Styrene Copolymers

III. Copolymerization of Styrene and Long Chain α-Olefins

Abstract

In order to find the effect of chain length of α-olefin on styrene (St) content and on distribution of St, in the copolymer the following experiments were performed. Homopolymers such as pentene-1, hexene-1, heptene-1, and St, and copolymers consisting of St and one of the monomers mentioned above were prepared with Ziegler-Natta catalyst systems.
Since optimum Al/Ti molar ratios were found from homopolymerizations of these monomers, the copolymerizations were carried out at those Al/Ti ratios.
Solvent extractions and IR measurements were performed for these products and the following conclusions were obtained.
i) Overall St content in the copolymer gradually increases as the chain length of α-olefin becomes longer.
ii) St content of the extract is varied by kind of solvent and the distribution of sequence length of St is very broad.
iii) The copolymer composition is entirely changed by changing the Al/Ti ratio.
The phenomenon can be considered to be due to multiplicity of active sites in heterogeneous catalyst system and also to the difference in steric hindrance for these monomers.