Effect of Light Intensity on the Free-Radical Photopolymerization Kinetics of 2-Hydroxyethyl Methacrylate: Experiments and Simulations

Abstract

The effect of UV light intensity on the kinetics of free radical polymerization 2-hydoxyethyl methacrylate (HEMA) triggered with phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO) photoinitiator was investigated experimentally and theoretically. The temporal evolution of the conversion yield and polymerization rate was followed by Raman spectroscopy. The experimental data were treated with a kinetic model, which takes into account significant diffusion controlled processes and termination pathways including bimolecular reaction and primary radical termination. This model showed a very good agreement with the experiment in a large range of the UV light intensities and shed light on the termination process. In particular, it was show that the primary radical termination is dominant for relatively low light intensities below 1 mW/cm², when the photoinitiator is weakly consumed during the polymerization process.

Free-radical polymerization of 2-hydroxyethyl methacrylate (HEMA) supported by a high electric field

“…Different techniques can be utilized to track the polymerization progress, such as Fourier transform infrared (FTIR) spectroscopy, 44 Raman spectroscopy, 41 NMR 45 and DSC. 38 Dielectric spectroscopy is also a powerful method for investigating systems that are undergoing chemical or physical changes as a consequence of chemical reaction, vitrification, crystallization, etc .…”

“…, the Trommsdorf–Norrish effect. In contrast, externally-regulated HEMA FRP supported by high-pressure, 39 ultra-waves, 40 or UV light irradiation 41 turned out to be more controlled processes reaching higher rates, HEMA consumptions and providing poly(2-(hydroxyethyl)methacrylate)s (PHEMA)s of much lower Đ . Thus, the above physical factors have become an alternative to the commonly known chemical method using polymerization of the trimethylsilyl protected monomer.…”

Printability during projection-based 3D bioprinting

“…3 , the amount of GelMA is sufficient in the chemical crosslinking reaction, and the crosslinking rate and the crosslinking density of the GelMA network depend on the production rate and the number of free radicals. Since free radicals only exist in areas where the light can penetrate due to the short half-life of free radicals [ 38 ], the production rate and density of crosslinked GelMA networks can be controlled by adjusting the light intensity and exposure time where LAP is abundant in the photophysical reaction.…”

Novel Copper Complexes as Visible Light Photoinitiators for the Synthesis of Interpenetrating Polymer Networks (IPNs)

“…The elaboration of polymers by photochemical means, such as free radical photopolymerization (FRP) and cationic photopolymerization (CP), have been mainly based on the use of metal-free organic dyes and photoinitiators at the industrial and academic levels [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ], and these synthetic processes (FRP and CP) are widely used in different fields, e.g., dentistry [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ], adhesives [ 24 , 25 , 26 , 27 , 28 ], coatings [ 29 , 30 , 31 , 32 , 33 ], composites [ 34 ], medicine [ 35 , 36 , 37 , 38 , 39 , 40 ], direct laser write, 3D and 4D printing [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ], etc. On the other hand, organometallic compounds are not really used in industry; in other words, manufac...…”