Kerr Effect and Wide Angle Light-Scattering Studies of a Para-Aromatic Polyamide in Dilute Solution

Abstract

The geometric and optical properties of a para-aromatic polyamide are characterized using wide angle light scattering and electric birefringence. The polydispersity correction was applied theoretically by assuming the most probable distribution. The aromatic polyamide studied can be satisfactorily modeled as a Kratky-Porod wormlike chain with a presistence length of 220 ( 50 Å and an optical unit anisotropy ratio of 2.2 ( 0.3 in tetrahydrofuran. The refractive index of 1.67 ( 0.03 is comparable to that of similar polyamides. The high persistence length of the polymer chain and the high inherent optical anisotropy of the repeat unit are found to be responsible for the exceptionally high birefringence observed in the oriented films. It is also conclusively established that there is no aggregation in the absence of moisture.

Spontaneous Chain Orientation of Aromatic Polyimides Evolved during Thermal Imidization from Shear-Oriented Glassy Liquid Crystalline Precursors

“…The values of q * and l p estimated from q * using l p = A / q * are listed in Table , revealing that l p decreased with increasing m . The estimated l p is comparable to that reported for similar aromatic polyamide with CF 3 side groups . Furthermore, the value of l p was much smaller than contour length (in the case of PM2, the contour length should be at least 50 nm), implying that the molecular weight did not affect l p .…”

“…The values of q* and l p estimated from q* using l p = A/q* are listed in Table 2, revealing that l p decreased with increasing m. The estimated l p is comparable to that reported for similar aromatic polyamide with CF 3 side groups. 66 Furthermore, the value of l p was much smaller than contour length (in the case of PM2, the contour length should be at least 50 nm), implying that the molecular weight did not affect l p . The diameter of the isolated chain, D, was estimated from the distance between the methyl carbon atoms at the end of the side chain for the most energetically stable conformation calculated from the DFT, as listed in Table 2.…”

Determination of Scattering Parameters of a New Copolymer by Using a Laser Scattering Method

“…The intercept with the axis of ordinate gives the reciprocal value of Mw according to Eq. 1 (Shere et al, 1996) and the slope of the concentration dependence being twice the value of A 2 .…”

Determination of scattering parameters of polyvinyl alcohol by static laser scattering

“…The intercept with the axis of ordinatesmgives the reciprocal value of M w according to Eq. (1) (Shere et al, 1996) and the slope of the concentration dependence being twice the value of A 2 . In this simple way, i.e., through the measurement of scattered light intensity at a single angle q, the molecular weight can be obtained but only for particle diameters smaller than l/20, which is only found in a number of proteins and polymers.…”