In oduc ion
Mixed sys ems o mac omolecules and amphiphiles a e
ubiqui ous in echnical p oduc s (polyme ±su ac an
mix u es) and ha e a e y b oad ole in biology
(biopolyme ±lipid mix u es) [1, 2]. Con olling he
in e ac ions be ween mac omolecules and low-molecu-
la -weigh amphiphiles is he key o echnical pe o -
mance and biological unc ion [3].
Depending on he combina ion o a mac omolecule
and an amphiphile, he in e ac ion a ies and, as a
consequence, he mac oscopic beha io . Thus a ious
ypes o polyme s beha e qui e die en ly, i.e., cha ged
polyme s e sus nonionic, ca ionic e sus anionic,
homopolyme s e sus g a o comb copolyme s, e c.
Ea ly in es iga ions ocused on wa e -soluble homopol-
yme s in e ac ing wi h simple su ac an s, bu in ecen
yea s much in e es has conce ned mac omolecules wi h
p onounced amphiphilic cha ac e . Amphiphilic syn-
he ic polyme s comp ise a wide ange o g a , block
and s a copolyme s, while biological examples include
nucleic acids, p o eins and lipopolysaccha ides.
Associa ion and seg ega ion
Because o he low en opic d i ing o ce o mixing,
polyme ±polyme ±sol en sys ems ha e a s ong en-
dency o seg ega i e phase sepa a ion, i.e., wo solu ion
phases en iched in ei he polyme esul . Amphiphiles
show a s ong endency o sel -assemble in o micelles
and o he s uc u es. Since hese ha e a high eec i e
molecula weigh , seg ega ion also becomes a ypical
ea u e o mixed polyme ±su ac an solu ions [4].
The condi ions o seg ega ion a e en i ely die en
i one o he cosolu es, polyme o su ac an , is ionic.
Then he la ge en opic con ibu ion om he coun e -
ions becomes a s ong d i ing o ce o mixing.
An app eciable a ac i e in e ac ion be ween poly-
me and su ac an will modi y he si ua ion and wo
impo an phenomena a e
1. The binding o su ac an o he polyme .
2. An associa i e phase sepa a ion.
Piculell e al. [5] ha e iden i®ed h ee dis inc ly die en
ypes o su ac an binding o polyme s
P og Colloid Polym Sci (1999) 112 : 157±162
ÓSp inge -Ve lag 1999 POLYMERS
M.G. Miguel
E. Ma ques
R. Dias
S.M. Mel'niko
A. Khan
B. Lindman
Associa ing polyme ±su ac an sys ems
In i ed lec u e, 12 h Con e ence o he
Eu opean Colloid and In e ace Socie y,
Dub o nik ± Ca a , 1998
M.G. Miguel
1
áE. Ma ques
1
áR. Dias
1
S.M. Mel'niko áA. Khan
B. Lindman (&)
Physical Chemis y 1
Cen e o Chemis y
and Chemical Enginee ing
P.O. Box 124, S-22100 Lund, Sweden
Pe manen add ess:
1
Depa amen o de QuõÂmica
Uni e sidade de Coimb a
P-3049 Coimb a, Po ugal
Abs ac Some ecen illus a ions
o he phase beha io o polyme ±
amphiphile sys ems in solu ion a e
p esen ed. Su ac an ±polyme asso-
cia ion is demons a ed o a ious
amphiphilic syn he ic and biological
polyme s bo h on a mac oscopic and
on a single molecula le el.
Key wo ds Polyme ±su ac an sys-
ems ± Associa ion and seg ega ion ±
Phase beha io ± Su ac an sel -
assembly ± Ca anionic esicles
1. An ionic su ac an associa es wi h an opposi ely
cha ged polyme .
2. An ionic su ac an shows a s ong endency o
associa e o a sligh ly hyd ophobic, o a weakly
pola , polyme .
3. All su ac an s associa e o polyme s wi h s ongly
hyd ophobic pa s, o example, hyd ophobically-
modi®ed wa e -soluble polyme s.
In cases 1 and 2 he in e ac ions a e bes desc ibed in
e ms o a lowe ing o he c i ical micelle concen a ion
(cmc) o he su ac an and in case 3 in e ms o he
o ma ion o mixed micelles be ween polyme and
su ac an .
Typical phase diag ams
An aqueous mix u e o a a he hyd ophobic polyme
and a nonionic su ac an can phase-sepa a e in o one
dilu e solu ion and one concen a ed iso opic phase. As
illus a ed in Fig. 1, he ex en o phase sepa a ion
inc eases wi h inc easing empe a u e; his is due o he
dec eased pola i y o bo h su ac an and polyme a
highe empe a u es.
A e y s ong endency o associa i e phase sepa a-
ion is displayed by polyelec oly es mixed wi h oppo-
si ely cha ged su ac an s [7±13]. He e a co ec
ep esen a ion o he phase diag am is no possible in
he con en ional iangula diag am, bu a h ee-dimen-
sional ep esen a ion, ep esen ing he comple e ou -
componen sys em, is equi ed. In Fig. 2 he ypical
beha io is gi en in he illus a i e h ee-dimensional
py amid diag am. Wa e is placed a he op and he ou
sides o he py amid base a e assigned o he ou ionic
componen s o he sys em, wi h ions o he same cha ge
loca ed a opposi e sides. As can be seen, he e a e wo
wo-phase egions. In he low-sal one he e is an
associa i e phase sepa a ion, i.e., he su ac an and
he polyelec oly e o m a concen a ed phase in equi-
lib ium wi h a e y dilu e solu ion. A high sal
concen a ions he e is a seg ega i e phase sepa a ion,
i.e., he e is one su ac an - ich and one polyme - ich
solu ion. A in e media e sal concen a ions a homoge-
nous solu ion is o med. The py amid ep esen a ion
ce ainly con ains mo e in o ma ion han he no mally
used iangula ep esen a ion, in which one dimension
is omi ed, bu due o he dicul ies o ep esen he
py amids, iangula phase diag ams a e o be p e e ed
in many cases.
DNA and ca ionic su ac an s phase-sepa a e
associa i ely
The phase diag ams o DNA in combina ion wi h
die en ca ionic su ac an s ha e been in es iga ed. As
illus a ed in Fig. 3, he e is, as o he analogous
Fig. 1 Hyd ophobic in e ac ions be ween a su ac an and a polyme
may induce an associa i e phase sepa a ion; ypically his inc eases
wi h inc easing empe a u e. The phenomenon is exempli®ed by he
aqueous mix u e o an oxye hylene nonionic su ac an , C
12
E
4
,and
a nonionic polyme , e hyl(hyd oxye hyl) cellulose. F
1
e e s o an
iso opic one-phase egion and F
2
o an iso opic wo-phase egion.
F om Re . [6]
Fig. 2 A polyelec oly e and an opposi ely cha ged su ac an
ypically phase-sepa a e associa i ely a low elec oly e concen a ions
and seg ega i ely in he p esence o high sal con en s; a in e media e
elec oly e concen a ions, he e is miscibili y. The ``sail'' hanging
om he py amid op co esponds o he wo-phase egion. The dilu e
phase is loca ed o he uppe igh side, and he concen a ed phase o
he lowe side o he ``sail''. The example shown is hyalu onan, an
anionic polysaccha ide, and e adecyl ime hylammonium b omide,
a ca ionic su ac an . F om Re . [14]
158
polyelec oly e±su ac an sys ems [7], a s ong endency
o associa i e phase sepa a ion. Fo DNA he ole o
hyd ophobic polyme ±su ac an in e ac ions has o be
u he examined.
DNA compac ion in he p esence
o ca ionic su ac an s ± an illus a ion o associa ion
Wi h ¯uo escence mic oscopy i is possible o isualize
indi idual high-molecula -weigh DNA molecules [15].
Because o he high cha ge densi y, DNA in aqueous
solu ion exhibi s a highly ex ended coil s a e a low
elec oly e concen a ions. DNA compac ion o a glob-
ule esul s on sc eening he elec os a ics [16].
On addi ion o ca ionic su ac an , DNA compac ion
akes place [17]. A lowe su ac an concen a ions,
he e is a egion o coexis ence o coils and globules
(Fig. 4).
Ca ionic su ac an binding o DNA is s ongly
coope a i e [18] and is bes desc ibed as a DNA-induced
su ac an sel -assembly; di ec suppo o his iew
comes, apa om om s uc u al in es iga ions, om
he ac ha he ``binding iso he ms'' a e shi ed o he
die en su ac an alkyl chain leng hs in he same way
as he no mal cmc.
Su ac an -induced compac ion o a high-molecula -
weigh polyme molecule can be seen as a single-
molecula analogy o he associa i e phase sepa a ion.
The die en pa s o he DNA molecule s i e in he
p esence o he su ac an o o m a concen a ed
domain.
Ca anionic esicles
Mixed ca ionic±anionic su ac an sys ems, e e ed o
as ca anionic su ac an s [19], oe excellen possibili ies
o con ol he cha ge densi y o sel -assemblies [20]. A
pa icula ly in e es ing ea u e is he o ma ion o
he modynamically s able esicles [21]. In he phase
diag am, he wa e - ich pa o which is schema ically
indica ed in Fig. 5, he e a e wo egions o esicle
o ma ion. In one he esicles ha e a ne nega i e cha ge,
in he o he a ne posi i e cha ge. One o ou main
Fig. 3 DNA phase-sepa a es associa i ely wi h ca ionic su ac an s.
A simpli®ed wo-dimensional ep esen a ion o he p elimina y esul s
is gi en o he hexadecyl ime hylammonium b omide±DNA sys em
Fig. 4 Fluo escence mic oscopy isualizes ha he compac ion o
single DNA is induced by ca ionic su ac an s. As shown o he case
o dodecyl ime hylammonium b omide, DNA has an ex ended coil
s a e a low su ac an concen a ions aand a compac globule s a e
a high concen a ions c; a in e media e concen a ions he e is
coexis ence o coils and globules b
159
cu en in e es s conce ns he in e ac ion o ca anionic
esicles wi h polyme s [22].
Vesicle±polyme in e ac ions
The in e ac ion o esicles wi h a ne nega i e cha ge
and wo ca ionic cellulose de i a i es ha e been s udied:
one o hese (LM 200, he e deno ed HMP
+
) was o he
hyd ophobically modi®ed ype, while he o he (JR 400,
o P
+
) was no .
While he phase diag am (Fig. 6) is no ye well
in es iga ed in de ail, some gene al ea u es can be
singled ou :
1. Wi h excess polyme o excess su ac an , a homoge-
nous iso opic solu ion o ms.
2. In a b oad in e media e ange, associa i e phase
sepa a ion esul s.
3. The e is a close analogy wi h espec o phase
sepa a ion wi h p e ious s udies o polyme ±micelle
sys ems.
Rheological in es iga ions wi h P
+
show a iscoelas ic
beha io (Fig. 7). Fo HMP
+
he o ma ion o gels is
e y p onounced.
C yogenic ansmission elec on mic oscopic in es i-
ga ions (Fig. 8) display many no able ea u es, such as
he di ec isualiza ion o he polyme -induced esicle
associa ion and he o ma ion o ace ed esicles.
Simila ly DNA was obse ed o induce an associa ion
o esicles wi h a ne posi i e cha ge.
Fo hcoming wo k
Polyme ±su ac an associa ion in aqueous sys ems is
a esul o hyd ophobic and elec os a ic in e ac ions.
Su ac an sel -assembly is a gene al ea u e o hese
sys ems. I he polyme i sel is hyd ophobically associ-
a ing, pa icula ly s ong polyme ±su ac an associa-
ion akes place esul ing in e alia in iscosi ying and
gela ion.
In his accoun , we ha e p esen ed some ecen
illus a ions aken om an ongoing collabo a ion be-
Fig. 5 Schema ic ep esen a ion o he app oach used o he s udy o
he phase beha io o polyme -ca ionic esicle mix u es; he su ac -
an s s udied a e didodecyldime hylammonium b omide (DDAB)and
sodium dodecylsul a e (SDS). F om Re . [19] Fig. 6 Compa ison o phase maps o mixed polyelec oly e±su ac -
an sys ems show ha anionic micella (SDS) and esicula (SDS±
DDAB) sys ems beha e simila ly; he phase limi s a e gi en as a
unc ion o polyme and su ac an cha ge o wo ca ionic cellulose
de i a i es, JR 400 and LM 200. Lines a lowe su ac an cha ge:
coace a ion/p ecipi a ion bounda ies; lines a highe su ac an
cha ge: edissolu ion bounda ies. Fo any gi en sys em, he egion
be ween he wo bounda ies is a wo-phase egion. F om Re . [19],
da a o micella sys ems om Re s. [23±24]
Fig. 7 Mix u es o he ca ionic polyme JR 400, and ca anionic SDS±
DDAB esicles ha e a much highe elas ic (G¢) han loss modulus (G¢¢)
o e a wide ange o equencies; da a a e gi en o a o al su ac an
concen a ion o 5 mM and h ee die en polyme concen a ions
(0.50, 0.75, and 1.00 w %) a 25 °C. F om Re . [19]
160
ween ou g oups in Coimb a and Lund. The wo k on
ca anionic su ac an sys ems is om he PhD hesis
wo k o Edua do Ma ques and an ex ensi e accoun can
be ound in his hesis [25]. The wo k jus s a ed on he
phase beha io o DNA±su ac an and on DNA±
ca anionic esicle in e ac ions is he diploma wo k o
Ri a Dias. A ull accoun o his wo k, wi h de ailed
expe imen al ®ndings and expe imen al echniques, will
be p esen ed la e .
Acknowledgemen s The PhD s udies o Edua do Ma ques and his
s ay in Lund we e mainly suppo ed by JNICT and P axis XXI
h ough a esea ch s uden ship (BD/9295/96) and in pa by he
Cen e o Amphiphilic Polyme s (CAP) in Lund. The pos doc o al
s ay o Se gey Mel'niko in Lund was suppo ed by he Royal
Swedish Academy o Science and he Swedish Na u al Sciences
Resea ch Council. Ri a Dias is an EU E asmus exchange s uden .
The isi ing p o esso ship o Ma ia Miguel was suppo ed by he
CAP.
Fig. 8 C yogenic ansmission
elec on mic oscopy mic o-
g aphs o aqueous mix u es o a
ca ionic polyme , LM 200, and
ca anionic esicles wi h a ne
nega i e cha ge show a numbe
o in e es ing ea u es, such as
polyme -induced esicle clus-
e ing and ace ed esicles.
Scale ba 100 nm. F om
Re . [25]
161

Re e ences
1. Jo
Ènsson B, Lindman B, Holmbe g K,
K onbe g B (1998) Su ac an s and
polyme s in aqueous solu ion. Wiley,
New Yo k
2. Kwak JCT (ed) (1998) Polyme ±su -
ac an sys ems. Su ac an science se-
ies, ol 77. Dekke , New Yo k
3. Godda d ED, Anan hapadmanabhan
KP (eds) (1993) In e ac ions o su ac -
an s wi h polyme s and p o eins. CRC
P ess, Boca Ra on
4. Piculell L, Lindman B (1992) Ad
Colloid In e ace Sci 41:149
5. Piculell L, Lindman B, Ka ls o
ÈmG
(1998) In: Kwak JCT (ed) Polyme ±
su ac an sys ems. Dekke , New Yo k
1998, p 65
6. Zhang K, Ka ls o
Èm G, Lindman B
(1994) J Phys Chem 98:4411
7. Lindman B, Thalbe g K (1993) In:
Godda d ED, Anan hapadmanabhan
KP (eds) In e ac ions o su ac an s
wi h polyme s and p o eins. CRC
P ess, Boca Ra on, p 203
8. Iliopoulos I, Wang TK, Audebe R
(1991) Langmui 7:617
9. Magny B, Iliopoulos I, Audebe R,
Piculell L, Lindman B (1992) P og
Colloid Polym Sci 89:118
10. Hansson P, Almg en M (1995) J Phys
Chem 99:16684
11. Hansson P, Almg en M (1995) J Phys
Chem 99:16694
12. Hansson P, Almg en M (1996) J Phys
Chem 100:9038
13. An hony O, Zana R (1996) Langmui
12:1967
14. Thalbe g K, Lindman B (1991) In:
Mi al KL, Shah DO (eds) Su ac an s
in solu ion, ol 11. Plenum, New Yo k,
p 243
15. Bus aman e C (1991) Annu Re Bio-
phys Biophys Chem 20:415
16. G osbe g AYu, Khokhlo AR (1996)
Gian molecules. Academic P ess, Lon-
don
17. Mel'niko SM, Se geye VG, Yoshika-
wa K (1997) In: Pandalai SG (ed) Recen
esea ch de elopmen s in chemical sci-
ences, ol 1. T answo ld Resea ch Ne -
wo k, T i and um, India, p 69
18. Hayakawa K, Kwak JCT (1991) In:
Rubingh DN, Holland PM (eds) Ca -
ionic su ac an s: physical chemis y.
Dekke , New Yo k, p 189
19. Khan A, Ma ques E (1997) In: Robb
ID (ed) Specialis s su ac an s. Chap-
man & Hall, London, p 37
20. Lindman B, Khan A, Ma ques E,
Miguel MG, Piculell L, Thalbe g K
(1993) Pu e Appl Chem 65:953
21. Kale EW, Mu hy AK, Rod iguez BE,
Zasadzinski JA (1989) Science 245:
1371
22. Ma ques E, Rege O, Khan A, Miguel
MG (1999) Langmui 15:642
23. Guilleme F, Piculell L (1995) J Phys
Chem 99:9203
24. Godda d ED, Hannan RB (1977) J Am
Oil Chem Soc 54:561
25. Ma ques E (1998) PhD Thesis. Uni -
e sidade de Coimb a, Po ugal
162