Dielectric Relaxations in Poly(glycidyl phenyl ether): Effects of Microstructure and Cyclic Topology

Abstract

Cyclic and linear, isoregic and aregic, and isotactic and atactic poly­(glycidyl phenyl ether) (PGPE) with molecular weights up to M w = 5.5 kg/mol are synthesized by ring-opening polymerization of glycidyl phenyl ether. Initiation with tetrabutylammonium fluoride leads to isoregic linear polymers with ∼95% regular linkages, and initiation with B­(C6F5)3 and B­(C6F5)3/water leads to aregic cyclic and linear polymers, respectively, with ∼50% regular linkages as quantified by 13C NMR. Local, segmental, and chain dynamics in PGPE is investigated by broadband dielectric spectroscopy (10–2–106 Hz). The β-relaxation for linear PGPE is separated into two contributions arising from the motions of side groups and end groups with activation energies of 35.4 and 23.8 kJ/mol, respectively. The β-relaxation process for cyclic PGPE shows the same activation energy as that shown by the side-group contribution in linear PGPE, indicating that topology does not play a key role on the side-group local dynamics. Moreover, cyclic PGPE samples show higher calorimetric and dynamic glass transition temperatures as well as lower dynamic fragility compared to linear chains. Unexpectedly from topological considerations, cyclic PGPE shows low frequency dielectric contributions that can be attributed to short wavelength internal ring motions and that are detectable by dielectric relaxation due to the aregic nature of the rings.

Synthesis of macrocyclic poly(ethylene oxide)s containing a protected thiol group: a strategy for decorating gold surfaces with ring polymers

“…[32][33][34] For instance, macrocyclic poly(dimethylsiloxane) showed increasing T g values with the decreasing molecular weight, 35,36 in agreement with the theoretical model of Di Marzio and Guttman. 37 In contrast, macrocycles of polystyrene, 38 poly(2-vinylpyridine), 38 poly(α-methylstyrene), 38 poly (2-vinylnaphthalene), 38 poly( phenylmethylsiloxanes), 39 and poly(glycidyl phenyl ether) 40 exhibited decreasing T g values with the decreasing molecular weight. This is also the case for cyclic PEO according to the data recovered from the literature on amorphized samples of low molecular weight 41,42 and plotted in Fig.…”

The Complex Amorphous Phase in Poly(butylene succinate-ran-butylene azelate) Isodimorphic Copolyesters

“…In the framework of the Eyring description used above, the full width at half maximum of this Gaussian description of ε ᇱᇱ (݂) , ‫ܯܪܹܨ‬ εᇱᇱ = 2√݈݊2 ‫ݓ‬ , can be approximately related to the FWHM of the corresponding distributions of the enthalpic and entropic terms in the Eyring equation as: 33 (5)…”

Environmentally Sensitive Luminescence Reveals Spatial Confinement, Dynamics and Their Molecular Weight Dependence in a Polymer Glass

“…[22][23] In practice, it suggests that polymers with lower molecular weight and thus high chain end concentration typically have a lower T g that saturates to an asymptotic value as M n increases. Interestingly, in cyclic polymers having no chain ends the T g (M n ) dependence is largely supressed [24][25][26] and low M n cyclic polystyrenes [27][28] are barely distinguishable by their T g from cyclic PS of higher molecular weights. These data highlights connection between the local polymer structure at the chain end groups and the glassy behavior of the bulk.…”