The synthesis of ultra-high molecular weight poly(1-hexene)s by low-temperature Ziegler-Natta precipitation polymerization in fluorous reaction media

Abstract

An effective method of 1-hexene polymerization in fluorous reaction media has been developed. When using perfluorinated compounds (FCs) as a solvent, the process, catalyzed by highly active titanium-magnesium catalysts modified with 3,3-bis(methoxymethyl)pentane (BMMP) as an electron-donor, proceeds as a precipitation polymerization, and the reaction products represent highly stereo- and regioregular poly(1-hexene)s in the form of microparticles. In freons, polymerization can be carried out at sub-zero temperatures with monomer conversion up to 50% within 1 h and the formation of UHMW poly(1-hexene)s with Mn ∼2·106 Da. The polymers prepared in FCs demonstrate a high drag reducing effect (up to 40% in n-heptane for 0.25 ppm concentration), exceeding the previously described UHMW poly(1-hexene)s. Polymerization products after mixing with rapeseed oil form stable dispersions of ready-to-use drag reducing agents (DRAs) for pipeline oil transportation.