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1994
Technical R orOrt #10 S. FUNDING NUMBERS
4. TITLE AND SUBTITLE
Compatibility Studies of Some Azo Polymer Blends
N00014-93-1-0615
6. AUTHOR(S)
S. Xie, A. Natansohn and P. Rochon 8. PERFORMING ORGANIZATION
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
Department of Chemistry Kingston, Ontario Queen's University
.D
Canada
Q
REPORT NUMBER
T IC
10
AAi 10. SPONSORING I MONITnln'"-
"
9. SPONSORINGI MONITORING AGENCY NA
65 94,,0865
Department of the Navy0
Office of Naval Research
'"
94-08659
800 North Quincy Street Arlington, VA 22217-5000 11. SUPPLEMENTARY NOTES
submitted to Macromolecules
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Reproduction in whole or in part is permitted for any This purpose of the United States Government. document has been approved for public release and sale, its distribution is unlimited. 13. ABSTRACT (Maximum 200 words)
1k O'J
%
Polymer blends were made by mixing the azo polymers poly{ 4 '-[(2-(acryloyloxv)ethyl] -ethylamino]-4-nitroazobenzene}(PDRIA) ,poly {1'-[ [2-(methacryloyloxy)ethyl] [2-(acryloyloxy)ethyl] ethylamino] ethylamino]-4-nitroazobenzene} (PDRIM), and poly4 '(t poly(methyl 3-chloro-h-nitroazobenzene} (PDR13A) with some common polymers: Compatibility polystyrene (PS), and polycarbonate (PC). methacrylate) (PMMA), studies of these binary blends were carried out by differential scanning calorimetry Most of the azo polymer blends are not compatible, including and solid state NMR. The compability PDRIA/PC, PDRlM/PC, PDR13A/PC, PDR13A/PS, and PDR13A/PMMA blends. For PDRIA/PMMA and PDRIM/PMMA blends of the PDRIA/PS blend could not be determined. The DSC measurments showed only one glass transition temperature for each blend. The blends were further analyzed at the molecular level by CP-MAS NMR relaxation. (1H) values, slow-evaporated PDRIA/PMMA blend sample showed two separated T However, compatibility suggesting phase separation at the level of a few angstroms. The PDRIA/PM'M could be achieved by heating the slow-evaporated blend above 110 C. The and PDRIM/PMMA blends made by precipitation in methanol are also compatible. blends which are homogeneous at the molecular level are suitable for optical storage 15. NUMBER OF PAGES
14. SUBJECT TERMS
azo polymers, blends, compatibility
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Z39-'s
Compatibility Studies of Some Azo Polymer Blends Shuang Xle~t
Almeria NatansohaV~ and Psaul leehem'
Deparamnt of Chemistry. Queen's Univeruity. Kinguton, Oustsr*s KL 3M6 Canada. sand Department of Physics. Roya MilitowY College. Kingston. Ontwie K?K SW Canada Received September 22, 1993; Revised Manuscript Received November 30. 19930
ABSTRACT: Polymer blends were made by Wniinthe azo polymers poiyf4'.112-(&cryloyloxy).thyll. ethylaminoj.4-nftrourobenxenej (PDR1A), polyf4'.((2-(metha~oyrlozy)ethyliethylamanoJ4asobnz (PDRIM),sand poly(4'41(2-(a ryoylozy)ethyljethylaminoj-3-chloro-4-nitveasobamnma4(PDRI3A) withsom. common polymers poly(methyl metbacrylata) (PMMA), polystyrene (PS). and polycarbonaate (PC). Compatibility studies of thes binary blends were carried out by differential scannin cslorhootryandsolidstate NMR. Mostof theamopolymer blendsa nowt comapatible. including PDRWPCKPDRIM/PC, PDR13A/ PC, PDRIMIPS, PDR13AE'PS, and PI)R13A/PMMA blends. T'he comipat~bility of the PDRLAMP blind could not be determined. For PDRLA/PMMA and PDR1M/PMMA blends, DSC aesourmmawts showed cin* one glass transition temperature for each blend. The blends wer further sanalysed at the molecular leaid by CP-MAS NMR relaxation. The slow-evaporated PDRIJAIMMA blend @ampl obmi two speprated Tad,(1H)values. suggesting phase separation at the level of a few angstrms Howeve, uompatiblity could be achieved by heating th lowk-pvaporated blend above 110'C. The PDRUA/IMAG and I'DhIMPMMA blends made bypredpilationdis methanol are also compatihis. The blends which.. hoemoggasose t the molecilar level anresifta" for optical Storage Okwits. Introduction Azo polymers have many special properties.' In the search for new materials for optical applications, suha reversible optical storage and nonlinear optical devices, azo polymers have attracted much attention.2U Polymers with low azo concentrations are particularly useful. T7he writting and erasing efficiency depends on the energyinu, from the irradiation light during the process. Inpini le lower energies would be required to induce local variations of optical properties in polymers with low azo concentrations. ilue i poyme maerils, ao cntet oderto In te madeterialsow bed polymerr Inordlyer5tondlueteaocnnti arempeade turisknown coatpolymers andhpohlymerablndsito bthtepolymtermswthahiggltyoftheanriting infpematiorthane winomthionuted long ter stbilymofrthetwriting bettmerswt polmes it lw r5 oye ltYaSWt iu azo content can be desingned to have higher glass transition temperature than thoseeoftheewhomopolymems Another advantage is that cheap materials can be obtained from mixing the azo polymers with some conventional polymers. The study of compatibility in polymer blends is an area of practical importance because the degree of mixin and solid-state phase structure of a blend govern its physical and chemical properties. Inthecaseofwritinganderasing information on azo polymer blendsacceptable resolutions can be achieved only on homogeneous 'materiskl. When the am polymers are diluted with some optically inet materias it in necessary that the blends be compatible at the molecular level to ensure the homogeneity of the material for optical Studies. Dumnont at al. used some amo polymer blends to stuy the photoisornerization of the sic group. 7 T7he blends wire made by maixing MM copolymers with PMMA in order to get a certain optical densitymand thickness. No inhomogeneities were reported. This suggests that these amo polymer blends may be compatible. It is well known that the intimacy level of the componenta of a blend appears to be dependent on the method t Queen's University. I Royal Militar College. 0 Abstract published in Advance ACSAbstracts XmxxxzrzxYY,
77"-methacrylate)
0024-9297/xz/2200-M00104.50/0
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of measurement employed in the examinatilon. In this paper the compatibility of the azo polymer blends.i
studied by a combination of differential soann calo-
rmty(S)adsldsaohg eouinO-U Dspctrosbopey.sd osd~id~iyncliu asige lm traition ternwion wosf beds. The deten bed.Teetconfaszsglstrstonom perature, T., is generally considered asevidence of oeeDCi nySniiet hs cmaiiiy about 10 nm..U sie ratrta The 1 rsspolarization and magic angle Spinning (CPMAS) solid-state NMR technique offers an unique insight into the molecular phase structure and mobillty. of amorphous polymers. The parameter used toexmn the blends is Tl,( 1H), the proton spin lattice relaxation time constant in the rotating frame." As a criterion for miscibility, it is superior to T9 measurement sinc, it can be sensitive to phase usies at levels of a few angstromus. T1,(1H) measures the efficiency of spin diffusion in a sample and depends on intaprpoton distance and an the spectral density at the observation frequency. Strong homanuclwa dipolar interaction between protons umnaly average the valueof T1 4H) foralltheprotona in asampis. When the components of the blends have two wellseparated T1,(1H) values. do Presnce of a cornma Ti, Hinterbndmpishatesmles in the coherence Scale of a few angstroms ;n o!; the value of TXX(H) Thereface, T,,( 110 is used to d nwingn between Wlen& thatare intimately mixed and those that are not. It has been successully used to probe molecular maixn in many polymer blends.U .The present work is also apart; of the investigation of the amo polymers for optical applications such as information storage. The optical properties of the blends will be reported in a forthcoming paper.$ Experimental Section Matrils. Az polymer blends wer synthesized by mxn Lhe sic polymers poly$'4[2-(uaayoylox)ethyllethbylaminol4 1iir 1 _oenzsnej(PDRLA),polyW4'2-U2(mnsacyloyloxy~)etyl ethylaminoj--itroaobenzensj (PDR1M. and poWy4'42(acrloyloxy)othyllethyladmnl4-3-doco-4-nftrossobeessAe (PDR13A) with some cooventonal polymers polymemthyl (PMMA), polystyrene (PS). and polycarbonate 0 xzm Americans Chemical Society
'
8
owes
Xi. atal.M Scheme 1. Structure sand Glass Treanltlem Temperatures of the Azo Polymers13
140
120
I-.-yq
r
70 -Cft
0 10.2
0.3
0.6 0.4 PUA0.5 .migrt2
0.7
0.8
0.9
1C
Figre1.Gln tanitontemperature. of PDRWVPMMA
Table 1. Gas" TnaknulTie.1mpeauturesat &Me Ass
Scheme 2. Structure and Glass Transition
Temperatures of the Other Polymers Used in Blends
____________________
-t1 i
0
s
-VcPDR12
"P~AATV .i id'c
f
PC 96 an 142 N md 140 mmlInaadl46
PDRIA
fs"1U
I~sadlM
PUMM
ý:4S-ssadW S
icete are equivalent. For mastof the sampiw'MT(R wee measured using a pub %,equee- with a WV IN pulse of V7 ^s aflxedcontacttimoftms~ao8.srecysdmayhstweemplhas, 40lepectarmu dl and&aibedelay&mI~o2mu referenced according to the VC
~Q~i0Jo~
PS 1161
Ipsa dofbIc q. meri
P1 "Io. PCTo-vcCDCIs soludom.? The In eak- ntm dmlf dbffest TL('U) were plotted se a functionm of delay thus The PC1. '~eCsips!. values were obtained from the negative rstlcl
of Urns
pe.
(PC). ThU structures and the glass transition temperatures of RslsadDsuso icus the materials used are listed in Scheme I for s~ polymer anedlSad Thermal Analysis. DSC measuremenis of the hoScheme 2for the other polymers. Monomers and hoinopolyifls mopolymers showed onlytheglmstranaimtionmperatures PDRMA PDRIM. and PDR13A were prepared ns described in Allpeiio.M previous pubboations. PMMA (Aldrich, nmidi~un molecular ann other enthalpy changes beleret weight), PS, and PC (Aldrich) were used an receivedeplmr.n bed sdi hkb w mrhu Polymer blends were obtained by mixin solutions of the as confirmed by polarized microscopy polymer pairs in hot THF with stirring, followed by slow Two well-separated glas txanositon tompuartures were evaporation in beakers. T1his low evaporation method is also observed for PDRIA/PC, PDRI.WMPFDRISA/PC, used in preparing thin films for optical sudies. Fifty percentby PDRlM/PS, PDR13A/PSandPDR13A/PNMA blends weight amounts of the sac polymers were used for blend with Thie two temperatures for aeach bland wer chms to the T PC, PS, and PhIMA for initial thermal analysi. values of the two corresponding homopolymi&n..TewD On the other hand, 12.5,25,37.5,50,62.5,75, and 57.5 mol % results indicate that then blends are laompatible, PDRLAJPMMA blends were prepared by precipitation of THF aolutianintomethanoL Afterfltration~theprncipitatedaomplas therefore no further tesmb were, Falsd os. Mhe DSC were dried in vacuum for several days at -40 *C previous to reutfothblnsed aeVk ITM L n hls1 h bedststdmO reitsfr thermal tests and CP-MAtS OCN~nIW PDRIJA/MMA, PDRIJA/S, and PDal.4PWP MA of cme of the precipitated blends (50%) was checked by NMR ftansdion blends show only me Is. A.-iftbli spedrosewp in CDC6s. The result showed -t duang in the temperature may be an Indlaths of m hoaf at the Composition after Precipitation.
Anablyss. Thegleastrauuftiontemperati,?weameesune using differentia scanning calorimetry on a i"~te TMOO@ system at a scanning ratis of 20 C/mln. In aeder I* esni reproducibility. samples wers subjected to athlesthrooeheaftl scans in wosuccsan over the temperature rage 40-140 ea T. was taken as the peak of the first derivativ cuny othe or third heasting scan. The glass transition temperatures of the homopolymers used are listed in Schemes I and 2 together with the structures. solid-state NMR measurements were mae&on Bruker The "IC CXP-200 instrument operating at 200.044445 and 50.307 MHz for'H andMIC NMR, respectively. The sC spectra were collected using the methods of cosolarization, magc ang~le spinningI6 and dipolar decoupling (CP-MASIDD). Two pubso sequences have been developed to measurethe prto spin-latierelazstw~n time ewatant in the rotating frame TI4I,(H) by CP-MS NWL" One includes a variabl contact (CP) time, while the other uses avariablhdelayfcllowedbya fihed contacttims. Forth. polymers we tested. the T1,.Q) values are shorter than their corresponding T,(WCOvalwes.'s Hence we can apply eitherafthe twosequenees
level of about 10 am. Powemrs d. frms~e the glass transi"o te~pmtdres a otmcomponent poymam are lees than 6Q 'C. n Sawe cm, the udo& T.ma be a result of the poor zsslublin of the DSC ansealysis. DSC studies show that the EDR1A/PMMA blends posems a single 7'c at any composition. The DSC data of the series of blends is plotted as a function of weight fraction of PMMA in the blends in FIgure L hn order to study the broadening of the To range, we measured To. and Ts,1 values at the half height of the fizet derivative curves as shown in Figure 2. The T&&and Taz values are also plotted in Figure 1. The T5 transitions awe broader
olmer moo In fact, the for the blends than for the glass transition curves of the blends cover the range of Ts~ of both PMMA (110 60 and PDRIA (91 OM This broadening of the T. transition is known not only for 14 incompatible blends but also for compatibl blends.
o.L
Moo
Aso Polymr Bland Copemptlhly Studies C
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5
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-
-
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2
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12
14
TUX CON4TACT
L. Plot of ln(intanait) M Ak cbtioa Of deay tim, for
IF4"r
sip"3lasnod 7shws in gurs & DSC curve (right) and first derivative (left) o(PMMA. Table 2. Ti,(') Values (Ms) Cabulabd eeshim Signtals 7 SUNw In F~gure 3hr PKMA DAaai IheirBD~mds 4 *dp 4 1 6 T'.4 sapl it 10 U U - is 1 APDRIA 253 5a a eýJAPUMA 9 18 13 13 9 18 evaporated Ibiand-llow a 9 a 8 bleod-meowvaporated 9 7 3a and then heated aboev Tc 8 8 9 7 7 9 6bloed-precipitated 2
PDR1A). Thismayindicat~ieaeIarii Unmnthisblend. Because of this preparationstho~h sapeol o be dried very wel THFP salvet asaka wer.cdearly present4 in the spectra (two posh at about 30 said 70 ppm). The blend was 6=~ heated above the glas transition temperature (110 -) in the rotor for about 1
I
h Under spinning and then teste
_______________________
ISO
Figure 3. CP-MAS
120 3C-NIIR
46SI~rTiD('H) CHOMAL
0
spectrum of 50 mci %PDR1A/
PMMA blend prepared by p :pitation iodwtld.
apain The spectruIm
showed that the blend was now dry. ThIk time, simila values were obtained fima all signalsm listed in TableZ2 which indieelsdthttebUndbscams compatible
afterheating. T~hepha. separationin thealow-evaporated
aism stlvemt, or the blend sample may be due toths p valuse." ate difarnt TU presence of solvent mayg-e Heating of then.smlsdal produces compatible blends. Another ampl (~d ze %of PDRIA) obtained by prcptto aas nbe by acid-stat. NMRL Th reut ar honi Table 2. Similar TU(1 H values wer also obtained for all skupesh in the blend, with an average value of about Sua. The apin diffussion distance 3 (x) can then be estmasted aftdu *isfrmula
Therefore itis difficult to tell whether the PDRLA/PMMA blends are compatible or not from the DSC. NMR Belaxatlon Studies. For Tl,,OH) to be used as of miscibility, the components of the polymer a criterion blnshave to have two separated T1,( t H) values. Th 1H values similar to those blends can then have two TOM, of the two components when the two pOM entaU form separate phases, or just one T1 1(1H) when the blends an miscible. In the case of PDR1AIS blend, the T1,(')lS values at FS, and PDR1A are 7 and 6 a%,uesEstVINUMY."-41l They are too else to be disingiuahed On.doe blsmIL We M Ilirgest Do whth tpm~at whereDis the found that PUMA hasa T,4,(1H) v"alut.25 ma, wrhich is aIs).' For in organic sytmfor Analka 11.2 X to-2in quite different from that of PDRIA (10 mr). Therefore that.the lk 1W T1V,(H) - 8 =a, kU PDR41APMMA blends were 1nvestga~d by NMR. basuethan "pod p ,a bbwnds domain uis in the-I Fgre apresentia tpicalCP-MAS'UC-NMRupectnsm 3 nm and the PDRLWPWA polmrb h aren m of a PDRLA/PMMA blend (50 aol %)togethe with the 0 W patible at this level. assignmenta. There are some resonances in the spectrm The compatibility of the PDRIW/PMMA blend was of the polymer blend that come from onl one component, also checked by solid-state NP. The sample with 50 the aromatic carbons of PDRIA. Signals from PMMA mol % PDR1M was precipitated frm a nonsolvent alone are not available. For each resolvable signal the (methanol) and then heated above the Sim transition T1 ,(1H) values were measured. temperature (129 60. The signals showed a consistent Figured4 shows the magnetization for signal 3 (from T 1,('H) value of 4 ma, which indicated,that the PDR1M/ PDRIA only) and signal?7 (from both PMMA and PDR1A) PMMA blend is also compatible at the molecular level. of delay time for the slow-evaporated sample. asa function It is well known that when two polymers are blended, The Tt 1(1H) resultsare listed in Table 2 for blend and the most likely result is a two.-pb.. material as can be honiopolymers. a loas The predicted from A'Mtffsodyia.0mics uuidM Two different Tj,41 H) values (9ma for PDR1A and 13 compatibility of varios methkacylate and acryiate homa for the overlapped signals) were obtained from the mopolyiner blends has been analysed in the literature, It spectra of the slow-evaporated blend sample (80 wt %of
D Xies t aL
has been shown that the structural difference of the a-methyl group is sufficient to limit monophasic behavior of the blends.17 Only a few compatible methacrylate or acrylate polymer pairs can be found in the literature."s There may be two explanations for this unexpected compatibility. The firstexplanationnusuallyinvolvessome kind of nonbonding interactions which may be present in the system and which provide the driving force for compatibility. Ion-ion, ion-dipole, dipole-dipole, hyrogen-bonding, or charge-transfer interactions are known to perform this role. In the systems presented here such interactions are unlikely. Infrared spectra did not reveal any changes in absorbance bands which could have been related to such interactions. Indirect evidence of weak interactions can be given by chemical shifts in CP-MAS 13-NMR spectral' or even by a decrease in T,(1H) values for the two components due to a more efficient spin diffusion between closely interacting componants.1" For thes pairs, no chemical shifts could be observed in the solid state, and the difference in Tio('H) values of the blend (8 ms) and the fastest relaxing component (10.5 me for PDR1A) is too small tosuggestanyluteracim Hence, with the available experimental techniques, no evidence of interaction could be found. In terms of this first explanation, the compatibility here could be considered an anomaly, as in the case of polystyrene-poly(phenylene oxide) blends. would take into account the The second molecular weights of both PDR1A and low explanation
relatively
PDRIM (ca. 10-12 structural units).3 It is well known that miscibility can be greater for lower molecularweight polymers and oligomers, because the entropic factor may still be important Hence, in terms of this second explanation, the analysed pairs may be compatible only at these relatively low molecular weights and behave "normally"(i.e., become incompatibile) at higher molecular weight. This has still to be investigated, since we were not successful yet in preparing higher molecular weight azo
polymerS
Mocromolewla
PAGE E.' V7
polymers.
In any case, the real explanation for the compatibility of these systems is probably a combination of these two are rare systems which are compatibile explanations: these atthe molecular level at least in the range oflow molecular weights.
Blends ofPDRIAIPMMA canform bomogeneosflmin by solution casting and heating. PDRIA/PMMA blend samples prepared by the slow evaporation method showed separated Td,('H values which may indicate separated phases. However, homogeneouspmolymer blends could be obtained by either heati the sample above the glas transition temperature or by precipitation into a nonsolvent. The casted and then heated films ofthe PDR1A/PMMA blends are suitable for use in the optical storage tests." The azo polymer blends with low no concentration are very interesting because there is no opticaly inert neighboring group around the azo groups. In fact, the writing and erasing results will be compared with two other series of random copolymers made from disperse red I and methyl methacrylate to study the effect of the nearest neighbor in the polymers.44 Acknowledgment. We thank the Office of Naval Research USA and NSEC Canada for iAmding. References and Nets (1) X, S, Natumsob, A Rode•s P. Mom Mee-. 1"S,5. 403. 11, =2,8L ( Eaton D. Sci ,2)
ARO;omdcl.P.;PGa., J4Xi&&MaUCowkeCa 1112, X, 226
(3) Na,
(4) xM, S.; Natamsk. A.; Rodm4, P. SebIahdie MwcromooOft Ams. en, ilr, D.; Smith, (5) Walh, C.A. Burmd. D. W-Les. V.Y.; Ma. B. A.; Twie, R. J.; Volkmn W. MacrumoLIWaLS 11, 1 S, 3720. (6) Nataea, A.; Xi .; Rechda, P.; Dmw. D Ui ubished rumi. J. A. Damont, 1, K. D (7) LR;ihi, FNakastm So"it I aif MAW. IMal, &L B.;SpmILW.Ma~n(8) Schmidt-Ra9r, K.;itu&J.;Bz Science; Allen. G.; ,.yuw (9) Walsh. D. J. In Con mpehive P Ed.; Pergamoa Prm Oxford, 19M VoL 2, p M5 (10) McBriuty, V.J.; Dougam, D. C.; KiT.IL AaMrmomeada S .1,12M, (1911 (12) Siinmoa, A-. Natans"a A.Mwcotoeadekla MI.1 24, 3651. . J; S" AL D4 Mkaly. R A. OKSd 04 (12 Seja e Maocno ules 1961,14,27. (13) Xk, S, Natansoka, A.. Rochom, F. Unpubfithed results. B Catmw, IL D. IM,/ Schneider, C~en. (14) Ma/mmoin M, It. 23o77.Wndl"d, CQ.Lmu, 1G AT61. 1115,191oflaT A. (15) Simmokr A6, Ncu'so (16) V.nderbart, D. L.MakrorowL Chem, Mecxoion. Symp. 111S, 34,12L.
Conclusions Two separated T. values were observed for most of the azo polymer blends tested, except for the PDRAI/PMMA,
PDR1A/PS, and PDR1M/PMMA blends.
Fergusn, FL; Fernand, IL D4 (17) Cowis, 1"I. U. 170.Fernandez, M., J.; Mc.EmanJ4 L Moooa•d
Brandrup, J., (18) KraUm S. Pobmo encu"n1mm1 19 p 347. IL,Ed. John Wley & Soanr New York,19W, (19) Natanahn, A. PbinLt. ZM/.ScL 1, 3, 171L
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