Mechanistic study on mechanochemical polymerization of acrylamide

Abstract

The ESR study of the radicals formed in mechanochemical polymerization of acrylamide (AAM) was undertaken. The nature of the radical formation was compared with the mechano‐radical formation produced by mechanical fracture of polyacrylamide (PAAM). The structure of radicals formed were all identified to be an end‐chain radical, equivalent to a polymer‐chain propagating radical. The computer simulation disclosed that the observed spectra of the propagating radical can be approximated essentially by two kinds of component spectra, a large amount of triplet, and a small amount of quarter (a triplet of doublets). Thus, the existence of two major conformers in a single end‐chain radical has been proposed. The ESR kinetics of the radical formation were further studied and its correlation with the nature of polymerization (the changes in molecular weight and polymer conversion) was discussed.

Synthesis of Water-Soluble Polymeric Prodrugs Possessing 4-Methylcatechol Derivatives by Mechanochemical Solid-State Copolymerization and Nature of Drug Release.

“…[21][22][23][24][25][26][27][28][29][30][31][32][33] Several important conclusions were reached from a series of such studies. The monomers prepared on the basis of the structural criteria derived from quantum chemical considerations underwent facile mechanochemical solid-state polymerizations to give corresponding polymeric prodrugs essentially quantitatively.…”

Mechanochemical reactions of plasma-induced surface radicals on polyethylene.

“…We have used a Teflon-made vessel for mechanical vibration in the present study to eliminate any possibility of unnecessary side reactions such as mechanically-induced solid state single electron transfer (SSET) reaction in the case of metallic vessel. [13][14][15] It also appears based on the progressive changes of the spectral pattern during the period of mechanical vibration that the mechanical reactivity varies with the structure of the radicals, since plasma-irradiated PE consists of three kinds of radicals, midchain alkyl radical (sextet spectrum), allylic radical (septet spectrum) and dangling bond sites (DBS) (smeared-out broad line spectrum) as reported earlier. [9] The progressive changes of the spectral intensity determined by the double integration of ESR as a function of duration of mechanical vibration under various vibratory milling conditions are shown in Figure 2.…”

Construction of Matrix-type Drug Delivery System using Solid Phase Polymerization initiated by Plasma-induced Radicals

“…A prescribed quantity of each plasmairradiated powder was mechanically vibrated by vibratory milling apparatus (Shimadzu Co. Ltd.) equipped with a Teflon twin-shell blender ( Figure 2). The Teflon twin-shell blender was used in the present study to eliminate any possibility of unnecessary side reactions such as mechanicallyinduced solid state singe electron transfer (SSET) reaction as in the case of using a metallic vessel [7][8][9].…”