Solubility of thermotropic polybibenzoates with oxyethylene spacers

Summary Three polybibenzoates with two, three and four oxyethylene units in the spacer have been synthesized in order to analyze the influence of the length of the spacer on the stability of the mesophase and on the solubility behaviour. It was found that the thermal stability of the mesophase decreases as the length of the spacer increases, in such a manner that an amorphous polymer is obtained when four oxyethylene units are involved. On the other hand, although the value of the solubility parameter is little affected by the spacer, the solubility range is significantly widened by an increase in the number of oxyethylene units. Optimal characteristics are displayed by the polyester with three such units in the spacer.