592
Ind. Eng. Chem. Prod. Res. Dev. 1980, 1 9 , 592-595
perature renders the dienyllithium-vinyl group reaction more competitive with the corresponding reaction involving the alkylbenzyl ion. The broadened molecular weight distributions which we have observed at the higher DVB:RLi ratios (>8) perhaps can be explained in terms of the aforementioned reaction sequences. The presence of “excess” divinylbenzene could lead to the situation where greater overlap of the above sequences would occur with the possibility that some inter-nodule (the active star centers) reactions might occur. Our results, thus far, seem to indicate that relatively rapid consumption of divinylbenzene is a prerequisite for the preparation of divinylbenzene linked polydiene stars with moderately narrow molecular weight distributions. The influence of star arm molecular weight on linking extent and efficiency is somewhat unclear. Previous work of ours (Young and Fetters, 1978) showed generally higher number-average degrees of linking than are recorded here (Table 111). Those results were for polydiene chains with molecular weights of
