ISSN:
0449-2951
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The effect of solvent in the homogeneous anionic copolymerization of styrene with p-methylstyrene, p-tert-butylstyrene, and m-methylstyrene has been determined. In nonpolar media where the gegenion is lithium, a nonhomogeneous distribution exists with the more basic monomer in higher concentration at the growing chain end which shows as an enhanced relative reactivity. This is depressed by the addition of a small amount of more polar solvent. The influence of temperature as a function of solvent has been determined for selected anionic systems. In nonpolar media, an increase of temperature favors incorporation of the less basic monomer whereas a more polar solvent has only a small effect and favors a more ideal copolymerization. In cationic copolymerization the effect of hyperconjugation has been demonstrated. This effect of hyperconjugation appears to be enhanced in polar media. The cationic copolymerizations of styrene with p-tert-butylstyrene in nitrobenzene shows a steric hindrance of the bulkier monomer on its incorporation into the copolymer. Determination of reactivity ratios as defined for radical systems does not fully characterize ionic copolymerizations.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1965.100030813
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