ABSTRACT
Liquid polysulfide polymers, which are commercially more important than the solid elastomers, range from a molecular weight of 1000 to 8000. They are prepared from the high molecular weight polymers described earlier. The high molecular weight polymer is split into segments that are simultaneously terminated by mercaptan groups:
(3)
II 0 (8)
0 (10)
I S-S-R-S-SH
I S-S-R-S
\ ----+ R +NaSH \ S-S-R-S-Na S-S-R-S (ll)
Polymerization of propylene sulfide in the presence of carbonates and zinc, cadmium, or alkaline thiolates produces oligosulfides with -HS end groups [22]. It was found that at anionic polymerization of propylene sulfide, chains with regular structure of the type -(CH2-CH(CH3)-S-S)"- are obtained. In the catalytic BuLi-LiOR system, propylene sulfide polymerization take place according to the following mechanism [2]:
S CH3Li-OR
CH3 Li-OR CH3 CH3Li-OR (l2a)
CH, CH3
There are experimental data attesting to the synthesis of polysulfide oligomers by organic dimercaptan oxidation. By this method, polyalkylene di-and polysulfide silicium containing oligomers were produced, characterized by increased stability at lower temperatures and in organic solvents [23].
