Stiff Chain Behavior of Poly(terephthaloyl-trans-2,5-dimethylpiperazine) in Dilute Solution

Abstract

A number of narrow-distribution fractions of poly(terephthaloyl-trans-2,5-dimethylpiperazine) (PTDP) ranging in Mw (weight-average molecular weight) from 5,000 to 300,000 were prepared, and their molecular weights, z-average mean-square radii of gyration <S 2)., second virial coefficients A2, and intrinsic viscosities [r;] in appropriate solvents were measured. Trifluoroethanol (TFE) was used for the lightscattering study and m-cresol and TFE for the viscosity study. It was found that the observed data were quantitatively interpretable in terms of the Benoit-Doty theory for <S 2) and the Yamakawa-Fujii theory for [r;] of unperturbed wormlike chains. The persistence lengths q obtained in TFE and m-cresol were about 70 A, which suggests that the PTDP chain is fairly stiff. This q value is about 1.5 times larger than that of poly(phthaloyl-trans-2,5-dimethylpiperazine) (PPDP) in m-cresol. PPDP and PTDP differ only in the position at which the phenyl ring is linked to the piperazine ring. KEY WORDS Poly(terephthaloyl-trans-2,5-dimethylpiperazine)IPoly

Chain stiffness and excluded-volume effects in dilute polymer solutions. Poly(isophthaloyl-trans-2,5-dimethylpiperazine)

“…Because of this feature, the separately estimated q and ML values are not very accurate. Nevertheless, the Ml value of 310 nm-1 is compatible with the chemical structure of PIDP20 and close to those (300-360 nm-1) determined by Motowoka et al21,22 for poly-(phthaloyl-frans-2,5-dimethylpiperazine) and poly(terephthaloyl-ircms-2,5-dimethylpiperazine), the two polyamide isomers of PIDP, in various solvents. Our q of 1.2 nm in NMP is much smaller than the previously estimated values13 for PIDP in other solvents (4.9 nm in mcresol and 3.1 nm in trifluoroethanol).…”

New method for estimating the parameters of the wormlike chain model from the intrinsic viscosity of stiff-chain polymers

“…For this reason, we include the three isomeric polyamides in the present discussion, pursuing the following aims; (i) We wish to check the use of the method based on eq 11 for less stiff chains than those discussed so far. (ii) By analyzing the data for PIDP, we hope to find out if the method allows the effects of chain stiffness and expansion to be separated, (iii) Motowoka et al17,35 have found that the theory of Yamakawa and Fujii cannot account for the experimental data for PPDP and PTDP at < 2 X 104. We wish to explore the possibility of detecting such deviations by the proposed method.…”

Stiff-Chain Behavior of Poly(isophthaloyl-trans-2,5-dimethylpiperazine) in Dilute Solution

“…To estimate the persistence length of the remaining one of the three isomers, i.e., the meta-linked poly(isophthaloyltrans-2,5-dimethylpiperazine) (PIDP), we measured z-average mean-square radii of gyration (S 2 )z and intrinsic viscosities [ry] of narrow-distribution samples of this polymer over a range of weightaverage molecular weight Mw from 3.7 x 10 3 to 2.4 x 10 6 g mol-1 • This maximum M w was several times as large as any one of those treated in Motowoka's studies on PPDP 1 and PTDP. 2 Except at relatively low Mw, the data exhibited features usually observed for long flexible polymers in good solvents. In this paper, we report these experimental results and consider their significance in the study of semiflexible polymers in dilute solution.…”

“…For any fraction, the [17] value in m-cresol is larger than that in TFE by a constant factor of 1.45 ± 0.08. It is of interest that Motowoka et al 2 found [IJ1m-cresol/['7hFE to be 1.42 ± 0.08 for the PTDP fractions examined. In Figure 6, the molecular weight dependence of [17] for PIDP in m-cresol is compared with that for PPDP 1 and PTDP 2 in the same solvent.…”