In size exclusion chromatography (SEC) macromolecules are separated with respect to their hydrodynamic volume, which is proportional to a multiple of intrinsic viscosity and those of SEC chromatograms, the MHS constants K and a should be determined according to Weiss and Cohn-Ginsberg,' as demonstrated in this note for the case of poly( tert-butyl acrylate) (PtBA).

A combination of several methods and quantitative parameters (fraction p of immobilized monomer units, apparent molecular weight, and size, number, and concentration of aggregates) as a function of time, temperature, and polymer concentration were used to obtain data characterizing aggregation of syndiotactic poly(methyl methacrylate) in n-butyl acetate. The thermal history of the sample (viz., the content of surviving nuclei which were identified with aggregates of globules formed during the intramolecular condensation) was shown to be decisive for the setting in and steepness of the aggregation process. Another "hysteretic" effect has been found by NMR for the equilibrium value of p at elevated temperatures. Regarding all experimental and reported data, a plausible qualitative model of aggregation was suggested; three processes, "globulation", nucleation, and flocculation, were recognized and characterized.

The copolymerization of methyl methacrylate with small amounts (0.25‐1 mol %) of bis (4‐methacryloxybenzilidene)‐1,2‐diaminoethane in the pregelation stage was investigated. The mole fractions in the copolymers of the divinyl monomer, of the reacted vinyl groups of divinyl monomer, and of the totally reacted divinyl monomer units forming intermolecular crosslinks were determined experimentally and some other parameters were calculated from these quantities. The amount of intramolecular crosslinks, forming closed rings, has been shown to predominate over the amount of intermolecular crosslinks. The comparison of the experimental data with values calculated from Wesslau's theory, based on the classical concepts of copolymerization, reveals differences increasing up to an order of magnitude with rising content of the divinyl monomer. A major reason for this divergence appears to be the intramolecular crosslinking.

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