A facile one-pot synthesis of long chain highly branched polymers (LCHBPs) was accomplished by a tandem ring opening metathesis polymerization (ROMP) and acyclic diene metathesis (ADMET) polymerization procedure A telechelic polymer with two terminal allyloxy groups and many pendent acrylates was first prepared through the first generation Grubbs catalyst-mediated chain transfer ROMP of 7-oxanorborn-5-ene-exo,exo-2,3-dicarboxylic acid bis(2-(acryloyloxy)ethyl) ester in the presence of a symmetrical multifunctional olefin 1,4 diallyloxy cis 2 butene as chain transfer agent (CTA), and then utilized as an A(2)B(2n) type macromonomer in subsequent ADMET polymerization between allyloxy and acrylate triggered by the most activated second generation Grubbs catalyst yielding LCHBPs as the reacton time prolonged The CTA, monomer, macromonomer, and the resulting LCHBPs were characterized by mass spectroscopy, elemental analysis, gel permeation chromatography with multiangle laser light scattering, NMR and matrix-assisted laser desorption ionization time of flight mass measurements The LCHBPs have comparatively high molecular weights and relatively moderate polydispersity indices