BDS as an analytical tool for the analysis of polyethers with different architectures

Abstract

Synthesis of polymers with well-defined architectures has been among the top aspects in polymer science in recent years, in great part driven by the dependence of the physical properties on the defined molecular structure. Here, BDS has played a very important role in the study of molecular dynamics and chain structure in different polymer systems. In this study, we have placed our attention into poly(glycidyl phenyl ether) (PGPE), a polyether with pendant methoxyphenyl groups that is characterized by large dipole moments. In its linear and regioregular form, PGPE exhibits a dielectric relaxation highly sensitive to the net dipole moment of the whole chain, generally called normal mode We have exploited this dielectric relaxation to verify the success in cyclization reactions and in the formation of symmetric two-arm chains. Cyclic regioregular polymers are expected to have net zero dipole moment due to the cancellation of the dipole moment vectors parallel to the chain contour. This has been confirmed in our BDS measurements through the disappearance of the normal mode relaxation after cyclization. This signature of the dielectric spectra was very useful for evaluating the cyclic purity of synthesized cyclic topologies, highlighting the importance of BDS as an additional tool for verifying cyclization over traditional gel permeation chromatography and MALDI-ToF techniques. Moreover, since the normal mode relaxation is highly sensitive to the net dipole moment of the whole chain, we also have used BDS in this study to verify the formation of linear PGPE chains containing two symmetric arms with net dipole moments pointing in opposite directions and to characterize their cyclic topologies. The obtained results highlight again the value of BDS in the synthesis lab for structural verification, an information not readily accessible by complementary techniques.