Liquid polymers containing vinylidene (CH.sub.2 =C&lt;) groups are known. These polymers are prepared in a number of processes such as cleavage or degradation of high molecular weight dienic elastomers (U.S. Pat. No. 3,313,793 and British Pat. No. 1,057,014); the free-radical polymerization of dienic monomers in the presence of large amounts of a chain transfer agent; the solution polymerization of dienic monomers using lithium catalysts; and addition methods such as the polyaddition of dithiols with allene (Journal of Polymer Chemistry, Part C, Vol. 24, Page 113 (1968)).
These liquid polymers are cured through the vinylidene groups to solid elastomers. This has advantages in that compounding ingredients may be simply dissolved or dispersed in the polymer by mixing, and the compounded liquid poured or spread into place. Desirably, the compounded liquid will then quickly cure in situ at room temperature or with only slight application of heat. Unfortunately, the vinylidene groups of the previously known polymers are not highly reactive at room temperature. Cure to a dry elastomeric state may often take weeks. This has heretofore hindered or prevented the use of these liquid polymers in applications such as commercial caulks and sealants. Furthermore, most of these liquid polymers have their vinylidene groups pendant to the polymer backbone. This is not favorable for, in the vulcanized state, an optimum balance of tensile strength and extensibility is achieved when the cure sites are located at the terminal ends of the liquid polymer molecule. This disadvantage cannot be readily remedied as most preparation processes allow for little control over the location of the vinylidene group on the molecule. Liquid polymers containing terminal vinylidene groups are desirable, particularly if the vinylidene groups are of high activity that readily react with curing agents at room temperature to form solid elastomer.