902 rarr 0 Γ = 119863119902

2 119863 wasthe particle diffusion coefficient and 119902 was the scatteringvector This moment when the concentration was very low119863 extrapolated to zero point and particle size distribu-tions were obtained through Stokes-Einstein formulas 119863 =

119870119861119879(3120587120578119889) where 119870

119861was Boltzmann constant 119879 was

absolute temperature 120578 was solvent viscosity 119889 was particlediameter

27 Measurement of Molecular Aggregation MorphologiesAFM operating mode was tapping Probe model wasRTESP operating frequencywas 86 kHz force constantswere

1sim5Nmminus1The systemwas stirred at a low velocity for 5min toobtain a homogeneous solution concentration For the AFMmeasurements 01mL of the prepared polymer-surfactantmixed system was dropped onto freshly cleaved mica andthe redundant solution was blown off by a stream of highpurity nitrogen Samples were measured by Nanoscope IIIamicroscope in air at the ambient temperature [30]

3 Results and Discussions

31 Surface Tension of Polymer-Surfactant Mixed System Itis well known that surfactants reduce the surface tension ofwater by getting adsorbed on the liquid-gas interface TheCMC one of the main parameters for surfactants is theconcentration at which surfactant solutions begin to formmicelles in large amounts [22] Different techniques are usedto examine the water-soluble polymer-surfactant aggregatesformed in solution [31 32] Surface tensions of surfactant (BS-12) solutions at different concentrations were measured andplotted as a function of concentrations (Figure 3) Figure 3shows that the CMC and the surface tension have been alarge change after adding polymers into surfactant solutionsWhen polymers are not added the CMC and the CMC of thesurface tension areminimalTheCMCvalue of BS-12 is about300 ppm and the surface tension is about 313mNm Afterthe polymers being added the surfactant CMC and the CMCof surface tensions gradually increase with the incrementof polymer concentrations When HAPAM concentration isabout 2000 ppm the CMC of the mixed system is about500 ppm and the surface tension increases to 334mNmKhan et al also found the same behavior of polyacrylamidesolutions in the presence of SDBS [22] The reason for thisphenomenon is that hydrophobic groups of polymers willinteract with surfactant hydrophobic parts and some sur-factants are shackled in the bulk phase Shackled surfactantsincrease with the increment of polymer concentrationsTheyneed to consume more surfactants to form micelles [3]Therefore reaching critical micelles requires higher surfac-tant concentrations Mixed micelles of polymerssurfactantsthat are formed have been inhibitory effect to the surfacetension of surfactants in solution

32 Interfacial Tension of Polymer-Surfactant Mixed SystemThe polymer-surfactant mixed system has been applied inthe oil field owing to reducing the mobility ratio decreaseinterfacial tension (IFT) between the water and the oil [3334] It has been reported that addition of polymers increasesthe IFT of ionic surfactants [3 35] Interfacial tensionsof surfactant (BS-12) solutions at different concentrationsare measured and results are shown in Figure 4 Figure 4shows that oil-water IFT is decreased with the incrementof surfactant concentrations After a turning point the IFT


0 500 1000 1500 2000 250025

30

35

40

45

50

55

60

65

70

75

Surfa

ce te

nsio

n (m

Nm

)

Surfactant concentration (ppm)

CMC

0ppm HAPAM500ppm HAPAM1000 ppm HAPAM

1500ppm HAPAM2000 ppm HAPAM

Figure 3 Effect of HAPAM concentrations on surface tensions ofBS-12

0 500 1000 1500 2000 250001

1

10

Inte

rfaci

al te

nsio

n (m

Nm

)




Figure 4 Effect of HAPAM concentrations on interfacial tensionsof BS-12

becomes to balance If there are no polymers the turningpoint of surfactant concentration and the IFT isminimalTheturning point of surfactant concentration is about 300 ppmand the IFT is about 029mNm With the increment ofpolymer concentrations the turning point of surfactantconcentration and the IFT have shown a trend of incrementThis phenomenon is similar to Figure 2 Hydrophobic groupsof polymers will interact with surfactant hydrophobic partsand bound part surfactants in the bulk phase Ultimatelythe ability of reduced oil-water IFT is declined The shackledeffect is enhanced with the polymer concentrations increas-ing Therefore the reduced oil-water IFT needs to consumemore surfactants On the other hand the IFT of surfactants

0 20 40 60 80 100 12001

1

10

Inte

rfaci

al te

nsio

n (m

Nm

)

Time (min)



Figure 5 Effect of HAPAM concentrations on the dynamic interfa-cial tensions of BS-12

can be inhibited by the viscosity of polymer solutions Chenet al also confirm the result [3]

Figure 5 shows the result that the oil-water dynamicinterfacial tension (DIFT) of BS-12 is affected by the HAPAMconcentrations The DIFT is changed with time increasingThe reduced surfactant IFT and reaching steady state thatrequired time can be reflected by DIFT characteristics Whensurfactant concentrations are 500 ppm the DIFT change isfaster at lower polymer concentrations Therefore oil-waterIFT reaching a minimum need less time The higher concen-trations the polymer is the longer the time reaching a mini-mum of IFT is The reason is that surfactants and associatingpolymers have the strong interaction and oil-water interfacediffusion rates of surfactants which are significantly affectedIn addition the system viscosity increases with the incrementof polymer concentrations and the surfactant spread speed isalso slowed As a result the IFT reaching a minimum needslonger times at the higher polymer concentrations

33 Apparent Viscosity of Polymer-Surfactant Mixed SystemThe effect of BS-12 concentrations on the viscosity of poly-mers is shown in Figure 6 Figure 6 shows that the systemviscosity increases first and then declines with the incrementof BS-12 concentrations When the BS-12 concentration isabout 100 ppm the system viscosity is the largest Badoga etal [36] and Jiang et al [37] have reported that the viscosityof polymer-surfactant mixed systems increases first and thendeclines with the increment of surfactant concentrationsWhen the addition of surfactant concentrations is lowersurfactant molecules in single molecule state are distributedin aqueous solution Surfactant molecular ions and HAPAMmolecular chains interacting with each other make theinteraction of hydrophobic groups forming inner salt keys beopened and the intermolecular association is formed At thismoment the association between polymer molecules pro-moted role and polymer molecular chains is more diastolic


0 500 1000 1500 20000

20

40

60

80

100

120


Visc

osity

(mPamiddots)

Figure 6 Effect of BS-12 concentrations on the viscosity of1500 ppm HAPAM

0 500 1000 1500 20000

5

10

15

20

25

30


10minus7M

wa

(gmiddotm

olminus1)

Figure 7 Effect of BS-12 concentrations on apparent weight averagemolecular weight (119872

119908119886) of HAPAM

because of the addition of surfactants The solution viscosityis increased with the increment of surfactant concentrationsWhen surfactant concentrations exceed a certain value theinteraction between surfactants and hydrophobic groups ofpolymer chain segments is further enhanced Mixed micellesof polymer-surfactant are formed On the other hand theintermolecular association of polymers is shielded with theincrease of surfactant micellar numbers thus polymer net-work structures are damaged and collapsed The viscosity ofmixed systems is decreased

34 Laser Light Scattering Experiments It has been reported[23 38] that addition of ionic surfactants influences themolecular structure of the polymer The effects of BS-12concentrations on apparentweight averagemolecularweights(119872119908119886

) of polymers are tested at a 25∘CTheir result is shownin Figure 7 The root mean square radius of gyration (⟨119877

119892⟩)

is characteristic parameters of the polymer and directlyreflects the conformation of polymer chains In order to

0 500 1000 1500 20000

40

80

120

160

200


⟨Rg⟩

(nm

)

Figure 8 Effect of BS-12 concentrations on rootmean square radiusof gyration (⟨119877

119892⟩) of HAPAM

10 100 1000 100000

5

10

15

20

25

30

35

()

Particle size (nm)

0ppm BS-12100ppm BS-12200 ppm BS-12

400ppm BS-12600ppm BS-12

Figure 9 Particle size distributions of HAPAMwith different BS-12concentrations

0 500 1000 1500 20000

30

60

90

120

150


⟨Rh⟩

(nm

)

Figure 10 Effect of BS-12 concentrations on the hydrodynamicradius (⟨119877

ℎ⟩) of HAPAM


100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(a)

100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(b)

100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(c)

Figure 11 AFM images of 1500 ppmHAPAMwith different BS-12 concentrations (a) 0 ppmBS-12 (b) 100 ppmBS-12 and (c) 400 ppmBS-12

reduce the effect of polymer concentrations the preparationconcentration of polymers is 2 ppm in experiment For thedilute polymer solution ⟨119877

119892⟩ can be concluded through

extrapolation of the same concentrationswith different anglesin solution then some ⟨119877

119892⟩ are received under different

surfactant concentrations in the same way Their results areshown in Figure 8

Figures 7 and 8 show that 119872119908119886

and ⟨119877119892⟩ of HAPAM

increase first and then decline with the increment of BS-12 concentrations When there are a few surfactants in thepolymer-surfactant mixed system the surfactant moleculesinteracting with polymer hydrophobic groups intermolec-ular association of polymers is strengthened and polymersare more likely to gather to form super molecular structures119872119908119886

and ⟨119877119892⟩ show a trend of increment When surfac-

tant concentrations are about 100 ppm the system viscosityis the largest With the further increment of surfactantconcentrations hydrophobic groups of polymer moleculesare inhibited by cationic groups of surfactant molecularchains The intramolecular association of associating poly-mers forms inner salt key 119872

119908119886and ⟨119877

119892⟩ become smaller

When surfactant concentrations are more than its criticalmicelle concentrations the number of surfactant micellesis increased Hydrophobic groups of associating polymersare separated by surfactant micelles The intermolecularassociation is weakened and supramolecular aggregations aredismantled Thus119872

119908119886and ⟨119877

119892⟩ are further smaller

In order to study zwitterionic surfactant (BS-12) effect onhydrodynamic sizes of polymers in solution the preparationconcentration of polymers is 2 ppm in the experimentParticle size distributions and hydrodynamic radius (⟨119877

ℎ⟩)

of the polymer under different surfactant concentrations aremeasured by dynamic light scattering at a 25∘C and the scat-tering angle is 90∘Their results are shown in Figures 9 and 10Figure 9 shows that particle sizes of HAPAM are unimodaldistribution under no surfactant condition When surfactantconcentrations are about 100 ppm the particle size distri-bution of HAPAM is a wider unimodal and moves to theright Surfactants can enhance intermolecular association ofpolymers and make polymer chains stretch and hydrody-namic radius increase When surfactant concentrations aremore than 400 ppm particle sizes of HAPAM are multi-modal distributions and wider unimodal move to left Thereason is that surfactant micelles are increased with the

increment of surfactant concentrations in solution Somepolymer hydrophobic groups are embedded by surfactantmicelles The intermolecular association of HAPAM is par-tially blocked and the hydrodynamic radius appears to bereducing

Figure 10 shows that ⟨119877ℎ⟩ is increased because of a

small amount of surfactants to be added When surfactantconcentrations are lower the intermolecular association ofHAPAM is strengthened and ⟨119877

ℎ⟩ is increased But the

surfactant concentrations exceed a certain value polymeraggregations are dismantled therefore ⟨119877

ℎ⟩ is reduced

35 Molecular Aggregation Morphologies of Polymer-Surfact-ant Mixed System The previous research results had beenconfirmed that space network structures of hydrophobi-cally associating polymer are formed exceeding the crit-ical association concentration (CAC) of polymer [3 24]When ionic surfactants are added molecular aggregationmorphologies of HAPAM are affected Different BS-12 con-centrations affectingmolecular aggregationmorphologies areobserved Their results are shown in Figure 11 Figure 11(a) isan AFM photo of HAPAM without surfactants When theHAPAM concentration exceeds the CAC it can be formedobvious spatial network structures in distilled water [39]Figure 11(b) is an AFM photo of HAPAM solution to add100 ppm surfactants Compared with Figures 11(a) and 11(b)when BS-12 concentrations are about 100 ppm the spacenetwork structures become more intense in solution andthe connecting mesh chain beams are thicker especially theintersection part of chain beam Figure 11(c) is an AFMphotoof HAPAM solution to add 400 ppm surfactants Comparedwith Figures 11(b) and 11(c) when BS-12 concentrations areabout 400 ppm the space network structures become sparserWhen surfactants continue to be added the connectingnetwork chain beams are thinner These results show thatadding a few surfactants has a promoting effect on theself-assembly of polymer molecules but the self-assemblyof polymer molecules is inhibited for adding too manysurfactants

4 Conclusions

(1) Adding polymers into dodecyl dimethyl betaine (BS-12) solutions the CMC and surface tensions of the


CMC are increased with the increment of HAPAMconcentrations

(2) Zwitterionic surfactant (BS-12) can reduce dodeca-noic-water interfacial tension to about 03mNm BS-12 has been a good ability to reduce the oil-waterinterfacial tension The surfactant (BS-12) interfaceactivity is affected by HAPAM The required timeof interfacial tension balance is longer with polymerconcentrations increasing

(3) When the surfactant (BS-12) concentrations arelower the apparent viscosity apparent weight averagemolecular weights (119872

119908119886) root mean square radius

of gyration (⟨119877119892⟩) and hydrodynamic radius (⟨119877

ℎ⟩)

of HAPAM increase with the increment of BS-12concentrations When surfactant concentrations are100 ppm they are maximum surfactant concentra-tions continue to increase and they begin to declineBS-12 has a great influence on performances ofHAPAM solutions

(4) The hydrophobically associating polymer (HAPAM)can form the obvious spatial network structures ex-ceeding the critical association concentration (CAC)in distilled water When added surfactant (BS-12)concentrations are about 100 ppm the space networkstructures become more intense and the connectingnetwork chain beams are thicker BS-12 concentra-tions continue to increase when concentrations areabout 400 ppm loose network structures are formedand partially loose network structures are broken

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors gratefully appreciated the National Science andTechnology Major Projects China (no 2011ZX05011) Theauthors appreciated the State Key Laboratory of Oil and GasReservoir Geology and Exploitation for experiment help too

References

[1] CWang X-R Li and P-Z Li ldquoStudy on preparation and solu-tion properties of hydrophobically associating polyacrylamideby emulsifier-free ultrasonic assisted radical polymerizationrdquoJournal of Polymer Research vol 19 no 8 pp 9933ndash9939 2012

[2] S-L Cram H-R Brown M-S Geoffrey D Hourdet and CCreton ldquoHydrophobically modified dimethylacrylamide syn-thesis and rheological behaviorrdquoMacromolecules vol 38 no 7pp 2981ndash2989 2005

[3] H Chen E-X Li Z-B Ye L-J Han and P-Y Luo ldquoInteractionof hydrophobically associating polyacrylamide with geminisurfactantrdquo Acta Physico-Chimica Sinica vol 27 no 3 pp 671ndash676 2011

[4] G-O Yahaya A-A Ahdab S-A Ali B-F Abu-Sharkh andE-Z Hamad ldquoSolution behavior of hydrophobically associ-ating water-soluble block copolymers of acrylamide and N-benzylacrylamiderdquo Polymer vol 42 no 8 pp 3363ndash3372 2001

[5] F S Hwang and T E Hogen-Esch ldquoEffects of water-solublespacers on the hydrophobic association of fluorocarbon-modified poly(acrylamide)rdquo Macromolecules vol 28 no 9 pp3328ndash3335 1995

[6] M LiM Jiang Y-X Zhang andQ Fang ldquoFluorescence studiesof hydrophobic association of fluorocarbon-modified poly(N-isopropylacrylamide)rdquoMacromolecules vol 30 no 3 pp 470ndash478 1997

[7] Y-J Feng L Billon B Grassl G Bastiat O Borisovand J Francois ldquoHydrophobically associating polyacrylamidesand their partially hydrolyzed derivatives prepared by post-modification 2 Properties of non-hydrolyzed polymers in purewater and brinerdquo Polymer vol 46 no 22 pp 9283ndash9295 2005

[8] P Deo and P Somasundaran ldquoInteractions of hydrophobicallymodified polyelectrolytes with nonionic surfactantsrdquoLangmuirvol 21 no 9 pp 3950ndash3956 2005

[9] G Nizri S Lagerge A Kamyshny D T Major and S Mag-dassi ldquoPolymer-surfactant interactions binding mechanismof sodium dodecyl sulfate to poly(diallyldimethylammoniumchloride)rdquo Journal of Colloid and Interface Science vol 320 no1 pp 74ndash81 2008

[10] A-E GoddardM-L FranciscoM-J Arturo andH-A RoqueldquoTwo-dimensional colloidal aggregation concentration effectsrdquoJournal of Colloid and Interface Science vol 246 no 2 pp 227ndash234 2002

[11] D-X Wang L Luo L Zhang Y-Y Wang S Zhao and J-Y Yu ldquoStudy on interfacial interaction between hydrophobi-cally modified polyacrylamide and surfactantsrdquo Acta Physico-Chimica Sinica vol 21 no 11 pp 1205ndash1210 2005

[12] A-S Anna R-A Campbell and C-D Bain ldquoDynamic adsorp-tion of weakly interacting polymersurfactant mixtures at theairwater interfacerdquo Langmuir vol 28 no 34 pp 12479ndash124922012

[13] N Beheshti A-L Kjoslashniksen K Zhu K D Knudsen and BNystrom ldquoViscosification in polymer-surfactant mixtures atlow temperaturesrdquo Journal of Physical Chemistry B vol 114 no19 pp 6273ndash6280 2010

[14] L-D Jiang B-J Gao and L Gang ldquoInteraction betweencationic Gemini surfactant with hydrophobically associatiedpolyacrylamide of a new familyrdquo Acta Physico-Chimica Sinicavol 23 no 3 pp 337ndash342 2007

[15] N-V Sastry and H Hoffmann ldquoInteraction of amphiphilicblock copolymer micelles with surfactantsrdquo Colloids and Sur-faces A vol 250 no 1ndash3 pp 247ndash261 2004

[16] L Piculell M Egermayer and J Sjostrom ldquoRheology of mixedsolutions of an associating polymer with a surfactant Why aredifferent surfactants differentrdquo Langmuir vol 19 no 9 pp3643ndash3649 2003

[17] G-L Smith and C-L McCormick ldquoWater-soluble polymers79-Interaction of microblocky twin-tailed acrylamido terpoly-mers with anionic cationic and nonionic surfactantsrdquo Lang-muir vol 17 no 5 pp 1719ndash1725 2001

[18] J-R Enrique S Joseph and C Francoise ldquoEffect of surfactanton the viscoelastic behavior of semidilute solutions of multi-sticker associating polyacrylamidesrdquo Langmuir vol 16 no 23pp 8611ndash8621 2000

[19] X-Y Wang Y-J Li J-B Wang et al et al ldquoInteractionsof cationic gemini surfactants with hydrophobically modified


poly(acrylamides) studied by fluorescence and microcalorime-tryrdquo Journal of Physical Chemistry B vol 109 no 26 pp 12850ndash12855 2005

[20] H Chen W-T Lu Z-B Ye L-J Han and P-Y Luo ldquoInfluenceof hydrolysis degree on properties of associating polymerssolutionrdquo Oilfield Chemistry vol 29 no 2 pp 190ndash194 2012

[21] E Minatti and D Zanette ldquoSalt effects on the interaction ofpoly(ethylene oxide) and sodium dodecyl sulfate measured byconductivityrdquo Colloids and Surfaces A vol 113 no 3 pp 237ndash246 1996

[22] M Y Khan A Samanta K Ojha and A Mandal ldquoInteractionbetween aqueous solutions of polymer and surfactant and itseffect on physicochemical propertiesrdquo Asia-Pacific Journal ofChemical Engineering vol 3 no 5 pp 579ndash585 2008

[23] L-J Han Z-B Ye H Chen and P-Y Luo ldquoSelf-assemblyof hydrophobically associating polyacrylamide and geminisurfactantrdquoActa Physico-Chimica Sinica vol 28 no 6 pp 1405ndash1410 2012

[24] H Chen X-Y Wu Z-B YE L-J Han and P-Y Luo ldquoSelf-assembly behavior of hydrophobically associating polyacry-lamide in salt solutionrdquoActa Physico-Chimica Sinica vol 28 no4 pp 903ndash908 2012

[25] Q-W Zhang J Ye Y-J Lu et al ldquoSynthesis folding andassociation of long multiblock (PEO 23-b-PNIPAM124)750chains in aqueous solutionsrdquoMacromolecules vol 41 no 6 pp2228ndash2234 2008

[26] L Hong F-M Zhu J-F Li T Ngai Z-W Xie and C WuldquoFolding of long multiblock copolymer (PI-b-PS-b-PI)n chainsprepared by the Self-Assembly Assisted Polypolymerization(SAAP) in cyclohexanerdquo Macromolecules vol 41 no 6 pp2219ndash2227 2008

[27] D Xie X Ye Y-W Ding et al ldquoMultistep thermosensi-tivity of Poly(N-n-propylacrylamide)-block-poly(N-isopropy-lacrylamide)-block-poly(NN-ethylmethylacrylamide) triblockterpolymers in aqueous solutions as studied by static and dy-namic light scatteringrdquoMacromolecules vol 42 no 7 pp 2715ndash2720 2009

[28] X Wang X Qiu and C Wu ldquoComparison of the coil-to-globule and the globule-to-coil transitions of a single poly(N-isopropylacrylamide) homopolymer chain in waterrdquo Macro-molecules vol 31 no 9 pp 2972ndash2976 1998

[29] P-A Fuierer B Li and H S Jeon ldquoCharacterization of particlesize and shape in an ageing bismuth titanate sol using dynamicand static light scatteringrdquo Journal of Sol-Gel Science andTechnology vol 27 no 2 pp 185ndash192 2003

[30] R Zhang Z-B Ye L Peng N Qin Z Shu and P-Y LuoldquoThe shearing effect on hydrophobically associative water-soluble polymer and partially hydrolyzed polyacrylamide pass-ing through wellbore simulation devicerdquo Journal of AppliedPolymer Science vol 127 no 1 pp 682ndash689 2012

[31] Y Dong and D-C Sundberg ldquoEstimation of polymerwaterinterfacial tensions hydrophobic homopolymerwater inter-facesrdquo Journal of Colloid and Interface Science vol 258 no 1pp 97ndash101 2003

[32] M Nedjhioui N Moulai-Mostefa A Morsli and A BensmailildquoCombined effects of polymersurfactantoilalkali on physicalchemical propertiesrdquo Desalination vol 185 no 1ndash3 pp 543ndash550 2005

[33] J-X Liu Y-J Guo J Hu et al ldquoDisplacement characters ofcombination flooding systems consisting of gemini-nonionic

mixed surfactant and hydrophobically associating polyacry-lamide for bohai offshore oilfieldrdquo Energy Fuels vol 26 no 5pp 2858ndash2864 2012

[34] Y-J Guo J-X Liu X-M Zhang et al ldquoSolution property inves-tigation of combination flooding systems consisting of gemini-non-ionic mixed surfactant and hydrophobically associatingpolyacrylamide for enhanced oil recoveryrdquo Energy and Fuelsvol 26 no 4 pp 2116ndash2123 2012

[35] H-J Gong X Xin G Y Xu and Y-J Wang ldquoThe dynamicinterfacial tension between HPAMC17H33COONa mixedsolution and crude oil in the presence of sodium haliderdquoColloids and Surfaces A vol 317 no 1ndash3 pp 522ndash527 2008

[36] S Badoga S-K Pattanayek A Kumar and L-M PandeyldquoEffect of polymer-surfactant structure on its solution viscosityrdquoAsia-Pacific Journal of Chemical Engineering vol 6 no 1 pp78ndash84 2011


[38] Y-J Mei Y-X Han H Zhou L Yao and B Jiang ldquoSynergismbetween hydrophobically modified polyacrylic acid and worm-like micellesrdquo Acta Physico-Chimica Sinica vol 28 no 7 pp1751ndash1756 2012

[39] R Zhang Z-B Ye and P-Y Luo ldquoThe atomic force microscopystudy on the microstructure of the polymer solutionrdquo Journal ofChinese Electron Microscopy Society vol 29 no 5 pp 475ndash4812010

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


CH NCl

CH2 CH3

CH3

CH3

(CH2)17H2C+

minus

Figure 1 Molecular structure of 18-alkyl-dimethyl diallyl ammo-nium chloride (C

18DMAAC)

good application prospects in washing textile daily chemicaland oil field development and so on

2 Experiment

21 Materials and Instruments Acrylamide (AM) acrylicacid (AA) anhydrous sodium carbonate (Na

2CO3) potas-

sium persulfate (K2S2O8) and sodium hydrogen sulfite

(NaHSO3) were provided by Chengdu Kelong Chemical

Reagents Corporation China and all drugs were analyt-ical pure 18-Alkyl-dimethyl diallyl ammonium chloride(C18DMAAC its molecular structure be shown in Figure 1)

and dodecyl dimethyl betaine (BS-12) were supplied bySouthwest Petroleum University TX-500C full range ten-siometer was purchased from the United States BowingIndustry Corporation Brookfield DV-III viscometer waspurchased from the United States Brookfield InstrumentCorporation BI-200SM dynamicstatic wide angle laserlight scattering apparatus was purchased from the UnitedStates Brooke Haven Instrument Corporation NanoscopeIIIa atomic force microscope was purchased from the UnitedStates Digital Instrument Corporation

22 Synthesis of Hydrophobically Associating PolyacrylamideHydrophobically associating polyacrylamide (HAPAM) syn-thesis is as follows 80 g distilled water 149 g acrylamide(AM) 5 g sodium acrylate (acrylic acid and anhydroussodium carbonate) and 01 g 18-alkyl-dimethyl diallyl ammo-nium chloride (C

18DMAAC) were added into a three-necked

flask according to the literature [20] Adjusting the pH valueof the system was 60-70 and potassium persulfatesodiumhydrogen sulfite redox (003ndash005) were added The solu-tion was mixed and then bubbled with nitrogen for 30minto displace dissolved oxygen then quickly capped The poly-merization was carried out at 50∘C for 24 h Products wereprecipitated and purified by ethanol to remove unreactedmonomers and oligomers and then were baked in a vacuumdrying oven at the 50∘C to constant quality The polymermolecular structure was shown in Figure 2 and characteristicparameters were shown in Table 1

23 Solution Preparation The aqueous solutions (5000 ppm)of surfactant and polymer were always freshly prepared usinga mechanical stirrer for 8ndash10 h to form a consistent homo-geneous solution at a low rotation per minute Appropriatequantity of zwitterionic surfactants and hydrophobicallyassociating polymers were dissolved carefully in distilledwater for about 40min [21 22]

NO Na

CH CH2 CH CH2 CH CH2

CH2

NH2 CH3

CH3

CH3

(CH2)17

Cl

x y zC = OC = O

+ +minusminus

Figure 2 Molecular structure of hydrophobically associating poly-acrylamide (HAPAM) (theoretical mole percents of 119909 119910 and 119911wereabout 797 202 and 01 resp)

24 Measurement of Surface Tension and Interfacial TensionIn polymer-surfactant mixed systems polymer concentra-tions were 500 1000 1500 and 2000 ppm respectivelyand BS-12 concentrations were 10ndash2000 ppm The surfactantsolutionwith or withoutHAPAMas outer-phase was injectedinto the glass tube and 2 120583L air or oil as inner-phase wasput into the middle of the tube Then the tube was envelopedwith the plastic cover and put into the apparatus measuringthe surface tension or interfacial tension at a temperature of25∘C [3] In surface tension experiment the outer-phase waspolymer-surfactant mixed system and the inner-phase wasair Surface tensions of polymer-surfactant mixed systemswere measured at a rotating velocity of 6000 rpm whensurface tension reached a minimum value and stopped thetest In interfacial tension (IFT) experiment the outer-phasewas polymer-surfactant mixed system and the inner-phasewas dodecane Interfacial tensions of mixed systems weremeasured at a rotating velocity of 5000 rpm when interfacialtension reached a minimum value and stopped the test Indynamic interfacial tension (DIFT) experiment surfactantconcentration was selected to make oil-water interfacialtension minimum in different polymer concentrations andthen interfacial tensions of themixed systemas time changingwere measured a at a rotating velocity of 5000 rpm

25 Measurement of Apparent Viscosity In polymer-surfact-ant mixed systems the polymer concentration was 1500 ppmand BS-12 concentrations were 10ndash2000 ppm The viscositiesof polymer-surfactant mixed systems were measured byBrookfield DV-III viscometer with a shearing rate of 734 sminus1and at a temperature of 25∘C

26 Laser Light Scattering Experiment The diluted polymer-surfactant mixed system was dusted and filtered by theMillipore Corporation production of the disposable filterwith a 08120583mapertureThefiltratewas collected in the samplepool In the laser light scattering experiment toluene as astandard solution the laser wavelength was 532 nm and themeasured temperature was 25∘C [23 24]

According to the light scattering theory [25ndash27] weightaverage molecular weight (119872

119908) and root mean square radius

of gyration (⟨119877119892⟩) of polymers were measured by static light





HAPAM 6000000 250 800 146


(119870119862

119877VV (119902))

12

asymp (1

119872119882

)

12

(1 +1

6⟨1198772

119892⟩ 1199022

)

times (1 + 1198602119872119908119862)

(1)

where 119870 = 41205872

1198992

0(119889119899119889119862)

2

(1198731205824










119892⟩ and119872




119866(2)

(120591) = 119860 sdot (1 + 120573 sdot10038161003816100381610038161003816119892(1)

(120591)10038161003816100381610038161003816

2

) (2)


119892(1)

(120591) = int

infin

0

119866 (Γ) exp (minusΓ120591) 119889Γ (3)



119870119861119879(3120587120578119889) where 119870









0 500 1000 1500 2000 250025

30

35

40

45

50

55

60

65

70

75

Surfa

ce te

nsio

n (m

Nm

)


CMC




0 500 1000 1500 2000 250001

1

10

Inte

rfaci

al te

nsio

n (m

Nm

)






0 20 40 60 80 100 12001

1

10

Inte

rfaci

al te

nsio

n (m

Nm

)

Time (min)








0 500 1000 1500 20000

20

40

60

80

100

120


Visc

osity

(mPamiddots)


0 500 1000 1500 20000

5

10

15

20

25

30


10minus7M

wa

(gmiddotm

olminus1)


119908119886) of HAPAM




119892⟩)


0 500 1000 1500 20000

40

80

120

160

200


⟨Rg⟩

(nm

)


119892⟩) of HAPAM

10 100 1000 100000

5

10

15

20

25

30

35

()

Particle size (nm)




0 500 1000 1500 20000

30

60

90

120

150


⟨Rh⟩

(nm

)


ℎ⟩) of HAPAM


100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(a)

100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(b)

100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(c)








and ⟨119877119892⟩ of HAPAM




119908119886and ⟨119877



119908119886and ⟨119877



ℎ⟩)







ℎ⟩ is reduced


4 Conclusions








ℎ⟩)





Acknowledgments


References




















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





HAPAM 6000000 250 800 146


(119870119862

119877VV (119902))

12

asymp (1

119872119882

)

12

(1 +1

6⟨1198772

119892⟩ 1199022

)

times (1 + 1198602119872119908119862)

(1)

where 119870 = 41205872

1198992

0(119889119899119889119862)

2

(1198731205824










119892⟩ and119872




119866(2)

(120591) = 119860 sdot (1 + 120573 sdot10038161003816100381610038161003816119892(1)

(120591)10038161003816100381610038161003816

2

) (2)


119892(1)

(120591) = int

infin

0

119866 (Γ) exp (minusΓ120591) 119889Γ (3)



119870119861119879(3120587120578119889) where 119870









0 500 1000 1500 2000 250025

30

35

40

45

50

55

60

65

70

75

Surfa

ce te

nsio

n (m

Nm

)


CMC




0 500 1000 1500 2000 250001

1

10

Inte

rfaci

al te

nsio

n (m

Nm

)






0 20 40 60 80 100 12001

1

10

Inte

rfaci

al te

nsio

n (m

Nm

)

Time (min)








0 500 1000 1500 20000

20

40

60

80

100

120


Visc

osity

(mPamiddots)


0 500 1000 1500 20000

5

10

15

20

25

30


10minus7M

wa

(gmiddotm

olminus1)


119908119886) of HAPAM




119892⟩)


0 500 1000 1500 20000

40

80

120

160

200


⟨Rg⟩

(nm

)


119892⟩) of HAPAM

10 100 1000 100000

5

10

15

20

25

30

35

()

Particle size (nm)




0 500 1000 1500 20000

30

60

90

120

150


⟨Rh⟩

(nm

)


ℎ⟩) of HAPAM


100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(a)

100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(b)

100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(c)








and ⟨119877119892⟩ of HAPAM




119908119886and ⟨119877



119908119886and ⟨119877



ℎ⟩)







ℎ⟩ is reduced


4 Conclusions








ℎ⟩)





Acknowledgments


References




















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0 500 1000 1500 2000 250025

30

35

40

45

50

55

60

65

70

75

Surfa

ce te

nsio

n (m

Nm

)


CMC




0 500 1000 1500 2000 250001

1

10

Inte

rfaci

al te

nsio

n (m

Nm

)






0 20 40 60 80 100 12001

1

10

Inte

rfaci

al te

nsio

n (m

Nm

)

Time (min)








0 500 1000 1500 20000

20

40

60

80

100

120


Visc

osity

(mPamiddots)


0 500 1000 1500 20000

5

10

15

20

25

30


10minus7M

wa

(gmiddotm

olminus1)


119908119886) of HAPAM




119892⟩)


0 500 1000 1500 20000

40

80

120

160

200


⟨Rg⟩

(nm

)


119892⟩) of HAPAM

10 100 1000 100000

5

10

15

20

25

30

35

()

Particle size (nm)




0 500 1000 1500 20000

30

60

90

120

150


⟨Rh⟩

(nm

)


ℎ⟩) of HAPAM


100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(a)

100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(b)

100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(c)








and ⟨119877119892⟩ of HAPAM




119908119886and ⟨119877



119908119886and ⟨119877



ℎ⟩)







ℎ⟩ is reduced


4 Conclusions








ℎ⟩)





Acknowledgments


References




















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0 500 1000 1500 20000

20

40

60

80

100

120


Visc

osity

(mPamiddots)


0 500 1000 1500 20000

5

10

15

20

25

30


10minus7M

wa

(gmiddotm

olminus1)


119908119886) of HAPAM




119892⟩)


0 500 1000 1500 20000

40

80

120

160

200


⟨Rg⟩

(nm

)


119892⟩) of HAPAM

10 100 1000 100000

5

10

15

20

25

30

35

()

Particle size (nm)




0 500 1000 1500 20000

30

60

90

120

150


⟨Rh⟩

(nm

)


ℎ⟩) of HAPAM


100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(a)

100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(b)

100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(c)








and ⟨119877119892⟩ of HAPAM




119908119886and ⟨119877



119908119886and ⟨119877



ℎ⟩)







ℎ⟩ is reduced


4 Conclusions








ℎ⟩)





Acknowledgments


References




















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(a)

100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(b)

100

75

50

25

0010075502500

(nm

)

400

200

00

(120583m)

(c)








and ⟨119877119892⟩ of HAPAM




119908119886and ⟨119877



119908119886and ⟨119877



ℎ⟩)







ℎ⟩ is reduced


4 Conclusions








ℎ⟩)





Acknowledgments


References




















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of







ℎ⟩)





Acknowledgments


References




















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

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