Periodic ethylene-vinyl alcohol copolymers via ADMET polymerization: Synthesis, characterization, and thermal property

Periodic copolymers of ethylene and vinyl alcohol (EVA) were synthesized via acyclic diene metathesis (ADMET) polymerization of a series of structurally symmetric α,ω-diene monomers that containing two vinyl acetate (VAc) units, followed by exhaustive hydrogenation and subsequent hydrolysis. This synthetic methodology provided a new type of EVA copolymer with defined sequence and ever highest VA content via ADMET. These polymer samples were characterized by gel permeation chromatography (GPC), NMR, and matrix-assisted laser desorption/ionization time-of-fight mass spectroscopy (MALDI-TOF-MS). Thermal properties of EVAc and EVA copolymers were investigated by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). EVAc copolymers exhibited two-stage decompositions on TGA traces and displayed a glass transition on DSC thermograms. Meanwhile, the EVA copolymers showed glass transition stages and sharp melting peaks on DSC thermograms, with the Tm values being comparable to that of high density polyethylene (HDPE).