PRECISION POLYOLEFIN STRUCTURE: MODELING POLYETHYLENE CONTAINING METHYL AND ETHYL BRANCHES

摘要

Sequenced copolymers of ethylene and diverse species have been created using acyclic diene metathesis (ADMET) polymerization, a step growth, condensation-type polymerization driven to high conversion by the removal of ethylene. ADMET permits control over branch content and branch length, which can be predetermined during the monomer synthesis, allowing sequence control in the resultant unsaturated polymer. Monomers are symmetrical α,ω-dienes with a pendant functionality. Diverse functional groups are compatible with ADMET polymerization when Schrock's or first-generation Grubb's catalysts are used. Saturation with hydrogen after ADMET polymerization affords a polyethylene (PE) backbone bearing specific functionalities in precise places. Varying both the pendant functional group and the spacing between functionalities alters the physical and chemical properties of the polymer. Incorporation of alkyl chains into the PE backbone via ADMET leads to the study of perfect structures modeling the copolymerization of ethylene with α-olefins such as 1-propene, 1-butene, 1-hexene, and 1-octene.