Electrostatic dissipation and flexibility of poly(oxyalkylene)amine segmented epoxy derivatives

Abstract

A family of hydrophilic and flexible epoxy polymers was prepared from the reaction of poly(oxyalkylene)amines and diglycidyl ether of bisphenol-A (DGEBA) at 1:1 molar ratio of N-H to epoxide. The use of a high molecular weight (M-W = 1000-6000) poly(oxyethylene-oxypropylene)amine and a low M-W amine as curing agents provided epoxy materials with good properties in toughness and hydrophilicity. The hydrophilicity, probed by surface resistivity of these cured materials, was found to be affected by the nature and weight content of poly(oxyethylene) segment in the polymer backbone, and also by the degree of crystallinity. Specifically, in the presence of a water-soluble poly(oxyethylene-oxypropylene)diamine of M-W 2000 the cured epoxies can reach surface resistivity as low as 10(8.6-9.6) Omega/square. In comparison, the water-insoluble poly(oxypropylene) diamine of M-W 2000 afforded a higher surface resistivity of 10(10.5) Omega/square because of the difference in hydrophilicity between oxyethylene and oxypropylene functionalities. Poly(oxypropylene)diamine of M-W 230 as the sole curing agent generated an epoxy with even higher surface resistivity of 10(13) Omega/square due to a highly crosslinking structure. With proper selection of mixed poly(oxyethylene-oxypropylene)diamine (25 wt%) and 2-aminoethanol (9 wt%), the DGEBA cured polymer had an appropriate surface resistivity of 10(9.8) Omega/square for antistatics. Moreover, this material was extremely ductile in appearance and showed over 500% elongation at break during mechanical tests. The high flexibility is rationalized by the balanced chemical structure of poly(oxyalkylene) segments and bisphenol-A distributed in a slightly crosslinked system. (C) 2000 Society of Chemical Industry.