Properties of dilute polymer solutions IILight scattering and viscometric properties of solutions of conventional polymethyl methacrylate
TL;DR: Light scattering determinations of molecular weight and coil size made at room temperature with three different cells at two wavelengths of incident light and in two solvents (acetone and acetonitrile) on fourteen fractions and six whole polymers of polymethyl methacrylate ranging in molecular weight from 2.7 × 103 to 2.5 × 106 provide a basis for estimation of the validity and reliability of such measurements as mentioned in this paper.
About: This article is published in Polymer.The article was published on 1962-01-01. It has received 92 citations till now.
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TL;DR: The results of an extensive study of the intrinsic viscosity [η] of a series of linear, homogeneous (anionically prepared) polystyrenes (1.9 ∼ 106.
Abstract: The results of an extensive study of the intrinsic viscosity [η] of a series of linear, homogeneous (anionically prepared) polystyrenes (1.9 ∼106. Above this molecular weight the dependence of [η]/[η]0 on z is satisfactorily predicted by recent calculations of Fixman; [η]/[η]0 is not linear in z contrary to other recent suggestions. The failure of the data on lower molecular weight polymers to be a single‐valued function of z is discussed in terms of partial draining effects.
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22 Feb 1999
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TL;DR: The chain length dependence of mean-square radius of gyration ‹S2› for several polymers, stiff or flexible, in dilute solution is compared with that for the Kratky–Porod (KP) wormlike chain, using representative literature data.
Abstract: The chain length dependence of mean-square radius of gyration ‹S2› for several polymers, stiff or flexible, in dilute solution is compared with that for the Kratky–Porod (KP) wormlike chain, using representative literature data. In the region of nK, the number of Kuhn’s statistical segments, below about 50, ‹S2› for all polymers examined is accurately described by Benoit–Doty’s expression for the KP chain. Upward deviations from this expression occur at nK of about 50, regardless of the chain stiffness. Thus, the critical chain length Lc for the onset of excluded-volume effect on the average dimensions of a polymer is approximately proportional to q, the persistence length of the polymer, with a proportionality factor of about 100. The value of Lc estimated from this relation is at least one order of magnitude larger than that predicted theoretically by Yamakawa and Stockmayer.
114 citations
TL;DR: New neutral nickel(II) complexes bearing asymmetric β-ketoiminato (N,O) ligands (5a−c), [(2,6-iPr2C6H3)NC(R2)C(H)C1)O]Ni(Ph)(PPh3), have been synthesized as discussed by the authors.
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TL;DR: In this paper, a detailed kinetic analysis suggests that this order results from decreasing rates (in the given order) of self dimerization of the semipinacol radicals.
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1,475 citations
TL;DR: The design and performance of an absolute deviation type of differential refractometer is described and it is shown that the distance between the slit images in the eyepiece field, Δd, is accurately proportional to the difference in refractive index, Δn, of solution and solvent, and the factor of proportionality can be evaluated from accurately measurable geometrical quantities.
Abstract: The design and performance of an absolute deviation type of differential refractometer is described The apparatus comprises mercury and sodium lamps, monochromatic filters, slit, differential cell, projection lens, and micrometer microscope, all accurately aligned on an optical bench The cell is square with a thin partition separating solution and solvent, such that the angle of incidence is about 69° on the interface The cell and its holder, in a jacketed housing, can be turned through 180° in order to interchange solvent and solution and approximately double the deviation By ray tracing it is shown that the distance between the slit images in the eyepiece field, Δd, is accurately proportional to the difference in refractive index, Δn, of solution and solvent, and that the factor of proportionality can be evaluated from accurately measurable geometrical quantities: the cell partition angle, the virtual distance from slit to cell center, and the magnification of the system up to the field of the micrometer eyepiece The range of the instrument is approximately 001 unit and the limiting sensitivity about 3 × 10−6 unit of refractive index difference The accuracy in determination of Δn is about 05 percent The instrument is useful for determination of small differences in refractive index or concentration, and for determination of refractive index increments needed in the light-scattering method of evaluating high molecular weights
328 citations
TL;DR: In this paper, it has been shown that the light scattered from dilute solutions of macromolecules or colloidal particles is intimately related to the weight, size, and interaction of the solute species.
Abstract: During the past several years it has been demonstrated that the light scattered from dilute solutions of macromolecules or colloidal particles is intimately related to the weight, size, and interaction of the solute species. Theoretical developments and improved techniques have made possible the determination of the molecular weight, dimension and activity coefficient of a number of polymers and proteins in solution. In these investigations the intensity of light scattered at various angles from a monochromatic beam passing through the solution has been measured by means of specially designed photometers. However, it would appear that the equivalent information could be derived from a different means of observation—that of transmission measurements at various wave‐lengths. If this possibility could be exploited the common techniques of spectrophotometry could replace the more specialized ones now used. The extent to which this is feasible is explored in this paper.As a first step it is necessary to review...
266 citations
TL;DR: A photoelectric photometer designed for the measurement of absolute turbidity, dissymmetry, and depolarization of dilute solutions of high molecular weight materials, and hence determination of their molecular weights, is described in this paper.
Abstract: A photoelectric photometer designed for the measurement of absolute turbidity, dissymmetry, and depolarization of dilute solutions of high molecular weight materials, and hence determination of their molecular weights, is described. The photometer comprises essentially a monochromatic parallel primary beam of radiation, a six-sided scattering cell for measurements at 0°, 45°, 90°, and 135°, a multiplier phototube and galvanometer, a standard opal glass diffusor, and removable polarizer and analyzer. Turbidity is determined in terms of a ratio of deflections for the 90° scattering and for the primary beam reduced in intensity by neutral filters and diffused by an opal glass plate. Working relationships leading to determination of absolute turbidity are developed. These relationships include corrections for refraction and reflection effects, and for imperfect diffusion by the opal glass. The latter is evaluated by comparison of the opal glass with reflecting diffusors corrected for specular component of reflectance. The response of some multiplier photo-tubes is shown to be dependent on the plane of polarization of the incident radiation. Data illustrating the performance of the photometer include comparison of molecular weights of polystyrene fractions, beta-lactoglobulin, bovine serum albumin, lysozyme, sucrose octaacetate, Raleigh’s ratio and depolarization for benzene, turbidity of a “standard” polystyrene, and particle size of a GR-S latex, with data obtained by other methods or other investigators.
247 citations