Photopolymerization using sensitizers of binary system of aromatic hydrocarbon and amine

Photopolymerizations of acrylonitrile and methyl methacrylate, using binary sensitizers of aromatic hydrocarbon and amine, were investigated at 30°C in N,N-dimethylformamide under the irradiation with a light of λ > 300 nm. Naphthalene, anthracene, and phenanthrene were employed as aromatic hydrocarbons in the experiment. The binary system was effective for the initiation of the monomers. The combinations of naphthalene with tertiary amines, triethylamine and N,N-dimethylaniline, were remarkably effective among various combinations. The rate of polymerization with naphthalene–triethylamine sensitizer was observed to be proportional to the first, ½, and ½ powers of monomer, naphthalene, and triethylamine concentrations, respectively. The kinetics of the photopolymerization are proposed, and the initiation schemes are discussed, comparing them with those in the system sensitized by aromatic ketone–amine reported previously.     

Controllable ring‐opening polymerization of trimethylene carbonate catalyzed by aliphatic tertiary amines in the presence of benzyl alcohol or F127

With the increased awareness of avoiding residue metals, the field of organocatalysts is attracting more attention. Aliphatic tertiary amines, such as triethylamine (TEA), N, N, N, N‐tetramethylethylenediamine (TMEDA) and 1,1,4,7,7‐pentamethyldiethylenetriamine (PMDTA), have low boiling points which allow their easy elimination after a chemical reaction. Here, we used these aliphatic tertiary amines to catalyze ring‐opening polymerizations (ROPs) of trimethylene carbonate (TMC). In the presence of benzyl alcohol, the catalytic activities of the tertiary amines were in the order of TEA < TMEDA < PMDTA. Correlation between the molecular weight of polycarbonates and monomer conversions was linear, suggesting the polymerization was controlled. The polymerization pathway was presumed to follow an alcohol‐activated mechanism according to the end‐group fidelity determined using ¹H NMR spectroscopy. The ROP of TMC was also successfully initiated by PEO₉₉‐PPO₆₅‐PEO₉₉ (F127) under the catalysis of the tertiary amines, producing well‐defined PTMC_n‐F127‐PTMC_n copolymers with narrow dispersity ( ca 1.2) and with thermosensitive properties in aqueous solution. Furthermore, copolymerizations of TMC with acryloyl‐containing cyclic carbonate were catalyzed by the tertiary amines in the presence of F127. No crosslinking reactions were detected. Our results demonstrate that the aliphatic tertiary amines have the potential to catalyze TMC homo‐ or copolymerization featuring controllable structure and composition under mild conditions. Copyright © 2012 Society of Chemical Industry     

The photosensitive properties of polysiloxane acrylate resin containing tertiary amine groups

The photosensitive properties of a novel oligomer, di (N,N‐diacrylolyl)‐α, ω‐diaminopolysiloxane (ANS) with tertiary amine groups and acryloyl groups in its molecular structure were investigated using FTIR and gel yield method. It was noted that the ANS system showed a notable photosensitive property and its photosensitivity in air could be up to16.3 mJ/cm². The UV‐curing behavior of the ANS was studied by electron spin resonance (ESR). The results showed that amino‐alkyl radicals can be formed by excited BP abstracting hydrogen at a‐carbon bonded with nitrogen in the ANS molecule under UV irradiation, which can mitigate the oxygen inhibition in radical polymerization. It is proven that tertiary amine groups introduced into ANS could boost photosensitivity of the photopolymerization system. The oligomer ANS may find application in photopolymerization to improve the properties of UV‐curing coating materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Kinetic study on the UV‐induced photopolymerization of epoxy acrylate/TiO2 nanocomposites by FTIR spectroscopy

The kinetics of the photopolymerization of epoxy acrylate/TiO₂ nanocomposites, with 2′2‐dimethoxy‐1,2‐diphenylethan‐1‐one (Irgacure 651) or benzophenone/N‐methyl diethanolamine as photoinitiators, were studied by FTIR spectroscopy. It was found that nanocomposites had a decreasing photopolymerization rates in comparison with pure epoxy acrylate. The photopolymerization rate of the nanocomposite could also be influenced by initiator types, oxygen, film thickness, irradiation intensity, dispersing media of TiO₂ slurry, and so forth. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3281–3287, 2006     

Kinetic investigations on the UV‐induced photopolymerization of nanocomposites by FTIR spectroscopy

The kinetics of the photopolymerization for nanocomposites containing nanosilica with 2,2‐dimethoxy‐1,2‐diphenylethan‐1‐one or benzophenone/n‐methyl diethanolamine (BP/MDEA)as photoinitiators were studied by FTIR spectroscopy. It was found that nanocomposites containing nanosilica had higher conversion in comparison with pristine EA. The presence of MPS and ethanol accelerated the photopolymerization of nanocomposites, while the presence of water decelerated it. The photopolymerization of nanocomposites was more sensitive to oxygen than that of pristine EA. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99:1429–1436, 2006     

Mechanical properties of acrylate networks formed by visible laser-induced polymerization. I. Dependence on photopolymerization parameters

The mechanical properties of network molecular systems, prepared through visible (Ar⁺) laser-induced polymerization of multifunctional acrylates, were studied as a function of some of the photopolymerization parameters. The properties investigated were the Young's modulus of elasticity and the stress-at-break, both derived from the stress versus strain test of dogbone-shaped photopolymerized samples. The parameters studied included the dye and co-initiator concentrations, and the laser power. We also compared the mechanical properties of samples made using different types of fluorone dyes and using two different amines as co-initiator. Better polymers are formed by the dyes with low fluorescence quantum yield. The three photopolymerization parameters modify the mechanical properties in a very similar way: they initially tend to increase both the Young's modulus and the stress-at-break but have a deleterious effect on the material strength if used in excess. N-phenylglycine, NPG, was shown to form stronger polymers (higher Young's modulus) than if N,N-dimethyl-2,6-diisopropylaniline, DIDMA, was used as co-initiator. We discuss the possible molecular mechanisms for such observations. © 1994 John Wiley & Sons, Inc.     

Effect of the Introduction of Amide Oxygen into 1,10-Phenanthroline on the Extraction and Complexation of Trivalent Lanthanide in Acidic Condition

The extractability and complexation properties of lanthanides with N-alkyl-N-phenyl-1,10-phenanthroline-2-carboxamide were investigated. These ligands, which contain two aza-aromatic donors and an oxygen donor in a molecule, are newly developed extractants for actinides and lanthanides. N-Octyl-N-tolyl-1,10-phenanthroline-2-carboxamide exhibited high extractability of Eu³⁺ even under acidic conditions. In addition, strong complexation in acidic media was confirmed by spectroscopic titration experiments. Investigation of the complexation equilibrium revealed that the presence of an oxygen donor promotes ligand coordination with lanthanides over the competing protonation reaction in acidic solution.     

Synthesis of superabsorbent resin by ultraviolet photopolymerization

Synthesis of superabsorbent resin (SAR) was achieved by a new method, that of direct UV photopolymerization, and in particular the synthesis of a SAR of acrylic acid–potassium acrylate copolymer by UV photopolymerization was investigated. Influences of ratio (mol) of acrylate monomer to acrylic acid monomer, photoinitiators, crosslinking agents, and exposure time of UV light on the water‐absorbent properties were investigated. The results showed that the water absorbency (Q) of SAR based on Irgacure 1700 or Irgacure 1800 was 545–530 mL/g, but under the same conditions Q was 450 mL/g for the SAR based on Irgacure 651. N,N′‐Methylene bisacrylamide, hydroethyl acrylate, and glycerol were used as crosslinking agents, of which N,N′‐methylene bisacrylamide was the most effective. It crosslinked the molecular chains through attending the copolymerization with acrylic acid (AA) and potassium acrylate. When the exposure time was 5 min, the value of Q was 1368 mL/g (the content of N,N′‐methylene bisacrylamide was 100 ppm). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1618–1624, 2004     

Reaction of Aliphatic Amines with 49% Formic Acid. 1-Hexylamine,di-1-hexylamine,N,N-dimethyl-1-hexylamine, 1-dodecylamine,N,N-dimethyl-1-dodecylamine and N,N-dimethyl-1-butylamine

Two primary amines, 1-hexylamine 2 , 1-dodecylamine 19 , one secondary amine, di-1-hexylamine 18 , and three tertiary amines, N,N-dimethyl-1-hexylamine 6 , N,N-dimethyl-1-butylamine 3 , and N,N-dimethyl-1-dodecylamine 22 were each heated at 150 °C, 250 °C or 350 °C with 49% aqueous formic acid for varying periods of time. The aliphatic primary amines underwent easy N-formylation and subsequent reduction to give N-methyl- and N,N-dimethylalkylamines. Especially at higher temperatures, other reactions intervened including elimination of NH₃ to the corresponding alkenes followed by partial double bond isomerization. Tertiary amines were more reactive at higher temperatures undergoing hydrolysis and reductive cleavages to secondary and primary amines, which subsequently followed the reaction sequences seen for primary amines. This series of saturated amines showed none of the cleavage into smaller fragments that was observed in the reductive alkylation of pyridine and 4-methylpyridine to a series of N-alkylpiperdines. This result reinforces the bis-aza-retro-Aldol-fragmentation mechanism postulated for the formation of the N-alkylpiperidines.     

N‐Alkylation of Amines with Alcohols Catalyzed by a Water‐Soluble Cp*Iridium Complex: An Efficient Method for the Synthesis of Amines in Aqueous Media

An efficient and environmentally benign catalytic system for the synthesis of various organic amines catalyzed by the water‐soluble and air‐stable (pentamethylcyclopentadienyl)‐iridium‐ammine iod‐ ide complex, [Cp*Ir(NH₃)₃][I]₂ (Cp*=pentamethylcyclopentadienyl), has been developed. A wide variety of secondary and tertiary amines were synthesized by the N‐alkylation reactions of theoretical equivalents of amines with alcohols in water under air without a base. The synthesis of cyclic amines was also achieved by the N‐alkylation of benzylamine with diols. Furthermore, the recycle use of the present water‐soluble Cp*Ir catalyst was accomplished.     

The difficulty of reducing nitrogen oxides in the presence of oxygen

A hypothesis is made, based on the literature, which makes it very unlikely that NO can be selectively reduced by any reducing agent other than ammonia. The hypothesis is based upon the very fast reduction of NO₂, even in the presence of oxygen, and an easy reoxidation of NO to NO₂ which are both preferential to NO reduction in the presence of oxygen. The particular feature of ammonia originates from the fact that in parallel with this reaction, both reactants, under limiting conditions (defined by temperature), participate in a second scheme which leads to the formation of surface complexes dissociating into N₂ and/or N₂O. These surface complexes are most probably NH₄NO₂ and NH₄NO₃. In the presence of oxygen only this second scheme leads to the formation of N₂ and or N₂O and is even accelerated by the re-oxidation of NO to NO₂.     

Two‐dimensional regular nanopatterning on block copolymer substrate having lamellar morphology using star‐hyperbranched nanospheres by electrostatic interaction

Hyperbranched polystyrenes (PS) were prepared by living radical photopolymerization of 4‐vinylbenzyl N,N‐diethyldithiocarbamate as an inimer under UV irradiation. The star‐hyperbranched copolymers were derived by grafting from surface N,N‐diethyldithiocarbamate groups of hyperbranched macroinitiator with t‐butyl methacrylate in the presence of N,N‐tetraethylthiuram disulfide. We obtained poly(methacrylic acid) star‐hyperbranched PS nanospheres by hydrolysis of poly(t‐butyl methacrylate)‐grafted chains. We established two‐dimensional (2D) regular nanopatterning by aligning continuously such nanospheres on poly(2‐vinylpyridine) (P2VP) lamellar layers of PS‐block‐P2VP diblock copolymer film. Electrostatic interaction between nanosphere surface having negative charges (? COOCs) and P2VP lamellar layer acted effectively for the 2D nanopattern formation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4206–4210, 2006     

Volatile compounds from ponerine ants in the genusMesoponera

Volatile constituents have been characterized from two species of ponerine ants in the genusMesoponera. 2,5-Dimethyl-3-isopentyl-pyrazine has been identified from cephalic extracts ofM. castanea andM. castaneicolor, by gas chromatography-mass spectrometry. Combined gasters and thoraces of both species are also characterized by the presence of nonanal, nonanoic acid, isovaleric acid, phenylacetic acid, and undecanal, as well as a series of aliphatic amines and amides.N-Isoamylnonylamine was a major constituent that was accompanied byN-isoamylnonenylamine,N,N-diisoamylnonylamine,N-acetyl nonylamine,N-formyl isoamylnonylamine,N-isovaleroyl nonylamine, and several other secondary and tertiary amines. The possible significance of the amines and amides as idiosyncratic natural products ofMesoponera species is discussed.     

Effects of amines on the polymerization of isoprene with sec-butyllithium catalyst

Polymerization of isoprene (IP) with alkyllithium (RLi) catalysts in the presence of amines such as triethylamine (TEA), 1,2-dipiperidinoethane (DPPE) and N,N,N′,N′-tetramethyldiaminoalkanes [(CH₃)₂N(CH₂)_nN(CH₃)₂ where n=1, 2, 3, 4 and 6 (TMDAA)] has been studied. By adding the amines, the polymerization rate of IP was accelerated, and the contents of 3,4- and 1,2-units in the resulting polymers increased. The effects of methylene chain length of the TMDAA on the polymerization were examined. It was found that both the polymerization rates and the microstructure of the polymers depend on the methylene length of the TMDAA. The amines having 2 and 3 methylenes in (CH₃)₂N(CH₂)_nN(CH₃)₂ favoured production of the polymer consisting of predominantly 1,2- and 3,4-units. It was proposed that two types of active sites for the polymerization of IP were produced depending on the number n of the TMDAA. Two types of active species were confirmed to be produced with sec-BuLi in the presence of N,N,N′,N′-tetramethylethylenediamine (TMEDA) depending on the TMEDA/sec-BuLi mole ratios. © 1998 SCI.     

Effect of amines on the carbanilation of cellulose with phenylisocyanate

Various amines were added to carbanilation reactions of cellulose samples with phenylisocyanate in an effort to aid the preparation of cellulose tricabanilates (CTCs) for determining molecular weight distributions (MWDs). However, the amines catalyzed the conversion of phenylisocyanate to its trimer phenylisocyanurate, especially in dimethylsulfoxide (DMSO) and N,N-dimethylformamide (DMF) media. In some of the reactions to which amines were added, the CTC products had high-performance size exclusion chromatographic peaks that tailed badly. The tailing was not caused by incomplete carbanilation. The amines 1,4-diazabicyclo (2.2.2) octane (DABCO) and 4-N,N-dimethylaminopyridine (DMAP) accelerated the dissolution of cellulose during carbanilation, while others retarded the dissolution. DABCO in pyridine assisted the carbanilation of cellulose samples, which were otherwise unreactive in pyridine, although the reactions were slower than in uncatalyzed DMSO media. However, the reactions in DMSO with added amines gave CTCs with lower degree of polymerization (DP) values, and the DP reduction was particularly severe when N-methylimidazole was the added amine. The possible involvement of oxidation by DMSO in the depolymerization process is discussed. It was concluded that addition of amines to carbanilation reactions of cellulose has limited application for CTC preparation for MWDs.     

Use of photodegradable inhibitors in UV-curable compositions to form polymeric 2D-structures by visible light

The process of two-wave photopolymerization of a UV-curable composition with an optically degrading inhibitor is considered. By numerical simulation, it is shown that in the composition layer uniformly exposed to UV-radiation, such systems allow getting segments with different conversion under the action of inhomogeneous visible light. Based on the data on the photopolymerization kinetics of the compositions from triethylene glycol dimethacrylate (TEGDMA) and bisphenol-A glycidyl dimethacrylate (bis-GMA) with the UV-initiator 2,2-dimethoxy-2-phenylacetophenone (DMPA), it was shown that 3,5-di-tert-butyl-o-benzoquinone (35Q) with N,N-dimethylaniline (DMA, “Aldrich”, 99%) can serve as an inhibitor that degrades under action of visible radiation. Combining inhomogeneous visible light generated with a conventional DLP-projector and uniform UV-radiation of LED (365 nm) the two-wave lithographic process was implemented to create polymeric 2D-structures in 20 μm layer of the compositions from TEGDMA (70)/bis-GMA (30)/DMPA (0.05 wt%)/35Q (0.5 wt%)/DMA (1 wt%).     

Environmentally friendly synthesis and photopolymerization of acrylated methyl ricinoleate for biomedical applications

In this study, we aimed to develop an efficient synthesis and photopolymerization of acrylated methyl ricinoleate (AMR) for biomedical applications. During the first step of the synthesis, methyl ricinoleate (MR) and boric acid were esterified via azeotropic distillation in toluene. Afterward, MR–boric acid ester was acrylated with acrylic acid at 165 °C via a boric acid ester acidolysis reaction. The bulk photopolymerization of AMR was performed in the presence of the photoinitiator 2,2-dimethoxy-2-phenyl acetophenone (DMPA) under 365 nm UV irradiation. Even with the use of 0.4% DMPA, a 35% monomer conversion was achieved within 30 min. Moreover, AMR, the plant-oil-based monomer, was also copolymerized with N-isopropyl acrylamide to obtain thermoresponsive hydrogels on the glass surface for biomedical applications. The synthesized materials were characterized by Fourier transform infrared (FTIR) spectroscopy, ¹H-NMR spectroscopy, and thermal characterization via thermogravimetric analysis (TGA) and differential scanning calorimetry techniques. The surfaces were characterized by FTIR and Energy Dispersive X-ray (EDS) spectroscopy. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47969.     

A Reaction of Thioamides with Zinc Ammoniates Leading to Simple Amidines. Discovery of a New Zwitterionic Monomethylamidine

The reacion of thioamides with the R₁R₂N–ZnCl ammoniates leads to N-mono-, N,N′-di-, N,N-disubstituted, and unsubstituted amidines with high concentrations of amines in absolute ethanol. The efficient direct formation of the N,N′-dimethylamidine can be explained by a greater reactivity of methylamine compared with dimethylamine. Discovery of a new zwitterion (induced by a carbonyl oxygen) suggests that the stabilization in the thymine N-methylamidine is too slight to prevent the subsequent reaction with methylamine.     

The effect of aromatic amines on the photopolymerization of 1,6-hexanediol diacrylate

The ability of aromatic amines to accelerate the photoinitiated polymerization of multifunctional acrylates in the presence of oxygen is shown to be dependent on the structure of the amine. For N, N-dimethylaniline, a rapid oxygen-scavenging process which proceeds by a radical-chain mechanism accounts for the large polymerization rate increase. Conversely, aniline cannot sustain an oxygen-scavenging process and inhibits the polymerization of air-saturated monomers. In general, the degree of rate enhancement and/or inhibition of the aromatic amines investigated is subject to the amine concentration.     

On the reaction of (S)-trifluoroacetoxysuccinic anhydride with amines to produce hydroxysuccinamic (malamic) acid derivatives

L-Malic acid ( 2 ) reacts with trifluoroacetic anhydride under anhydrous conditions to give (S)-trifluoroacetoxy-succinic acid anhydride ( 3 ). The anhydride 3 undergoes regioselective ring opening with an excess of anilines or primary aliphatic amines leading to N-substituted-(S)-3-hydroxy-succinamic acids ( 4a – g ). Structural elucidation of the reaction products 4a – g was based on analytical and spectroscopic data and on an X-ray structure analysis of 4b . Secondary aliphatic amines react with 3 by condensation and subsequent elimination to furnish N,N′-disubstituted fumaric acid amides 5a , b . Some N-substituted-2-hydroxysuccinamic acids ( 7a , b ) were also prepared for spectral comparison with the 3-hydroxy compounds.