Carbonaceous materials modified with MAO employed as metallocene supports in syndiotactic polymerization of styrene

Carbonaceous materials with different degree of coalification, surface area, nitrogen content as well as electronic nature in their structure have been modified with prescribed amount of MAO and characterized by XPS analysis. Syndiospecific styrene polymerizations using half-titanocenes containing aryloxide ligands, Cp′TiCl2(OAr) [Cp′ = tBuC5H4, Ar = 2,6-iPr2C6H3 (1), 2,6-iPr2-4-tBuC6H2 (2); Cp′ = Cp⁎, Ar = 2,6-iPr2-4-tBuC6H2 (3)], have been explored in the presence of various MAO-supported organic materials. These catalyst systems were effective to afford syndiotactic polystyrene (sPS) exclusively, and the activity by 3 increased at higher temperature (25–55 °C). The Mn values in the resultant sPS prepared by 3 in the presence of the present supported cocatalysts were not strongly affected by the temperature, whereas the Mn values were highly dependent upon the temperature in the presence of MAO cocatalyst. Both, the activity and the Mn values were slightly affected by the nature as well as the chemical character of surface functional groups of the carbonaceous materials employed. The ethylene/styrene copolymerization by Cp⁎TiCl2(O-2,6-iPr2C6H2) afforded the copolymer exclusively with similar degree employed by the homogeneous system.

Graphical AbstractEffects of supports such as nitrogen content, surface area as well as the influence of polymerization temperature towards the catalytic activities and molecular weights of syndiotactic polystyrenes were explored. These materials are found to be effective as supported cocatalysts in stereospecific styrene polymerization using tBuCpTiCl2(O-2,6-iPr2C6H3) (1), tBuCpTiCl2(O-2,6-iPr2-4-tBuC6H2) (2) and Cp⁎TiCl2(O-2,6-iPr2-4-tBuC6H2) (3) and ethylene/styrene copolymerization by Cp⁎TiCl2(O-2,6-iPr2C6H2) (4).Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights►Nitrogen enriched carbonaceous materials as metallocene supports. ►MAO-pretreated modified carbonaceous materials effective as supported cocatalysts in syndiospecific styrene polymerization. ►Mn values were highly dependent upon the temperature in the presence of MAO cocatalysts. ►The activity highly affected by the nature of supports employed. ►The ethylene/styrene copolymerization by Cp⁎TiCl2(O-2,6-iPr2C6H2) afforded the copolymer as the product.