152 Macromolecular Solutio~

changes in poly.er solution properties is studied in detail for selected polymersurfactant co.binations. Specifically the effect of interactions between chargedand uncharged polyacrylamides and sodium dodecylsulfonate or dodecyla8ine hydro-chloride, on the polyeer solution properties such as surface tension, relativeviscosity, conductivity and precipitation behavior is considered in this paper.

Macr

Preci~40000the df

shake!ainutl

EXPERIMENTAL nte r.

LSIOO(

analy!

polys.vice.

Pol~rs: C-14 labeled nonionic (PAM) and ionic sulfonated acrylamide (PAMS) oraminiated acrylamide (PAKD) based polyuers were synthesized using radiationinduced heterogeneous polyuerization technique (Wada, Sekiya and Machi. 1975.1976). This polymerization technique was selected over other methods because inthe present study it is required that polymers not be conta.inated ~ surfactants

and other 8Odifiers. A description of the synthesis and characterization technique

has been given elsewhere (Koudgil. 1981).","~~~~;.4,

'-z~"1

;':

~

i

~Interis poMuratRobincbargsurfsto beviscobetwecondubetwehydrothanacticmdifsurfacondl

Anionic copolymers (PAHS) were synthesized using 3 .01 % of 2-acrylaaido -2-methylpropane sulfonic acid (AMPS) a product of Lubrizol Corp. as a CO8Onomer.

Cationic polyacrylamides (PAHD) were synthesized using 3 mol % of di_thylaaino-propyl~thacrylam1de (DHAPHA) as the cow>nomer. This reagent _8 received as astabilized liquid from Jefferson Che8ical Coapany. The hydroquinone inhibitor wasrew>ved by passing a 50:50 aqueous solution of this reagent through an activatedcarbon coluBn. The aqueous solution was used i8mediately after the inhibitorre~val stage.

Molecular weight of the respective P9lymers estimated ~ measuring the intrinsicviscosity using a capillary viscometer was detel"ained to be 2.2 laillion for non-ionic P9lyacrylamide PAM. 2.6 8illion for anionic P9lyacrylamide PAMS and 1.9million for cationic P91yacrylaaide PAND.

Sodium dodecylsulfonate: This Cheaical was purChased fro. Aldrich ChemicalCompany and was reported ~ the manufacturer to be 99.9+% pure. It was used witb-out further purification.

Dodecylya.ine hydrochloride: This chemical was a product of the Eastman KodakCompany and was used as received.

PAH-~

""ie8Ui

SurfE

~lc

and t

surfi

Bulfc

pre8t

mlec

8uIfc

Incrt

of 81

I Inorganic reagents: Fisher certified NaOH and HCI were used for pH 8odification.ACS Reagent Grade NaCI, a product of Amend Drug and Chemical Company, was used foradjusting the ionic strength.

-6Water: Triple distilled water of specific conductivity of about 10 8ho from aglass still and collected in a gla8S container was used in this investigation.

TECHNIQUES

Surface tension was measured ~ the Wilhelmy Plate Hethod using a sandblastedplatinum plate sensor supported from the arm of a Cahn aicrolBlance (Hodel 2000).Surface tension and all other measurements, unless otherwise specified, were cOn-ducted at roo. te8perature (25°C).

No sviscoin to'

J

~vt8CexpeIndlcapaniqu

Conductivity was w.asured using an A. H. Thomas Co., Model 275 conductivity Eter.

Relative viscosity 8easure8ents were conducted at 30°C using a suspended levelUbbelohde capillary visco8eter.

~~~i~~~~molecular Solutiom 153

,;.~-:~~;ii~pitation studies involved 8ixing different amount of sulfonate or amine and,<~ mg/kg of the polymer such that the resultant solution contained 1000 mg/kg of;;i~ desired polymer and a given concentration of the surfactant. The aixture was

;;':~en overnight in a wrist action shaker and centrifuged at 15,000 rpm for 10..c"1I\Ites. The supernatant was analyzed for the residual polymer and the surfactant.

, '-

rom~ SoIUtioaaor selected polYilerons b!tween charged

dodecylaltine hYdro-tensioo, relativered in this paper..

~residual amount of C-14 labelled polyJDers was determ.ined using a Beck_n Mode;~lQOC spectrophoto8eter (liquid scintillation counting technique). Surfactant:~lysis was conducted using a two phase titration 8ethod. It was confirmed that~tyacrylamide type polyJDers did not interfere with the surfactant analysis and~~~ versa (Moudgil. 1981).

:yIaldde (PAHS) orling radiation,nd Machi, 1975,~thods because iniated by surfactant.

:terization techniqueRESULTS AND DISCUSSION

acry la8ido -p. as a CO8OnOGer

of dimethylaaino-was received as .inone inhibitor' w.rough an activatedthe inhibitor

~i2:!?:!£. Polymer and Surfactant Interaction

~teraction between nonionic polyacrylamide (PAM) and sulfonate or aminej4cpossible through hydrocaroon chain interaction and hydrogen bonding (Arai.~ata, and Shinoda. 1971; Fishman and Eirich. 1971; Jones. 1967; Lewis and,~~nson, 1970; Saito, 1967; Schwuger. 1973; Tadros. 1974). Since there is no~rge on the polymer, electrostatic type of interaction ~tween PAM and the-aurfactant is not expected. With chain-chain interaction the polr-er is expected...

,~behave like a polyelectrolyte which is characterized ~ higher relative,~.cosity than of the poly.er alone. Depending upon the extent of interaction"~en the polymer and the surfactant species. there could ~ a decrease in the~ductivity of the 8ixture as co.pared to that when there is no interaction;;~een the two. Surface tension also is exected to ~ higher When there is\ydrocaroon chain interactin ~tween a hydrophilic polr-er and an ionic surfactant~ in the absence of the polymer. If on the other hand, the associative inter-~tions are not significant and the presence of the two species results only in~difications in the solvent power of the medium then instead of an increase in~face tension a decrease -y ~ obt.ained. The relative viscosity and~uctiVity under these circu88tances mayor -y Dot ~ affected.

ich CheaicalIt was used with-

r pH 8Odification.8pany, ws used for

~~lfO~~. Surface tension, relative viscosity, conductivity and precipitation~lts for this systea are presented in Figures I, 2, 3 and 4, respectively.~face tension of sulfonate in the presence of 1000 mg/kg PAM was determined to~lover up to 10-3 kIIOl/.3 , than that of the solution containi!l8 only sulfonate:~ higher when the sulfonate concentration was in excess of 10-3 kn>I/m3 . The~face tension was o~erved to attain a constant value at about 7.5 I 10-3 kmol/m3~1fonate. The decrease in surface tension below 10-3 kmol/.3 sulfonate in the:esence of PAM could have been caused by "salting out- of the sulfonate_~ecules. The decrease in dy/3 log CT' on the other hand with increase inc~fonate concentration suggests that, the n>nomer activity in the bulk is nototreasing in the presence of PAM, as in the a~ence of it, indicating some type

,;association collpleI foraation.

mho from a

tigation.

,~'ignificant cltange. however. was observed in the precipitation. relative~COSity and conductivity results suggesting that association complexes if formed:,the bilk are not significant enough to affect these Easure~nts."", .:~Aa1n~ . i e. As shown in Figures 2. 3 and 5. no significant change in the relative~"' cos t .:,~r18eY' conduct1vity and prec1pitation results were observed under the present~i ntal conditions wbeu polyacrylaaide and dodecylamine were mixed. This~p.~ted that. either there was no interaction between the pol~r And thp ..inp,~'Ue.ew:~ modifying the polymer 8Olecule oonfor88tion or. the 8eal,:: e not sens1tive enough to detect the changes caused by SI

onductivity _ter,

iuspended level

~

:ing the intrinsic! million for non-Ie PAHS aDd 1.9

a sandblBstedlace {Model 2000).!cified, ~re con-

156 Macromolecular Solutions

In sUalary. associative bilk interactions iX!tween nonionic polyacrylamide and oothanionic sulfonate and cationic aaine under the tested conditions are considered

negligible.

Mac!

Siailarly ~rRed PolY8er and Surfactant Interactions

In polyaer and surfactant systems where roth the species carry si8ilar m.rges..electrostatic type interactions can be ruled out. The possibility of chain-chaininteractions between the polyacrylamides and the surfactants, because of therelatively longer carron chain of the functional groups attached to the polY1Ers,-y be higher than similar interactions with non ionic polyacrylamides. In additionto associative type bilk interactions, changes in different properties -y also b!caused by mdifications in the solvent power of the .diu..

PAMS-Sulfonate. The surface tension data presented in Fig. 6 is sillilar to thatobtained forthe PAM-Sulfonate 8ystem indicating the fo~tion of associative typecoaplexes. The relative viscosity and conductivity results presented in Figs. 7and 8 respectively, suggest that either there was no associative type bulk inter-action between PAMS and sulfonate a>lecules or the changes caused by such inter-actions were not significant enough to modify the bulk solution properties.

~~;.-

~'""1A;?~~~

:/

~~

't~,"

~

PAHD-Aaine. No change was observed in the conductivity and precipitation behavioras a result of mixing the cationic polyacryla.Ide and amine indicating that theextent of the bilk complexation. 1£ any. was not 8ignificant (See Fig8. 9 and 10).The relative vi8co8ity re8u1t8 in the pre8ence30f 1000 .g/kg polymer on the band.were found to be lower up to a)x)ut 10-3 k801/. a.Ine and to be similar to solutioncontaining polymer and HaC1 above it (See Fig. 11). The lowering of the relativevisco8ity is indicative of the polymer charge neutralization Which i8 not possiblein the present ca8e since ooth the species are 8i.Ilar1y charged. The rea8on forthi8 ana.o1y is not known at pre8ent.

Summarizing the above discussion it is noted that in the case of PAMS and sulfon-ate and PAHD and amine the two siailarly charged polymer-surfactant systeas, therewas no substantial associative bulk interaction between the different species.

I

Oppositely Charged Polymer and Surfactant Interactions

In systems where the polymer and the surfactant are oppositely charged, hydrogenbonding and electrostatic, as well as chain-chain. interactions can be expected(Goddard and Hannan, 1976. 1977). Changes in bulk solution properties may alsooccur through modifications in the solvent power of the .ediua. Electrostaticinteractions should result in lowering of the relative viscfJsity and conductivity.Coaplexation between oppositely charged species can. on the other band. lead alsoto bulk precipitation.

PAMS-Amine. The PAMS polymer reing opositely charged to dodecylaaine can reexpected to interact electrostatically with the amine aolecules. In fact visualobservation of a IRixture of the two did indicate the for8ation of a fiocous pre-cipitate Which redissolved in the solution upon increasing the amine concen-tration. This pbenO8eDOn of precipitation and redissolution of the coaplex appear!to be si8ilar to tbat observed in 81ltivalent ions/sulfonate &ysteas (Celik.1981).

Results obtained for the relative viscosity of amine and PAHS systea (Figure 7)showed a minimum with increase in amine concentration and the position of theminimum corresponded to the point of maximum precipitation. However, the concen-tration at Which coaplete redissolution of the precipitate occurred, was deter-

fr~"' '-i~-"--

.I,

,~

:I ~,"

,~

'I

Macromolecmar Solutions MacromP AMSIIUfI F ACT ANT

, ~u_T_-2»'C

-0- NoCI + POI. YMEA

-6-ax.-TE + PCX.YMEA

'-0-- -- + POI. YMEA

...106

A&J-..A.>-

to

~>'

1. ,

I III I " >. - I

... ~.. &

1

158

"I '

<

,

;;~I. 111111111- I 1.10 ... 10-4 ~ r ,..1

~ENTMTII* -'-'

Fig- 7. Effect of addition of surfactant (dodecylsulfooateldodecylam1ne) on the relat1ve v1scosity of PAHS (anionic polyacrylamide)-

'~fACTANT

,It. "'~0.3_°-9--- M.fONATE IN TOW--0 IN TOW-0-- ~ +'AMI 11 '-6- aJLfONA TE + "-0--.+ "

-'

e:",p

I

1

<to2

"'-

~~

102

~

101

~-

':~, -' , ~..~" ~, ~'. ~ v

10'0 . 12 18 a 38 .

V-C-:-1.10.2'C~3,1I

Fig. 8. E!fect of addition of PAHS GanfDnic pqlya~ry~1de)on the conductivity of dodecylsulfonate and dbdetylam1ne.

':-a...'e.g

1

)1ecuIsc Solutions Macromolecular Solutions 159

PAMD!SURFACTANT1~

103

~e7.1~O.2---9--- SULFONATE IN TDW- -<>- - AMINE IN TOW

-0- NaC1 + PAMD (1000 mg/kg)-6- SULFONATE + ..

-0- AMINE + ...."I

..'ei

~~

<

late!.c.rylaaide) .

~

102

, ',

~

". '.V'-, -" ,"~, , , ... ..."

...

~

...'0

101

4 8 12 16 20 24 28

VC-(x10-2) (kmol/m3)'h

Fig. 9. Effect of addition of PAHD (cationic poly.crylaaide)on the conductivity of dodecylsulfonate and dodecylamine.

e)

Macromolecular Solutions Mactine,to irof ttevidtby tl

1~ -P_AMINE ~7.I~U

NTIAL ~ -- -. .1-

i- i~

- s..2

!ciIII~

i;..

~"""" ,Intel

pIeci

1 - I

- ~~-~t were

n .a1produ

The rva. 1aqueoappar.1:1 1occur

I-. ;. -;. I I I . I ':4 -;; ;:;

1VfM. 'I,0-'

Redls:zatlolFia. 10. Effect of dodecy~1De concentration on the pr~1-

p1t.at1on behavior of PAHS (cationk po1yacry~14e) alldiodecyl8a1De aixture.

This I

.lreat

PAKD-~

aI;O-"i

inatl<

itate

into t

_¥TMT

p.. ~~'J.1~1.a-.T_-"C-o-~. --6- ft .--~R-0- - . -- Y.aR

The SIJ

polyaethe PA

two sp

. D

~-..;;.~

Re8ultfl&ure10-3 kand 8U

I~.

prec1p.~ .~. .. ~ ~ ~~_T-.~

Pia. 11. Effect of addition of 8Urfactant (dodecy1sulfonate/dod~y~) on the relative viscosity of pAHI) (cationicpolyacry~ide) .

,-I'SoIutiom 161

to be lower than that at which the relative Vi8cosity of the aixture .tarted~'t:o tacruse (see Fig. 12). This observation -y te ~rtly attrit.1ted to the effect

.:l~:the Increa.e in ionic strength on viSCO8ity. Conductivity .easurements are:~~:;::"~~ntly DOt senaitive under high ionic .trengtb conditions to the change. cau.ed

:'~;;.~~,the precipitation/redi8so1ution phe_oa.

,"'" ..C-r . , -- _.!-,- ,- i

~- ,

~

of the anionic pol~r with the cationic 8urfactant: leading to th~

- can be represented by the following reaction~ -n +~.(; P + na.. PI.~;,;: n

}~' I. - [P-I1). [1.+)11-::.-:' ap +c~ -n

::;; 101 [P ) - log K -11 101 [I. ):,]\~ 'p~.~ere p-n is the anionic polyacrylaaide with n negatively charged sites with wtlich

~~IaiDe rot- ~lecule8 react to for. precipitate PI . ~ i8 the solubility~-, n en

,tOduct. -r

" +",!be reaction constant for tbe precipit8tion can be obtained by plotting log [J ):';~.. log [rn]. In view of the fact tbat otber dtarged co.plexe8 my exi.t in the-~_s phase. any ut~te of the solubility product ay only te considered as ani,parent "Blue. U8uaing that there are no other c08plexe8 in the 8Y8te8 and only.1:1 interaction between the pol~r functionsl group and the 8ui!actant species

eecar. the solubility product ~sp was utiuted to te 3.3 x 10- .

'c,ta.ulolution of the precipitate can take place either due to 8icellar solubili-

:'~tion or due to co8plexation in the following anner

.cC +-

".:~i1

i-

prKi-

PI. + 88.' - (n J'-n 0+.

this co.plexation caD result froa the dhain-chaiD interaction of an aaine aolecule

already bound to the polr-er electro8tatically.

:'~Sulfonate. The PAHD polYMr being oPpo8itely marKed to the sulfonate can~o be expected to interact electrostatically in th, bulk eolution. Visual exa.-.s.&tion of a 8ixture of the two clearly indicated the fo~tion a fibrous precip-itate Which, however unlike in the case of PAMS-A8ine &yste8 did not redissolve.tuo the solution upon increasing the concentration of the sulfonate.

,"sults fot' the conductivity, relative viaco8ity and precipitation studies (Seeli'rfea 9, 11 and 14 re8pectively) provide support for the contention that above10- k.ol/m3 8ulfonate concentration 8ignificant bulk complexation between PAMD

.~ sulfonate mlecules ia occurriaa.

w'

':~ interaction of the sulfonate with the cationic polyacrylsaide leading to

,'~ipitation can be represented ~:

p+n + nR # PRn

; ~ -Ip+n). [i n). sp

-" log [ p+n) . 101 K - n log [r]." sp

I

164 Macromolecular Solutions+nwhere P is the concentration of the Charsed polyacrylaaide Which reacts with n

8O1ecules of sulfonate a- to for. PR precipitate.n

Macrom(.-Jones, M.

oxide.-Lewis, K.

sulfatScl..

Moud""if[,- !

Procas., Saito, S.

Colloi

Schw;a8r-;-polYSl

Somasundarthe. 0

"'Tadro8, 1118OdiU8

pol~528-53

Wada. T.,poly.e~-

Wada, T..polyac~, 32

The reaction co_tanto as before, can be obtained by plotting log concentration ofthe polr-er as a function of the log concentration of the sulfonate. Once aaaiD.assua1ng the absence of other CO8plexes and only 1: 1 interaction between PAM» 14functional group. and the sulfonate 8)lecules. I: va. esti_ted to be 1.6 z 10- ,

'pThe absence of redissolution ..y be indicative of the 8echanis. responsible forsolubilizing the precipitaje forme~. The solubility limit of the sulfonate wasdeterained to ~ 7.2 x 10"" k-.l/r. If solubilization of the precipitate wasoccurring through co.plexation, some evidence of it in terms of higher residualpolyaer content and possibly higher relative viscosity 8hould have ~en obbtained,which was not. On the other hand it is conceivable that the CHC of the systea wasaoove the solubility li.it of the 8ulfonate and therefore, micellar solubilizationdid not occur under the present experiaental conditions.

~~t\,;i'r'~

,

!11:';f

<X>NCLUSIONS

Based on the above discussion it can be concluded that DO significant bulkinteraction occurs between DOnionic polyacryleaide and the anionicdodecylsulfonate or the cationic dodecyleainehydrochloride. On the other hand, inthe case of the oppositely charged polr-er and surfactsnt systems bulkcomplexation takes place to a significant extent. Also, dependins on the ionicoature of the poly.er and the surfactant they csn precipitate and in 808e casesthe precipitate thus for.ed can redissolve upon increasins the surfacantconcentration. Redissolution of the precipitate is suggested to occur eitherthrough 8icellar eolubilization and/or coaplexation. It is to be noted that thetype of modification observed in the bulk properties here can conceivably resultin 88jor chanses in che adsorption behavior of different species at variousinterfaces and thereb, affect processes such as froch flotaCion and flocculation.

ACKNOWLEDGEMENTS

The authors wish to thank Dr. ~. P. Aaanthapad8anabhan for helpful discu8sions andHrs. Regina Gorelik for help in e~perimentation. Partial financial support of thisinvestigation ~ the National Science Foundation (Grant No. DAR-79-o9295) and theINCO, Inc. ia a180 acknowledged.

REFERENCES

'Arai. B.. !tArata. H.. and Sbinoda. 1:. (1971). The interaction between polYlEr and8urfactant: the c0ap08ition of the CO8plex between polyvinyl pyrrolidone and8odiua alkyl 8ulfate a8 revealed ~ surface ten8ion dialyai8 and8olutdlization. J. Colloid Interface Sci.. 37.22)-227.

Celik. H. (1981). In annual progress repo~"Ad8orption of surfactants andpolyaer. on reservoir aiDerala,. ~ SO8aaundaran. P.. Coluabia Univer8ity. New

.I York.Fish8an. H. L. and Eirich. F. R. (1971). Interaction8 of aqueou8 poly

(n-vinylpyrrolidone) with 8Odiua dodecyl sulfate I-equilibriua dialy.i.aea8ureaent8. J. Phys. Chea. 75 . 3135-3140.

Goddard. E. D.. an~Bannan. R. B. ~1976). Catioaic polyaer/aaionic surfactantinteractions. J. Colloid Interface Sci., 55. 73-79.

v Goddard. E. D. and Bannan. R. B. (1977). Poly;er/.urfactant interactions. I. ~-

Oil Chea18t8_'~. -~. 561-566