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Miscibility of poly(styrene-co-acrylic acid) with polymethacrylates or poly(methacrylate-co-4-vinylpyridine)
Eur. Polym.J. Vol. 31, No. 7, pp. 665-669,1995 Copyright0 1995Elsevier Science Ltd Printed in Orcat Britain. All rights reserved
0014-3057/95 $9.50+ 0.00
MISCIBILITY OF POLY(STYRENE-CO-ACRYLIC ACID) WITH POLYMETHACRYLATES OR POLY(METHACRYLATE-CO-4-VINYLPYRIDINE) FATIMA FERAZ, ASSIA SIHAM HADJ HAMOU and SAID DJADOUN* Institute of Chemistry, University of Sciences and Technology Houari Boumediene, BP 32 El Alia, Algiers 16111, Algeria (Received I2 April 1994; accepted in final form 28 June 1994) Abstract-The miscibility of poly(styrene-co-acrylic acid) with polymethacrylates or poly(methacrylateco+vinylpyridine) was studied by differential scanning calorimetry and inverse gas chromatography using decane, octane and benzene as molecular probes. The results showed that poly(isobutyl methacrylate) is immiscible with styrene-acrylic acid copolymers of different acrylic acid content as evidenced from the appearance of two glass transition temperatures determined with both techniques. Positive values of the apparent polymer-polymer interaction parameter x23 (app.) obtained with all probes in the temperature range 160-180°C over the entire blend composition confirm the immiscibility of these blends. Blends of the former styrene-acrylic acid copolymers are, however, miscible in all proportions with poly(ethy1 methacrylate), poly(ethy1 methacrylate-co-4-vinylpyridine) and poly(isobuty1 methacrylateco-Cvinylpyridine). A single composition dependent-glass transition temperature and negative values of xz3 (app.) were obtained with these blends
It is well known that polymers are generally immiscible with each other. The miscibility of a pair of polymers has been attributed in most cases to some specific intermolecular interactions between the components of the blend [l-7]. it has also been shown that a homopolymer and a random copolymer may form a miscible blend even in the absence of specific interactions provided strong intranolecular repulsions exist between the comonomers [8-12). Inverse gas chromatography and differential scanning calorimetry have been extensively used to interpret the miscibility of polymer blends [13-231. Polystyrene is immiscible with poly(ethyl methacrylate) and poly(isobuty1 methacrylate). In the present study, the miscibility of poly(styrene-co-acrylic acid) with poly(ethy1 methacrylate) or poly(isobuty1 methacrylate) or poly(ethy1 methacrylate-co-4-vinylpyridine) or poly(isobuty1 methacrylate-co4-vinylpyridine) was examined by differential scanning calorimetry (DSC) and inverse gas chromatography (IGC) using decane, octane and benzene as molecular probes. Glass transition temperatures (r,) and apparent polymer-polymer interaction parameters xzs were used to determine the miscibility of these blends.
15% by weight, we have also synthesized copolymers of (1) styrene and acrylic acid (SAA-20 and SAA-32) containing respectively 20 and 32 mol.% of acrylic acid and (2) of ethyl methacrylate and 4-vinylpyridine (EM4VP-8 and EM4VP23) and of isobutyl methacrylate and Cvinylpyridine (IBM4VP-10) containing respectively 8, 23 and 10 mol.% of 4-vinlypyridine. The styrene content in the SAA copolymers was determined by U.V. spectroscopy as previously described (131 and by titration with a base in benzene-methanol mixture. The 4-vinylpyridine in the EM4VP or IBM4VP copolymers was also determined by U.V. spectroscopy and elemental analysis. Intrinsic viscosities of these polymers in butanone at 23 or 25°C are summarized in Table 1. The molecular weights of PME (Mw = 1.004 x 106) and PIBMA (M, = 1.43 x 106) were calculated from the intrinsic viscosities measured in butanone at 23°C and using the Mark-Howink-Sakurada equation [24].
EXPERIMENTAL Polymerization and polymer characterization
Using Chromosorb W AWDMCS 80/ 100 mesh, obtained from Johns Mainville as a solid support, chromatographic columns of 9% polymer loading were prepared in the usual way [14]. The IGC measurements were carried out on HP 5730A gas chromatograph equipped with a dual flame ionization detector. Helium was the carrier gas and methane the non-interacting marker. A small amount (0.1 ~1) of benzene or decane or octane used as molecule probes was injected manually using a Hamilton syringe. The specific retention volume Y, (ml/g) of the molecular probe was measured in the temperature range 6C-180°C from the following relation Y,=t,.F,J,/w
Poly(ethyl methacrylate) (PEM) and ply(isobuty1 methacrylate) (PIBMA) were prepared by free radical polymerization. In a similar way, controlling the conversion below *To whom all correspondence
IGC and DSC measurements
where J rate of mixture column
should be addressed. 665
(1)
is the James-Martin correction factor, F the flow carrier gas at 273 K w, the polymer or polymer loading weight and tN the net retention time. A containing the inert support only was prepared in
666
Feraz et al.
Fatima Table Copolymer mol.% of A.A.
Polymer PME PIBMA EM4VP-8 EM4VP-23 IBM4VP-IO SAA-20 SAA-32
I. Characteristics composition mol.% of 4VP
n 0 0 0 0 20 32
of polymers Intrinsic
0 I) X 23 IO 0 0
@l/d
viscosity
TE by DSC ( ‘C)
1.56 I 76 I.51 1.16 I .38 0.37 0.55
14.5 69 77.5 86.5 15.5 II2 129.5
a similar way and used to correct the specific retention volume of the probe from the contribution of the support. The glass transition temperatures of these polymers and of the studied blends were first determined by IGC and then using a PerkinElmer DSC-7 Differential Scanning Calorimeter at a heating rate of 20K/min under nitrogen blanket. Each sample was scanned at least twice. The blends used in DSC measurements were prepared by coprecipi-
(a non-solvent) as molecular probe are in good agreement with those determined by DSC. The positive deviation of these T, values from the weight average of the TBs of the pure components is considered as an evidence of strong polymer-polymer interactions. The Kwei equation [25]
tation.
7‘ii = (n’, T,, + k w2 Tg2)l(w, + kw,) + q w, w2 (2) was used to estimate the attractive interactions between the two polymers. In this equation k and q are adjustable parameters; w, and wr are the weight fractions of the components. When k = 1, the equation above can be written as
RESULTS
AND DlSCUSSIONS
Glass transition temperatures
As shown in Fig. 1, the two “Z-shaped” curves corresponding to the glass transition temperatures of the constituents of the blend observed in the retention diagram In V, vs the reciprocal of the temperature show qualitatively that PIBMA is immiscible with SAA-20. Similar results were also confirmed by DSC. Poly(ethy1 methacrylate) was, however. found to be miscible in all proportions with the same acidic copolymer SAA-20, as evidenced from the appearance af a single glass transition temperature for all the blends as displayed in Figs 2 and 3 which shows as an example, the retention diagrams for the 1: I ratio blend of this system; one “Z-shaped curve” only at around 96°C is observed. Similarly blends of SAA-20/EMWP-8, SAA-32/EMWP-23 and SAA20/IBM4VP-10 were all miscible as confirmed from the single composition dependent-glass transition temperature as illustrated in Fig. 4. As summarized in Table 2 the T, determined by IGC using n-decane
15
SO
100 Temperature
125
150
(“C)
f-lg. 2. DSC thermograms of SAA-20 (a), PME (b) and of their blends containing 20%(c), 33%(d), 49%(e) and 63%(f) of SAA-20 respectively.
r
2.2
(3)
2.4
2.6
2.8
3.0
1000/T Fig. 1. Retention diagrams of SAA-20 (O), PIBMA (0) and SAA-20/PIBMA 1: 1 ratio (0) using benzene as a probe.
2.2
2.4
2.6
2.8
3.0
3.2
1000/T Fig. 3. Retention diagrams of SAA-20 (O), PME (+) and SAA-20/PME I:1 ratio (A) using deeane as a probe.
Poly(styrene-co-acrylic acid) with polymethacrylates
667
Table 3. q values of SAA-20/IBM4VP-IO, SAA-IOIPME, SAA-2O/EM4VP-8 and SAA32/EM4VP-23
System
q Value
SAA-ZO/IBMQVP- IO SAA-2OIPME SAA-ZOIEMIVP-8 SAA-32lEM4VP-23
0.5 16.0 20.0 41.0
We have also analysed the glass transition temperature-composition results using the third power equation [26] from 70 , 0
(T, - r,, )/(T*, -T,,)Wzc=(l+K) 0.2
0.4
0.6
08
1.0
Weight fraction of SAA-20 or SAA-32 Fig. 4. Glass transition temperature as a function of SAA-20 or SAA-32 content in SAA-20/IBM4VP-10 (0, SAA20/EM4VP-8 (m) and SAA-32/EM4VP-23 (a).
where q is a measure of the specific interactions between the constituents of the blend. We have applied this latter equation to the SAA-20/PME, SAA-20/EM4VP-8, SAA-32/EM4VP-23 and SAA20/IBM4VP-10 blends. As shown in Table 3 the q value increased as the densities of interacting species in the polymeric chains was raised. The obtained results show that steric effects play an important role, in that stronger specific interactions are observed with SAA-20/EM4VP-8 blends than in SAA20/IBM4VP- 10 systems. The miscibility of these blends has also been analysed from the width of TB as shown in Fig. 5. Sharper transitions characteristic of blend miscibility are observed with SAA-32/EM4VP-23 blends. As the polymer-polymer interactions decrease, broader transitions are observed as in the case of SAA20/IBM4VP- 10 blends.
- (K, + Kr ) Wr, + Kr WE
(4a)
where the corrected weight fraction of component of highest glass transition temperature W, is given by W, = KWJ(Wi + KU’,) and K = pI TBIlpz Tg
(4b)
with W, , W,, T,, and Tg2are the weight fractions and glass transition temperatures of the constituents 1 and 2 of the blends; p 1 and pZ are their respective densities. Equation (4a) reduces to (T, - T,,)/(T,, - T’,)W, = 1 for
volume
(T, - T,,)/(T,,
(4)
additivity
K, = Kl = 0. A plot of - T,, ) W,, as a function of W,, will
give a straight horizontal line about unity. Figure 6 shows the plot of (T, - T,,)/ for SAA-2O/PME, SAA(T, - Tg,W’2, vs W2c 20/IBM4VP-10 and SAA-32/EM4VP-23 blends. The results confirm that stronger specific interactions as characterized by large positive deviation from volume additivity are observed for SAA-32/EM4VP23 blends and weaker interactions occurred for SAA-20/IBM4VP-10 systems as compared to SAA20/EM4VP-8 blends. Polymer-polymer
interaction parameter
To interpret the miscibility of these blends, we have
also, in the usual way, determined Table 2. Glass transition temperatures as determined by DSC and IGC usinp: decane as a probe System
T,(“C) (DSC)
Ts(“C) (IGC)
112 129.5 74.5 77.5 86.5 75.5
110 130 74 80 87 -
86.5 91.5 98 101
85.5 89.5 96 101.5
SAA-20/EM4VP-8 (1: 2) SAA-20/EM4VP-8 (I : I) SAA-20/EM4VP-8 (2 : I )
95.5 98.5 104
94.5 97.5 104
SAA-32/EM3VP-23 SAA-32/EM4VP-23 SAA-32/EM4VP-23 SAA-32/EM4VP-23
104.5 114 117.5 121.5
119 -
SAA-20 SAA-32 PME EM4VP-8 EM4VP-23 IBM4VP- 10 SAA-ZO/PME SAA-ZO/PME SAA-ZO/PME SAA-ZO/PME
(I : 4) (1: 2) (I : I) (2: I)
(I : 4) (I : 2) (1: I) (3 : I)
SAA-20/IBM4VP-IO(I:4) SAA-20/IBM4VP-lO(l:2) SAA-20/IBM4VP- IO (I : 1) SAA-ZO/IBM4VP- 10 (2 : I)
81.5 90 93 98
the apparent
21
18
12
0
0.2
0.4
0.6
0.8
1.0
Weight fraction of SAA-20 or SAA-32
94 100
Fig. 5. Glass transition temperature width for SAA20/IBM4VP-IO (m) and SAA-32/EM4VP-23 (0) blends vs SAA-20 or SAA-32 content.
668
Fatima Feraz et
al.
3.0
3r r
0
I
I
I
I
0.2
0.4
0.6
0.8
I I.0
-3
-
0
W?c
interaction
0.6
parameter
~~~(app.) for
each blend using various probes from
where u, w, and 4 are respectively the specific volume, weight fraction and volume fraction; subscripts 2 and 3 refer to polymer 2 and polymer 3. Table 4 summarizes the values of Xz3(app.) of the SAA-20/PIBMA systems. The positive values obtained with all probes in the temperature range 160-180°C over the entire composition of the blend confirm the immiscibility of these blends. These results in agreement with those reported by Paul et al. [27], confirm that due to steric effect, there are no strong interactions between the carboxylic groups Table 4. Apparent
polymer
parameters
for SAA-20iPIBMA
blends
Probe
160 C
17O’C
180°C
SAA-2OiPIBMA
(I : 3)
BetK?en+Z /I,(aPP.) Octane d?,(aPP.I DeGme ZZT(WP.)
0.776 0.704 0.192
0.624 0.513 _
0.737 0.689 0 380
SAA-2O/PIBMA
(I : I I
BtXLeWZ Octane DeGiIVZ
L,,(aPP.) AJiG+PP.) ki@PP.)
0.604 0.665 0.229
0.438 0.888 0.087
0.561 I.002 0.171
SAA-ZO/PIBMA
(3: I)
Bell2enlZ Octane DGme
/?iNPP.) X!I(“PP.) iz,G+PP.)
0.560 0.293 0.32
0.739 0.476 0.100
I.097 0.390 0.243
Table 5. Apparent
polymer-polymer
Phase
mteractmn
parameters
Probe
for SAA-ZO/PME
blends
IWC
170°C
180°C
(I : 4)
Benzene octane Decane
Xz,@PP.) X*,@PP.) X&PP.)
-0.481 -0.375 -0.310
- 0.404 -0.518 -0.604
- 1.033 -0.725 -0.807
SAA-ZO/PME (I : 2)
Benzene octane DW%Ie
Xu@PP.) Xx(aPP.) xx(aPP.)
- 1.729 -2.113 - 1.805
-1.642 - 2.072 -2.174
- 1.773 - 1.890 - I.769
BeIUetle
X23@PP.)
Octane
Uvp.)
Lkcane
X*,(aPP.)
-0.429 -0.757 -0.864
-0.228 -0.573 -0.875
-0.278 -0.587 -0.665
SAA-2O/PME
SAA-ZO/PME (2: I)
I.0
and the ester groups of the PIBMA. The contribution due to the repulsions between the two comonomers in the SAA-20 is not sufficient to ensure the miscibility of these blends. As the alkyl group of the polymethacrylate becomes smaller, specific interactions occurred between the acidic groups of SAA-20 and the ester groups of poly(ethyl methacrylate) and led to miscible blends in all proportions. Negative values of ~~,(app.) as shown in Table 5 were obtained with all these blends in the temperature range 160-180°C. In this temperature range, the In VP varied linearly with the reciprocal of the temperature. The apparent polymer-polymer interaction X13(app.) varied for all probes with the blend composition and goes through a maximum of interactions located around 67% of PME. Figure 7 shows, as an example, the variation of x13(app.) vs the blend composition for the SAA-20/PME. systems.
polymer mteractwn
PhWZ
0.8 SAA-20
Fig. 7. Composition dependence of X2,(app.) at 170°C for blends of SAA-20 with PME using benzene (A), octane (m) and decane (0) as probes.
Fig. 6. Glass transition temperture-composition of SAA-32/EM4VP-23 (O), SAA-20/PME (0) and SAA20/IBM4VP-10 (*) blends according to the third power equation. polymer-polymer
0.4
0.2
Weight fraction of
Poly(styrene-co-acrylic Table 6. Apparent polymer-polymer
acid) with polymethacrylates
669
interaction parameters for SAA-2O/EM4VP-8 blends
Phase
PrObe
xz3kvu.)
160°C
170°C
180°C
SAA-20/EM4VP-8
(I :2)
Benzene Octane Decane
Uapp.) zz3(app.)
-0.609 - 1.290 - I.480
-0.635 - 1.302 - 1.425
-0.356 -1.007 -1.465
SAA-20/EM4VP-8
(I : I)
Benzene Octane Decane
xIl(app.) xzI(app.) x2] (app.)
-0.288 -0.647 -0.825
-0.095 -0.574 -0.877
+0.261 -0.128 -0.669
Benzene
x,(app.)
SAA-20/EM4VP-8
(2: I)
Octane Decane
~~~(app.) ~~~(app.)
+ 0.282 -0.338
+0.109 - 0.392
+0.191 -0.287
-0.449
-0.551
-0.441
Table 7. Apparent
polymer-polymer
Phase
interaction
parameters
Probe
x23hw)
for SAA-20/IBM4VP-IO
blends
160°C
170°C
180°C
- I .399 - 1.068 -1.016
-1.063 - 1.083 -0.999
(I :4)
Benzene Octane Decane
xz3(app.)
x&w.)
- I.538 - I .205 -1.371
SAA-20/IBM4VP-IO
(I :2)
Benzene Octance Decane
x&app.) x2,(app.) x2,(app.)
-0.378 -0.310 -0.204
-0.183 -0.204 -0.006
-0.053 -0.145 +0.056
(2: I)
Benzene Octane Decane
x23 (wp.)
SAA-20/IBM4VP-IO
x2](app.) r,,(aou.)
+0.170 -0.183 + 0.039
+0.317 +0.071 +0.040
+0.335 +0.233 +0.060
SAA-20/IBM4VP-IO
The introduction by copolymerization of a small amount of 4-vinylpyridine within the chains of not only poly(ethyl methacrylate) but also poly(isobuty1 methacrylate) has led to miscible blends of these copolymers with SAA-20. Strong specific interactions between these copolymers are characterized by negative values of x2,(app.) as shown in Tables 6 and 7. Due to steric effects, a slightly higher content of 4-vinylpyridine incorporated within the poly(isobuty1 methacrylate) led, however, to less specific interactions with the carboxylic groups of the SAA-20 copolymer.
4. A. S. Hadj Hamou, S. Djadoun and F. E. Karasz. Polym. Prep. 34, 815 (1993). 5. S. Djadoun. Polym. Bull. 9, 313 (1983). 6. E. M. Pearce, T. K. Kwei and B. Y. Min. J. Macromolec. Sci. Chem. A21, 1181 (1984). 7. L. C. Cesteros. E. Meaurio and I. Katime. Macromelecules 26, 2323 (1993). 8. G. ten Brinke, F. E. Karasz and W. J. MacKnight. Macromolecules 16, 1827 (1983). 9. S. Cimmino, F. E. Karasz and W. J. Macknight. J. Polym. Sci. Part B, Polym. Phys. 30, 49 (1992).
10. J. Kressler, H. W. Kammer, U. Morgenstem, B. Litauszki, W. Berger and F. E. Karasz. Makromol. Chem. 191, 243 (1990). 11. D. Lath, J. M. G. Cowie and E. Lathova. Polym. Bull. 28, 361 (1992).
CONCLUSIONS
PIBMA/SAA-20 was found to be immiscible as confirmed from the observation of two glass transition temperatures and the positive apparent polymer-polymer interaction parameter x2,(app.). SAA-20/PME, SAA-20/EM4VP-8, SAA-32/EM4VP23 and SAA-20/IBM4VP-10 were, however, miscible over the entire blend composition within the temperature range 160-180°C as evidenced from the negative xZ3(app.) values and the single compositiondependent glass transition temperature. The positive deviation from the weight average of the TBs of the components observed with the T,-composition of these latter blends is characteristic of specific interactions that occurred between the constituents of the blend.
REFERENCES
M. M. Coleman, J. F. Graf and P. C. Painter. Specific Interactions and the Miscibility of Polymer Blends. Technomic (1991). J. M. G. Cowie and A. A. N. Reilly. Eur. Polym. J. 29, 455 (1993). J. R. Isasi, L. Cesteros and I. Katime. Polymer 34, 2375 (1993).
12. M. E. Fowler, H. W. Barlow and D. R. Paul. Polymer 28, 1177 (1987). 13. D. E. Cherrak and S. Djadoun. J. appl. Polym. Sci. appl. Polym. Symp. 51, 209 (1992). 14. D. E. Cherrak and S. Djadoun. Polym. Bull. 27, 289 (1991).
15. Z. H. Shi and H. P. Schreiber. J. appl. Polym. Sci. 46, 787 (1992).
16. 2. S. Shi and H. P. Schreiber. Macromolecules 24, 3522 (1991). 17. K. K. Chee. Polymer 31, 1711 (1990). 18. 2. Y. Al-Saigh and P. Chen. Macromolecules 24, 3788 (1990).
19. G. dipaola-Baranyi. Polym. Prep. ACS DIV. Polym. Chem. 21, 214 (1980). 20. A. C. Su and J. R. Fried. ACS Symp. Serv. 391, 155 (1989). 21. Z. Y. Al-Saigh and P. Munk. Macromolecules 17, 803 (1984).
22. Y. Mbrakami. Polym. J. 20, 549 (1988). 23. M. J. El-Hibri, W. Cheng, P. Hattam and P. Munk. ACS Symp. Serv. 391, 121 (1989). 24. J. Brandrup and E. H. Immergut. Polymer Handbook (2nd I%). Chao. IV-l 1. Wilev. New York (1975). 25. ?. K. Kwei. J.-Polym. Sci.; &lym. L&t. e& 22,. 307 (1984). 26. M. J. Brekner, H. A. Schneider and H. Cantow. J. Polymer 29, 78 (1988).
27. G. R. Brannock,
J. W. Barlow and D. R. Paul.
J. Polym. Sci., Part B, Polym. Phys. 28, 871 (1990).
0014-3057/95 $9.50+ 0.00
MISCIBILITY OF POLY(STYRENE-CO-ACRYLIC ACID) WITH POLYMETHACRYLATES OR POLY(METHACRYLATE-CO-4-VINYLPYRIDINE) FATIMA FERAZ, ASSIA SIHAM HADJ HAMOU and SAID DJADOUN* Institute of Chemistry, University of Sciences and Technology Houari Boumediene, BP 32 El Alia, Algiers 16111, Algeria (Received I2 April 1994; accepted in final form 28 June 1994) Abstract-The miscibility of poly(styrene-co-acrylic acid) with polymethacrylates or poly(methacrylateco+vinylpyridine) was studied by differential scanning calorimetry and inverse gas chromatography using decane, octane and benzene as molecular probes. The results showed that poly(isobutyl methacrylate) is immiscible with styrene-acrylic acid copolymers of different acrylic acid content as evidenced from the appearance of two glass transition temperatures determined with both techniques. Positive values of the apparent polymer-polymer interaction parameter x23 (app.) obtained with all probes in the temperature range 160-180°C over the entire blend composition confirm the immiscibility of these blends. Blends of the former styrene-acrylic acid copolymers are, however, miscible in all proportions with poly(ethy1 methacrylate), poly(ethy1 methacrylate-co-4-vinylpyridine) and poly(isobuty1 methacrylateco-Cvinylpyridine). A single composition dependent-glass transition temperature and negative values of xz3 (app.) were obtained with these blends
It is well known that polymers are generally immiscible with each other. The miscibility of a pair of polymers has been attributed in most cases to some specific intermolecular interactions between the components of the blend [l-7]. it has also been shown that a homopolymer and a random copolymer may form a miscible blend even in the absence of specific interactions provided strong intranolecular repulsions exist between the comonomers [8-12). Inverse gas chromatography and differential scanning calorimetry have been extensively used to interpret the miscibility of polymer blends [13-231. Polystyrene is immiscible with poly(ethyl methacrylate) and poly(isobuty1 methacrylate). In the present study, the miscibility of poly(styrene-co-acrylic acid) with poly(ethy1 methacrylate) or poly(isobuty1 methacrylate) or poly(ethy1 methacrylate-co-4-vinylpyridine) or poly(isobuty1 methacrylate-co4-vinylpyridine) was examined by differential scanning calorimetry (DSC) and inverse gas chromatography (IGC) using decane, octane and benzene as molecular probes. Glass transition temperatures (r,) and apparent polymer-polymer interaction parameters xzs were used to determine the miscibility of these blends.
15% by weight, we have also synthesized copolymers of (1) styrene and acrylic acid (SAA-20 and SAA-32) containing respectively 20 and 32 mol.% of acrylic acid and (2) of ethyl methacrylate and 4-vinylpyridine (EM4VP-8 and EM4VP23) and of isobutyl methacrylate and Cvinylpyridine (IBM4VP-10) containing respectively 8, 23 and 10 mol.% of 4-vinlypyridine. The styrene content in the SAA copolymers was determined by U.V. spectroscopy as previously described (131 and by titration with a base in benzene-methanol mixture. The 4-vinylpyridine in the EM4VP or IBM4VP copolymers was also determined by U.V. spectroscopy and elemental analysis. Intrinsic viscosities of these polymers in butanone at 23 or 25°C are summarized in Table 1. The molecular weights of PME (Mw = 1.004 x 106) and PIBMA (M, = 1.43 x 106) were calculated from the intrinsic viscosities measured in butanone at 23°C and using the Mark-Howink-Sakurada equation [24].
EXPERIMENTAL Polymerization and polymer characterization
Using Chromosorb W AWDMCS 80/ 100 mesh, obtained from Johns Mainville as a solid support, chromatographic columns of 9% polymer loading were prepared in the usual way [14]. The IGC measurements were carried out on HP 5730A gas chromatograph equipped with a dual flame ionization detector. Helium was the carrier gas and methane the non-interacting marker. A small amount (0.1 ~1) of benzene or decane or octane used as molecule probes was injected manually using a Hamilton syringe. The specific retention volume Y, (ml/g) of the molecular probe was measured in the temperature range 6C-180°C from the following relation Y,=t,.F,J,/w
Poly(ethyl methacrylate) (PEM) and ply(isobuty1 methacrylate) (PIBMA) were prepared by free radical polymerization. In a similar way, controlling the conversion below *To whom all correspondence
IGC and DSC measurements
where J rate of mixture column
should be addressed. 665
(1)
is the James-Martin correction factor, F the flow carrier gas at 273 K w, the polymer or polymer loading weight and tN the net retention time. A containing the inert support only was prepared in
666
Feraz et al.
Fatima Table Copolymer mol.% of A.A.
Polymer PME PIBMA EM4VP-8 EM4VP-23 IBM4VP-IO SAA-20 SAA-32
I. Characteristics composition mol.% of 4VP
n 0 0 0 0 20 32
of polymers Intrinsic
0 I) X 23 IO 0 0
@l/d
viscosity
TE by DSC ( ‘C)
1.56 I 76 I.51 1.16 I .38 0.37 0.55
14.5 69 77.5 86.5 15.5 II2 129.5
a similar way and used to correct the specific retention volume of the probe from the contribution of the support. The glass transition temperatures of these polymers and of the studied blends were first determined by IGC and then using a PerkinElmer DSC-7 Differential Scanning Calorimeter at a heating rate of 20K/min under nitrogen blanket. Each sample was scanned at least twice. The blends used in DSC measurements were prepared by coprecipi-
(a non-solvent) as molecular probe are in good agreement with those determined by DSC. The positive deviation of these T, values from the weight average of the TBs of the pure components is considered as an evidence of strong polymer-polymer interactions. The Kwei equation [25]
tation.
7‘ii = (n’, T,, + k w2 Tg2)l(w, + kw,) + q w, w2 (2) was used to estimate the attractive interactions between the two polymers. In this equation k and q are adjustable parameters; w, and wr are the weight fractions of the components. When k = 1, the equation above can be written as
RESULTS
AND DlSCUSSIONS
Glass transition temperatures
As shown in Fig. 1, the two “Z-shaped” curves corresponding to the glass transition temperatures of the constituents of the blend observed in the retention diagram In V, vs the reciprocal of the temperature show qualitatively that PIBMA is immiscible with SAA-20. Similar results were also confirmed by DSC. Poly(ethy1 methacrylate) was, however. found to be miscible in all proportions with the same acidic copolymer SAA-20, as evidenced from the appearance af a single glass transition temperature for all the blends as displayed in Figs 2 and 3 which shows as an example, the retention diagrams for the 1: I ratio blend of this system; one “Z-shaped curve” only at around 96°C is observed. Similarly blends of SAA-20/EMWP-8, SAA-32/EMWP-23 and SAA20/IBM4VP-10 were all miscible as confirmed from the single composition dependent-glass transition temperature as illustrated in Fig. 4. As summarized in Table 2 the T, determined by IGC using n-decane
15
SO
100 Temperature
125
150
(“C)
f-lg. 2. DSC thermograms of SAA-20 (a), PME (b) and of their blends containing 20%(c), 33%(d), 49%(e) and 63%(f) of SAA-20 respectively.
r
2.2
(3)
2.4
2.6
2.8
3.0
1000/T Fig. 1. Retention diagrams of SAA-20 (O), PIBMA (0) and SAA-20/PIBMA 1: 1 ratio (0) using benzene as a probe.
2.2
2.4
2.6
2.8
3.0
3.2
1000/T Fig. 3. Retention diagrams of SAA-20 (O), PME (+) and SAA-20/PME I:1 ratio (A) using deeane as a probe.
Poly(styrene-co-acrylic acid) with polymethacrylates
667
Table 3. q values of SAA-20/IBM4VP-IO, SAA-IOIPME, SAA-2O/EM4VP-8 and SAA32/EM4VP-23
System
q Value
SAA-ZO/IBMQVP- IO SAA-2OIPME SAA-ZOIEMIVP-8 SAA-32lEM4VP-23
0.5 16.0 20.0 41.0
We have also analysed the glass transition temperature-composition results using the third power equation [26] from 70 , 0
(T, - r,, )/(T*, -T,,)Wzc=(l+K) 0.2
0.4
0.6
08
1.0
Weight fraction of SAA-20 or SAA-32 Fig. 4. Glass transition temperature as a function of SAA-20 or SAA-32 content in SAA-20/IBM4VP-10 (0, SAA20/EM4VP-8 (m) and SAA-32/EM4VP-23 (a).
where q is a measure of the specific interactions between the constituents of the blend. We have applied this latter equation to the SAA-20/PME, SAA-20/EM4VP-8, SAA-32/EM4VP-23 and SAA20/IBM4VP-10 blends. As shown in Table 3 the q value increased as the densities of interacting species in the polymeric chains was raised. The obtained results show that steric effects play an important role, in that stronger specific interactions are observed with SAA-20/EM4VP-8 blends than in SAA20/IBM4VP- 10 systems. The miscibility of these blends has also been analysed from the width of TB as shown in Fig. 5. Sharper transitions characteristic of blend miscibility are observed with SAA-32/EM4VP-23 blends. As the polymer-polymer interactions decrease, broader transitions are observed as in the case of SAA20/IBM4VP- 10 blends.
- (K, + Kr ) Wr, + Kr WE
(4a)
where the corrected weight fraction of component of highest glass transition temperature W, is given by W, = KWJ(Wi + KU’,) and K = pI TBIlpz Tg
(4b)
with W, , W,, T,, and Tg2are the weight fractions and glass transition temperatures of the constituents 1 and 2 of the blends; p 1 and pZ are their respective densities. Equation (4a) reduces to (T, - T,,)/(T,, - T’,)W, = 1 for
volume
(T, - T,,)/(T,,
(4)
additivity
K, = Kl = 0. A plot of - T,, ) W,, as a function of W,, will
give a straight horizontal line about unity. Figure 6 shows the plot of (T, - T,,)/ for SAA-2O/PME, SAA(T, - Tg,W’2, vs W2c 20/IBM4VP-10 and SAA-32/EM4VP-23 blends. The results confirm that stronger specific interactions as characterized by large positive deviation from volume additivity are observed for SAA-32/EM4VP23 blends and weaker interactions occurred for SAA-20/IBM4VP-10 systems as compared to SAA20/EM4VP-8 blends. Polymer-polymer
interaction parameter
To interpret the miscibility of these blends, we have
also, in the usual way, determined Table 2. Glass transition temperatures as determined by DSC and IGC usinp: decane as a probe System
T,(“C) (DSC)
Ts(“C) (IGC)
112 129.5 74.5 77.5 86.5 75.5
110 130 74 80 87 -
86.5 91.5 98 101
85.5 89.5 96 101.5
SAA-20/EM4VP-8 (1: 2) SAA-20/EM4VP-8 (I : I) SAA-20/EM4VP-8 (2 : I )
95.5 98.5 104
94.5 97.5 104
SAA-32/EM3VP-23 SAA-32/EM4VP-23 SAA-32/EM4VP-23 SAA-32/EM4VP-23
104.5 114 117.5 121.5
119 -
SAA-20 SAA-32 PME EM4VP-8 EM4VP-23 IBM4VP- 10 SAA-ZO/PME SAA-ZO/PME SAA-ZO/PME SAA-ZO/PME
(I : 4) (1: 2) (I : I) (2: I)
(I : 4) (I : 2) (1: I) (3 : I)
SAA-20/IBM4VP-IO(I:4) SAA-20/IBM4VP-lO(l:2) SAA-20/IBM4VP- IO (I : 1) SAA-ZO/IBM4VP- 10 (2 : I)
81.5 90 93 98
the apparent
21
18
12
0
0.2
0.4
0.6
0.8
1.0
Weight fraction of SAA-20 or SAA-32
94 100
Fig. 5. Glass transition temperature width for SAA20/IBM4VP-IO (m) and SAA-32/EM4VP-23 (0) blends vs SAA-20 or SAA-32 content.
668
Fatima Feraz et
al.
3.0
3r r
0
I
I
I
I
0.2
0.4
0.6
0.8
I I.0
-3
-
0
W?c
interaction
0.6
parameter
~~~(app.) for
each blend using various probes from
where u, w, and 4 are respectively the specific volume, weight fraction and volume fraction; subscripts 2 and 3 refer to polymer 2 and polymer 3. Table 4 summarizes the values of Xz3(app.) of the SAA-20/PIBMA systems. The positive values obtained with all probes in the temperature range 160-180°C over the entire composition of the blend confirm the immiscibility of these blends. These results in agreement with those reported by Paul et al. [27], confirm that due to steric effect, there are no strong interactions between the carboxylic groups Table 4. Apparent
polymer
parameters
for SAA-20iPIBMA
blends
Probe
160 C
17O’C
180°C
SAA-2OiPIBMA
(I : 3)
BetK?en+Z /I,(aPP.) Octane d?,(aPP.I DeGme ZZT(WP.)
0.776 0.704 0.192
0.624 0.513 _
0.737 0.689 0 380
SAA-2O/PIBMA
(I : I I
BtXLeWZ Octane DeGiIVZ
L,,(aPP.) AJiG+PP.) ki@PP.)
0.604 0.665 0.229
0.438 0.888 0.087
0.561 I.002 0.171
SAA-ZO/PIBMA
(3: I)
Bell2enlZ Octane DGme
/?iNPP.) X!I(“PP.) iz,G+PP.)
0.560 0.293 0.32
0.739 0.476 0.100
I.097 0.390 0.243
Table 5. Apparent
polymer-polymer
Phase
mteractmn
parameters
Probe
for SAA-ZO/PME
blends
IWC
170°C
180°C
(I : 4)
Benzene octane Decane
Xz,@PP.) X*,@PP.) X&PP.)
-0.481 -0.375 -0.310
- 0.404 -0.518 -0.604
- 1.033 -0.725 -0.807
SAA-ZO/PME (I : 2)
Benzene octane DW%Ie
Xu@PP.) Xx(aPP.) xx(aPP.)
- 1.729 -2.113 - 1.805
-1.642 - 2.072 -2.174
- 1.773 - 1.890 - I.769
BeIUetle
X23@PP.)
Octane
Uvp.)
Lkcane
X*,(aPP.)
-0.429 -0.757 -0.864
-0.228 -0.573 -0.875
-0.278 -0.587 -0.665
SAA-2O/PME
SAA-ZO/PME (2: I)
I.0
and the ester groups of the PIBMA. The contribution due to the repulsions between the two comonomers in the SAA-20 is not sufficient to ensure the miscibility of these blends. As the alkyl group of the polymethacrylate becomes smaller, specific interactions occurred between the acidic groups of SAA-20 and the ester groups of poly(ethyl methacrylate) and led to miscible blends in all proportions. Negative values of ~~,(app.) as shown in Table 5 were obtained with all these blends in the temperature range 160-180°C. In this temperature range, the In VP varied linearly with the reciprocal of the temperature. The apparent polymer-polymer interaction X13(app.) varied for all probes with the blend composition and goes through a maximum of interactions located around 67% of PME. Figure 7 shows, as an example, the variation of x13(app.) vs the blend composition for the SAA-20/PME. systems.
polymer mteractwn
PhWZ
0.8 SAA-20
Fig. 7. Composition dependence of X2,(app.) at 170°C for blends of SAA-20 with PME using benzene (A), octane (m) and decane (0) as probes.
Fig. 6. Glass transition temperture-composition of SAA-32/EM4VP-23 (O), SAA-20/PME (0) and SAA20/IBM4VP-10 (*) blends according to the third power equation. polymer-polymer
0.4
0.2
Weight fraction of
Poly(styrene-co-acrylic Table 6. Apparent polymer-polymer
acid) with polymethacrylates
669
interaction parameters for SAA-2O/EM4VP-8 blends
Phase
PrObe
xz3kvu.)
160°C
170°C
180°C
SAA-20/EM4VP-8
(I :2)
Benzene Octane Decane
Uapp.) zz3(app.)
-0.609 - 1.290 - I.480
-0.635 - 1.302 - 1.425
-0.356 -1.007 -1.465
SAA-20/EM4VP-8
(I : I)
Benzene Octane Decane
xIl(app.) xzI(app.) x2] (app.)
-0.288 -0.647 -0.825
-0.095 -0.574 -0.877
+0.261 -0.128 -0.669
Benzene
x,(app.)
SAA-20/EM4VP-8
(2: I)
Octane Decane
~~~(app.) ~~~(app.)
+ 0.282 -0.338
+0.109 - 0.392
+0.191 -0.287
-0.449
-0.551
-0.441
Table 7. Apparent
polymer-polymer
Phase
interaction
parameters
Probe
x23hw)
for SAA-20/IBM4VP-IO
blends
160°C
170°C
180°C
- I .399 - 1.068 -1.016
-1.063 - 1.083 -0.999
(I :4)
Benzene Octane Decane
xz3(app.)
x&w.)
- I.538 - I .205 -1.371
SAA-20/IBM4VP-IO
(I :2)
Benzene Octance Decane
x&app.) x2,(app.) x2,(app.)
-0.378 -0.310 -0.204
-0.183 -0.204 -0.006
-0.053 -0.145 +0.056
(2: I)
Benzene Octane Decane
x23 (wp.)
SAA-20/IBM4VP-IO
x2](app.) r,,(aou.)
+0.170 -0.183 + 0.039
+0.317 +0.071 +0.040
+0.335 +0.233 +0.060
SAA-20/IBM4VP-IO
The introduction by copolymerization of a small amount of 4-vinylpyridine within the chains of not only poly(ethyl methacrylate) but also poly(isobuty1 methacrylate) has led to miscible blends of these copolymers with SAA-20. Strong specific interactions between these copolymers are characterized by negative values of x2,(app.) as shown in Tables 6 and 7. Due to steric effects, a slightly higher content of 4-vinylpyridine incorporated within the poly(isobuty1 methacrylate) led, however, to less specific interactions with the carboxylic groups of the SAA-20 copolymer.
4. A. S. Hadj Hamou, S. Djadoun and F. E. Karasz. Polym. Prep. 34, 815 (1993). 5. S. Djadoun. Polym. Bull. 9, 313 (1983). 6. E. M. Pearce, T. K. Kwei and B. Y. Min. J. Macromolec. Sci. Chem. A21, 1181 (1984). 7. L. C. Cesteros. E. Meaurio and I. Katime. Macromelecules 26, 2323 (1993). 8. G. ten Brinke, F. E. Karasz and W. J. MacKnight. Macromolecules 16, 1827 (1983). 9. S. Cimmino, F. E. Karasz and W. J. Macknight. J. Polym. Sci. Part B, Polym. Phys. 30, 49 (1992).
10. J. Kressler, H. W. Kammer, U. Morgenstem, B. Litauszki, W. Berger and F. E. Karasz. Makromol. Chem. 191, 243 (1990). 11. D. Lath, J. M. G. Cowie and E. Lathova. Polym. Bull. 28, 361 (1992).
CONCLUSIONS
PIBMA/SAA-20 was found to be immiscible as confirmed from the observation of two glass transition temperatures and the positive apparent polymer-polymer interaction parameter x2,(app.). SAA-20/PME, SAA-20/EM4VP-8, SAA-32/EM4VP23 and SAA-20/IBM4VP-10 were, however, miscible over the entire blend composition within the temperature range 160-180°C as evidenced from the negative xZ3(app.) values and the single compositiondependent glass transition temperature. The positive deviation from the weight average of the TBs of the components observed with the T,-composition of these latter blends is characteristic of specific interactions that occurred between the constituents of the blend.
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