'" ..': ~ ' j .,.- "r"'-' ., ~ .', --.;',.. -'1" 7426 -, , Macromolecules 1996,29, 7426-7431 : , , . -;-:.,,: ;1:: Laser Light Scattering Studies of Soluble High-Performance Polyimides: Solution Properties and Molar Mass Distributions :,~ '.~: MohammadSiddiq,t Huizhen Hu,* Mongxian Ding,* Baozhang Li,* and Chi Wu.,t ' : ~:- --'- Department of Chemistry, T~ Chinese University of Hong Kong, N.T., HongKong, and ~~I:; r ~:: ,G Polymer Physics Laboratory, Changchun Instituteof Applied Chemistry, Academia Sinica, ::!;":';\,,~9~'I,?I,. \ Changchun, China :;') c, ~~'l"r~ ~\:1i!)4"'~" Received April 18,1996; Revised ManuscriptReceived August15, 1996* -' ) ." G ~"":;-~ ,tJ.,~ : ),:. ..:..J.'r...~ttG'"f'""~~" ~~.) ~iI;::; ,:~_c;. ,-, -' c .:~",,~ ,,' ABSTRACT: Two soluble high-performance polyimides, poly(BCPOBDA/DMMDA) and poly(ODPA/ . I DMMDA), in CHCla at 25°Chavebeen studied using laserlight scattering. Wefoundthat the z-average .: radiUS of gyration «RJ) canbe scaledto the weight-average molecular weight (Mw) as (R,) (nm)= 4,95 ; x 10-2Mwo.s2 and (R.) (nm) = 1.25x 10-2Mwo,66 respectively for poly(BCPOBDA/DMMDA) and poly(ODPA/ Z DMMDA), indicating that poly(ODP A/DMMDA) in CHC~at 25°Chasa more extended chainconformation than polY(BCPOBDA/DMMDA), Using the wormlike chain modelapproach, we found that the Flory characteristicratios (C.) of poly(BCPOBDA/DMMDA) and poly(ODPA/DMMDA) are -20 and -31, .j respectively, indicating that both of then1 have a slightly extended chain conformation in comparison, ' !! with typicalflexible polymer chaim, such 8S polystyrene, whose C. is -10, A combination ofthe weight- .. ; / average molar mass(Mw) with the translational diffusioncoefficient distributions (G(D)) has led to D,: " , ! (cm2/s) = 3,53 x 10-4M-O.579 and D (cm2/s) = 4.30 x lO:-W-O61S respectively for two soluble high- -' ;l performance polyimides, poly(BCPO~DA/DMMDA) and poly(ODPA/DMMDA), in CHC~ at 25°C. Us~ (~; these-two calibrations, we have successfully characteri~ed the molar mass distributions of the two ,', polyimides from their corresponding G(D)s,The exponents ofthese two calibrations further confirmthat both of the polyimides have a slightly extended coil chain conformation in CHCls, The chain flexibility difference between these two polyimides has also been discussed, Introduction .:;~i;;;:~~~',':~ ;:i6f.~ f::::~._i,f,..!;,~~j "','; c' '" ,-, ':',:," "co CHJ ,.CH] Polyi~des, in particular. those de~ved fro~ fully ~~O~O~CO)*CH.-rn aromatIc monomers, represent a very 1mportant class ofhigh-perfonna.nce synthetic polymers because of their "..., . excellent mechanical, optical, and chemical properties. I and poly[3,3 ,4,4 -oxydl(phthal1c anhydnde)/2,2-dl- It is well known that a fully thennoimidizedpolyimide methyl-4,4'-methylenedianiline] , tenDed poly(ODPA/ is ridim'a11y insoluble in common organic solvents. On DMMDA), with a similar structure of the 'one hand,' this insolubility leads to chemical resis- ;~#~; oh"the'~ther ha~d,this ins~lubility be.comes a CH3 CH3 m8Jorobstat1el~studY1ngthesolutlonpropertles,such t N'OC: -r(31 r'C)I co, 3~ ~ 1" 0 as the ch?infleXibilit:Y and conformation. In the past, ~c J.~o-J~, JI-'Q;-CHi~~: the solutIon propertIes and molecular parameters of co . these insoluble polyimides had to be estimated from their precursor, e.g.,poly(amic acid) fonned by the first- It is worth noting that poly(BCPOBDAlDMMDA) has stage reaction of an aromatic diamine with an anhy- two flexible ether linkages in its repeating unit, while dride. This approach has some intrinsic and serious poly(ODPAlDMMDA) has only one. Both of them are proble~, including polyelectrol.i'teeffectsand the chain soluble in organic solvents such as chlorofonn (CHCls), rigidity difference between a poly(amic acid) and its dichloromethane (CH2CI2), and dimethylacetamide correspon4i!lgpQlYimide chain,2-4 Moreover, infonna- (DMAc). This enhanced solubility provides us with an tion obtained from the Study of those soluble poly(amic opportunity to directly study their solution properties. acids) can be s~roIigly irifluenced by both the nature of The Mark-Houwink equation of poly(BCPOBDAlDM- iInidaza~,on and the reversible reaction.5 MDA) in CHCla at 25 °C, namely [77] = 1.27 x 10-IW,60, In order to tailor a PQlyimide to satis~ various specific has been previously established.6 requirements in industry, a careful examination and As for the characterization of the molar mass distri- con~l ofit$chain co~onnation are ofgreat.impo~.ce' butions of soluble polyirnid~s, size exclusion chroma- PractIcally, a cOr:rel~tIO~ bet~e~n the cham fleXlbllity t.9graphy (SEC; also known as GPC) is often used.3 and bulkpropertjes ~s ~~ll mlssmg. Rece~tl>:, we have However calibrating a SECcolumn is rather difficult. ~ad;e two $ol,uble .}?igh.penormance polYlm1des, poly- M ' h bli ' h dl ' b ' I b d [l,4'-bis(3,4-carboxyphenoxy)benzenedianhydride/2,2'- .oreove~, eac esta .s e C8I ratIon c~ ony e,use dimethyl-4,4'-methyle~~di~e], tenned poly(BCPOB- m a partIcul~r SEC mst:ument. Receni;ly,couphng.a DAlDMMDA) with a struCture of s~al~-angle light ~cat.~~g.detector,with S~ has, m , pnncIple, solvedthis calIbration problem. In this report, we will focus on the solution properties of poly(B- .To whom correspondence should be addressed. CPOBDAlDMMDA) and'poly(ODPAID~A) and show t The Chinese Un~verBity of H?ng Kong: an alternative laser light scattering method for the * Changch~ Instltute of Applied Chemlstry, , * Abstract published in Aduance ACS Abstracts; October 1, charactenzation of molar mass distnbutlons of soluble 1996. polyimides, 97