Kinetic investigations on the photopolymerization of di- and tetrafunctional (meth)acrylic monomers in polymeric matrices. ESR and calorimetric studies. I. Reactions under irradiation

Abstract

The photopolymerization of several di‐ and tetrafunctional (meth)acrylic monomers in the presence of a styrene–butadiene–styrene polymeric matrix (SBS) has been studied. Electron spin resonance spectroscopy (ESR) and differential scanning photocalorimetry (photo‐DSC) were used as monitoring techniques to identify the photogenerated radicals and analyze photopolymerization profiles, radical environments, and radical secondary reactions. The study of the photopolymerization and/or photocrosslinking reactions of these monomers in the solid media was carried out by taking into consideration different factors, such as the influence of both monomer and photoinitiator structures on the hydrogen abstraction in the binder with formation of benzylic and allylic radicals, the polymerization of the monomers itself and the hydrogen abstraction reaction in the polymerized acrylic chains. Finally, irradiation of the system SBS/photoinitiator in the absence of monomer was also accomplished. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2775–2783, 1998

Photoinitiated polymerization of methacrylic monomers in a polystyrene matrix: Kinetic, mechanistic, and structural aspects

“…The ESR spectrum of the PS/EHMA 20% system under irradiation (Fig. 7) is practically the same as that obtained with the SBS matrix 22. The ESR signals correspond to the very strong nine‐line spectra of the propagating methacrylic radical 23.…”

“…The ESR signals correspond to the very strong nine‐line spectra of the propagating methacrylic radical 23. The nine‐line spectrum can be separated into two groups of lines, five intense ones (relative intensities of 1/4/6/4/1) equally separated by 23 G and four inner lines (relative intensities of 1/3/3/1) equally separated by 25 G. The 1/4/6/4/1 relative intensity between the five strong lines changes gradually, and the central line gradually increases with conversion as in the SBS matrix 22. The central line corresponds to the benzylic radical, which is superimposed on the central line of the multiplet.…”

A Two‐Step Interval and Modified Rosenbrock Method for Kinetic Parameter Estimation in Copolymerization Systems: A Robust and Reliable Approach

“…Correct estimates of the kinetic parameters and their uncertainties are fundamentally important for polymerization kinetics, because such data are needed for assessing microscopic rate theories and kinetic models. Various methods have been developed and applied for kinetic parameter estimation 1–7. The best estimate of the parameters can be obtained by optimizing a suitable objective function subject to model constraints.…”

The Stability of Free Radicals in Densely Crosslinked Acrylate Polymer Networks

“…[25] The substitution reactions of free radicals in addition to bimolecular termination were considered in the photopolymerization of multifunctional (meth)acrylic monomers in the presence of styrene-butadiene polymer matrix. [26,27] In the present work, the four types of crosslinked polymeric systems based on pentaerythrite tetraacrylate (PETA) and propylene glycol-425-diacetoacetate (PGDAA) were studied from the point of view of free radical decay and network density. The polymer networks were prepared by two step synthesis.…”