Figures
Explore figures and images from publications
Figure 2 - uploaded by Ahmad Ibrahim
Content may be subject to copyright.
Examples of commercially available type I photoinitiators. 

Examples of commercially available type I photoinitiators. 

Source publication
Chapter
Full-text available
In this chapter, a compilation of different systems able to photogenerate active radicals toward polymerization reaction( type I, type II and three component photoinitiating systems) for application in holographic grating recording when associated to monomers is reviewed. In particular, the visible curable system is associated to fluorinated acryla...

Contexts in source publication

Context 1
... type I photoinitiators, one can find hydroxylalkylphenones, benzylketals, benzoin ether derivatives, α-aminoketones and acylphosphine oxides (Figure 2). In these compounds, the cleavage rate constants are high, leading to very good quantum yields of radical generation Φ R . ...
Context 2
... full description of the electron transfer reactions occurring in three-components (and type II) PIS is summarized in Figure 5. Four electron transfer reactions are identified: the first one ( Figure 5 [1]) is the thermal electron transfer (ET) which should be avoided; the second one is the photoinduced electron transfer (PET) (Figure 5 [2]) and is discussed in point iv. (vide supra), the third one is the so-called back electron transfer (BET) (Figure 5 [3]), an intra-encounter complex recombination of reduced photosensitizer (PS) an oxidized coinitiator (Co) which gives the reactants back and lower the quantum yield of radical generation. ...

Similar publications

Chapter
Full-text available
In this chapter, a compilation of different systems able to photogenerate active radicals toward polymerization reaction(type I, type II and three component photoinitiating systems) for application in holographic grating recording when associated to monomers is reviewed. In particular, the visible curable system is associated to fluorinated acrylat...
Article
Full-text available
Photoinitiating systems based on BF2 derivatives and tetramethylammonium phenyltriethylborate salt were tested in photopolymerization reactions through the photo-DSC method. The good rates of TMPTA polymerization and final monomer conversion were obtained for tested system. The effect of the type of heterocycle on their properties was revealed. The...

Citations

... HDDA as bifunctional linear monomer contributes to the increase of the mechanical properties [24,36]. The photoinitiator used in this study is TPO and belongs to the Norrish Type I PI [37], where absorption of visible and ultra-violet (UV) lights causes homolytic bondage cleavage and generates two highly reactive radical species, which then initiate the polymerization and irreversibly incorporate into the polymer matrix. In the present study, the ratio between AESO/TMPTA/HDDA was kept constant at 65/30/5, and the photoinitiator was loaded at different concentrations ranging from 1% to 7%. ...
Article
Full-text available
Typical resins for UV-assisted additive manufacturing (AM) are prepared from petroleum-based materials and therefore do not contribute to the growing AM industry trend of converting to sustainable bio-based materials. To satisfy society and industry’s demand for sustainability, renewable feedstocks must be explored; unfortunately, there are not many options that are applicable to photopolymerization. Nevertheless, some vegetable oils can be modified to be suitable for UV-assisted AM technologies. In this work, extended study, through FTIR and photorheology measurements, of the UV-curing of epoxidized acrylate from soybean oil (AESO)-based formulations has been performed to better understand the photopolymerization process. The study demonstrates that the addition of appropriate functional comonomers like trimethylolpropane triacrylate (TMPTA) and the adjusting of the concentration of photoinitiator from 1% to 7% decrease the needed UV-irradiation time by up to 25%. Under optimized conditions, the optimal curing time was about 4 s, leading to a double bond conversion rate (DBC%) up to 80% and higher crosslinking density determined by the Flory–Rehner empirical approach. Thermal and mechanical properties were also investigated via TGA and DMA measurements that showed significant improvements of mechanical performances for all formulations. The properties were improved further upon the addition of the reactive diluents. After the thorough investigations, the prepared vegetable oil-based resin ink formulations containing reactive diluents were deemed suitable inks for UV-assisted AM, giving their appropriate viscosity. The validation was done by printing different objects with complex structures using a laser based stereolithography apparatus (SLA) printer.
... According to this, photosensitive systems can be classified as one, two or even three-component systems, with the one-component system having all required functionalities being encoded in one single molecule and the three component system using three individual molecules to fulfill the task. From this simplistic point of view, the material development has either to prepare the perfect molecule or to select a smart combination of two [35] or three components [36]. Since there is good evidence for all these concepts, one example for each one-and two-component system is discussed first. ...
... In this system, irradiation of the photo initiator (PI) provides the reactive species for the initiation step. In more detail the PI absorbs the light energy and transforms intra molecularly into a reactive species, here an initiating radical R  that attacks a monomer M and finally converts into the (photo) polymer (Scheme 1): [36]. The use of titanocene complexes (e.g., CGI-784 from BASF AG, Ludwigshafen, Germany, see Scheme 2) in experiments where several high refractive index organic monomers were incorporated into acrylate oligomer-based formulations, irradiated at 546 nm was described in [37]. ...
... In the two wave approximation outlined in Kogelnik's work [1] for the first diffraction order of the hologram only the first order Fourier components ∆n1 of the refractive index profile ∆n is of interest. At each time t we can therefore write for ∆n1, which is then identical to the index modulation of the holographic grating: (36) Here ndark denotes the refractive index of the unrecorded photopolymer, nu the refractive index of the monomer, nB the refractive index of the contrast agent, nN the refractive index of the polymerized monomers and nb the refractive index of the matrix. These refractive indices were measured independently in our case. ...
Article
Full-text available
Holographic photopolymers are a new technology to create passive diffractive optical elements by a pure laser interference recording. In this review, we explain the chemistry concepts of light harvesting in an interference pattern and the subsequent grating formation as chemical response. Using the example of the newly developed Bayfol® HX film we discuss the reactiondiffusion driven photo-polymerization process for an index modulation formation to create volume phase gratings. Further we elucidate the selection of monomer chemistry and discuss details of the recording conditions based on the concept of exposure dosage and exposure time. Influences ranging from high dosage recording to low power recording are explained and how to affect the desired diffraction efficiency. Finally, we outline and demonstrate the process to mass manufacturing of volume phase gratings.
Article
Full-text available
The in situ inter calative polymerisation of acrylated palm oil and isocyanate with the presence of Hidroxyethylacrylate (HEA) was undertaken to produce Palm Oil Based Urethane Acrylate (POBUA). Several coatings formulations from POBUA with different types of photoinitiators were prepared and applied on a mild steel surface before being exposed under UV irradiation toward green anticorrosion coatings formation. The disappearance of the FTIR spectrum of cured POBUA coatings at around 810 cm⁻¹ has confirmed the development of the crosslinked network. Soxhlet extraction and pendulum hardness test were carried out to investigate the crosslinked network performance in the cured film. Meanwhile, potentiodynamic polarization analysis in 3.5% NaCl solution was conducted to explain the anticorrosion mechanism of POBUA, and the TAFEL plot was manipulated in measured the corrosion rate of mild steel. Contact angle (CA) and X-Ray Diffraction analysis are also demonstrated in this work in order to study the surface properties of POBUA. The results indicate mild steel coated with POBUA film owes better corrosion resistance compared to blank mild steel. Crosslink polymer network formation from POBUA has effectively protected the mild steel surface from corrosion agents such as oxygen and water. CA result also showed hydrophobicity behavior of POBUA gives value-added properties in reducing corrosion process.
Chapter
DESCRIPTION The past few decades have seen a demand for developing structures of polymers at micro and sub-micro levels having definite sizes and functionality. Photophysics- and photochemistry-based properties of various polymeric materials have been used repeatedly in several research or industry-oriented applications as in microelectronics, tissue engineering, imaging, copying and recording systems, etc. Photochemical reactions promote excitation of a substrate from the ground state to a higher energy state by absorbing ultraviolet, visible, or infrared radiation, causing the substrate to undergo physical and chemical changes. The physical changes can lead to fluorescence and internal conversions, while a chemical change may lead to a rearrangement, elimination, addition, isomerization, or transfer of electrons within a substrate. The abundance of natural light forms and development of specific technologies such as spatial light modulators, photosensitive materials, and other advanced photonic technologies have caused extensive use of this property for the fabrication of polymeric material with increasing resolutions. This chapter will be mainly dealing with a review of the basic photochemical processes used for the fabrication of different polymeric materials in various applications. Recent advancements and future application prospects for the same are also discussed in detail.
Article
The goal of this paper concerns on the evaluation of efficiency of novel three-component systems, initiating the photopolymerization process of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate (TMPTA). The combination of 1,3-bis(phenylamino)squaraine (SQG1) with different types of coinitiators are proposed as effective UV-Vis light photoinitiators. The coinitiators used in experiment, such as: silane (TTMSS), borate salt (B2), carbazole (NVC) and group of iodonium salts (I1, I2, I77, I81) are active radical sources for initiation of polymerization of TMPTA. The effect of the composition of the system on the photopolymerization kinetics was analyzed. The optimal photoinitiator concentration, that gives high monomer conversions and high values of rate of polymerization was indicated and presented in this article.
Article
To broaden the application of oxime ester and obtain a photoinitiating system with high performance in visible light photopolymerization, we prepared the two arylaminocarbazole oxime ester (CZ–OXE), OXE1 and OXE2, with visible absorption. The multicomponent initiation systems of OXE as one of the components were evaluated in visible photopolymerization. Synergism between OXEs and diaryliodonium salt (ION), N-vinylcarbazole (NVK), ethyl 4-dimethylamino benzoate (EDB), and triphenylphosphine (TPP) were experimentally studied via steady state photolysis and fluorescence quenching. The thermodynamic feasibility for electron transfer reaction in photoinitiating systems was confirmed by cyclic voltammetry experiments. Electron spin resonance techniques proved the production of active species in the systems. Polymerization experiments under a 405 nm light source showed that the two-component initiation system OXEs/ION was more efficient than the one-component initiator OXEs. Similarly, three-component OXEs/ION/co-initiator photoinitiating systems are more efficient than OXEs/ION systems.
Thesis
The development of a new photoinitiator/photoinitiatng system being capable of strongly absorbing light in the visible-light region and working under LED irradiation has made gratifying advance. Herein, notably the fluorescent brightener as one class of fluorophore derivetives, has been confirmed as an efficient Pl for free radical photopolymerization (FRP), one of the major advantages is thalthey could efficiently work under air even exposure to a low LED light intensity. When incorporated into multicomponent photoinitiating systems (in the presence of iodonium salt (and optionally N-vinyl carbazole or amine)), the derivatives of naphthalene­ benzoxazole, sulfonated triazinylstilbenes, sulfonated stilbene-biphenyl and coumarinmexhibit quite excellent photoinitiating abilities for FRP of acrylates under air. Moreover, they are particularly efficient for the formation of interpenetrated polymernetwork through a concomitant cationic/radical photopolymerization of epoxides/acrylates blend.Additionally, substitution of a certain content of acrylate monomer with water is found to positively increase the final conversion of polymerizable acrylate functions, especially formulated with the hydrophilic brighteners-based initiating systems. Besides, an aqueous acrylate formulation containing brighteners-based initiating systems enabled the LED-assisted synthesis of hydrogels. This synthetic method is less energy-intensive and the hydrogels produced are typically of high water content. And, the investigation of photopolymerizations thal proceed in acrvlate/water blends broadens the perspectives for qreen polvmer and organic chemistry.
Article
The interaction of cationic organic dye Astrazon Orange with the synthetic phyllosilicate Laponite® leads to very interesting hybrid materials. Indeed, the Laponite® nanoparticles modify the photophysical properties of Astrazon Orange inducing a stabilization of its excited emissive state by preventing ultrafast isomerisation. The long lived emissive Clay-dye hybrid complex can be used to develop efficient photoinitiating systems leading to organic-inorganic hybrid crosslinked polymer materials.