Triphenyl Phosphite Research Articles

Silicon-containing poly(amide-imide)s: preparation, characterization, and properties

Reactions of 3-aminophenol with dichlorodiphenylsilane in the presence of triethylamine resulted in the preparation of a diamine named as bis(m-aminophenoxy)diphenylsilane. Reaction of the diamine with two moles of trimellitic anhydride led to the preparation of a diacid with preformed imide structures. Silicon-containing poly(amide-imide)s were then prepared by polycondensation reactions of the diacid with different diamines in the presence of triphenyl phosphite. All the products and polymers were characterized and the physical properties of the polymers including solubility, solution viscosity, thermal stability, thermal behavior, flameretardency, crystallinity, and morphology were studied. The polymers showed high thermal stability and flameretardency, as well as enhanced solubility in polar solvents. The glass transition temperature of the polymers was about 187–196 °C, the temperature for 10% gravimetric loss was in the range of 375–400 °C, and also the weight of the polymer remaining at 700 °C was about 39–44%. They were flame-retardant, soluble in dipolar aprotic solvents, and showed some crystalline structures.

Structure effect of phosphite on the chain extension in PLA

PLA is synthesized from natural resource and can degrade easily, so it is a reasonable substituent of petroleum base plastic. Phosphites can increase the stability of PLA through the chain extension with PLA. In this paper, the molecular weights, complex viscosities and storage modulus of virgin PLA and PLA stabilized by different phosphites were characterized by gel permeation chromatography and rheometer. The results show that when there is a bigger substituent around the P–O bound in the phosphite molecule, the contact between the PLA and phosphite chain extender is inhibited and the chain extension becomes weak. In point of the three phosphite chain extenders of bis-2,2′-methyl-4,6-di-tert-butylphenyl phosphite (M46TBPP), tris(2,4-di-tert-butylphenyl) phosphite (Irgafos 168) and triphenylphosphite (TPP), the hindrance order around P–O bound is M46TBPP > Irgafos168 > TPP, and the hindrance of TPP is the smallest. So TPP takes the most effective chain extension in PLA. Furthermore, the by-product phenol formed due to chain extension of TPP has the weakest hydrogen donating ability, which makes PLA degrade weakest. So the average molecular weight values, complex viscosities and storage modulus of PLA stabilized by TPP are the biggest. In addition, the product, which was formed due to the chain extension of PLA and TPP, has some plasticization, so it makes PLA stabilized by TPP move free, crystallize easy. At last, compared to virgin PLA, PLA-TPP represents better mechanical properties.

Possible existence of two amorphous phases of D-mannitol related by a first-order transition.

We report that the common polyalcohol D-mannitol may have two amorphous phases related by a first-order transition. Slightly above its glass transition temperature Tg (284 K), the supercooled liquid (SCL) of D-mannitol transforms to a low-energy, apparently amorphous phase with stronger hydrogen bonds. The enthalpy of this so-called Phase X is approximately halfway between those of the known amorphous and crystalline phases, a position low for glass aging and high for crystal polymorphs. Similar to the SCL, Phase X is transparent with broad X-ray diffraction and Raman scattering; upon temperature cycling, it exhibits a glass-transition-like change of heat capacity. On fast heating, Phase X transforms back to the SCL near Tg + 50 K, enabling a determination of their equilibrium temperature. The presence of D-sorbitol as a plasticizer enables observation of a first-order transition from the SCL to Phase X entirely in the liquid state (liquid-liquid transition). The transition from D-mannitol's SCL to Phase X has intriguing similarities with the formation of the glacial phase of triphenyl phosphite (TPP) and the conversion from high-density to low-density amorphous ice, both studied intensely in the context of polyamorphism. All three processes occur near Tg with substantial enthalpy decrease toward the crystalline phases; the processes in water and D-mannitol both strengthen the hydrogen bonds. In contrast to TPP, D-mannitol's Phase X forms more rapidly and can transform back to the SCL. These features make D-mannitol a valuable new model for understanding polyamorphism.

Stereospecific Deoxygenation of Aliphatic Epoxides to Alkenes under Rhenium Catalysis.

The combination of a catalytic amount of Re2O7 and triphenyl phosphite as a reductant is effective for the deoxygenation of unactivated aliphatic epoxides to alkenes. The reaction proceeds stereospecifically with variously substituted epoxides under neutral conditions and is compatible with various functional groups. Protection and deprotection of a double bond functionality using an epoxide are shown as an example of the current rhenium-catalyzed deoxygenation protocol. The effect of reductants for the stereoselectivity has also been studied, indicating that the use of electron-deficient phosphines or phosphites is the key for the stereospecific deoxygenation.

Surface Treatment of ZrO2 Nanoparticles with Biosafe Citric Acid and Its Utilization for the Synthesis of L-leucine Based Poly(Amide–Imide) Nanocomposites

This study aimed at preparing three nanocomposites of optically active poly(amide–imide) and zirconium dioxide (ZrO2) inorganic nanoparticles through the ultrasonic process. First, the surface of ZrO2 nanocomposites was chemically modified with bio-active citric acid in the basic media. Then, the poly(amide–imide) was reinforced with modified nanocomposites and three poly(amide–imide)/ZrO2-citric acid nanocomposites were synthesized by ultrasonic irradiation. The poly(amide–imide) was prepared by polycondensation of N-trimellitylimido-L-leucine with 4,4′-diaminodiphenylsulfone using of triphenyl phosphite and molten tetra-n-butylammonium bromide as green media. The obtained poly(amide–imide)/ZrO2-citric acid nanocomposites were characterized by different techniques.

Synthesis of Amidines and Benzoxazoles from Activated Nitriles with Ni(0) Catalysts

Amidines and 2-substituted benzoxazoles were synthesized from N-heterocyclic nitriles under mild conditions (50 °C, 48 h, two steps) in an atom-economical process that involves addition of methanol, the solvent, to a nitrile moiety to yield a methyl imidate and the subsequent extrusion of solvent in the presence of amines to afford the title compounds. Methyl imidate formation was achieved by developing a new catalytic pathway using [(dippe)Ni(H)]2 (dippe = 1,2-bis(diisopropylphosphino)ethane), [Ni(cod)2]/dppe, or [Ni(cod)2]/P(OPh)3 (cod = 1,5-cyclooctadiene, dppe = 1,2-bis(diphenylphosphino)ethane, P(OPh)3 = triphenyl phosphite) as the catalyst precursor. Regarding the ligands, for a given substrate, namely 4-cyanopyridine, the best performance for the Ni(0)-catalyzed system was found for the σ-donor bidentate dippe, whereas the monodentate π acceptor P(OPh)3 was less efficient. In relation to the substrates, for a given Ni–dippe system, steric hindrance and, more importantly, substrate electron-withdrawing character control imidate formation and thus the yield of amidines and benzoxazoles.

Microscopic identification of the order parameter governing liquid–liquid transition in a molecular liquid

A liquid-liquid transition (LLT) in a single-component substance is an unconventional phase transition from one liquid to another. LLT has recently attracted considerable attention because of its fundamental importance in our understanding of the liquid state. To access the order parameter governing LLT from a microscopic viewpoint, here we follow the structural evolution during the LLT of an organic molecular liquid, triphenyl phosphite (TPP), by time-resolved small- and wide-angle X-ray scattering measurements. We find that locally favored clusters, whose characteristic size is a few nanometers, are spontaneously formed and their number density monotonically increases during LLT. This strongly suggests that the order parameter of LLT is the number density of locally favored structures and of nonconserved nature. We also show that the locally favored structures are distinct from the crystal structure and these two types of orderings compete with each other. Thus, our study not only experimentally identifies the structural order parameter governing LLT, but also may settle a long-standing debate on the nature of the transition in TPP, i.e., whether the transition is LLT or merely microcrystal formation.

Surface coating of α-Al2O3 nanoparticles with poly(vinyl alcohol) as biocompatible coupling agent for improving properties of bio-active poly(amide-imide) based nanocomposites having l-phenylalanine linkages

Nanocomposites (NCs) containing metal oxide nanoparticles (NPs) as fillers are used in a wide range of applications and in various fields. Poly(vinyl alcohol) (PVA) is an attractive polymer because of its many desirable applications and characteristics. In this investigation, at first, the surface of alumina (α-Al2O3) NPs was modified with PVA as a biocompatible modifier. Then, the optically active poly(amide-imide) (PAI) nanostructure was prepared by using molten tetrabutylammonium bromide as a molten ionic liquid and triphenyl phosphite as the condensing agent. Finally, the modified α-Al2O3 (α-Al2O3-PVA) NPs were incorporated into the PAI matrix for the preparation of PAI/Al2O3-PVA NCs (PAPNCs). To investigate effect and nature of coating on the surface of the α-Al2O3 NPs and preparation of PAPNCs, the samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. The surface morphology examination demonstrated the monodispersed characteristics of α-Al2O3 NPs after surface modification with the PVA and incorporation into the PAI matrix.

A facile and green method for the production of novel and potentially biocompatible poly(amide-imide)/ZrO2–poly(vinyl alcohol) nanocomposites containing trimellitylimido-l-leucine linkages

Abstract We have reported the synthesis of nanocomposites (NCs) based on chiral poly(amide-imide) (PAI) and modified zirconium nanoparticles (ZrO2 NPs) with poly(vinyl alcohol) (PVA). The optically active PAI was prepared under the green condition via the direct polycondensation of biocompatible trimellitylimido- l -leucine diacid and 4,4′-diaminediphenylsulfone in the presence of tetrabutylammonium bromide and triphenyl phosphite as the green solvent and the activating agents. NPs, due to a high surface to volume ratio, have a great tendency to agglomerate in the polymer matrix. So, at first, the surface of ZrO2 NPs was modified with the PVA as the biodegradable and biocompatible polymer. Afterward, the modified NPs were added into the PAI matrix in the ethanol solution under ultrasonic irradiations. The obtained PAI/ZrO2–PVA NCs (PZ–PNC)s were characterized by various techniques. The Fourier transform infrared proved the formation of PZ–PNCs. Field emission-scanning electron microscopy exhibited that ZrO2 NPs had good dispersion in the PAI matrix, and transmission electron microscopy indicated that ZrO2 NPs were coated by a nanometer-thick layer of PVA that was about 10 nm. X-ray diffraction analysis showed that the ZrO2 NPs retained their crystalline structure after they were added in the PAI matrix. Thermogravimetric analysis illustrated that the prepared PZ–PNCs had a better thermal stability than the neat PAI.

A Quick and Clean Procedure for Synthesis of α‐Aminophosphonates in Aqueous Media

ABSTRACTA green and efficient procedure for the synthesis of α‐aminophosphonates has been developed in water as a green and nonhazardous solvent, from condensation between aromatic aldehydes, aniline, and triphenyl phosphite at 80°C. This methodology has a number of advantages including clean reaction conditions, easy work‐up, and environmentally friendly.

Synthesis of Functionalized Oxaphosphaphenanthrenes and Chromenes via Multicomponent Reactions of Trivalent Phosphorus Nucleophiles

 Abstract—Stable derivatives of oxaphosphaphenanthrenes were prepared using multicomponent reactions of dialkyl acetylenedicarboxylate with 3-bromo-2-naphthol in the presence of trimethyl or triphenyl phosphite in good yields. Chromene derivatives were produced by using triethyl phosphite and dialkyl acetylenedicarboxylate in the presence of OH-acids in excellent yields.

Synthesis of new oxindole derivatives containing benzothiazole and thiazolidinone moieties using nano silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (NSB-DBU) as catalyst

A facile one-pot synthesis of novel oxindole derivatives bearing benzothiazolylmethyl-2-thioxothiazolidin-4- one was accomplished via one-pot reaction of 5-oxoindolinylidene rhodanine-3-acetic acid derivatives, 2-aminothiophenol, and triphenyl phosphite in the presence of tetrabutylammonium bromide (TBAB) and nano silica-bonded 5-n-propyl- octahydro-pyrimido(1,2-a)azepinium chloride (NSB-DBU) as heterogeneous reusable nanocatalyst. The target com- pounds were obtained in excellent yields (85%{92%) and short reaction times under fairly mild reaction conditions.

Order Parameter of the Liquid-Liquid Transition in a Molecular Liquid.

Liquid-liquid transitions (LLTs) between amorphous phases of a single (chemically unchanged) liquid were predicted to occur in most molecular liquids but have only been observed in triphenyl phosphite (TPP) and n-butanol, and even these examples have been dismissed as "aborted crystallization". One of the foremost reasons that LLTs remain so controversial is the lack of an obvious order parameter, that is, a physical parameter characterizing the phase transition. Here, using the technique of fluorescence lifetime imaging, we show for the first time that the LLT in TPP is characterized by a change in polarity linked to changes in molecular ordering associated with crystal polymorphs. We conclude that the LLT in TPP is a phase transition associated with frustrated molecular clusters, explaining the paucity of examples of LLTs seen in nature.

Synthesis and characterization of novel aliphatic–aromatic polyamide/Fe3O4 nanocomposites containing pendent 9H-xanthene groups

New magnetic polyamide/Fe3O4 nanocomposites containing pendent 9H-xanthene were prepared via solution intercalation technique from polyamide 9 and Fe3O4 nanoparticle in a solution of N,N-dimethylacetamide. A new polyamide 9 as a source of polymeric matrix was synthesized by direct polycondensation reaction of 3,5-diamino-N-(4-(1,3,6,8-tetramethyl-9H-xanthen-9-yl)phenyl)benzamide (7) with adipic acid in a medium consisting of N-methyl-2-pyrrolidone, triphenyl phosphite, calcium chloride, and pyridine. The synthesized polyamide was characterized by Fourier transform infrared spectra, nuclear magnetic resonance, UV–vis, and photoluminescence spectroscopy. The structural and electronic properties of xanthene-based polyamide unit were studied by ab initio density functional theory method using the B3LYP/6-31G (d) level of theory. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LOMO) level energy, and band gap (ΔE = ELUMO − EHOMO) of the polyamide unit were calculated. Fe3O4 nanoparticles have been synthesized using a chemical co-precipitation route. Using a combination of dissolving the polymer and mixing Fe3O4 nanoparticles, we have demonstrated the formation of nanocomposites with uniform nanoparticle dispersion. The morphology, crystalline phase, thermal stability, and magnetization properties of the resultant materials were characterized by means of transmission electron microscope, X-ray diffraction, thermal gravimetric analysis, and vibrating sample magnetometer. The results indicated that the as-prepared nanocomposites exhibited superparamagnetic properties and improvements in the thermal stability compared to neat polyamide.

Thermal and morphology characterization study of bio‐active poly(amide‐imide)‐based nanocomposites reinforced with modified SiO2nanoparticle with poly(vinyl alcohol)

Among the nanoparticles (NPs), the amorphous SiO2NPs are very useable, because of their important characteristics for different applications, such as mechanical performance, thermal properties, and biodegradability effects. For this manifest features SiO2NPs were used as filler in this study. Firstly, these NPs were modified with poly(vinyl alcohol) (PVA). Then, the poly(amide‐imide) (PAI) was synthesized from reaction betweenN‐trimellitylimido‐l‐methionine and 4,4′‐diaminodiphenylether in the presence of ionic liquid and triphenyl phosphite. Next, the modified SiO2NPs with PVA (SiO2‐PVA) were incorporated into the PAI matrix for the preparation of PAI‐SiO2‐PVA nanocomposites (PSiPNs). Finally, the resulting SiO2‐PVA and PSiPNs were characterized by different analyses like field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, and thermogravimetric analysis (TGA). TGA showed high thermal stability of the obtained PSiPNs compared to the pure PAI. POLYM. COMPOS. 37:1231–1237, 2016. © 2014 Society of Plastics Engineers

Opportunities and Challenges in the Use of TiO2 Nanoparticles Modified with Citric Acid to Synthesize Advanced Nanocomposites Based on Poly(amide-imide) Containing N,N′-(Pyromellitoyl)-bis-L-leucine Segments

In this study, the goal was the preparation, characterization, and surface morphology of poly(amide-imide)/TiO2-citric acid nanocomposites (PAI/TiO2-CA NCs). Owing to the high surface energy and tendency for agglomeration, the surface of TiO2 nanoparticles was modified with citric acid. Then poly(amide-imide) was synthesized by direct polycondensation reaction of N,N′-(pyromellitoyl)-bis-L-leucine diacid with 4,4′-diaminodiphenylmethane by triphenyl phosphite and tetra-n-butylammonium bromide as a green medium. The attained polymer and modified TiO2 nanoparticles were used to prepare PAI/TiO2-CA NCs through ultrasonic irradiation. The resulting PAI/TiO2-CA NC was characterized with FT-IR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis.

Morphological and Thermal Properties of Poly(amide-imide)/ZnO Nanocomposites Derived from 4,4′-methylenebis(3-chloro-2,6-diethyl trimellitimidobenzene) and 3,5-diamino-N-(4-hydroxyphenyl)benzamide

A new nanostructure poly(amide-imide) (PAI) was prepared from the polymerization of 4,4′-methylenebis(3-chloro-2,6-diethyl trimellitimidobenzene) as a diacid with 3,5-diamino-N-(4-hydroxyphenyl)benzamide using triphenyl phosphite as a condensing agent and tetra-n-butylammonium bromide as a green media. The synthesized polymer was used to prepare PAI/ZnO nanocomposites (PZNC)s using nano-ZnO surface-coupled by N-trimellitylimido-L-alanine diacid as a coupling agent through ultrasonic process. The resulting PZNCs were also characterized by FT-IR, powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The TEM and FE-SEM results showed a good dispersion of nanoscale inorganic particles in the polymer matrix.

Effect of modified ZnO capped with N-trimellitylimido-L-alanine diacid as an optically active coupling agent on the morphology and thermal properties of poly (amide-imide)/ZnO nanocomposites

In this study, the poly(amide-imide) (PAI)/ZnO nanocomposites (NC) were prepared by means of ultrasonic irradiation. For this purpose, at first, surface of ZnO NPs was modified with N-trimellitylimido-L-alanine diacid as a new capping agent which has features such as nontoxicity, optical activity, and environmentally friendly. Then, the PAI was synthesized by the utilizing of tetra-n-butylammonium bromide and triphenyl phosphite as a condensing agent and green media. This method suggests simple, high-yield (>90%) polymerization reaction with green aspects using ionic liquid. Then, modified ZnO NPs were incorporated into the PAI matrix for the preparation of NCs. The obtained NCs were characterized by several techniques. Field emission scanning electron microscopy and transmission electron microscopy analyses of the NCs were accomplished to study the dispersion of fillers in the polymer matrix and demonstrated a rather good amount of dispersion. According to the thermogravimetric analysis results, the addition of ZnO NPs enhanced thermal stability of the obtained NCs.

Preparation of a new liquid thermal stabilizer from rosin and fatty acid and study of the properties of the stabilized PVC

In this work, a new liquid thermal stabilizer (LTS) was prepared using rosin and fatty acids as feedstock and evaluated for its stabilizing effects on poly(vinyl chloride) (PVC). First, a rosin/oil-based dimer acid (RODA) was prepared by the addition reaction of rosin and industrial fatty acids and then converted into its zinc soap (RODA-Zn) and calcium soap (RODA-Ca). The chemical structures were examined by UV–Vis and Fourier Transform infrared spectroscopies. Liquid form thermal stabilizers (RODA-LTS) were obtained by treating the solid RODA-Zn and RODA-Ca soaps with epoxidized soybean oil, triphenyl phosphite and liquid paraffin at 120 °C for 3 h. Thermal stabilizing effects of the resulting RODA-LTS for PVC were compared with that of two commercial LTSs. Thermal stability of PVC compounds was determined using dehydrochlorination test, thermogravimetric analysis (TGA), Congo red test and torque rheological analysis. Results indicated that RODA-LTS had overall superior thermal stability. Tensile and dynamic mechanical properties of the PVC compounds were also studied, and the results indicated that the PVC compounds stabilized with RODA-LTS and commercial LTSs displayed comparable strength, modulus and glass transition temperatures.

Improvement of the Interactions between Modified ZrO2 and Poly(amide-imide) Matrix by Using Unique Biosafe Diacid as a Monomer and Coupling Agent

This research explores the synthesis of a high-performance poly(amide-imide) (PAI) from the polycondensation reaction of N-trimellitylimido-L-leucine as a bioactive diacid with 4,4′-diaminediphenylsulphone using combination of triphenyl phosphite and tetra-n-butylammonium bromide as a condensing agent. ZrO2 nanoparticle (NP) was used as a filler for the formation of PAI nanocomposites (NC)s. For a unique dispersion of NPs in the PAI matrix, the surface of ZrO2-NPs was modified with bioactive N-trimellitylimido-L-leucine using ultrasonic technique. The obtained polymer and modified ZrO2-NPs were used to produce PAI/ZrO2 NCs under ultrasonic irradiation. The obtained NCs were characterized by different methods.