Photopolymerization of acrylamide in the very low monomer concentration range

Abstract

Photopolymerization of acrylamide in the very low monomer concentration rangeIgnác Capek slovak academy of sciences, Polymer institute, institute of Measurement sciences, Bratislava, slovakia ABSTRACTThe polymerization kinetics of acrylamide (AAm) initiated by the photoinitiator DAROCUR 2959 (DAR 2959 ) under UV light irradiation were investigated. Variations of polymerization rate with AAm concentration and conversion were studied. Under the present low monomer concentrations the gel effect as well the difusion-controlled termination reactions are expected to be postponed or suppressed. The polymerization rate vs. conversion curve of the photoinduced polymerization of AAm was described by two non-stationary rate intervals and the initial rate maximum. In both intervals the polymerization rate decreased with conversion and the decrease was much more pronounced in the low conversion region. Furthermore, the polymerization rate was observed to decrease with increasing monomer concentration. The polymerization behavior was discussed in terms of the intra and intermolecular chain transfer processes (mainly to backbiting) and the decrease of propagation rate coefficient with the monomer concentration. Furthermore, the chain transfer reactions including backbiting step initiate the formation of less reactive radicals and/or the retardation of the polymerizaton.

Self-Organization Induced by Self-Assembly in Microheterogeneous Reaction-Diffusion System

“…At [AA] = 50 mM (or smaller), several separate peaks are observed (Figure a), while at larger [AA] (>0.1 M and around 0.5 M), all these peaks merge to a very broad peak spanning from 10 up to 100 nm (or even larger) (Figure c). A broad distribution of the sizes of the PAA nanogel particles at a relatively small [AA] was found elsewhere …”

“…So, to produce the AA gel, we do not need both methods (i) and (ii) mentioned in the Introduction Section. If however [AA] is small enough, polymerization leads to the formation of small polymer particles rather than a continues gel …”

Structural Investigation: Anionic Polymerization of Acrylamide under Microwave Irradiation using Maghnite-Na+ Clay (Algerien MMT) as Initiator

“…The interaction of propagating ion pairs with functional groups of the vinyl monomer or the polymer chain can affect the propagation rate and in some cases induces side reactions that can cease the polymerization [48]. In a side reaction-free anionic vinyl polymerization; the termination is a simple rapid reaction wherein anions are quenched through acidic hydrogen or another suitable electrophile [49]. Hence, it is important to match the reactivity of the initiator with the propagating species in order to have fast and homogeneous initiation [50].…”

Synthesis and Characterization of Polymeric Material Consisting on Acrylamide Catalyzed by Maghnite (Algerian MMT) under Microwave Irradiation

“…Mechanical properties of APAm/maghnite samples. the formation of a strong proton donor by the reaction of the maghnite-Na + , followed by the protonation of the acrylamide molecule, whose ensuing carbenium ion rearranges to form a carbocation responsible for the propagation reaction [60] . This process is extremely rapid and exothermic.…”