Determination of absolute rate constants for elementary reactions in radical polymerization of diethyl fumarate

Abstract

The absolute rate constants of propagation and termination (kp and kt) for radical polymerization of diethyl fumarate (DEF) were evaluated to be 0.015 and 164 L mol"1 s'1, respectively, by means of a rotatingsector method at 30 °C. The average lifetime of the propagating radical was Í66 s under the present polymerization conditions, and the steady-state concentration of the radical was estimated to be as high as 3.6 X 10"5 mol L"1. The presence of the polymer radical in such a high concentration was also confirmed by ESR spectroscopy. The exceptionally small kp and kt values were accounted for by the inherently less reactive nature of poly(DEF) radical, probably arising from considerable steric hindrance and slow diffusion of the polymer radical. Because the small rate constants are compensated by the high concentration of the radical, the rates of propagation and termination rationalize high-polymer formation.

A single center experience with same‐day transradial‐PCI patients: A contrast with published guidelines

“…The Q , e values are calculated from the terminal model reactivity ratios to be 0.48 and + 1.55 for the 1a , 0.66 and +1.16 for the 1b , 0.60 and +1.16 for the 1c , respectively, indicating that the 1a – c are conjugative, electron‐accepting monomers. The e values (+1.16 ∼ +1.55) of the 1a – c are smaller than that for diethyl fumarate (DEF), which is reported to be +2.26 7. This is ascribed to more electron‐donating property of alkoxyethyl chain compared with ethyl group.…”

“…In 1975, Bengough et al1 reported the polymerization of diethyl fumarate (DEF) by radical initiator, where the homopolymer with relatively high number‐average molecular weight ( M n = 15,000) was obtained. After that, Otsu et al prepared various fumarates2–4 and fumaramides,5, 6 and investigated their monomer reactivities in the homopolymerizations and the copolymerizations and polymerization kinetics in detail 7–10. They reported that the polymerization reactivities of the fumarates are significantly enhanced by introduction of a bulky substituent into side chain, which might be explained with an effective suppression of the radical coupling termination reaction by the increase in rigidity of the main chain with bulky substituents 11, 12…”

“…Polymerizations of amphiphilic fumarate monomers are expected to provide polymers with high oxygen permeability, hydrophilicity and transparency required for CL materials, because both groups with different properties exist along the polymer main chain in homogeneous and high density. Moreover, until now there are many reports related to the fumarate monomers with symmetric or dissymmetric dialkyl substituents,1–4, 7–17 but the fumarate‐type monomers with both of hydrophilic and hydrophobic substituents in the same molecule have not been synthesized and their polymerization behavior has not been investigated yet.…”

Thermal and mechanical properties of random copolymers of diisopropyl fumarate with 1‐adamantyl and bornyl acrylates with high glass transition temperatures

“…This was due to the suppression of termination reactions between PDRF radicals by the introduction of the bulky alkyl groups in the ester side chain . The termination rate constants decreased in the order of the isopropyl, cyclohexyl, and tert ‐butyl esters for the DRFs . The rate and fashion of propagation reaction were also influenced by the ester alkyl groups .…”

Radiation polymerization of diethyl fumarate

“…Most of the published articles about polymerization of fumarate described the conventional method for polymerization or photo-polymerization with diethyl fumarate (DEF) as crosslinking agent (Fisher et al, 2002). There are few data about polymerization of DEF in bulk (Otsu and Ishikaa, 1991), but there are some works about copolymerization with monomers, like free-radical copolymerization of styrene and DEF (Ma et al, 2001), and nitroxideterminated poly(styrene-co-diethyl fumarates) and derived block copolymers (Lokaji et al, 2002).…”