Addition of polar modifiers to alkyllithium‐initiated homopolymerizations of butadiene causes substantial changes in the microstructure of the polymers produced. These changes are shown to depend not only on the concentration of modifier, but also on the polymerization temperature. The combined effects of modifier concentration and reaction temperature have been considered, and a method is presented for quickly determining the proper conditions for preparation of a polybutadiene of any 1,2‐microstructure within a range of 10–80%. It is also shown that in anionic polar‐modified copolymerizations of butadiene–styrene, the reaction temperature is again critical. Within a certain concentration range of modifier, the temperature will influence the rate of styrene incorporation or the randomness of styrene units in the resulting copolymers.

Organolithium reagents substituted with hydroxyl‐carrying mixed acetals (i.e., tetra‐hydropyranyl and α‐ethoxyethyl ethers) have been prepared in high yields and used to polymerize 1,3‐butadiene to various acetal‐terminated polybutadiene polymers. A method is described for converting acetal‐containing polymers into hydroxyl‐containing polymers. The polybutadienes have been characterized with regard to endgroup types, quantitative functionalities, molecular weights, molecular weight distributions, and microstructures. Dihydroxyl terminated polymers are prepared anionically in the absence of gel. Such materials are more suitable from the standpoint of f(OH) and M̄w/M̄n for chain extension studies than are prepolymers prepared by radical methods.

Polybutadiene was successfully metalated by use of tert‐butyllithium activated with alkoxides of Group I metals without chain degradation. The metalated polymer was grafted with styrene and 1,3‐butadiene to give novel graft copolymers of varying microstructure. This metalating system was found to be highly efficient; however, its catalyst effectiveness is less than that of organolithium‐TMEDA metalation agent.

synopsisThe use of N,N,N',N'-tetramethylethylenediamine (TMEDA) is known to enhance the metallation capability of butyllithium. It has been found that this TMEDA-BuLi reagent smoothly metallates olefins in high yields at 50°C in less than 4 hr by replacement of allylic hydrogen. This reaction has been applied to unsaturated polymers such as polybutadiene and polyisoprene. The resulting products have lithium atoms emttered along the chain. The amount of Iithium on the chain can be varied over wide limits. Each lithium atom on the chain can act as a site for grafting or adding functional groups to the base polymer. Thus, this method allows the preparation of polymem having controlled amounts of branching as well as the introduction of functional groups into the polymer. Through the use of this metallation technique, polymers containing styrene and butadiene grafts are specifically reported. In addition, polymers containing hydroxyl or carboxyl groups along the backbone are prepared by using this technique.

This paper is a review of the alkyllithium system for the copolymerization of butadiene and styrene. The alkyllithium system offers a very versatile tool by which a wide variety of styrene butadiene copolymers can be made to fit a particular application. Included are discussions of block and non-block copolymers of styrene butadiene, copolymers with functional groups, and copolymers with varying microstructure. I n addition, wear and traction data on a series of styrene butadiene copolymers with varying styrene content and microstructure are presented. ZUSAMMENFASSUNG :Hier wird ein 'iiberblick uber die Copolymerisation von Butadien und Styrol rnit Alkyl-Lithium-Initiatoren gegeben, mit denen eine grol3e Vielfalt von Butadien/Styrol-Copolymeren fur spezielle Anwendungen hergestellt werden kann. So werden Block-und Nichtblock-Copolymere, Copolymere mit funktionellen Gruppen und Copolymere rnit verschiedener Mikrostruktur beschrieben. Ferner werden Daten uber die Abrieb-und Zug-Eigenschaften von Styrol/Butadien-Copolymeren rnit unterschiedlichem Styrolgehalt und verschiedener Mikrostruktur angegeben.