Poly‐n‐butyl methacrylate prepared by the emulsion technique was fractionated three times by the fractional precipitation procedure to obtain eight fractions. Relationships between viscosity and weight‐average molecular weight were obtained in both an ideal solvent, isopropanol, and a nonideal solvent, methyl ethyl ketone. These relationships are represented by equations:
The effect of the size of the pendant groups (‐methyl, ‐ethyl, and n‐butyl ester) on the degree of extension of macromolecules in ideal solvents is discussed. It was found that the degree of flexibility of the macromolecule increases as the size of the pendant group increases. These results are believed to be due to the short‐range interference effect of the solvent molecule on the degree of free rotation of the macromolecule.
The preparation of a completely isopropylated polystyrene by polymerization of p‐isopropylstyrene monomer is described. This polymer was autoxidized in cyclohexane with lauroyl peroxide to give a material of good reproducibility and high purity. Methyl methacrylate was successfully grafted to the polymeric hydroperoxide by using a sugar‐containing recipe. Homopolymer was separated from the graft copolymer by extraction. Evidence for grafting was obtained from solubility and fractionation behavior, as well as from light‐scattering and viscosity measurements.
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