Polymer Association Structures - American Chemical Society

Chapter 18

of

Colloidal Properties Surface-Active Cellulosic Polymer

Downloaded by PURDUE UNIV on July 5, 2016 | http://pubs.acs.org Publication Date: December 30, 1989 | doi: 10.1021/bk-1989-0384.ch018

K. P. Ananthapadmanabhan, P. S. Leung, and E. D. Goddard Specialty Chemicals Division, Research and Development, Union Carbide Corporation, Tarrytown, NY 10591 A new class of water soluble cellulosic polymers currently receiving attention is characterized by structures with hydrophobic moieties. Such polymers exhibit definite surface activity at air-liquid and liquid-liquid interfaces. By virtue of their hydrophobic groups, they also exhibit interesting association characteristics in solution. In this paper, results are presented on the solution and interfacial properties of a cationic cellulosic polymer with hydrophobic groups and i t s i n teractions with conventional surfactants are discussed. Aqueous solutions containing both polymers and surfactants are encountered i n a number of i n d u s t r i a l l y important areas such as detergents, cosmetics, pharmaceutics, p a i n t s , EOR, metal working/ hydraulic f l u i d s , and mineral/ceramic/material processing systems. In these systems, the polymers and surfactants can i n t e r a c t leading to marked changes i n such properties as v i s c o s i t y , s o l u b i l i z a t i o n capacity, i n t e r f a c i a l tension, w e t t a b i l i t y , foam s t a b i l i z a t i o n , adsorption, etc. A d e t a i l e d review of polymer-surfactant i n t e r a c t i o n s can be found i n references 1 to 4. Depending upon the actual system, the i n t e r a c t i o n s between the polymers and surfactants may or may not be desirable. For example, while the enhanced thickening and solub i l i z a t i o n e f f e c t s which can be encountered are often desirable, the p r e c i p i t a t i o n of polymer-surfactant complexes leading to depletion of reagents would generally be undesirable. However such complexes can be useful i n controlled release systems. In short, polymer-surfactant complexes have several i n t e r e s t i n g actual (and p o t e n t i a l ) a p p l i cations . Polymer-surfactant aggregates formed " i n - s i t u " i n s o l u t i o n can d i s s o c i a t e or change t h e i r structure depending upon the s o l u t i o n conditions. Such changes can be avoided by e i t h e r polymerizing app r o p r i a t e l y chosen structures of surfactants or by using preformed e n t i t i e s which combine the two features i n the same molecule. We r e f e r here to polymeric surfactants. The concept of polymeric surfactants i s not new. To some extent proteins themselves embody t h i s p r i n c i p l e . Strauss and co-workers studied "polysoaps" derived from 0097-6156/89/0384-0297S06.00/O « 1989 American Chemical Society

El-Nokaly; Polymer Association Structures ACS Symposium Series; American Chemical Society: Washington, DC, 1989.


298

POLVMER ASSOCIATION STRUCTURES

p o l y v i n y l p y r i d i n e i n the e a r l y 1950*s (5). Since then there has been considerable work with surface a c t i v e polymers f o r s t a b i l i z a t i o n of p a r t i c l e s i n non-aqueous media, but l i t t l e further work on water s o l uble hydrophobic polymers, u n t i l very recently when there has been a surge of a c t i v i t y (6-14). While on one hand attempts are being made to polymerize surfactant aggregates to obtain i n t e r e s t i n g c o n t r o l l e d release/membrane type structures, on the other hand major e f f o r t s are underway to synthesize novel hydrophobe modified polymers with i n t e r e s t i n g r h e o l o g i c a l , i n t e r f a c i a l and s o l u b i l i z i n g properties. In t h i s paper, the r e s u l t s on s o l u t i o n and i n t e r f a c i a l propert i e s of a c a t i o n i c c e l l u l o s i c s polymer with hydrophobic groups are presented. I n t e r a c t i o n of such polymers with added surfactants can be even more complex than that of "unmodified" polymers. In the past we have reported the r e s u l t s of i n t e r a c t i o n s of unmodified c a t i o n i c polymer with various surfactants investigated using such techniques as surface tension, précipitâtion-redissolution, v i s c o s i t y , s o l u b i l i z a t i o n , fluorescence, e l e c t r o k i n e t i c measurements, SANS,etc.(15-17). B r i e f l y , these r e s u l t s showed that as the concentration of the surfactant i s increased at constant polymer l e v e l s i g n i f i c a n t binding of the surfactant to the polymer occurred leading to marked increases i n the surface a c t i v i t y and v i s c o s i t y . These systems were able to s o l u b i l i z e water i n s o l u b l e materials at surfactant concentrations w e l l below the CMC of polymer-free surfactant s o l u t i o n s . Excess surfactant beyond that required to form stoichiometric complex was found to s o l u b i l i z e t h i s i n s o l u b l e complex and information on the structure of these s o l u b i l i z e d systems has been presented. In t h i s paper, the r e s u l t s on the i n t e r a c t i o n s of hydrophobe modified c a t i o n i c polymer with surfactants i s presented and the res u l t s are compared with those f o r the unmodified polymer. EXPERIMENTAL QUATRISOFT® LM 200, a c a t i o n i c c e l l u l o s i c polymer with hydrophobic groups, i s a product of Union Carbide Corporation as i s the c a t i o n i c c e l l u l o s i c polymer, Polymer JR. Both have a molecular weight i n excess of 100,000. T e r g i t o l NP 10, a nonyl phenol ethoxylate used i n t h i s study i s also a product of Union Carbide Corporation. Sodium dodecyl s u l f a t e i s a high p u r i t y sample purchased from EM Science Corporation. Pyrene which i s used as a fluorescence probe was obtained from A l d r i c h Chemicals Co. The surface tension of various solutions was measured by the Wilhelmy p l a t e technique with a sand blasted platinum p l a t e as the sensor. Fluorescence measurements were carried out using a PerkinElmer LS 5 spectrophotometer. The solutions f o r fluorescence measurements were prepared using pyrene saturated ( 10~^kmol/m^ ) water. The measurement i t s e l f was done by e x c i t i n g the samples at 332 nm and monitoring the emission i n the range of 360 to 520 nm. The v i s c o s i t y of the solutions was measured using the CannonFenske viscometer. The foam t e s t s were done by the conventional cyl i n d e r shake test i n which a fixed amount of the s o l u t i o n i s shaken vigorously f o r a minute and the foam height i s monitored with time. The surface pressure measurements were c a r r i e d out using a convention a l Langmuir trough set-up, again with a platinum p l a t e sensor. See text f o r further d e t a i l s .


18.

ANANTHAPADMANABHAN E T AL.

Surface-Active Cellulosic Polymer

RESULTS AND DISCUSSION


SURFACE ACTIVITY. The surface tension r e s u l t s f o r aqueous solutions of Polymer JR and Ouatrisof t are given i n Figure 1. The hydrophobe modified polymers c l e a r l y show more surface a c t i v i t y than the unmodif i e d polymer. The surface a c t i v i t y of the modified polymers as measured by the surface tension c r i t e r i o n i s only moderate compared to conventional surfactants which e x h i b i t ultimate surface tension v a l ues i n the range of 20-40 mN/m. The e f f e c t of the molecular changes r e s u l t i n g i n t h i s moderate surface a c t i v i t y can, however, be considerable on other properties of the polymer, as w i l l be shown i n subsequent sections. SURFACE PRESSURE. An a u x i l i a r y method to examine f i l m s adsorbed at the air/water i n t e r f a c e used the Langmuir trough. Although normally applied to spread i n s o l u b l e monolayers, we took advantage of the w e l l known c h a r a c t e r i s t i c of adsorbing high molecular weight polymers that, even from d i l u t e s o l u t i o n s , e.g. 0.01%, s u b s t a n t i a l accumulation w i l l occur at the surface i f s u f f i c i e n t time i s allowed(18). I t can be seen i n Figure 2 that over a 3-hour period the surface pressure r i s e s from about 2 to over 10 mN/m subsequent compression of the f i l m , corresponding to a three f o l d reduction of surface area, increases the surface pressure of t h i s d i l u t e polymer s o l u t i o n to as much as 20 mN/m. This behavior has i m p l i c a t i o n s regarding foaming where, owing to continual rearrangements such as bubble rupture and consequent r e s t r u c t u r i n g of the foam lamellae, l o c a l stresses w i l l r e s u l t i n continuous compressions and extensions of these lamellae. Given s u f f i c i e n t time, the r e l a t i v e l y non-surface a c t i v e Polymer JR also accumulates at the air/water i n t e r f a c e , and also develops addit i o n a l surface pressure on compression - but to a much lower extent than i t s surface a c t i v e counterpart. ASSOCIATIVE INTERACTIONS. Fluorescence c h a r a c t e r i s t i c s of pyrene i n solutions of Quatrisoft and Polymer JR are given i n Figure 3. The r a t i o of the i n t e n s i t y of the f i r s t p e a k ^ at 373 nm) to that of the t h i r d peak ( I 3 at 384 nm) i n pyrene fluorescence spectra has been used extensively to detect the formation of m i c e l l e s and other hydrophobic aggregates i n s o l u t i o n (19). This r a t i o has a value of 1.65 i n water, l . l i n surfactant m i c e l l e s , and 0.6 i n hydrocarbon o i l . The r e s u l t s given i n Figure 3 show that f o r Q u a t r i s o f t , the r a t i o decreases from 1.65 at 0.01% l e v e l to 1.25 at the 1% l e v e l . In the case of Polymer JR, the I 1 / I 3 r a t i o does not show any s i g n i f i c a n t reduction i n the above concentration range. In hydrophobe modified polymer s o l u t i o n s , pyrene i s s o l u b i l i z e d i n a r e l a t i v e l y hydrophobic environment somewhat comparable i n p o l a r i t y to surfactant m i c e l l e s . Comparison with r e s u l t s f o r sodium dodecylsulfate given i n the same figure show that, u n l i k e m i c e l l e formation, aggregation i n polymer solutions takes place over a wide range of concentration. I t i s therefore not a " c r i t i c a l " phenomenon of the phase transformation type.


299


300

P O L Y M E R ASSOCIATION STRUCTURES

POLYMER CONC, % Figure 1. Surface a c t i v i t y of unmodified (Polymer JR 400) and hydrophobe modified (Quatrisoft LM 200) c a t i o n i c c e l l u l o s i c poly mers as a function of polymer concentration. LANGMUIR F I L M BALANCE (0.01Z POLYMER)

Π SURFACE PRESSURE (DYNE/CM)

20

10

POLYMER JR-IOO

x

.91 FRESH

AGED

SURFACE

3 HOURS

COMPRESSED

Figure 2. E f f e c t of ageing and compression of adsorbed layers of unmodified and hydrophobe modified c a t i o n i c c e l l u l o s i c poly mers on t h e i r surface pressure. (Reprinted with permission from r e f . 21. Copyright 1985 A l l u r e d Publishing.)



18. ANANTIIAPADMANABHAN ET AL.


1.7i

. · JL

0,01

0.1

1,0

CONCENTRATION, %

Figure 3. The fluorescence c h a r a c t e r i s t i c s of pyrene i n s o l u tions of hydrophobe modified and unmodified c a t i o n i c c e l l u l o s i c polymers both i n the presence and absence of SDS.


301

302

POLYMER ASSOCIATION STRUCTURES

The concentration of pyrene i n the above tests corresponded to i t s saturation s o l u b i l i t y i n water which i s less than 10"6 kmol/m . Our past studies have shown that at such low l e v e l s the probe does not influence the properties of the system (20). The concentration of the probe can be increased i n solution by contacting the m i c e l l a r or other solutions containing associated hydrophobic structures with excess probe material. Pyrene and other organic materials i n such systems are s o l u b i l i z e d i n the hydrophobic region of the aggregates. The amount of pyrene s o l u b i l i z e d i s influenced by such factors as the s i z e and number of m i c e l l e s . When more than one pyrene molecule i s s o l u b i l i z e d i n a m i c e l l e and such systems are excited at a p a r t i cular wavelength, excited pyrene molecules tend to i n t e r a c t with ground state molecules to form excimers. Thus the extent of excimer formation i s an i n d i c a t i o n of the s i z e of the aggregate as w e l l as the f l u i d i t y of the region i n which the molecules are s o l u b i l i z e d . In the present study, excess pyrene was contacted with Quatrisoft solutions. I n t e r e s t i n g l y , the solutions d i d not show the formation of any excimer i n the system. The fluorescence spectra of solutions made up of pyrene saturated water, with or without subsequent contact with excess pyrene, exhibited e s s e n t i a l l y the same c h a r a c t e r i s t i c s . This indicates that the aggregates present i n Quatrisoft solutions are s i g n i f i c a n t l y smaller than conventional surfactant m i c e l l e s . These observations indicate that c e l l u l o s i c polymers, i n view of t h e i r r e l a t i v e r i g i d i t y , have l i m i t e d a b i l i t y to c o i l up, maximize hydrocarbon-hydrocarbon i n t e r a c t i o n s , and form aggregates capable of s o l u b i l i z i n g water insoluble materials. I t i s not, however, clear from these r e s u l t s as to whether the hydrophobic interactions detected by pyrene are due to inter-molecular or ihtra-molecular i n t e r actions. This aspect i s reexamined i n a subsequent section.


3

POLYMER-SURFACTANT INTERACTIONS. Interactions of the above types of polymers with surfactants are of importance I n a number of p r a c t i c a l applications. The interactions of surfactants such as sodium dodec y l s u l f a t e (SDS) with Polymer JR and Quatrisoft LM 200, as measured by changes i n the fluorescence c h a r a c t e r i s t i c s of pyrene, are shown i n Figure 3. Note that i n these tests the r a t i o of surfactant to polymer (by weight) was 1 to 100, and was maintained constant along the curve, unless otherwise s p e c i f i e d . I t i s evident that i n the case of Quatrisoft strong interactions between the polymer and the surfactant e x i s t even at concentrations as low as 10-2% polymer and 10"4% SDS. The interactions between the polymer and the surfactant follow the order: Quatrisoft LM 200 »Polymer JR. In f a c t , Quatrisoft showed d e f i n i t e i n t e r a c t i o n with SDS even when the surfactant was present at l e v e l s three orders of magnitude lower than the polymer (see Figure 3). In contrast to t h i s , Quatrisoft exhibited only marginal interactions with a non-ionic surfactant, T e r g i t o l NP-10. I t i s c l e a r from these r e s u l t s that while the primary force of i n t e r a c t i o n between the anionic surfactant and the polymer i s e l e c t r o s t a t i c i n nature, the presence of both c a t i o n i c and hydrophob i c groups i n the polymer makes the Quatrisoft LM 200/SDS i n t e r a c t i o n much stronger than that between Polymer JR and SDS. In Figure 4, the interactions between SDS and the polymers are shown at a p a r t i c u l a r l e v e l of polymer as a function of the concentration of



18.

ANANTHAPADMANABHAN ET A L


the surfactant. Note that, unlike the e a r l i e r p l o t , here the r a t i o of the polymer to surfactant decreases as the surfactant concentrat i o n increases. The sharp reduction i n I 1 / I 3 at concentrations w e l l below the CMC of SDS c l e a r l y show the presence of aggregates at such low l e v e l s , which are capable of s o l u b i l i z i n g pyrene. Again, i t i s clear that, while both Quatrisoft and Polymer JR i n t e r a c t strongly with SDS, the former with both c a t i o n i c and hydrophobic groups e x h i b i t s interactions at lower concentrations than Polymer JR. As the concentration of SDS i s increased, both systems show a p r e c i p i t a t i o n stage followed by complete r e d i s s o l u t i o n . The mechanism of p r e c i p i t a t i o n - r e d i s s o l u t i o n i n Polymer JR-SDS system has been examined i n d e t a i l (17) and s i m i l a r mechanisms can be expected to operate i n Quatrisoft-SDS systems as w e l l . While p r e c i p i t a t i o n i s due to n e u t r a l i z a t i o n of the c a t i o n i c s i t e s on the polymer by the added surfactant, r e d i s s o l u t i o n i s considered to be due to the i n t e r a c t i o n of the polymer with conventional surfactant micelles formed at higher concentrations(4). The c a t i o n i c polymer can be viewed as being "wrapped around" the anionic micelle or a group of micelles i n the l a t t e r case. Note that the fluorescence c h a r a c t e r i s t i c s of pyrene i n the r e d i s s o l u t i o n region tends to become s i m i l a r to that observed i n simple SDS m i c e l l a r solutions. A clearer picture of the configuration of the polymer i n s o l u t i o n can be obtained from the discussion given below on the v i s c o s i t y of polymer-surfactant s o l u tions. VISCOSITY. Changes i n the v i s c o s i t y of Quatrisoft LM 200 (0.5%) sol u t i o n s upon adding SDS are shown i n Table I . In the p r e - p r e c i p i t a t i o n region an increase i n the concentration of SDS i s found to i n crease the s o l u t i o n v i s c o s i t y markedly. In the post p r e c i p i t a t i o n region the v i s c o s i t y i s found to decrease with increase i n the surfactant concentration. The changes i n the v i s c o s i t y c h a r a c t e r i s t i c s of Quatrisoft solutions are s i m i l a r to those of Polymer JR s o l u t ions reported elsewhere (16) but the v i s c o s i t y reduction i s not as great. As mentioned e a r l i e r , adding SDS i n the p r e - p r e c i p i t a t i o n region r e s u l t s i n the n e u t r a l i z a t i o n of charges on the polymer. Under conditions of "complete" n e u t r a l i z a t i o n , p r e c i p i t a t i o n of the polymer-surfactant complex occurs. In general, n e u t r a l i z a t i o n of charges of a p o l y e l e c t r o l y t e can be expected to lead to a collapse of the extended polymer configuration and r e s u l t i n a reduction i n v i s c o s i t y . The presence of hydrophobic groups i n aqueous polymersurfactant complexes i n the p r e - p r e c i p i t a t i o n region, on the other hand, promotes associative i n t e r a c t i o n s between polymer molecules which would lead to enhanced thickening. In the present systems, these interactions are predominantly intermolecular i n nature, since i n t r a molecular interactions would have resulted i n a decrease rather than an increase i n s o l u t i o n v i s c o s i t y . For Polymer JR, the configuration of the polymer-surfactant complex i n the post p r e c i p i t a t i o n region i s more analogous to "polymer molecules wrapped around micelles"(17). For Quatrisoft more elongated structures with micelles bound through the polymer's hydrophobic groups, appear to be involved i n view of the r e l a t i v e l y higher v i s c o s i t i e s observed. The discussion so f a r has been l i m i t e d to polymer-surfactant interactions i n the bulk s o l u t i o n . In the section to follow, i n t e r actions at the a i r - l i q u i d interface are examined.



304


FOAMING. The foaming of Quatrisoft LM 200 was studied by the convent i o n a l c y l i n d e r shake t e s t . While the immediate foam height of Quatrisoft LM 200 was much higher than that of Polymer JR (30 ml vs. 10 ml), the foam decay r e s u l t s of Figure 5, show that the foam stabi l i t y of the former polymer i s also much greater. Quatrisoft LM 200 i n the adsorbed state w i l l have i t s hydrophob i c groups i n " a i r " and i t s h y d r o p h i l i c polymeric loops and t a i l s submerged i n the subsolution. Because of the polymeric nature of the h y d r o p h i l i c moiety, the v i s c o s i t y of the s o l u t i o n i n the lamellae region can be expected to be considerably higher than that observed i n conventional surfactant lamellae. Furthermore, the hydrophob i c groups of the adsorbed polymers may form hemimicelle type s t r u c tures at the l i q u i d - a i r i n t e r f a c e . The resultant viscous surface and subsurface regions are evidently responsible f o r the slow d r a i n age and the consequently long-term s t a b i l i t y of the foams generated by the hydrophobic polymer. THE DRAINING LAMELLA TEST. A s p e c i a l l y designed test c e l l , d e s c r i bed i n reference 21, was used to study the drainage c h a r a c t e r i s t i c s of polymer s t a b i l i z e d f i l m s . In t h i s procedure a s i n g l e , planar lamella of s o l u t i o n i s formed i n a glass frame by t i l t i n g the c e l l from the v e r t i c a l to the h o r i z o n t a l p o s i t i o n and then re-erecting i t (21). The lamella can be regarded as the u l t i m a t e l y simple model of a foam. A study of i t s s t a b i l i t y and drainage c h a r a c t e r i s t i c s can be viewed as r e f l e c t i n g these properties f o r a corresponding foam. Several c h a r a c t e r i s t i c s observed f o r lamellae formed from 1% solutions of the new polymer are noteworthy: 1. Lamellae are comp a r a t i v e l y t h i c k and uneven. 2. They drain very slowly. 3. They are l o n g - l i v e d . Lamellae from comparable solutions of weakly surface a c t i v e Polymer JR are very much less stable. C h a r a c t e r i s t i c s 1 and 2 above were noted by examining the films f o r l i g h t interference patterns. Most of the area of a p a r t i c u l a r f i l m was so t h i c k that no i n t e r f e r ence patterns were d i s c e r n i b l e . At best, s t r u c t u r e l e s s , i r r e g u l a r " s w i r l s " could be seen i n the uppermost region of the f i l m . For comparison, a "fast draining" surfactant f i l m shows a series of f a i r l y widely spaced, p a r a l l e l bands moving downwards quite r a p i d l y : A "slow d r a i n i n g " surfactant f i l m shows a pattern of more c l o s e l y , but s t i l l r e g u l a r l y spaced, and "wavy" interference bands moving more slowly downward as the f i l m drains. In conclusion, lowering surface tension, which translates i n t o some surface accumulation, while necessary f o r foaming, i s only part of the process. A companion e f f e c t i s the formation of viscous surface and subsurface layers which can s t a b i l i z e the lamellae. The new polymer would seem i d e a l f o r the l a t t e r e f f e c t . A depiction of the s i t u a t i o n p r e v a i l i n g i s attempted i n Figure 6 which shows i n t e r and intramolecular bonds between hydrophobic groups i n the polymer chains. Polymers which e x h i b i t these types of i n t e r a c t i o n are r e f e r red to as associating polymers. I t should be noted that considerable l e v e l s of surface v i s c o - e l a s t i c i t y were also detected i n adsorbed f i l m s of the polymer. The s i n g l e lamellae formed from 1% solutions of the new polymer had remarkable s t a b i l i t y . They generally lasted f o r several hours and i n some cases f o r a day or longer. The lamellae seemed completely s t a t i c , giving l i t t l e i n d i c a t i o n of drainage despite the


18.

ANANTHAPADMANABHAN ET AL.


305

1.7


SDS ALONE

QUATRISOFT LM 200 (0.1%) • SDS

-

10 '

10 SDS CONC, X

Figure 4. The fluorescence c h a r a c t e r i s t i c s of pyrene i n solutions of SDS i n the presence and absence of hydrophobe modified and unmodified c a t i o n i c c e l l u l o s i c polymers.

TIME, HRS

Figure 5. The s t a b i l i t y of foams formed i n the presence of hydrophobe modified and unmodified c a t i o n i c c e l l u l o s i c polymers.



306


Figure 6. A schematic of the draining of a foam lamellae formed i n the presence of a hydrophobe modified polymer. (Reprinted with permission from r e f . 21. Copyright 1985 A l l u r e d Publishing.)

Figure 7. The mousse test one minute a f t e r dispensing shows the s t a b i l i t y of foam generated by the hydrophobe modified polymer. (Reprinted with permission from r e f . 21. Copyright 1985 A l l u r e d Publishing.)


18. ANANTHAPADMANABHAN ET AL.


TABLE I EFFECT OF SDS ON THE SOLUTION VISCOSITY OF QUATRISOFT LM 200 QUATRISOFT LM 200 = 0.5%


SDS Conc.,%

V i s c o s i t y , cs

None 1x10-4 3xl0" 1x10*3 3x10-3 1x10" 1x10" 3X10" UO

3.6 4.7 4.7 5.0 350 Precipitation Precipitation 7.9 3 25

4

>0

2

1

1

JL

TABLE I I SYSTEM:

QUATRISOFT LM 200 0.1% (30 ml)

Additive None SDS (0.001%)

Foam Height, ml 24 h r . 17

Initial 30

1 hr. ** 26

3hr. 22

32

28

28

22

30

30

30

26

30

29

29

25

32

32

32

30

35

30

30

25

TEALS (0.001%) NH4LS (0.001%

L(EO) S0 2

(0.001%)

4

LAS (0.001%)

TEALS « Triethanolamine l a u r y l s u l f a t e , L(E0)2S04=Lauryl ethoxylated s u l f a t e , LAS = Linear alkylbenzene sulfonate.


307


308


fact that the f i l m s were so t h i c k . By contrast, single lamellae formed from the Polymer JR s o l u t i o n s , although i n i t i a l l y f a i r l y t h i c k , showed incessant a c t i v i t y ( i . e . , u n t i l f i l m rupture), with s w i r l s continually r i s i n g along the v e r t i c a l rods of the frame. These films seldom lasted more than 5-20 seconds. The dramatic d i f ference i n behavior of the two polymers i n the above test undoubtedl y helps to explain t h e i r considerable difference i n a b i l i t y to s t a b i l i z e an extruded foam. This i s obviously due to hydrophobic groups i n the new polymer. Yet another method of t e s t i n g foamability employs a pressurized aerosol container and the r e s u l t s have a d i r e c t a p p l i c a b i l i t y t o a new cosmetic form known as "mousse". This concept was employed with the hydrophobic and other c a t i o n i c polymers. In these experiments, a 1.0 wt.% aqueous s o l u t i o n of the polymer, with no extra additive other than the isobutane/propane propellant A-46, was charged to aluminum containers i n the r a t i o of 80 wt.% aqueous s o l ution and 20 wt.% propellant. Photographs of generated foam a f t e r 1 minute standing show the foam produced using the Quatrisoft LM 200 was stable;when using Polymer JR and another c a t i o n i c polymer, the foam collapsed (see Figure 7). The foam generated using the Quatrisoft was found to be stable up to about 90 minutes when i t collapsed. This aspect of the work i s described i n d e t a i l e l s e where (6). FOAMING OF POLYMER-SURFACTANT SYSTEMS. As discussed e a r l i e r , Quatrisoft LM 200 e x h i b i t s strong interactions with surfactants such as SDS at extremely low concentrations. I t i s therefore r e sonable to expect polymer-surfactant combinations to have a marked influence on the foaming c h a r a c t e r i s t i c s of the i n d i v i d u a l components. Foam data f o r Quatrisoft LM 200 i n the presence of a number of surfactants, as measured by the cylinder shake t e s t , are given i n Table I I . Note that the concentration of the anionic surfactants i s two orders of magnitude lower than that of the polymer. At t h i s l e v e l , they do not seem to a f f e c t the i n i t i a l foam height s i g n i f i cantly. The e f f e c t of surfactants i s to increase the long term s t a b i l i t y of the foam and t h i s e f f e c t appears to be s i g n i f i c a n t . In the presence of anionic surfactants, i t i s reasonable to expect that the hydrophobic groups of the polymer and of the surfactant would combine to form a mixed f i l m at the l i q u i d - a i r i n t e r f a c e . The interactions between the c a t i o n i c groups of the polymer and the anionic groups of the surfactant would further strengthen the i n t e r actions i n the monolayer. These e f f e c t s can be expected to increase the surface and sub-solution v i s c o s i t y i n lamellae and i n turn enhance t h e i r s t a b i l i t y . LITERATURE CITED 1. 2. 3.

Saito, S. Colloid Polym. Sci. 1979, 257, 266. Breuer, M. M.; Robb, I.D. Chem. Ind. 1972, 530 Robb, I.D. In Anionic Surfactants in Physical Chemistry of Surfactant Action; E. H. Lucassen-Reynders, Ed.; Dekker: New York, N.Y. 1981, p 109. 4. Goddard, E. D. Colloids and Surfaces 1986, 19,255; 301. 5. Strauss, U.P.; Jackson, J. Polym. Chem. Ed. 1951, 6, 649.



18. ANANTHAPADMANABHAN ET AL.

309 Surface-Active Cellulosic Polymer

6. Landoll, L. M. Polym. Sci., Polym. Chem. Ed. 1982, 20, 443 7. Camp, R. L., U. S. Patent 4,354,956, Oct. 19. 1982 8. Nagai, K.; Ohishi, Y.,; Inaba, H.; Kudo, S. J. Polym. Sci Polym. Chem. Ed. 1985, 23, 1221. 9. Fendler, J. H. Israel J. of Chemistry 1985, 25, 3 10. Schulz, D. N.; Kaladas, J.J.; Maurer, J. J.; Bock, J.; Pace, S. J.; Schulz, W. W. Polymer 1987, 28, 2110 11. Hamid, S. M.; Sherrington, D. C. Polymer 1987, 28, 325. 12. Jahns, E.; Finkelmann, H. Colloid and Polymer Sci. 1987, 265, 304 13. Valint, P. L.; Bock, J. Macromolecules 1988, 21, 175. 14. Binana-Limbele, W.; Zana, R. Macromolecules 1987, 20, 1331 15. Goddard, E. D.; Hannan, R. B. J. Colloid Interface Sci. 1976, 55, 73 16. Leung, P. S., Goddard, E. D.; Han, C.; Glinka, C. J. Colloids and Surfaces 1985, 13, 47 17. Ananthapadmanabhan, K. P.; Leung, P. S.; Goddard, E. D. Colloids and Surfaces; 195, 13, 63 18. Lion, S. J.; Fitch, R. M. In Polymer Adsorption and Dispersion Stability; Goddard E. D.; Vincent B., Eds.; ACS Symposium Series No.240; American Chemical Society: Washington, DC, 1983; pp 185-202. 19. Thomas, J. K. The Chemistry of Excitation at Interfaces; ACS Monograph 181; American Chemical Society: Washington DC, 1984. 20. Ananthapadmanabhan, K. P.; Goddard, E. D.; Turro, N.J.; Kuo, P. L. Langmuir 1985, 1,352-355. 21. Goddard, E. D.; Braun, D. B. Cosmetics and Toiletries 1985, 100 (7), 41-47. RECEIVED September 12, 1988


Polymer Association Structures - American Chemical Society

Recommend Documents