Determination of polymer branching with gel‐permeation chromatography. I. Theory
01 Aug 1970-Journal of Polymer Science Part A-2: Polymer Physics (John Wiley & Sons, Inc.)-Vol. 8, Iss: 8, pp 1361-1371
TL;DR: In this paper, the effect of long and short-chain branching in polymer molecules on gel-permeation chromatographic (GPC) separation is discussed, and the calculation of calibration curves for branched polymers is developed from the universal calibration technique based on the hydrodynamic volume concept.
Abstract: The effect of long-and short-chain branching in polymer molecules on gel-permeation chromatographic (GPC) separation is discussed. The calculation of calibration curves for branched polymers is developed from the universal calibration technique based on the hydrodynamic volume concept and previously established relationships for the effect of branching on molecular dimensions. Typical calibration curves are shown for different branching models and degrees of branching. As branching increases, the curves are shown to converge. Methods of characterizing branching and molecular weight distributions of franctions and whole polymers from GPC and intrinsic viscosity data are presented.
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TL;DR: In this paper, the authors describe the synthesis and characterization of polymers with well-defined structures that serve as models for polyethylene with long chain branching, and show that polybutadiene can be made by using anionic polymerization techniques and controlled chlorosilane chemistry to give nearly monodisperse polybutadienes with precise control of the number, length and placement of long (Mw > 1500 g/mol) branches on each chain.
Abstract: We describe the synthesis and characterization of a number of polymers with well-defined structures that serve as models for polyethylene with long chain branching. All of them have been made by using anionic polymerization techniques and controlled chlorosilane chemistry to give nearly monodisperse polybutadienes with precise control of the number, length, and placement of long (Mw > 1500 g/mol) branches on each chain. This was followed by hydrogenation to give saturated polymers with the same well-defined long chain branching and the local structure of a typical linear low-density polyethylene. That is, both the backbones and the long branches had 17−25 ethyl branches per 1000 total carbons. Among the structures made were some with no long branches (“linears”), some with a single long branch (“stars”), others with exactly two branch points (the α−ω type, “H's”, “super-H's”, and “pom-poms”), and some with several long branches randomly distributed along the backbone (“combs”). Essentially all types of b...
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TL;DR: The polymerization of dimethylsufoxonium methylide to produce linear polymethylene polymers is described, providing control over molecular weight and functionality at the polymer chain ends.
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TL;DR: In this paper, size-exclusion chromatography (SEC) is used to measure the unperturbed dimensions of a polyelectrolyte which include the surrounding diffuse double layer and any other interactions of the solvent.
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