[CONTRIBUTION FROM
THE
NOYESCHEMICAL LABORATORY, UNIVERSITYOF ILLINOIS]
Copolymerization of 1,3-Butadiene with Some Polynuclear Aromatic Hydrocarbons H Y C . S. MARVEL AND W. S. AKDERSON RECEIVED J U X E 21, 1964
A number of aromatic hydrocarbons have been tested as comonomers for copolymerization with l&butadicnc. Anthrdccne, pyrene and trans-stilbene form copolymers having marked ultraviolet absorption. Under similar coiiditioiis benzene, naphthalene, phenanthrene and cis-stilbene do not give copolymers with detectable absorption maxima. The reactivities of these aromatic compounds fall in an order predicted from their free valence numbers as calculated by the molecular orbital method. These calculations predict high reactivity for several as yet untested polynuclear systems.
During the course of a search for some new inonomers for copolymerization with 1,3-butadiene i t has been found that trans-stilbene and pyrene will yield copolymers and their ultraviolet absorption spectra have been obtained. Conditions for the preparation were approximately those used on an industrial scale for the emulsion copolynierizations of styrene and butadiene. As expected from the low reactivity of benzene in copolymerization reported by Stockmayer and Peebles2 no special evidence could be obtained for copolymerization of benzene and 1,3-butadiene.:' The butadiene polymer prepared in the presence of naphthalene shows none of the absorption maxima of a 1,4-dialkyl-l,4-dihydronaphthalene. Butadiene in the presence of phenanthrene likewise yields polymers without aromatic absorption. It may be calculated that O . O l ~ oof phenanthrene incorporated by reaction at the 9,lO-bond should be readily detected through the absorption of the diphenyl unit in the copolymer. It might have been anticipated that the double-bond character of the phenanthrene 9,lO-bond would lead to copolymerizability ; however the molecular orbital calculations predict equal reactivity for phenanthrene and naphthalene.? \\%xi butadiene is polymerized in the presence of phenanthrene which is not sufficiently pure, the polymers hape marked absorption maxima in the 2000-3000 A, range. This absorption may be traced to the presence of anthracene and fluorene incorporated by copolymerization and chain transfer, respectively. Magat and BonCme5 noted t h a t the thermal polymerization of styrene was sharply retarded by phenanthrene. Their sample of phenanthrene was not subjected to purification, however, : tncl probably contained anthracene as an impurity.6 Polyiiicrization of butadiene in the presence of fluorene yields relatively low molecular weight Iwlpiiicrs having the absorption spectruni of a 9alliylfluorene. 'I'he gcnerally accepted mechanism o f c-hain transfer by a-inethylene groups is thus ( I ' T h e ir.ork discussed herein w a y performed a i a part of the resrarch project sponsored by the Reconstruction Finance Corporation, Ollicc of Synthetic Rubber in connection with t h e Government Synthetic Rubber Program. Abstracted from a thesis submitted by W. S . Anderson in partial fu!fillment of t h e requirements for the degree of Doctor of Philu-ophy in chemistry i n t h e Graduate College of t h e Uni versity of Illinois, 1054. ( 2 ) W.11. Stockmnycr and L. H. Peebles, J r . , THISJ O U R N A L , 78, 2279 (1953). ( 3 ) C . S. Xlarvel and TT'. S Anderson, i b i n . , 7 5 , 4GOO (1953) ( 4 ) r:. H . Burkitt, C. A . Coulsun a n d FI. C . I.onyuet-ITiggin%,'l'roizv. I'avodoy Soc., 47, 5 5 8 (1951). (i) h f . h f a g a t arid R . Boneme, Coi7rfil. vcild., 232, l(i.57 ' l l l > l ) . (1;) 13 C . Ko
