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Study of polysiloxane-polycarbonate urethane block copolymers synthesized by heterophase polycondensation
Polysiloxane-polye arbonate urethane block copolymers
1529
:REFERENCES:
1. L. I. ABRAMOVA, Ye. N. ZIL'BERMAN and I-,. S. CHUGUNOVA, Vysokom01. soyed. 1121: 813, 1979 (Not translated in Polymer Sci. U.S.S.R.) 9 .2. Ye. N. ZIL'BERMAN, R. A. NA~COLOKINA and O. P. KUVARZINA, 1bid. A22: 2006, 1980 (Translated in Polymer Sei. U.S.S.R. A22: 1980) 3. Ye. N. ZIL'BERMAN, R. A. NA'VOLOKINA and N. A. ABRAMOVA, 1bid. B25: 279, i983 (Not translated in Polymer Sci. U.S,S.R.) -4. V. A. KABANOV and D. A. TOPCHIYEV, Polimerizatsiya' ionizuyushchikhsya monomerov (Polymerization of Ionizing Monomers). Nauka, Moscow, 1975 5. A. CHAP1RO and Z. MANKOWSKA, Europ. Polymer J. 14: 15, 1978 6. V. A. MYAGCHENKO and S. Ya. FRENKEL'~UsPekh. khim. 37: 2247, 1968 7. T. AIAFREY and G. GoLDFINGER, J. Phys. Chem. 12: 332, 1944 8. J. OUDIAN, Osnovy khimii polimerov (Essentials of Polymer Chemistry). p. 355, Mir, Moscow, 1974 :~ 9. Ye. N. ZIL'BERMAN, L. I. ABRAMOYA, V. I. TRACHENKO and O. K. TUMAYE'V'A, Fizikokhimicheskiye osnovy sinteza i pererabotki polimerov (Physicochemical Bases of Polymer Synthesis and Processing). No. 3, p. 31, Mezhvuz. sb. Gorkii,Univ., Gorkii, 1978 10. Ye. N. ZIZ,'BERMAN, Yu. P. CHERNENKOYA, G. N. SH'VAREYA, A. K. KUMAKSHEVA and A. A. TERSKAYA, Ibid., 3, 20, 1978 11. M. FINEMAN and S. ROSS, J. Polymer Sci. 5: 259, 1950
~PolymerScienceU.S.S.R.Vol.26, No. 7, 1529-1538, 1984 .Printe-Jin Poland
0032-3950184SI0.O0.+.00 '~' 1985PergamonPress Ltd.
STUDY OF POLYSILOXANE-POLYCARBONA'IE URETHANE BLOCK COPOLYMERS S'YN'IHESIZED BY HETEROPHASE POLYCONDENSATION* E. SH. GOL'DBERG, I. M. RAIGORODSKII, G. N. KOVALEV, B. S. EL'TSEFON, V. V. KORSHAK, A. I. KUZAYEV, S. G. ALEKSEYEVA, YA. G. URMAN a n d I. YA. SLON1M All-Union Medical Polymer Research Institute
(Received 28 October 1982) In conditions of heterophase polycondensation new polysiloxane-polycarbonate ure-' thane block copolymers have been synthesized displaying a biphasie morphology. Study of :the reaction of the initial oligomers in various heterophasic systems showed that the patterns o f their interaction are of a diffusional and not kinetic character. The block copolymers obtained possess high deformation-strength properties, permeability for gases and thermal and .hydrolytic stability. * Vysokomol. soyed. A26: No. 7, 1369-1376, 1984.
1530
E. SH. "GOL'DBERG-et aL
IN THE last few )'ears much attention h~isbeenpaid to study of block copolymers which_ del~..n~!.ing on the nature of the blocks, their size and s.eque.n_ceo.f_alternation exhibit. properties fundamentally differing from those of the starting components. Of special interest are block copolymers with macromolecules"Of:flexible antt'rigid blocks, in particular, containing polyorganosiloxane [1]. Earlier polysilox~ine carbonate [2, 3]and tSoiysiloxane urethane [4, 51 copolymers werestudied with a Statistical distribfftioh ofthe comonomer units in the chain in which monophasie morphology is found,. .. The aim of the present work was to synthesize in heterophasie conditions and study the properties of polysiloxane-polycarbonate urethane block copolymers (PSCU) o f the structure (AB)~ ~vith a regular block distribution in the chain. " ntlgocarbonate urethane (OCL0 oligomers: (OCU) of structure
t
~,
O /~-m
Jx
CHj ~here A r ~ - - ~ f f ' ~ - - ~ , X = - N H ( C H 2 ) 6 N H -
or - N ~ N - ,
m=0-05-0-31,.
CH~ x=2Zl0~vere obtained by the technique in reference [6]. It should ben0ted that even for a'largequa'r~tity of a diamine in the conditions of synthesis urea bonds do not form in OCU. " Hexamethylene diamine and piperazine were purified by the techniques in reference [7]. Their constants corresponded to the published data. ",r (BCFS) of formula
CHa
I
CII~
I
CICO(CtI~)aOCtt~SI--(--OSi--)n--CII~O(C'It.,)~OCCI, I] I I II 0 C!ta Ctta 0 where n = 12-75, were obtained by phosgenation of the corresponding diols [2]; the content of theCOCl-groups was determined by potentiomctric titration, it corresponded to the M of the BCFSs indicated (1220-5910). Methylene chloride, chloroform, THF and triethylamine were purified by the standard tech-niques [8]. The'properties of the OCUs and BCFSs obtained are indicatecl in Tables 1 and 2 respec-lively.9 A solution of 2.96 g OCU in 30 mi chloroform was treated for.5 rain with a solution of 0-16 g NaOH in 20 ml distilled water, a catalytic amount of triethylamine added and with vigorous agitation a solution of 3-72 g BCFS rapidly introduced (n=46) in 20 ml chloroform. The reaction was continued until the COCi groups disappeared. At the end of the reaction the organic layer was separated off, acidified with 107o HCi solution and washed with distilled water to neutral reaction o f the washing waters. The copolymer was precipitated from the solution in chloroform into ethanol, giving 4"6 g (70yo) of a white powdery substance (thog=0"67 dlJg, ~-Iw=75,000).
Polysiloxane-pol2~'earb6nate ur~thahe block copolymers
1531
The PSCUs Were synthe~iz6cl b~' similar techniques using methylene chloride and THF as solvent. The thermomechanieal characteristics were recorded on Kargin balances at a specific pressure of 98 kPa on samples first presse d at 180 and 49 MPa and also-on films samples obtained by irrigation from solution in methylene chloride by the technique in reference [9]. Thermogravimetric an/~lysis of the polymers was with a derivatograph (weighed batch of sample 0"4 g, heating i'ate 5~ The physicomechanical cha'rficteristics of the polymers were studied on films poured from solution in chloroform with the lnstron instrument at 25~ with a constantly applied load of 490 kPa and rate of stretching of the samples 5 ram/rain. The gas permeability of the films was determined by the gas chromatographic method at 25~ il0]. The ttI-NMR spectra (90 MHz) were recorded with the WH-90 Fourier spectrometer (Bruker) With accumulation (~ 100). To i'ecord the spectra we prepared ,.-5 % solutions of the OCUs and PSCUs in CDCia. To calibrate the chemicai shifts we used the chloi'oform signal (~a=7-24 ppm relative to tetramethylsilane). The IR spectra of the film samples of the block copolymers were recorded With the PerkinElmer speetrophotometer. The gel chromatographic investigations were run with the Waters instrument fitted with three Styrogel columns connected in series (eluent "rHi:, rate of clelivery 1 ml]min, 25~ [11]. The optimal cofiditions for heterophasic p01ycondensation were chosen by the system CIIa CHa 1
i
II[(OArOC)~_m--(X)m--]~OA~OII+ CiCO(CH..O:OCII.,Si (OSi)~CII.:O(CII.2)~.OCCI- , II !~ I I 9 II 0 0 CIIa Gila 0 GIla CII~ L~aon " I I ~---[(OArCO)I m--(X)m--] --OAr--OCO(CH,).OClI.Si(OSi)nClI,O (CII.,),OC---2NaCl !1 I" l- I II O 0 CIt3 Gila 0 .
- -
.
-
.
.
.
.
.
using an O C U with 3 I n = 1040 and BCFS with 3"~,=3720. PSCUs with m a x i m u m viscosities and yields were obtained at concentrations of the initial components 0.02-0'04 mole/l. The use of double (as compared with the stoichiometric) excess of N a O H as HCI acceptor gives copolymers with high M (3Iw= 10s). However, further increase in the content of the acceptor in the system leads to fall in the viscosity (from 0.72 to 0"46 dl/g) and yield (from 80 to 509/0) of the PSCUs formed probably as a result of alkaline hydrolysis. It should be noted that for the same quantity of acceptor increase in the volume of the aqueous phase makes it easier to obtain a block copolymer with large M evidently by reducing the rate of hydrolysis as a result of fall in the concentration of N a O H in the aqueous phase and also by improving the solubility of the low molecular weight reaction products (NaCI, HCI) and their removal from the reaction zone..Thus, 9with change in the ratio of the volume of the organic phase to that of the aqueous phase from 5 : 1 to 2"3 : 1 the viscosity of the PSCU rose from 0.56 to 0.72 dl/g.
1532
E. SH. GOL'DBERG et
T A B L E I . PROeERTIES OF I N I T I A L O C U s
m 0-12 0.05 0.10 0.24 0-12 0.13 0"20 0.21 0"31
al.
--
Amine of urethane fragment 10'0 8"9 7"6 6"1 5"7 3"0 2"5 2"2 1"9
Hexamethylene diamine Piperazine t, tt 9~ iJ
Hexamethylene diamine Piperazine Hexamethylene diamine
O
_[=
"~/~*
Yield, ~.
tho, 1" dllg
Zsort,$ ~
2960 2960 2250 1990 1760 1040 950 850 830
70 65 70 75 75 70 85 90 85"
0"16 0"14 0-12 .0"12 0"13 0"09 0'06 0"09 0"04
206-210
186-188 I
180-185 160-166 90-102 155-160 108-115
* Calculated f r o m the data o f the I I I o N M R spectra. 1' In chloroform at 25~ $ Dctermlned in capillary at heating rate o f 1 ~
T A B L E 2. PROPERTIES OF I N I T I A L
Number of SiO(CttD, blocks 1220 2960 3720 4700 5920
Content of COC! groups~ gray. Yo 10"4 4"29 3"41 2"70 2"16
12 36 46 59 75
BCFSs
n~~
Density, g/cm 3
Dynamic viscosity (20~ cP
1"4095 1"4098 1"4090 1"4065 1"4079
0"99 0'99 0"99 0'99 0"98
11"0 38"4 39"2 45"7 58"2
* Calculated f r o m content o f terminal groups.
ql09 ~dl/3
0.2~ 50
25 0 25 Exce~ ~mole ~ BCFS ~ OCU
40
80 Yield, %
Fio. 1. Specific logarithmic viscosity of PSCU (a) and yield of copolymer (b) as a function of the ratio of the initial oligomcrs on polycondensation in the system methylene chloride-water (1) and THF-water (2).
Polysiloxane-polycarbonate urethane block copolymers
1533:
Since the location of the reaction zone determines the basic patterns of polyconden-sation we tried to evaluate it in the real conditions of the reaction o f formation o f the PSCU in various heterophasic systems. As organic phase we used solvents miscible: (THF) and immiscible (methylene chloride) with the aqueous phase.
a
f
1
z
II
JO
11
18
I 8 w lO~cm-~
10
b
"!
J
I 7
II
I
9~11z
I
I10
6.,pp.p.[']'l.
Fie. 2. IR (a) and PMR (b) spectra of PSCU: a-numerals denote the bands Of the valence vibrations. of the CH2Si group (1), C = O ester group (2), NC(O) group (3), SiOSi group (4) and SiCH3 group. (5); b--numerals denote the protons9 1
IIa
FI'--
3
ff'===~ ~ /~"~"
.
/C[|2CH2~ N
0
6
7
CH3~----~ I
2
4
II3C 5 I
I
9
9
3
113C
. -I
"~N )m
9
CII 3 I
I
CII 3
"
"1
"
"11/ 9
O
.
J
t534
E. SH. GOL'DBERGet al.
.~ T!1eresults of tile experiment presented in Fig~ 1 show that the dependence of tho~ onthe yie!d is of a complex extremal character and with change in the ratio of the oligomers in the reaction system to the maximum M (viscosity) corresponds a non-equimolar :ratio of the initialcorqpounds. TABLE 3. I~{OLECULAR-MASS CHARACTERISTICS OF BLOCK. COPOLYblERIC
OCU
BCFS
830 950 1040 1760
3720 3720 3720 3720 3720 3720 4700
2250 2960 1760 1760 2250 296O
PCSUs
Block copolymeric PCSUs content of yield after t~*loz )0 Si(CH,)20 reprecipidl/g m~ • I0-~ ~1! • 10-~ blocks, tation, % gray. 0"35 82 60 55 22"6 60 .0"50 30"0 80 64 r 17"8 55 0"24 49"8 78 0"81 53"4 67 60' 109 0"59 32"5 62 70 110 0"67 37"0 56 70 75 0"40 73 70 0"48 77 95 65 73 0"43 55"5 19'0 n 70 0"43 67
M../M. 2.4 2.1 2"8 2-0 3"4 2.0
.
592o 5920 5920
2.9
* In chloroform at 25~ t According to GPC.
Since these relations differ f r o m similar ones for polycondensation in solution o r e m u l s i o n [12] it m a y be assumed that polycondensation in the system studied is not o f a v o l u m e t r i c but o f a superficial character and the reaction zone where HCI is also split -off is at the interface or c l o s e t o it, leading to the f o r m a t i o n o f the block-copolymer. Further indirect confirmation o f the diffusional character o f the process m a y be that the rate o f introducing a n excess o f one o f the c o m p o n e n t s (BCFS) to the reaction
T A B L E 4. TIIERMOMECHANICAL CtlARACTERISTICS OF P S C U s .. 9
~r. of blocks
Sample, No.
1 2 3 4 5 ._llO
polycarbonate urcthane I]
]
1040 1760 2250 2540 2960
.
polydimethyl siloxane ] .
3720 3720 5920 2960 5920
Content of block polydimethyl si!oxane, gray. ~ 78 67 73 54 67
T,,
."
--110 105 108 108 )
:
Glass transition points, ~
9
I
T,~
--
36 42
--
55
--
108"
70 65
* For polysiloxanc pob'carbonatc with the/~f o f the polycarbonate block 2500 and the polydimcthylsiioxanc block 2960 T,t ~ =87~
Polysiloxane-polycarbonateurethane block copolymers
i 535
system does not fundamentally affect the M (viscosity) of the block copolymers (0"60 and 0.58 dl/g on rapid and slow introduction respectively). Thus, despite the fact that on synthesis of a PSCU with oligomeric compounds which are insoluble in the aqueous phase the patterns of the process are rather o f a diffusional than kinetic character. Fall in the viscosity of PSCUs obtained in the system THF-water (as compared with the system methylene chloride-water) is associated with rise in the degree of hydrolysis of the BCFS on polycondensation. The structure of the PSCUs obtained was confirmed by IR and IH-NMR spectroscopy. The characteristic absorption bands and the assignment of the ~H-NMR signals are indicated in Fig. 2. The properties of the synthesized block copolymers are indicated in Table 3. The M of the block copolymers according to GPC reaches l~-lw= 11 x 10~. It should be noted that the polydispersity of the block copolymers is 2.0-3.4 and does not depend on the M. The MD is of unimodal character, which points to the absence of low molecular weight impurities and non-reacting initial oligomers (Fig. 3). However in some cases these impurities are found at VR=23-26 (Fig. 3, curve 3). Since GPC is a very sensitive method and picks up traces of the initial components, their presence will evidently also lead to fall in M,. As a result the polydispersity rises to 3.0-3-4 and does not depend on the nature of the urethane fragment and the value of the M of the initial oligomers. "From certain M (Table 3) we found the values of the coefficients K and 0~ in the Mark-Houwinck equation for-the PSCU samples [pl] = 1"8 x 1 0 - 4 M ~
Table 4 presents the results of the thermomechanical tests of the block copolymers obtained. As may be seen, the PSCUs are characterized by two relaxation transitions, which testifies to their structural microheterogeneity. The first low temperature transition ( - 1 0 5 - - l l 0 ~ refers to the glass transition point ot the polydimethyl siloxane block and depends little on its length. These values are close to Tg of high molecular weight polydimethyl siloxane rubber (-120~ The temperature transition in the region 36-70~ characterizes the glass transition o f the carbonate urethane phase and shifts to the region of higher temperatures with increase in the length of the carbonate urethane block. In the region - 5 3 - - 6 6 ~ over the whole interval of compositions studied one observes a weakly marked transition which is probably due to crystallization of the polydimethyl siloxane phase [13]. Since the parameters of solubility calculated from reference [14] for polycarbonate based on diphenylolpropane and polycarbonate urethane have practically identical values,(10.9 and 11.0, respectively) it may be assumed that the morphology of the PSCU is similar to that of polysiloxane-polycarbonate block copolymers. In the interval of compositions of the PSCUs studied (> 54 gray. ~o Si block) the Continuous phase is polydimethylsiloxane in which the polycarbonate urethane component is discretely
E. SIL GOL'DBERGet aL
1536
distributed. The influence of the lengths o f both blocks on the values of Tg for P S C U and polysiloxane carbonates is identical. The smaller value of Tg for the polycarbonate urethane phase as compared with the polycarbonate (70 and 87~ respectively) in the copolymers o f identical composition and length of the blocks is probably connected with !ncrease in the mobility of the rigid polycarbonate urethane block (Table 4, Sample 4 and the sample the characterization of which is given in the footnote). The character of the curves of stretching o f the films based on PSCUs obtained f r o m a solution of a solvent good for b o t h blocks (chloroform) is typical o f t h e r m o elastoplasts (Fig. 4). By changing the ratio of the carbonate urethane and siloxane blocks
G'MPa
1
3
lO
!
lq
16
22
26 VR~counts
0
F1o. 3
500
~,%
lO00
Fxo. 4
FIe. 3. Chromatograms of PSCU. The M of OCU and BCFS blocks are respectively equal to 1760 and 3720 (1), 2960 and 3720 (2), 2250 and 5920 (3), 1040 and 3720 (4) and 830 and 3720 (5). Fie. 4. Curves of the stretching of PSCU. The M of the blocks in OCU and BCFS are equal respectivelY to 2960 and 3720 (I), 2250 and 3720 (2), 2960 and 5920 (3), 1760 and 3720 (4) and 1760 and 5920 (5). Content of Si(CH3),O block in PCSU is 56 (1), 62 (2), 67 (3, 4) and 77 (5) gray. ~ . TABLE 5. INFLUENCE OF M OF POLYCARBONATE URETHANE AND POLYDIMETHYL SILOXANE BLOCKS ON THE GAS PERMEABILITY COEFFICIENT O F P S C U
Moco/MBcrs
0"14 0.22 0.26 0-30 0.38 0-47 0.50 0.60 0.80
Gas permeability coefficient, mole-m/sec.m2- Pa Pco~ x 10ta Po2 x 10ta 12"5 2"3 2.0 11"7 11"6 1"9 11"4 2-0 9"5 1-7 7"8 1"3 7"2 1"3 1.0 6"I 4"6 0"6
FILMS
Selectivity Pco~ : Po~ 5.5 5-9 6.0 5.6 5.6 5.7 5.7 5"9 7.4
Polysiloxane-polycarbonate urethane block copolymers
1537
one may vary the properties of the PSCU within wide limits. Thus, with increase in the length of the rigid block the failing stress at rupture of the films changes from 6 to 25 MPa and the relative elongation at rupture from 1000 to 200 Yo. The strength and deformation of the block copolymers is determined both by the content of the polydimethyl siloxane block and the molecular mass of the PSCU. F o r the same content of the polydimethyl siloxane block (67 ~o) the strength of the copolymer with Mw = 10.9 x 104 is 15 MPa (Fig. 4, curve 4) and for the copolymer for M,~ = 5"6 x 10" (Fig. 4, curve 3) only 8 MPa; deformation 1000 and 250~o respectively.
100 m
60 1 2O I
I
300
1
I
500 T ~
Fro. 5. Integral curves of the weight loss of PSCU. The M of the OCU and BCFS blocks are equal respectively to 2960 and 3720 (l) and 1760 and 3720 (2). The gas permeability coefficient P o f the synthesized PSCUs was determined at 25~ on film samples of the copolymers with M o f the polycarbonate urethane block 830-2960 and of the polydimethyl siloxane 3720-5920. Since the temperature of measurement far exceed Tg of the flexible siloxane block [15] the PSCUs, as to be expected, are characterized by high values of gas permeability for oxygen and carbon dioxide (Table 5). Increase in the content of the polycarbonate urethane block released in the separate little permeable phase leads to rise in the number and size o f its particles in the PSCU. The attendant additional diffusional hindrances determine the fall in the gas permeability coefficient. According to the results o f thermogravimetric analysis (Fig. 5) the block copolymers are stable on heating in air to 300~ irrespective o f the nature of the diamine in the urethane fragment and the length of the siloxane block. TABLE 6. HYDROLYTITC SABiLITY OF P S C U
Medium Water 1 Y. NaCI solution 0.5 ~ NaOH solution 5 Y. NaOH solution 10~ HCI solution
T~ I00 37 I00 I00 I00
Exposure, hr 6 4320 6 6 6
Weight loss, 0
0"3 0
3 0"3
1538
E. St-[. GOL'DBERGet aL
Comparison of the I R spectra of the initial PSCU films with the spectra of the films held.in different media (Table 6) shows no appreciable changes in the structure of the polymers, insignificant (down to 3 ~ ) weight losses being observed only on heating the samples in a 5 ~o aqueous solution of sodium hydroxide. Thus, the polysiloxane-polycarbonate urethane b l o c k c o p o l y m e r s synthesized by us and displaying heterophasicity possess a complex of useful properties, in particular, -high strength characteristics, gas permeability and thermal and hydrolytic stability. Translated by A. CROZY REFERENCES
1. A. NOStlEI and J. McGRATH, Blok-sopolimery (Block Copolymers). p. 30, Mir, Moscow, 1980 2. I. M. RAIGORODSKII, G. P. BAKHAYEVA, L. I. ~IAKARO'VA, V. A. SA'VIN and K. A. ANDRIA_NOV, Vysokomol. soyed. A17: 84, 1975 (Translated in Polymer Sci. U.S.S.R. 17: 1975) 3. I. M. RAIGORODSKII, G. P. BAKHAYEVA, V. A. SAVIN, V. D. SHELUDAKOV, S. S. MKI-IITARYAN, D. Ya. SHINKIN, K. A. ANDRIANOV, L. I. MAKAROVA, V. I. ZHITKOV, V. N. KOTRELEV and T. D. KOSTRYUKOVA, U.S.S.R. Pat. 604855; Byul. izobret., 16, 91, 1978 4. 1. M. RAIGORODSKII,E. Sh. GOL'DBERG, V. A. SAVIN and O. F. ALKAYEVA, Vysokomol. soyed. B20: 621, 1978 (Not translated in Polymer Sei. U.S.S.R.) 5. I. M. RAIGORODSKII, I. G. URMAN, E. Sh. GOL'DBERG, S. G. ALEKSEYEYA, "V. A. SAVIN and I. Ya. SLONIM, _Ibid. A20: 1486, 1978 (Translated in Polymer Sci. U.S.S.R. 20: 7, 1673, 1978) 6. V. FOLDI and T. CAMPBEL, J. Polymer Sci. 56: 1, 1962 7. J. STI'LL and T. CAMPBELL, Monomery dlya polikondensatsii (Monomers for Polycondensation), p. 154, Mir, Moscow, 1976 8. A. GORDON and R. FORD, Sputnik khimika (Chemist's Companion). p. 437, Mir, Moscow, 1976 9. I. F. KAIMhN', Plast. massy, 9, 62, 1966 I0. R. PASTERNAK and J. MeNULTY, Mud. Packaging 43: 89, 1970 11. A. I. KUZA.YEV, Vysokomol. soyed..422: 2082, 1980 (Translated in Polymer Sci. U.S.S.R. t~ 22: 9, 2284, 1980) 12. L. B. SOKOLOV, Osnovy sinteza polimerov metodom polikondensatsii (Bases'of Polymer Synthesis by the Polycondensation Method). p. 172, K_himiya, Moscow, 1979 13. S. TANG and F. MEINECE, Rubber Chem. and Technol. 53: 1160, 1980 14. D. VAN KREVELEN, Svoistva i k.himicheskoye stroyeniye polimerov (Properties and Chemical Structuie of Polymers). p. 135, Khimiya, Moscow, 1976 15. S. A. REITLINGER, Pronitsayemost' polimernykh materialov (Permeability of Polymer Materials), p. 111, K.himiya, Moscow, 1974
1529
:REFERENCES:
1. L. I. ABRAMOVA, Ye. N. ZIL'BERMAN and I-,. S. CHUGUNOVA, Vysokom01. soyed. 1121: 813, 1979 (Not translated in Polymer Sci. U.S.S.R.) 9 .2. Ye. N. ZIL'BERMAN, R. A. NA~COLOKINA and O. P. KUVARZINA, 1bid. A22: 2006, 1980 (Translated in Polymer Sei. U.S.S.R. A22: 1980) 3. Ye. N. ZIL'BERMAN, R. A. NA'VOLOKINA and N. A. ABRAMOVA, 1bid. B25: 279, i983 (Not translated in Polymer Sci. U.S,S.R.) -4. V. A. KABANOV and D. A. TOPCHIYEV, Polimerizatsiya' ionizuyushchikhsya monomerov (Polymerization of Ionizing Monomers). Nauka, Moscow, 1975 5. A. CHAP1RO and Z. MANKOWSKA, Europ. Polymer J. 14: 15, 1978 6. V. A. MYAGCHENKO and S. Ya. FRENKEL'~UsPekh. khim. 37: 2247, 1968 7. T. AIAFREY and G. GoLDFINGER, J. Phys. Chem. 12: 332, 1944 8. J. OUDIAN, Osnovy khimii polimerov (Essentials of Polymer Chemistry). p. 355, Mir, Moscow, 1974 :~ 9. Ye. N. ZIL'BERMAN, L. I. ABRAMOYA, V. I. TRACHENKO and O. K. TUMAYE'V'A, Fizikokhimicheskiye osnovy sinteza i pererabotki polimerov (Physicochemical Bases of Polymer Synthesis and Processing). No. 3, p. 31, Mezhvuz. sb. Gorkii,Univ., Gorkii, 1978 10. Ye. N. ZIZ,'BERMAN, Yu. P. CHERNENKOYA, G. N. SH'VAREYA, A. K. KUMAKSHEVA and A. A. TERSKAYA, Ibid., 3, 20, 1978 11. M. FINEMAN and S. ROSS, J. Polymer Sci. 5: 259, 1950
~PolymerScienceU.S.S.R.Vol.26, No. 7, 1529-1538, 1984 .Printe-Jin Poland
0032-3950184SI0.O0.+.00 '~' 1985PergamonPress Ltd.
STUDY OF POLYSILOXANE-POLYCARBONA'IE URETHANE BLOCK COPOLYMERS S'YN'IHESIZED BY HETEROPHASE POLYCONDENSATION* E. SH. GOL'DBERG, I. M. RAIGORODSKII, G. N. KOVALEV, B. S. EL'TSEFON, V. V. KORSHAK, A. I. KUZAYEV, S. G. ALEKSEYEVA, YA. G. URMAN a n d I. YA. SLON1M All-Union Medical Polymer Research Institute
(Received 28 October 1982) In conditions of heterophase polycondensation new polysiloxane-polycarbonate ure-' thane block copolymers have been synthesized displaying a biphasie morphology. Study of :the reaction of the initial oligomers in various heterophasic systems showed that the patterns o f their interaction are of a diffusional and not kinetic character. The block copolymers obtained possess high deformation-strength properties, permeability for gases and thermal and .hydrolytic stability. * Vysokomol. soyed. A26: No. 7, 1369-1376, 1984.
1530
E. SH. "GOL'DBERG-et aL
IN THE last few )'ears much attention h~isbeenpaid to study of block copolymers which_ del~..n~!.ing on the nature of the blocks, their size and s.eque.n_ceo.f_alternation exhibit. properties fundamentally differing from those of the starting components. Of special interest are block copolymers with macromolecules"Of:flexible antt'rigid blocks, in particular, containing polyorganosiloxane [1]. Earlier polysilox~ine carbonate [2, 3]and tSoiysiloxane urethane [4, 51 copolymers werestudied with a Statistical distribfftioh ofthe comonomer units in the chain in which monophasie morphology is found,. .. The aim of the present work was to synthesize in heterophasie conditions and study the properties of polysiloxane-polycarbonate urethane block copolymers (PSCU) o f the structure (AB)~ ~vith a regular block distribution in the chain. " ntlgocarbonate urethane (OCL0 oligomers: (OCU) of structure
t
~,
O /~-m
Jx
CHj ~here A r ~ - - ~ f f ' ~ - - ~ , X = - N H ( C H 2 ) 6 N H -
or - N ~ N - ,
m=0-05-0-31,.
CH~ x=2Zl0~vere obtained by the technique in reference [6]. It should ben0ted that even for a'largequa'r~tity of a diamine in the conditions of synthesis urea bonds do not form in OCU. " Hexamethylene diamine and piperazine were purified by the techniques in reference [7]. Their constants corresponded to the published data. ",r (BCFS) of formula
CHa
I
CII~
I
CICO(CtI~)aOCtt~SI--(--OSi--)n--CII~O(C'It.,)~OCCI, I] I I II 0 C!ta Ctta 0 where n = 12-75, were obtained by phosgenation of the corresponding diols [2]; the content of theCOCl-groups was determined by potentiomctric titration, it corresponded to the M of the BCFSs indicated (1220-5910). Methylene chloride, chloroform, THF and triethylamine were purified by the standard tech-niques [8]. The'properties of the OCUs and BCFSs obtained are indicatecl in Tables 1 and 2 respec-lively.9 A solution of 2.96 g OCU in 30 mi chloroform was treated for.5 rain with a solution of 0-16 g NaOH in 20 ml distilled water, a catalytic amount of triethylamine added and with vigorous agitation a solution of 3-72 g BCFS rapidly introduced (n=46) in 20 ml chloroform. The reaction was continued until the COCi groups disappeared. At the end of the reaction the organic layer was separated off, acidified with 107o HCi solution and washed with distilled water to neutral reaction o f the washing waters. The copolymer was precipitated from the solution in chloroform into ethanol, giving 4"6 g (70yo) of a white powdery substance (thog=0"67 dlJg, ~-Iw=75,000).
Polysiloxane-pol2~'earb6nate ur~thahe block copolymers
1531
The PSCUs Were synthe~iz6cl b~' similar techniques using methylene chloride and THF as solvent. The thermomechanieal characteristics were recorded on Kargin balances at a specific pressure of 98 kPa on samples first presse d at 180 and 49 MPa and also-on films samples obtained by irrigation from solution in methylene chloride by the technique in reference [9]. Thermogravimetric an/~lysis of the polymers was with a derivatograph (weighed batch of sample 0"4 g, heating i'ate 5~ The physicomechanical cha'rficteristics of the polymers were studied on films poured from solution in chloroform with the lnstron instrument at 25~ with a constantly applied load of 490 kPa and rate of stretching of the samples 5 ram/rain. The gas permeability of the films was determined by the gas chromatographic method at 25~ il0]. The ttI-NMR spectra (90 MHz) were recorded with the WH-90 Fourier spectrometer (Bruker) With accumulation (~ 100). To i'ecord the spectra we prepared ,.-5 % solutions of the OCUs and PSCUs in CDCia. To calibrate the chemicai shifts we used the chloi'oform signal (~a=7-24 ppm relative to tetramethylsilane). The IR spectra of the film samples of the block copolymers were recorded With the PerkinElmer speetrophotometer. The gel chromatographic investigations were run with the Waters instrument fitted with three Styrogel columns connected in series (eluent "rHi:, rate of clelivery 1 ml]min, 25~ [11]. The optimal cofiditions for heterophasic p01ycondensation were chosen by the system CIIa CHa 1
i
II[(OArOC)~_m--(X)m--]~OA~OII+ CiCO(CH..O:OCII.,Si (OSi)~CII.:O(CII.2)~.OCCI- , II !~ I I 9 II 0 0 CIIa Gila 0 GIla CII~ L~aon " I I ~---[(OArCO)I m--(X)m--] --OAr--OCO(CH,).OClI.Si(OSi)nClI,O (CII.,),OC---2NaCl !1 I" l- I II O 0 CIt3 Gila 0 .
- -
.
-
.
.
.
.
.
using an O C U with 3 I n = 1040 and BCFS with 3"~,=3720. PSCUs with m a x i m u m viscosities and yields were obtained at concentrations of the initial components 0.02-0'04 mole/l. The use of double (as compared with the stoichiometric) excess of N a O H as HCI acceptor gives copolymers with high M (3Iw= 10s). However, further increase in the content of the acceptor in the system leads to fall in the viscosity (from 0.72 to 0"46 dl/g) and yield (from 80 to 509/0) of the PSCUs formed probably as a result of alkaline hydrolysis. It should be noted that for the same quantity of acceptor increase in the volume of the aqueous phase makes it easier to obtain a block copolymer with large M evidently by reducing the rate of hydrolysis as a result of fall in the concentration of N a O H in the aqueous phase and also by improving the solubility of the low molecular weight reaction products (NaCI, HCI) and their removal from the reaction zone..Thus, 9with change in the ratio of the volume of the organic phase to that of the aqueous phase from 5 : 1 to 2"3 : 1 the viscosity of the PSCU rose from 0.56 to 0.72 dl/g.
1532
E. SH. GOL'DBERG et
T A B L E I . PROeERTIES OF I N I T I A L O C U s
m 0-12 0.05 0.10 0.24 0-12 0.13 0"20 0.21 0"31
al.
--
Amine of urethane fragment 10'0 8"9 7"6 6"1 5"7 3"0 2"5 2"2 1"9
Hexamethylene diamine Piperazine t, tt 9~ iJ
Hexamethylene diamine Piperazine Hexamethylene diamine
O
_[=
"~/~*
Yield, ~.
tho, 1" dllg
Zsort,$ ~
2960 2960 2250 1990 1760 1040 950 850 830
70 65 70 75 75 70 85 90 85"
0"16 0"14 0-12 .0"12 0"13 0"09 0'06 0"09 0"04
206-210
186-188 I
180-185 160-166 90-102 155-160 108-115
* Calculated f r o m the data o f the I I I o N M R spectra. 1' In chloroform at 25~ $ Dctermlned in capillary at heating rate o f 1 ~
T A B L E 2. PROPERTIES OF I N I T I A L
Number of SiO(CttD, blocks 1220 2960 3720 4700 5920
Content of COC! groups~ gray. Yo 10"4 4"29 3"41 2"70 2"16
12 36 46 59 75
BCFSs
n~~
Density, g/cm 3
Dynamic viscosity (20~ cP
1"4095 1"4098 1"4090 1"4065 1"4079
0"99 0'99 0"99 0'99 0"98
11"0 38"4 39"2 45"7 58"2
* Calculated f r o m content o f terminal groups.
ql09 ~dl/3
0.2~ 50
25 0 25 Exce~ ~mole ~ BCFS ~ OCU
40
80 Yield, %
Fio. 1. Specific logarithmic viscosity of PSCU (a) and yield of copolymer (b) as a function of the ratio of the initial oligomcrs on polycondensation in the system methylene chloride-water (1) and THF-water (2).
Polysiloxane-polycarbonate urethane block copolymers
1533:
Since the location of the reaction zone determines the basic patterns of polyconden-sation we tried to evaluate it in the real conditions of the reaction o f formation o f the PSCU in various heterophasic systems. As organic phase we used solvents miscible: (THF) and immiscible (methylene chloride) with the aqueous phase.
a
f
1
z
II
JO
11
18
I 8 w lO~cm-~
10
b
"!
J
I 7
II
I
9~11z
I
I10
6.,pp.p.[']'l.
Fie. 2. IR (a) and PMR (b) spectra of PSCU: a-numerals denote the bands Of the valence vibrations. of the CH2Si group (1), C = O ester group (2), NC(O) group (3), SiOSi group (4) and SiCH3 group. (5); b--numerals denote the protons9 1
IIa
FI'--
3
ff'===~ ~ /~"~"
.
/C[|2CH2~ N
0
6
7
CH3~----~ I
2
4
II3C 5 I
I
9
9
3
113C
. -I
"~N )m
9
CII 3 I
I
CII 3
"
"1
"
"11/ 9
O
.
J
t534
E. SH. GOL'DBERGet al.
.~ T!1eresults of tile experiment presented in Fig~ 1 show that the dependence of tho~ onthe yie!d is of a complex extremal character and with change in the ratio of the oligomers in the reaction system to the maximum M (viscosity) corresponds a non-equimolar :ratio of the initialcorqpounds. TABLE 3. I~{OLECULAR-MASS CHARACTERISTICS OF BLOCK. COPOLYblERIC
OCU
BCFS
830 950 1040 1760
3720 3720 3720 3720 3720 3720 4700
2250 2960 1760 1760 2250 296O
PCSUs
Block copolymeric PCSUs content of yield after t~*loz )0 Si(CH,)20 reprecipidl/g m~ • I0-~ ~1! • 10-~ blocks, tation, % gray. 0"35 82 60 55 22"6 60 .0"50 30"0 80 64 r 17"8 55 0"24 49"8 78 0"81 53"4 67 60' 109 0"59 32"5 62 70 110 0"67 37"0 56 70 75 0"40 73 70 0"48 77 95 65 73 0"43 55"5 19'0 n 70 0"43 67
M../M. 2.4 2.1 2"8 2-0 3"4 2.0
.
592o 5920 5920
2.9
* In chloroform at 25~ t According to GPC.
Since these relations differ f r o m similar ones for polycondensation in solution o r e m u l s i o n [12] it m a y be assumed that polycondensation in the system studied is not o f a v o l u m e t r i c but o f a superficial character and the reaction zone where HCI is also split -off is at the interface or c l o s e t o it, leading to the f o r m a t i o n o f the block-copolymer. Further indirect confirmation o f the diffusional character o f the process m a y be that the rate o f introducing a n excess o f one o f the c o m p o n e n t s (BCFS) to the reaction
T A B L E 4. TIIERMOMECHANICAL CtlARACTERISTICS OF P S C U s .. 9
~r. of blocks
Sample, No.
1 2 3 4 5 ._llO
polycarbonate urcthane I]
]
1040 1760 2250 2540 2960
.
polydimethyl siloxane ] .
3720 3720 5920 2960 5920
Content of block polydimethyl si!oxane, gray. ~ 78 67 73 54 67
T,,
."
--110 105 108 108 )
:
Glass transition points, ~
9
I
T,~
--
36 42
--
55
--
108"
70 65
* For polysiloxanc pob'carbonatc with the/~f o f the polycarbonate block 2500 and the polydimcthylsiioxanc block 2960 T,t ~ =87~
Polysiloxane-polycarbonateurethane block copolymers
i 535
system does not fundamentally affect the M (viscosity) of the block copolymers (0"60 and 0.58 dl/g on rapid and slow introduction respectively). Thus, despite the fact that on synthesis of a PSCU with oligomeric compounds which are insoluble in the aqueous phase the patterns of the process are rather o f a diffusional than kinetic character. Fall in the viscosity of PSCUs obtained in the system THF-water (as compared with the system methylene chloride-water) is associated with rise in the degree of hydrolysis of the BCFS on polycondensation. The structure of the PSCUs obtained was confirmed by IR and IH-NMR spectroscopy. The characteristic absorption bands and the assignment of the ~H-NMR signals are indicated in Fig. 2. The properties of the synthesized block copolymers are indicated in Table 3. The M of the block copolymers according to GPC reaches l~-lw= 11 x 10~. It should be noted that the polydispersity of the block copolymers is 2.0-3.4 and does not depend on the M. The MD is of unimodal character, which points to the absence of low molecular weight impurities and non-reacting initial oligomers (Fig. 3). However in some cases these impurities are found at VR=23-26 (Fig. 3, curve 3). Since GPC is a very sensitive method and picks up traces of the initial components, their presence will evidently also lead to fall in M,. As a result the polydispersity rises to 3.0-3-4 and does not depend on the nature of the urethane fragment and the value of the M of the initial oligomers. "From certain M (Table 3) we found the values of the coefficients K and 0~ in the Mark-Houwinck equation for-the PSCU samples [pl] = 1"8 x 1 0 - 4 M ~
Table 4 presents the results of the thermomechanical tests of the block copolymers obtained. As may be seen, the PSCUs are characterized by two relaxation transitions, which testifies to their structural microheterogeneity. The first low temperature transition ( - 1 0 5 - - l l 0 ~ refers to the glass transition point ot the polydimethyl siloxane block and depends little on its length. These values are close to Tg of high molecular weight polydimethyl siloxane rubber (-120~ The temperature transition in the region 36-70~ characterizes the glass transition o f the carbonate urethane phase and shifts to the region of higher temperatures with increase in the length of the carbonate urethane block. In the region - 5 3 - - 6 6 ~ over the whole interval of compositions studied one observes a weakly marked transition which is probably due to crystallization of the polydimethyl siloxane phase [13]. Since the parameters of solubility calculated from reference [14] for polycarbonate based on diphenylolpropane and polycarbonate urethane have practically identical values,(10.9 and 11.0, respectively) it may be assumed that the morphology of the PSCU is similar to that of polysiloxane-polycarbonate block copolymers. In the interval of compositions of the PSCUs studied (> 54 gray. ~o Si block) the Continuous phase is polydimethylsiloxane in which the polycarbonate urethane component is discretely
E. SIL GOL'DBERGet aL
1536
distributed. The influence of the lengths o f both blocks on the values of Tg for P S C U and polysiloxane carbonates is identical. The smaller value of Tg for the polycarbonate urethane phase as compared with the polycarbonate (70 and 87~ respectively) in the copolymers o f identical composition and length of the blocks is probably connected with !ncrease in the mobility of the rigid polycarbonate urethane block (Table 4, Sample 4 and the sample the characterization of which is given in the footnote). The character of the curves of stretching o f the films based on PSCUs obtained f r o m a solution of a solvent good for b o t h blocks (chloroform) is typical o f t h e r m o elastoplasts (Fig. 4). By changing the ratio of the carbonate urethane and siloxane blocks
G'MPa
1
3
lO
!
lq
16
22
26 VR~counts
0
F1o. 3
500
~,%
lO00
Fxo. 4
FIe. 3. Chromatograms of PSCU. The M of OCU and BCFS blocks are respectively equal to 1760 and 3720 (1), 2960 and 3720 (2), 2250 and 5920 (3), 1040 and 3720 (4) and 830 and 3720 (5). Fie. 4. Curves of the stretching of PSCU. The M of the blocks in OCU and BCFS are equal respectivelY to 2960 and 3720 (I), 2250 and 3720 (2), 2960 and 5920 (3), 1760 and 3720 (4) and 1760 and 5920 (5). Content of Si(CH3),O block in PCSU is 56 (1), 62 (2), 67 (3, 4) and 77 (5) gray. ~ . TABLE 5. INFLUENCE OF M OF POLYCARBONATE URETHANE AND POLYDIMETHYL SILOXANE BLOCKS ON THE GAS PERMEABILITY COEFFICIENT O F P S C U
Moco/MBcrs
0"14 0.22 0.26 0-30 0.38 0-47 0.50 0.60 0.80
Gas permeability coefficient, mole-m/sec.m2- Pa Pco~ x 10ta Po2 x 10ta 12"5 2"3 2.0 11"7 11"6 1"9 11"4 2-0 9"5 1-7 7"8 1"3 7"2 1"3 1.0 6"I 4"6 0"6
FILMS
Selectivity Pco~ : Po~ 5.5 5-9 6.0 5.6 5.6 5.7 5.7 5"9 7.4
Polysiloxane-polycarbonate urethane block copolymers
1537
one may vary the properties of the PSCU within wide limits. Thus, with increase in the length of the rigid block the failing stress at rupture of the films changes from 6 to 25 MPa and the relative elongation at rupture from 1000 to 200 Yo. The strength and deformation of the block copolymers is determined both by the content of the polydimethyl siloxane block and the molecular mass of the PSCU. F o r the same content of the polydimethyl siloxane block (67 ~o) the strength of the copolymer with Mw = 10.9 x 104 is 15 MPa (Fig. 4, curve 4) and for the copolymer for M,~ = 5"6 x 10" (Fig. 4, curve 3) only 8 MPa; deformation 1000 and 250~o respectively.
100 m
60 1 2O I
I
300
1
I
500 T ~
Fro. 5. Integral curves of the weight loss of PSCU. The M of the OCU and BCFS blocks are equal respectively to 2960 and 3720 (l) and 1760 and 3720 (2). The gas permeability coefficient P o f the synthesized PSCUs was determined at 25~ on film samples of the copolymers with M o f the polycarbonate urethane block 830-2960 and of the polydimethyl siloxane 3720-5920. Since the temperature of measurement far exceed Tg of the flexible siloxane block [15] the PSCUs, as to be expected, are characterized by high values of gas permeability for oxygen and carbon dioxide (Table 5). Increase in the content of the polycarbonate urethane block released in the separate little permeable phase leads to rise in the number and size o f its particles in the PSCU. The attendant additional diffusional hindrances determine the fall in the gas permeability coefficient. According to the results o f thermogravimetric analysis (Fig. 5) the block copolymers are stable on heating in air to 300~ irrespective o f the nature of the diamine in the urethane fragment and the length of the siloxane block. TABLE 6. HYDROLYTITC SABiLITY OF P S C U
Medium Water 1 Y. NaCI solution 0.5 ~ NaOH solution 5 Y. NaOH solution 10~ HCI solution
T~ I00 37 I00 I00 I00
Exposure, hr 6 4320 6 6 6
Weight loss, 0
0"3 0
3 0"3
1538
E. St-[. GOL'DBERGet aL
Comparison of the I R spectra of the initial PSCU films with the spectra of the films held.in different media (Table 6) shows no appreciable changes in the structure of the polymers, insignificant (down to 3 ~ ) weight losses being observed only on heating the samples in a 5 ~o aqueous solution of sodium hydroxide. Thus, the polysiloxane-polycarbonate urethane b l o c k c o p o l y m e r s synthesized by us and displaying heterophasicity possess a complex of useful properties, in particular, -high strength characteristics, gas permeability and thermal and hydrolytic stability. Translated by A. CROZY REFERENCES
1. A. NOStlEI and J. McGRATH, Blok-sopolimery (Block Copolymers). p. 30, Mir, Moscow, 1980 2. I. M. RAIGORODSKII, G. P. BAKHAYEVA, L. I. ~IAKARO'VA, V. A. SA'VIN and K. A. ANDRIA_NOV, Vysokomol. soyed. A17: 84, 1975 (Translated in Polymer Sci. U.S.S.R. 17: 1975) 3. I. M. RAIGORODSKII, G. P. BAKHAYEVA, V. A. SAVIN, V. D. SHELUDAKOV, S. S. MKI-IITARYAN, D. Ya. SHINKIN, K. A. ANDRIANOV, L. I. MAKAROVA, V. I. ZHITKOV, V. N. KOTRELEV and T. D. KOSTRYUKOVA, U.S.S.R. Pat. 604855; Byul. izobret., 16, 91, 1978 4. 1. M. RAIGORODSKII,E. Sh. GOL'DBERG, V. A. SAVIN and O. F. ALKAYEVA, Vysokomol. soyed. B20: 621, 1978 (Not translated in Polymer Sei. U.S.S.R.) 5. I. M. RAIGORODSKII, I. G. URMAN, E. Sh. GOL'DBERG, S. G. ALEKSEYEYA, "V. A. SAVIN and I. Ya. SLONIM, _Ibid. A20: 1486, 1978 (Translated in Polymer Sci. U.S.S.R. 20: 7, 1673, 1978) 6. V. FOLDI and T. CAMPBEL, J. Polymer Sci. 56: 1, 1962 7. J. STI'LL and T. CAMPBELL, Monomery dlya polikondensatsii (Monomers for Polycondensation), p. 154, Mir, Moscow, 1976 8. A. GORDON and R. FORD, Sputnik khimika (Chemist's Companion). p. 437, Mir, Moscow, 1976 9. I. F. KAIMhN', Plast. massy, 9, 62, 1966 I0. R. PASTERNAK and J. MeNULTY, Mud. Packaging 43: 89, 1970 11. A. I. KUZA.YEV, Vysokomol. soyed..422: 2082, 1980 (Translated in Polymer Sci. U.S.S.R. t~ 22: 9, 2284, 1980) 12. L. B. SOKOLOV, Osnovy sinteza polimerov metodom polikondensatsii (Bases'of Polymer Synthesis by the Polycondensation Method). p. 172, K_himiya, Moscow, 1979 13. S. TANG and F. MEINECE, Rubber Chem. and Technol. 53: 1160, 1980 14. D. VAN KREVELEN, Svoistva i k.himicheskoye stroyeniye polimerov (Properties and Chemical Structuie of Polymers). p. 135, Khimiya, Moscow, 1976 15. S. A. REITLINGER, Pronitsayemost' polimernykh materialov (Permeability of Polymer Materials), p. 111, K.himiya, Moscow, 1974