Investigations on the structure of poly(dimethacrylate)s

Two series of urethane dimethacrylates were synthesized from monomethacrylates of oligoethylene glycols and aromatic diisocyanates. The formation of associated monomer molecules in solution was evaluated quantitatively by 1H-NMR spectroscopy. The monomers were polymerized free radically to form crosslinked polymers. The conversion of double bonds was determined with the aid of FT-IR spectroscopy. The polymers were examined by dynamic mechanical thermal analysis (DMTA) to obtain values of the glass transition temperature and storage modulus. The latter enabled the network parameters for individual polymers to be evaluated. On the basis of the experimental results, relationships between the crosslink density and the network parameter in poly(dimethacrylate)s are discussed.