Particle clustering in photocurable nanocomposites: Dependence of curing kinetics and viscoelastic properties

Abstract

The aim of this article is to investigate the effect of nanoparticle clustering on the mobility of nanoparticles in nanocomposites, using spectroscopic methods (Brillouin and Raman). Special attention is paid to the effect of particle clustering on photocuring kinetics. The model system was poly(2-hydroxyethyl acrylate) filled with fumed nanosilica in concentration range encompassing the percolation threshold. Results obtained from Brillouin spectroscopy show substantial changes in the sound velocity and the attenuation coefficient with increasing filler content. The damping of acoustic waves reaches the maximum at the percolation threshold ($15 wt %), which is related to changes in the mechanism of acoustic wave propagation. The formation of the cocontinuous silica phase strongly affects the curing kinetics of the monomer/silica system: the polymerization rate is the highest at a silica content corresponding to the percolation threshold. These results correlate well with the results of AFM surface roughness analysis. V C 2013Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39895.

Surface-dependent effect of functional silica fillers on photocuring kinetics of hydrogel materials

“…The increase in the polymerization rate is often associated with the increase in the viscosity of the system, which suppresses the termination by slowing the diffusion of macroradicals and thereby accelerates the polymerization . This results in the inverse proportionality of the k t b and system viscosity η : k t b – η −1 .…”

“…The reproducibility of the kinetics results was about ±3%. For computations, the heat of polymerization was taken to be 56 KJ mol −1 per one double bond …”

“…HEMA, 1,6‐hexanediol diacrylate (HDDA), trimetylolpropanetriacrylate (TMPTA), thiol‐ene systems). The following cases were observed: (i) no change in the polymerization rate after silica addition, (ii) decrease of the polymerization rate, (iii) a maximum on the dependence of the polymerization on the silica content: monomer TMPTA, maximum at 10% of silica, monomer HDDA, maximum at 15% of silica, monomer polyethylene glycol dimethacrylate or monomer mixture, maximum at 5% of silica, monomer HEA, maximum at 15% of silica . Thus, every system may behave in a different, not predictable, way.…”

Recent Advances in Photo-Induced Free-Radical Polymerization

“…in the case of silica both increase, decrease, or no effect on the polymerization rate was observed. 19,20 Recent works indicate that the kinetics depends to a high degree on the stability of the monomer/filler dispersion 21,22 or particle size. 23 A decreased photopolymerization rate of an acrylate monomer was observed in the presence of nano-TiO 2 , which was associated with the light absorption by this filler in the range of photoinitiator absorption.…”

New fluorescent hyperbranched polymeric sensors as probes for monitoring photopolymerization reactions

“…It is still highly interesting and attracts a large attention in materials science. Elucidation of its mechanism and kinetics is of crucial importance for the development of new monomers [7], photoinitiators [8] and materials, such as optoelectronic materials [9], biomaterials [10], nanocomposites [11], IPNs [12], holographic recording [13], multilayer hydrogels [14], and many more. With the emergence of LEDS as new irradiation sources new environmental and economic possibilities have put increasing interest in the field [15,16].…”