Influence of solvent on the network structure formed by free radical polymerization of tri-ethylene glycol dimethacrylate: A dielectric study

• Published in: Journal of non-crystalline solids Vol. 356; no. 11; pp. 616 - 620
• Main Authors: Sabater i Serra, R., Plaza, M.T. Viciosa, Dionísio, M., Balado, A. Andrio, Dueñas, J.M. Meseguer, Ribelles, J.L. Gómez
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier B.V 01.04.2010; Elsevier
• Subjects: Applied sciences; Dielectric properties; Electric modulus; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; Relaxation; Relaxation; Electric modulus; Dielectric properties; Solvent effect; Methacrylate polymer; Free radical polymerization; Molecular mobility; Crosslinked polymer; Experimental study; Solution polymerization; Dielectric relaxation
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2009.06.048

Molecular mobility of a series of tri-ethylene glycol dimethacrylate (TrEGDMA) samples polymerized with different amounts of ethyl acetate up to 40% (w/w) as diluent was investigated by dielectric relaxation spectroscopy. In the first measuring scan, the samples show three secondary relaxation processes: a γ process related to the twisting motions within the ethylene glycol moiety as found in the unreacted monomer, a β process assigned to hindered rotations of carboxylic groups residing in non-bonded ends of the monomers linked to the network only by one side of the molecule; and additionally, at higher temperatures, a third process was detected designated as β pol, ascribed to a π flip of the ester unit accompanied by a restricted main chain rearrangement. While the γ and the β pol processes remain in the second scan, the β relaxation goes to extinction due to post-polymerization that took place at the highest temperatures scanned in the previous run, leading to complete polymerization of the network. The strength of γ and β relaxation measured in the first scan increases with the amount of solvent present in the initial mixture, nevertheless, in any case, β relaxation completely disappears in the second scan.