Molecular Dynamics in Poly(ethene-alt-N-alkylmaleimide)s As Studied by Broadband Dielectric Spectroscopy

Abstract

Broadband dielectric spectroscopy has been used to analyze the molecular dynamics in a set of nine poly(ethene-alt-N-alkylmaleimide)s. The polymers were studied in the frequency range from 0.1 Hz to 10 MHz and at temperatures between 120 and 500 K. The alternating maleimide copolymers possess alkyl side chains varying in length from methyl to octadecyl. Four relaxation processes are observed: (i) a (secondary) β-relaxation corresponding to librational fluctuations of the terminal end group of the alkyl side chain, (ii) the α‘-relaxation being assigned to a relaxation of the side chain, (iii) the dynamic glass transition (α-relaxation), being designated to motions of the succinimide ring, and (iv) the αs-relaxation reflecting cooperative fluctuations of an ensemble of about 2−3 maleimide rings in an underlying helical superstructure. This model is supported by calorimetric measurements and published nuclear magnetic resonance data.

The Effect of Side Chain Length and Hydrogen Bonding on the Viscoelastic Property of Isobutene/Maleimide Copolymers

“…This value corresponds to 8.7 kJ per repeating unit of the polymer main chain. Kremer and coworkers [16] reported that the DH c value for poly(1d-altethylene) was 45.9 J Á g À1 (i.e., 17.3 kJ per repeating unit), being higher than the DH c value for poly(1d-alt-IB) in the present study. This is because the methyl groups of the IB repeating units in the main chain prevent reorganization of the methylene units in the side chains.…”

A one‐step preparation of compatibilized polypropylene‐nanocomposites by reactive extrusion processing

“…Primary aliphatic amines were used because of their fast reaction in solution with anhydride groups at low temperatures, without the need of a catalyst. The reaction with amines has been used extensively for MA copolymers, such as poly(styrene-co-MA), 47,48 poly(ethylene-co-MA), 48,49 and poly(propylene-co-MA), 47 usually to obtain maleimide copolymers. It is well known that the reaction of anhydride unit of MA copolymers with alkylamine proceeds via formation of an amide-acid linkage which then undergoes ring closure to form an imide structure.…”

Molecular dynamics in semifluorinated side-chain polyesters as studied by broadband dielectric spectroscopy

“…The Arrhenius-type temperature dependence relaxation rate with low activation energy (w20 AE 5 kJ/mol, see Table 4) and the weak dielectric strength (D3 < 0.05) are characteristic of localized fluctuations [36]. This process is assigned to librational fluctuations of the alkoxy linker [37,38]. Since the aliphatic spacer itself is nonpolar, its mobility can be dielectrically active only if some adjacent polar group is connected to it, for example an oxygen atom.…”