Photopolymerization Of Trimethylolpropane Triacrylate Research Articles

Monoacylphosphine oxides with substituents in the phosphonyl moiety as Norrish I photoinitiators: Synthesis, photoinitiattion properties and mechanism

In order to study the effect of the substituents in the phosphonyl moiety of monoacylphosphine oxide (MAPO) on its stability and initiation performance, (2,4,6-trimethylphenyl)(phenyl)(benzoyl)phosphine oxide (TMBPO), (4-tolyl)(phenyl)(2,4,6-trimethylbenzoyl)phosphine oxide (4-MTPO) and (2,4-xylyl)(phenyl)(2,4,6-trimethylbenzoyl)phosphine oxide (2,4-DMTPO) were designed and prepared. Studies on TMBPO showed that the introduction of methyl groups into the phosphonyl moiety of MAPO significantly enhanced its stability and light absorption abilities. The photopolymerization of trimethylolpropane triacrylate (TMPTA) showed that the initiation efficiency of 4-MTPO and 2,4-DMTPO were higher than that of TPO, regardless of whether it was initiated upon LED at 385 nm or 420 nm. In addition, the migration rates of 4-MTPO and 2,4-DMTPO in cured TMPTA were approximately 1/2 and 1/4 that of TPO, respectively.

A novel acyl phosphine compound as difunctional photoinitiator for free radical polymerization

In order to use the visible light for light curing, a new compound named 4-diethylaminobenzoyldipenylphosphine oxide (DEAPO) was designed and synthesized. Firstly, DEAPO shows good performance as the cleavage photoinitiator in the photopolymerization of trimethylolpropane triacrylate (TMPTA). The double bond conversion obtained with DEAPO system was even higher than the widely used acyl phosphine photoinitiator (2,4,6-trimethylbenzoyl) diphenylphosphine oxide (TPO). With the same initial quality, the migration of DEAPO was much lower than TPO. Secondly, DEAPO was successfully used as coinitiator in the H-abstraction type photoinitiation system because of the diethyl amino group. Results mean that the novel acylphosphine oxide DEAPO was an efficient difunctional photoinitiator.

One-component thioxanthone-based polymeric photoinitiators

The photochemical and photophysical properties of new polymeric photoinitiators (PPIs) containing pendant thioxanthone (TX) and amine moieties are studied. The PPIs are synthesized by copolymerization of tert-butyl 2-((9-oxo-9H-thioxanthen-2-yloxy)methyl)acrylate (TX1) with N,N-dimethylaminoethyl methacrylate (DMAEM) at two different ratios using free radical polymerization. UV–vis spectra indicate that PPIs possess similar absorption characteristics to TX1 in the violet range (∼400 nm; absorption red-shift 20 nm). The photochemical mechanisms are studied by electron spin resonance (ESR), steady state photolysis, laser flash photolysis, and cyclic voltammetry. ESR studies indicate formation of two different aminoalkyl radicals on the hydrogen donor amine. The triplet state of the PPIs is short-lived compared to isopropyl thioxanthone and TX1, due to the built-in amine functionality. Photopolymerization of trimethylolpropane triacrylate (TMPTA) initiated by these photoinitiators under LED exposure at 385 and 405 nm using real-time FTIR spectroscopy shows that they exhibit higher efficiency than TX/N-methyldiethanolamine (MDEA) and TX1/MDEA systems with the advantage of a much higher molecular weight that can be very helpful to overcome migration issues. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3370–3378

Thioxanthone photoinitiator containing polymerizable N-aromatic maleimide for photopolymerization

A novel polymerizable free radical photoinitiator, 2-maleimidethioxanthone (MTX), was synthesized by introducing directly maleimide (MI) group into the molecule of thioxanthone (TX). N-methyldiethanolamine (MDEA) was chosen as coinitiator for TX, TX/N-phenylmaleimide (NPMI) and MTX. FT-IR and 1H NMR confirm the structure of MTX. UV–vis spectra of the three photoinitiators are similar and both exhibit the maximal absorption about 390 nm. Fluorescence spectra show MTX/MDEA has lower fluorescence intensity than the other two systems. The photopolymerization of trimethylolpropane triacrylate (TMPTA), initiated by TX/MDEA, TX/NPMI/MDEA, and MTX/MDEA systems, was studied by differential scanning photocalorimetry (photo-DSC). The results show that MTX/MDEA is much more efficient than TX/NPMI/MDEA and TX/MDEA, and TX/NPMI/MDEA is more efficient than TX/MDEA, due to the synergistic effect between TX moiety and maleimide group. Meanwhile, MTX also enjoys the unique advantage of being consumed during polymerization, which will certainly reduce the migration of the species.

A thioxanthone-based photocaged superbase for highly effective free radical photopolymerization

Abstract Thioxanthone-based N -phthalimidoamino acid ammonium salt (thioxanthen-DBU) as a photocaged base was synthesized and characterized. The photochemical properties and initiation mechanism were analyzed. It was found that the compound absorbs over the UV and visible region with relatively high absorption coefficients. Furthermore, the covalent binding of N -phthalimidoamino acid and type II chromophores (thioxanthone, TX) remarkably improved the photoreactivity. Specifically, in combination with a benzoyl peroxide initiator, thioxanthen-DBU was able to initiate the amine-mediated redox photopolymerization of trimethylol propane triacrylate (TMPTA), and an excellent photopolymerization profile was obtained.

Effect of photosensitive groups on the photoefficiency of polymeric photoinitiators

The purpose of this paper is to determine the effect of photosensitive groups contained in the main chain of polymeric photoinitiator on photopolymerization. Through polycondensation of toluene-2,4-diisocyanate (TDI), different diamines and N-phenyldiethanolamine (PDEA), three novel polymeric photoinitiators containing in-chain benzophenone (BP) and coinitiator amine were synthesized in comparison with the corresponding side-chain ones. FT-IR, 1H NMR and GPC analyses confirm the structures of all polymers. UV-Vis spectra showed that the maximal absorption and the molar extinction coefficient of polymeric photoinitiator can be greatly improved by the electron donating groups and the imino nitrogen that directly link to BP structure. The photopolymerization of trimethylolpropane triacrylate (TMPTA) and PU prepolymer, initiated by these polymeric photoinitiators, was studied by photo-DSC. The results indicate that the location of photosensitive group has an important effect on the photoefficiency of polymeric photoinitiators. The efficiency order of polymeric photoinitiators comprising in-chain BP is different from that of the side-chain ones: PUIBA-s and PUIBA-n are the most efficient for TMPTA and PU prepolymer, respectively.

Fabrication of Novel Transparent Inorganic Polymer Derived Microchannels and Application for Photopolymerization

The present work describes fabrication of novel inorganic microfluidic channels derived from commercially available inorganic polymer allylhydridopolycarbosilane (AHPCS) by UV imprinting lithography process. The UV transparency and solvent resistance of the microfluidic channels was measured when the polymer was cured at various conditions. The microchannel cured at 160 degrees C for 3 h showed excellent transparency, especially in visible region. The photopolymerization of trimethylolpropanetriacrylate (TMPTA) in the microchannel resulted in greater yield and 20 times faster reaction than that in batch process. These preliminary results demonstrated that novel AHPCS derived microchannel can be useful as an alternative platform for optical and photochemical microfluidic devices.

Novel Photosensitive Thio-Containing Polyurethane as Macrophotoinitiator Comprising Side-Chain Benzophenone and Co-Initiator Amine for Photopolymerization

A novel thio-containing polyurethane (PU) as macrophotoinitiator (PUIA) was synthesized through polycondensation of 3,5-diamino-4‘-thiophenylbenzophenone (DATBP), hexamethylene-1, 6-diissocyanate (HDI), and N-methyldiethanolamine (MDEA). The beznophenone and co-initiator amine structures were successfully introduced into the backbones of PUIA. A macrophotoinitiator without co-initiator amine in polymer chain (PUI) and a macroamine (PUA) were also synthesized for comparison. FT−IR, 1H NMR and GPC analyses confirmed the structures of all polymers. The UV−vis spectra of PUIA and PUI are similar and both exhibit the maximal absorption near 320 nm. ESR spectra indicate PUIA can efficiently generate free radicals. The photopolymerization of trimethylolpropane triacrylate (TMPTA) and PU prepolymer, initiated by PUIA, PUI/MDEA, PUI/PUA, DATBP/MDEA, and DATBP/PUA, was studied by photo-DSC. The results show that PUIA is the most efficient photoinitiator for both TMPTA and PU prepolymer. As for the polymerization of PU prepolymer, the final conversion is higher than 97%.

Study of Novel PU‐Type Polymeric Photoinitiators Comprising of Side‐Chain Benzophenone and Coinitiator Amine: Effect of Macromolecular Structure on Photopolymerization

AbstractThree PU‐type polymeric photoinitiators containing side‐chain benzophenone and coinitiator amine, PUSBA‐h, PUSBA‐t and PUSBA‐i, were synthesized via polycondensation of 3,5‐diamino‐4′‐thiophenylbenzophenone, different diisocyanates and N‐methyldiethanolamine. FT‐IR, 1H NMR and GPC analyses confirm the structures of all polymers. The UV‐vis spectra of polymeric photoinitiators are similar and all exhibit the maximal absorption near 320 nm. ESR spectra show PUSBA‐h and PUSBA‐t can efficiently generate free radicals. The photopolymerization of trimethylolpropane triacrylate and the PU prepolymer, initiated by these polymeric photoinitiators, was studied by photo‐DSC. The results indicate that the macromolecular structure has an important effect on photopolymerization, and different photoinitiators exhibit different behavior towards different monomers: PUSBA‐t is the most efficient for TMPTA and PUSBA‐h is the most efficient for PU prepolymer. The final conversion for the photopolymerization of PU prepolymer initiated by PUSBA‐h is greater than 97%.magnified image

Photopolymerization of trimethylolpropane triacrylate in a matrix of linear polymers

Photopolymerization of trimethylolpropane triacrylate in a matrix of linear polymers

Polymeric Foam by Photoinitiated Polymerization of Trimethylolpropanetriacrylate: Initiator and Solvent Effects

A comprehensive examination of the preparation of polymeric foam via the photopolymerization of trimethylolpropanetriacrylate, TMPTA, was undertaken. Foam properties such as uniformity, shrinkage, density, microstructure, physical integrity, and machinability were measured as a function of initiator, solvent, and processing conditions. The photopolymerization rate of TMPTA in poly(oxyethylene[4]) lauryl ether, or Brij 30, and glycol ethers is enhanced using active photoinitiators such as benzoinethylether and 2,2-dimethoxy-2-phenylacetophenone. The properties of the TMPTA foams were identical for all photoinitiators examined. The properties of the TMPTA foams were dramatically changed when a co-solvent was employed. The co-solvents were triethyleneglycol dimethyl ether and triethyleneglycol monomethyl ether. The use of co-solvents leads to greater shrinkage and a higher than expected foam density. Unlike foams prepared in Brij 30, foams prepared using glycol ethers possess good physical properties and can be machined into cylinders with a smooth surface finish.