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ABSTRACT:Poly[trans-bis(tributylphosphine)platinum I ,4-butadiynediyl] (PPBD) in heptane at 25cC was studied by viscosity and sedimentation velocity measurements over a range of weightaverage molecular weight Mw from 7 x 10 3 to 1.4 x 10 5 Although the chemical structure of PPBD suggests a very rigid nature of the chain, the measured value 1.1 for the exponent in the Mark-Houwink-Sakurada [IJ] (intrinsic viscosity)-Mw relation indicated an appreciable flexibility of the chain. The data for [IJ] and sedimentation coefficient as functions of M w were analyzed by the Yamakawa-Fujii theories for a wormlike cylinder, yielding ML = 810± 60nm -l, q= 13 ± 3 nm, and d= 1.2 ± 0. 3 nm, where M Lis the molecular weight per unit contour length, q is the persistence length, and dis the diameter of the cylinder. The flexibility ofPPBD indicated by this q value is comparable to that of cellulose nitrate which is known to be a typical stiff polymer. solvents were essentially independent of solvent (about 1.2x 10 2 cm 3 g-1 ) and that the exponent in the Mark-Houwink-Sakurada relation between [17] and weight-average molecular weight M w was close to I. 7.These preliminary results indicate that PPBD can be used as a model substance for investigating rodlike polymers in solution. In contrast with aromatic polyamides, considered model substances for rodlike molecules, 5 -7 PPBD does not involve the problem of difficulty in solubility; Hagihara et al. found that it dissolves in a number of common organic solvents. This is a very inviting feature for a solution study of PPBD.

ABSTRACT:Fractionated samples of poly(phthaloyl-trans-2,5-dimethylpiperazine) in various organic solvents at 25"C were studied by light scattering, viscosity, and sedimentation velocity. The data obtained for z-average mean-square radii of gyration (S2)z, intrinsic viscosities [7)], and sedimentation coefficients so exhibited features predictable for stiff or semiflexible chains. Thus an attempt was made to analyze the data by combination of the Yamakawa-Fujii theory for intrinsic viscosity and the Benoit-Doty expression for mean-square radius of gyration of unperturbed wormlike chains with a reasonable assumption for the partial specific volume. In this way, three parameters q, ML, and d characterizing the wormlike cylinder were estimated for each solvent; for example, q=33 A, ML=33 daltons/A, and d=7.4 A in N-methyl-2-pyrrolidone. Here q is the persistence length, ML is the molecular weight per unit length of the wormlike cylinder, and d is the its diameter. The estimated parameter values were found to reproduce quite closely the observed molecular weight dependence of (S 2 ),, [ri], and so.KEY WORDS Poly(phthaloyl-trans-2,5-dimethylpiperazine) / Wormlike Chain / Persistence Length / Dilute Solution / RefractiveIndex Increment / Light Scattering / Intrinsic Viscosity / Sedimentation Coefficient / Yamakawa-Fujii Theory / Benoit-Doty Theory / Poly (phthaloyl-trans-2, 5 -dimethylpiperazine) (abbreviated PPDP in the following presentation) is one of a series of polyamides synthesized by Morgan, et al.

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