Preparation and characterisation of ion-conductive unsaturated polyester resins for the on-site production of resistivity sensors

Synergistic effects in cross-linked blends of ion-conducting PEO-/PPO-based unsaturated polyesters

“…A higher dielectric constant shifts the occurrence of ion pairing to higher salt concentrations, similar to higher temperatures which reduce the solution viscosity. [4] For lithium perchlorate-doped pure PEO, the minimum was found to be O/Li + = 50 [23] and this was also found for the PEO-based UP which is consistent with previously reported literature [39,40,62].…”

“…The theoretical degree of polymerisation was adjusted to 6 by using a calculated excess of the diol. All types of polyesters were doped with lithium perchlorate to achieve ion conductivity and then cross-linked (cured) by radical copolymerisation with styrene using methyl ethyl ketone peroxide (MEKP) and cobalt(II) 2-ethylhexanoate (Co-Oct) as redox initiator to increase the mechanical stability [40].…”

“…The unsaturated polyesters are then doped with LiClO 4 to cause ion conductivity and, with regard to future applications as sensor materials, cross-linked with styrene in order to increase the mechanical stability [40]. The styrene polymerisation was found to go to completeness, as IR spectroscopy did not show any signs of residual monomer evidenced by the absence of the characteristic styrene bands at e v = 778, 912, and 1296 cm −1 .…”

“…In addition, polyesters are not as toxic as polyurethanes and, therefore, are more suitable for the use in structural health monitoring of infrastructural buildings. [40] The use of carbonyl-coordinating polymers in the form of carbonates such as poly(ethylene carbonate) [41] or poly(trimethylene carbonate) [42] or polyesters such as poly(caprolactones) [43][44][45] or poly(lactic acids) has additional advantages due to the interaction between the Li + ions and the carbonyl function. High dielectric constants of these polymers lead to effective charge separation of the salts, which further results in high concentration of charge carriers [20,30].…”

“…[56][57][58][59][60] In our previous paper, we studied the curing kinetics and impedance behavior of PEO-based unsaturated polyesters. [40] Since cross-linking can potentially suppress the crystallisation of PEO, the question, thus, arises how increasing the molecular weight of the polyether block and to what extent substituting PEO for PPO affects the performance of these systems. Herein, we present the combination of the conductive properties of PEO-based UP with the structural properties of PPO-based UP, which appear to exhibit a synergistic effect in terms of the ionic conductivity.…”