Poly((methylene oxide)oligo(ethylene oxide)); and poly(ethylene oxide) doped with rare earth metal compounds: Solubility, complex formation, morphology, and applications.

摘要

The IR, DSC, TGA, WAXD, SAXS, and SEM techniques were employed to investigate the solubility, complexation, stoichiometry, morphology, and the effects of absorbed moisture in PEO and aPEO doped with compounds containing rare earth metal ions. Defined as the maximum concentration below which features characteristic of neat dopant are absent from the anhydrous doped systems, solubility was evaluated on the basis of DSC thermograms and WAXD patterns. Polymer-metal ion complexation was identified by IR band shifts associated with the stretching modes of the EO unit. Attempts were also made to determine film homogeneity, Verdet coefficient, and fluorescence lifetime to assess the potential for optical and laser applications of the resultant macromolecular complexes. Results from this thesis research are highlighted as follows: (1) In NdCl{dollar}sb3{dollar}-, Nd(NO{dollar}sb3)sb3{dollar}-, and Tb(NO{dollar}sb3)sb3{dollar}-PEO systems characterized by strong polymer-metal ion interactions, anhydrous amorphous complexes formed leaving no residual crystallinity, and significant elevations in {dollar}Tsb{lcub}g{rcub}{dollar} relative to the pure polymer host were observed. Tightly bound moisture was found to enhance the apparent solubilities while retaining the amorphous character. Nevertheless, these complexes tended to absorb moisture from the ambient (i.e. loosely bound moisture), which led to a depression of {dollar}Tsb{lcub}g{rcub}{dollar} relative to the anhydrous complexes and precipitation of dopants. (2) In Nd(act){dollar}sb3{dollar} and Nd(dpm){dollar}sb3{dollar}-PEO systems characterized by weak polymer-metal ion interactions, {dollar}Tsb{lcub}g{rcub}{dollar} elevation was absent; however, solubilities comparable to systems with strong polymer-metal ion interactions were observed. Both systems were repellent to ambient moisture, and hence there were no solubility enhancements by tightly bound moisture. (3) A smaller cation, Tb{dollar}sp{lcub}3+{rcub}{dollar} compared to Nd{dollar}sp{lcub}3+{rcub},{dollar} was found to present lower solubility and a higher coordination number, which was responsible for the lower asymptotic {dollar}Tsb{lcub}g{rcub}{dollar} and a partial precipitation of the dopant by absorbed moisture. (4) Representing a perturbation to the structural regularity present in PEO, aPEO was found to present lower solubilities for dopants Nd(act){dollar}sb3{dollar} and Nd(acac){dollar}sb3.{dollar} On the other hand, no difference in solubility was observed for dopant Nd(NO{dollar}sb3)sb3.{dollar} Laser interferometry was employed to assess film homogeneity of the Nd(NO{dollar}sb3)sb3{dollar} doped systems across a 20 mm diameter, and the measured peak-to-valley distortion values turned out to be encouraging for practical applications.