Highly cross-linked networks for dental applications obtained by photocuring of tris[2-(acryloyloxy)ethyl]isocyanurate, 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate, and pentaerythritol triacrylate

Recent advances in additive manufacturing made it feasible to fabricate products with desired shapes and features. Herein, a new, photocurable 3D printer ink mainly based on pentaerythritol triacrylate (PETA) is reported. To achieve rapid curing needed for 3D printing process, high performance water‐soluble photoinitiator, lithium phenyl‐2,4,6‐trimethylbenzoylphosphinate (LAP), was emulsified in PETA monomers and this suspension was evaluated for its polymerization kinetics by exposing to 395 nm UV‐light. The distinct influences of LAP and triethanolamine (TEA) concentrations on photo‐polymerization and printability were examined and an optimum concentration for extrusion‐based 3D printing was found to be 10 mM and 1.62 M for LAP and TEA, respectively. Synthesized PETA‐based 3D printer ink was functionalized by dispersing magnetic particles/flakes into the mixture, and consequently, a magneto responsive ink was obtained to be used in specialized applications. A ring‐shaped structure embedded with micron sized iron flakes was printed as a prototype. This study presents a versatile photo‐curable polymer formulation with possible translation to high performance 3D printing of customizable shapes that can be utilized in a wide range of areas such as micro‐robotics and medical science.

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Photocurable pentaerythritol triacrylate/lithium phenyl‐2,4,6‐trimethylbenzoylphosphinate‐based ink for extrusion‐based 3D printing of magneto‐responsive materials

Erkoc

Odeh

Alrifai

et al. 2020

J of Applied Polymer Sci

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EPR Studies of Amine Radical Cations, Part 1: Thermal and Photoinduced Rearrangements of n‐Alkylamine Radical Cations to their Distonic Forms in Low‐Temperature Freon Matrices

Janovský¹,

Knolle²,

Naumov³

et al. 2004

Chemistry A European J

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The thermal and photochemical transformations of primary amine radical cations (n-propyl 1.+, n-butyl 5.+) generated radiolytically in freon matrices have been investigated by using low-temperature EPR spectroscopy. Assignment of the spectra was facilitated by parallel studies on the corresponding N,N-dideuterioamines. The identifications were supported by quantum chemical calculations on the geometry, electronic structure, hyperfine splitting constants and energy levels of the observed transient radical species. The rapid generation of the primary species by a short exposure (1-2 min) to electron-beam irradiation at 77 K allowed the thermal rearrangement of 1.+ to be monitored kinetically as a first-order reaction at 125-140 K by the growth in the well-resolved EPR signal of the distonic radical cation .C(2CH2CH2NH3+. By comparison, the formation of the corresponding .CH2CH2CH2CH2NH3+ species from 5.+ is considerably more facile and already occurs within the short irradiation time. These results directly verify the intramolecular hydrogen-atom migration from carbon to nitrogen in these ionised amines, a reaction previously proposed to account for the fragmentation patterns observed in the mass spectrometry of these amines. The greater ease of the thermal rearrangement of 5.+ is in accordance with calculations on the barrier heights for these intramolecular 1,5- and 1,4-hydrogen shifts, the lower barrier for the former being associated with minimisation of the ring strain in a six-membered transition state. For 1.+, the 1,4-hydrogen shift is also brought about directly at 77 K by exposure to approximately 350 nm light, although there is also evidence for the 1,3-hydrogen shift requiring a higher energy. A more surprising result is the photochemical formation of the H2C=N. radical as a minor product under hard-matrix conditions in which diffusion is minimal. It is suggested that this occurs as a consequence of the beta-fragmentation of 1.+ to the ethyl radical and the CH2=NH2+ ion, followed by consecutive cage reactions of deprotonation and hydrogen transfer from the iminonium group. Additionally, secondary ion-molecule reactions were studied in CFCl2CF2Cl under matrix conditions that allow diffusion. The propane-1-iminyl radical CH3CH2CH=N. was detected at high concentrations of the n-propylamine substrate. Its formation is attributed to a modified reaction sequence in which 1.+ first undergoes a proton transfer within a cluster of amine molecules to yield the aminyl radical CH3CH2CH2N.H. A subsequent disproportionation of these radicals can then yield the propane-1-imine precursor CH3CH2CH=NH, which is known to easily undergo hydrogen abstraction from the nitrogen atom. The corresponding butane-1-iminyl radical was also observed.

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Camphorquinone–amines photoinitating systems for the initiation of free radical polymerization

Jakubiak

Allonas

Fouassier

et al. 2003

Polymer

266

204

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Highly cross-linked networks for dental applications obtained by photocuring of tris[2-(acryloyloxy)ethyl]isocyanurate, 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate, and pentaerythritol triacrylate

Cited by 5 publications

References 15 publications

Photocurable pentaerythritol triacrylate/lithium phenyl‐2,4,6‐trimethylbenzoylphosphinate‐based ink for extrusion‐based 3D printing of magneto‐responsive materials

Photocurable pentaerythritol triacrylate/lithium phenyl‐2,4,6‐trimethylbenzoylphosphinate‐based ink for extrusion‐based 3D printing of magneto‐responsive materials

EPR Studies of Amine Radical Cations, Part 1: Thermal and Photoinduced Rearrangements of n‐Alkylamine Radical Cations to their Distonic Forms in Low‐Temperature Freon Matrices

Camphorquinone–amines photoinitating systems for the initiation of free radical polymerization

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