Chain length dependence common monomers

Table 5.1 Parameters Characterizing Chain Length Dependence of Termination Rate Coefficients in Radical Polymerization of Common Monomers 1...

Table 5 Parameters characterizing chain length dependence of termination rate coefficients in radical polymerization of common monomers...

Methods for measurement of kp have been reviewed by Stickler,340 41 van Herk Vl and more recently by Beuermann and Buback.343 A largely non critical summary of values of kp and k, obtained by various methods appears in the Polymer Handbook.344 Literature values of kp for a given monomer may span two or more orders of magnitude. The data and methods of measurement have heen critically assessed by IUPAC working parties"45"01 and reliable values for most common monomers are now available. 43 The wide variation in values of kp (and k,) obtained from various studies docs not reflect experimental error but differences in data interpretation and the dependence of kinetic parameters on chain length and polymerization conditions. 

Polymerization of these monomers is commonly achieved by radical polymerization in solution and/or in bulk. Poly(monoitaconate)s may be considered as typical comblike-polymers depending on the length of the side chain in the case of aliphatic derivatives [191,192],... 

The size and shape of micelles have been a subject of several debates. It is now generally accepted that three main shapes of micelles are present, depending on the surfactant structure and the environment in which they are dissolved, e.g., electrolyte concentration and type, pH, and presence of nonelectrolytes. The most common shape of micelles is a sphere with the following properties (i) an association unit with a radius approximately equal to the length of the hydrocarbon chain (for ionic micelles) (ii) an aggregation number of 50-100 surfactant monomers (iii) bound counterions for ionic surfactants (iv) a narrow range of concentrations at which micellization occurs and (v) a liquid interior of the micelle core. 

The radius R is dependent on the solvent. Where the polymer is represented as an ideal, freely jointed chain, no account is taken of the effect of the solvent. This represents the borderline case between a poor and good solvent. Here, each link is in a random direction with respect to its neighbors and the end-to-end distance is proportional to aN where a is the effective monomer length. This distance is much smaller than the molecular length aN and is characteristic of the molecular radius R. For the more common case of a chain in a good solvent, excluded volume effects must be considered, and where this volume is of the order of it can be shown that (de Gennes 1979, 1990)... 

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