Effect of the diisocyanate on the structure and properties of polyurethane acrylate prepolymers

In this study, we investigated the role of diisocyanate on the properties of polyurethane acrylate (PUA) prepolymers based on polypropylene oxide (M̄_n = 2000 g · mol⁻¹). The diisocyanates studied were isophorone diisocyanate, 4‐4′dicyclohexylmethane diisocyanate, and toluene diisocyanate (pure 2,4‐TDI, pure 2,6‐TDI, and a TDI mixture, TDI_tech). The molecular structure of the diisocyanate had a major role on the course of the polycondensation and, more precisely, on the sequence length distribution of the final prepolymer. Moreover, the structural organization of the prepolymer also strongly depended on the nature of the diisocyanate. Two types of behaviors were particularly emphasized. On the one hand, the PUA synthesized from 2,4‐TDI displayed an enhanced intermixing between soft polyether segments and hard urethane groups, as revealed by the analysis of hydrogen bonding in Fourier transform infrared. Consecutively, the glass transition shifted to higher temperatures for these polymers. On the other hand, strong hard–hard inter‐urethane associations were observed in 2,6‐TDI‐based prepolymers; these led to microphase segregation between polyether chains and urethane groups, as revealed by optical microscopy. This inhomogeneous structure was thought to be responsible for the unusual rheological behavior of these PUA prepolymers. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2750–2768, 2000     

Composition of Laprol-373 and Products of Its Reaction with 2,4-Toluylene Diisocyanate

The composition of oligoethers that are components of Laprol-373 and of products of their reaction with 2,4-toluylene diisocyanate were studied by matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF).     

Synthesis of poly(urethane‐imide) using aromatic secondary amine‐blocked polyurethane prepolymer

A set of poly(urethane‐imide)s were prepared using blocked Polyurethane (PU) prepolymer and pyromellitic dianhydride (PMDA). The PU prepolymer was prepared by the reaction of polyether glycol and 2,4‐tolylene diisocyanate, and end capped with N‐methyl aniline. The PU prepolymer was reacted with PMDA until the evolution of carbon dioxide ceased. The effect of tertiary amine catalysts, organo tin catalysts, solvents, and reaction temperature were studied and compared with the poly(urethane‐imide) prepared using phenol‐blocked PU prepolymer. N‐methyl aniline blocked PU prepolymer gave a higher molecular weight poly(urethane‐imide) at a lower reaction temperature in a shorter time. Amine catalysts were found to be more efficient than organo tin catalysts. The reaction was favorable in particular with N‐ethylmorpholine and diazabicyclo(2.2.2)octane (DABCO) as catalysts, and dimethylpropylene urea as a reaction medium. The poly(urethane‐imide)s were characterized by FTIR, GPC, TGA, and DSC analyses. The molecular weight decreased with an increase in reaction temperature. The thermal stability of the PU was found to increase by the introduction of imide component. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4032–4037, 2000     

Mössbauer study of structurally ordered iron coordination compounds and polyurethanes crosslinked by them

The structure of a metal-complex system based on ferric chloride and monoethanolamine and the products of interaction of this system with ε-caprolactam and a urethane prepolymer was studied by Mössbauer spectroscopy. It was found that iron ions in the coordination compounds of interest are linked with one another in a chain structure via chloride bridges. The columnar structure of metal complexes, the presence of magnetic ordering in these complexes below 70 K, and the feasibility of formation of metal complexes ordered in the same manner in a flexible-chain polymer matrix containing electron-donating groups were revealed.     

Coordination Sphere Tuning of the Electron Transfer Dissociation Behavior of Cu(II)–Peptide Complexes

In contrast to previous electron capture dissociation (ECD) studies, we find that electron transfer dissociation (ETD) of Cu(II)–peptide complexes can generate c- and z-type product ions when the peptide has a sufficient number of strongly coordinating residues. Double-resonance experiments, ion-molecule reactions, and collision-induced dissociation (CID) prove that the c and z product ions are formed via typical radical pathways without the associated reduction of Cu(II), despite the high second ionization energy of Cu. A positive correlation between the number of Cu(II) binding groups in the peptide sequence and the extent of c and z ion formation was also observed. This trend is rationalized by considering that the recombination energy of Cu(II) can be lowered by strong binding ligands to an extent that enables electron transfer to non-Cu sites (e.g., protonation sites) to compete with Cu(II) reduction, thereby generating c/z ions in a manner similar to that observed for protonated (i.e., nonmetalated) peptides.     

A high-strength technological compound on the basis of oligobutane diendiol,isophorone diisocyanate,and aromatic diamine

2,4-Toluene diisocyanate is substituted with isophorone diisocyanate during the synthesis of polybutadiene urethane urea. The obtained polydiene urethane urea is shown to be superior to the physicomechanical and rheological properties of the traditional material synthesized with the use of 2,4-toluene diisocyanate. It is established that polybutadiene urethane urea is more than twice as good as steel adhesion to polydiene urethane epoxy compounds.     

Intermolecular interactions in metal-containing polymers based on 2,4-toluylene diisocyanate and open-chain analogs of crown ethers

The interaction of 2,4-toluylene diisocyanate with open-chain analogs of crown ethers containing potassium alcoholate groups is studied, and the mechanism of stabilization of the formed O-polyisocyanate end units via intermolecular interactions is proposed. The electron delocalization in intermolecular cyclic structures may be responsible for electron-transfer processes in the polymers under study.     

Viscosity of melts and solutions of polyolefins modified with binary mixtures of 2,4-toluylene diisocyanate and lactams of various structrues

The influence of binary mixtures of 2,4-toluylene diisocyanate and lactams of various structures on the viscosity of melts and solutions of polyolefin formulations was examined.     

Sequence distribution of poly(ether)urethane elastomer

Poly(ether)urethane elastomers (PEUE) having different sequence distributions can be synthesized by the reaction of p-phenylene diisocyanate, poly(oxytetramethylene glycol), and hydrazine by four different routes. The degree of the sequence distribution of PEUE was determined by high-resolution NMR spectroscopy. The sequence distribution of PEUE synthesized by the prepolymer method in solvent (method 1) was found to coincide with the sequence distribution calculated from the reactivity ratio of two isocyanate groups in p-phenylene diisocyanate. On the other hand, the sequence distribution of PEUE obtained by the prepolymer method without solvent (method 2) was found to deviate from that expected from the reactivity ratio. The degree of the distribution of monomers in PEUE having the same composition ratio corresponded to the infrared absorbance ratio at 1720 and 1700 cm^?1.     

Filling of Castable Polyurethanes with Solid Wastes from Petrochemical Production

Physicochemical properties of castable polyurethanes based on polyethylene glycol adipate and mixture of 2,4- and 2,6-toluylene diisocyanate (NCO : OH molar ratio 1.6) and filled to 10 wt % with silica gel (waste from petrochemical production) were studied.     

Framework control by a metalloligand having multicoordination ability: new synthetic approach for crystal structures and magnetic properties

By utilizing the novel metalloligand l(Cu), [Cu(2,4-pydca)(2)](2)(-) (2,4-pydca(2)(-) = pyridine-2,4-dicarboxylate), which possesses two kinds of coordination groups, selective bond formation with the series of the first-period transition metal ions (Mn(ii), Fe(ii), Co(ii), Cu(ii), and Zn(ii)) has been accomplished. depending on the coordination mode of 4-carboxylate with Co(ii), Cu(ii), and Zn(ii) ions, L(Cu) forms a one-dimensional (1-d) assembly with a repeating motif of [-M-O(2)C-(py)N-Cu-N(py)-Co(2)-]: {[ZnL(Cu)(H(2)O)(3)(DMF)].DMF}(N)() (2), [ZnL(Cu)(H(2)O)(2)(MeOH)(2)](N)() (3), and {[ML(Cu)(H(2)O)(4)].2H(2)O}(N)() (M = Co (4), Cu (5), Zn (6)). the use of a terminal ligand of 2,2'-bipyridine (2,2'-bpy), in addition to the cu(ii) ion, gives a zigzag 1-d assembly with the similar repeating unit as 4-6: {[Cu(2,2'-bpy)L(Cu)].3H(2)O}(N)() (9). on the other hand, for Mn(ii) and Fe(ii) ions, L(Cu) shows a 2-carboxylate bridging mode to form an another 1-d assembly with a repeating motif of [-M-O-C-O-CU-O-C-O-]: [ML(Cu)(H(2)O)(4)](N)() (M = Mn (7), Fe (8)). this selectivity is related to the strength of lewis basicity and the electrostatic effect of L(Cu) and the irving-williams order on the present metal ions. according to their bridging modes, a variety of magnetic properties are obtained: 4, 5, and 9, which have the 4-carboxypyridinate bridge between magnetic centers, have weak antiferromagnetic interaction, whereas 7 and 8 with the carboxylate bridge between magnetic centers reveal 1-d ferromagnetic behavior (Cu(II)-M(II); M(II) = Mn(II), J/k(B) = 0.69 K for 7; M(II) = Fe(II), J/k(B) = 0.71 K for 8).     

Synthesis and characterization of poly(urethane‐benzoxazine) films as novel type of polyurethane/phenolic resin composites

Poly(urethane‐benzoxazine) films as novel polyurethane ( PU )/phenolic resin composites were prepared by blending a benzoxazine monomer ( Ba ) and PU prepolymer that was synthesized from 2,4‐tolylene diisocyanate (TDI) and polyethylene adipate polyol (MW ca. 1000) in 2 : 1 molar ratio. DSC of PU/Ba blend showed an exotherm with maximum at ca. 246 °C due to the ring‐opening polymerization of Ba, giving phenolic OH functionalities that react with isocyanate groups in the PU prepolymer. The poly(urethane‐benzoxazine) films obtained by thermal cure were transparent, with color ranging from yellow to pale wine with increase of Ba content. All the films have only one glass transition temperature (T_g ) from viscoelastic measurements, indicating no phase separation in poly(urethane‐benzoxazine) due to in situ polymerization. The T_g increased with the increase of Ba content. The films containing 10 and 15% of Ba have characteristics of an elastomer, with elongation at break at 244 and 182%, respectively. These elastic films exhibit good resilience with excellent reinstating behavior. The films containing more than 20% of Ba have characteristics of plastics. The poly(urethane‐benzoxazine) films showed excellent resistance to the solvents such as tetrahydrofuran, N,N‐dimethyl formamide, and N‐methyl‐2‐pyrrolidinone that easily dissolve PU s. Thermal stability of PU was greatly enhanced even with the incorporation of a small amount of Ba . © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4165–4176, 2000     

Supramolecular Assembly and Headgroup Effect in Interfacial Organized Films (I): A Study of Some Bolaamphiphiles

Two bola form Schiff bases derivatives with different substituted head groups have been designed and their interfacial phase behaviors and coordination with Cu(II) ions were investigated. It has been found that while one molecule with benzene headgroup formed dotted aggregations at the air/water interface, another with naphthyl moiety as head group formed crystalline multilayer films on water surface. When on the sub phase containing Cu(II) ions, both of the Schiff bases can coordinate with Cu(II) in situ in the spreading films with the obvious conformational change of alkyl chains. The in situ Cu(II)-coordinated films could be transferred onto solid substrates and subsequently characterized by various spectroscopic methods such as UV-vis and Fourier transform infrared spectra as well as the morphological character with atomic force microscopy measurement. In comparison, the ex situ coordination process at the liquid/solid interface have also been investigated by continuous spectral measurement. Depending on the different head groups, these amphiphiles showed different aggregation behaviors in the Langmuir-Blodgett films. Particularly, during the coordination process of ligand with Cu(II) ions in organized molecular films, great conformational change of the alkyl chains was observed. At the same time, a rational explanation about the head group effect on regulating the aggregation behaviors was discussed.     

Effects of temperature and concentration factors on the conformational state and reactivity of potassium poly(oxyethylene glycolate)

With the use of pulsed magnetic-field gradient NMR, self-diffusion coefficients of potassium poly(oxyethylene glycolate) macromolecules and solvent molecules (acetone) and the variation in the dimensions of supramolecular structures of potassium poly(oxyethylene glycolate) with temperature and its concentration in acetone are measured. It is discovered that the temperature dependences of change in the rate constants of reactions that proceed during the interaction of potassium poly(oxyethylene glycolate) with 2,4-toluylene diisocyanate do not fit Arrhenius coordinates.     

Coordination assembly of p-substituted aryl azo imidazole complexes: Influences of electron donating substitution and counter ions

The formation of a series of Cu(II), Zn(II) and Cd(II) complexes using the p-substituted aryl azo system has been reported. Presence of electron donating –Me, –OMe groups impart some unusual coordination behaviors in Cu(II) complexes. Varying coordination mode and electron density in the ligand results in the formation of an unusual Cu–S bond in complex 1 and an unusual equatorial coordination of H₂O in Cu(II) complex 2 with a square-pyramidal geometry.The hydrogen bonding site along with the metal coordination site in the ligand results in the formation of higher dimensional self-assembled supramolecular architectures. Compatibility of the hard–soft nature of the metal ion and symbiosis effect of the ligand with metal is responsible for the formation of long range higher dimensional networks in the solid-state, which were confirmed by single crystal X-ray structure analysis. Furthermore, various physicochemical studies, viz. thermal behaviors, absorption spectra, electrochemistry and EPR studies, have been conducted to rationalize the structures in the solution phase.     

Characterization of polyurethane network chains by gel permeation chromatography

Starting materials, prepolymers, chain-extended oligomers, and polyurethane network chains were characterized by gel permeation chromatography in order to make clear the change of molecular distribution in the formation of polyurethane networks. The polyurethane networks were prepared from poly(oxypropylene)glycol (PPG 1000, M _n = 997, M _w/M _n = 1.04), 2,4-tolylene diisocyanate, and 1,4-butanediol by the prepolymer method. Polyurethane networks were degraded by the amine degradation method, by which allophanate groups as crosslinking sites were decomposed selectively. The prepolymer had four species. The polydispersity index of the prepolymer (M _w/M _n) was about 2, that is, the most probable distribution. The product of the chain-extending reaction of prepolymer with BD had five species. The molecular-weight distribution of this product was narrower than that of the prepolymer. The polydispersity of the interstitial chains between crosslinking sites was also narrower than that of the chain-extended product. The polyaddition mechanism in the formation of PPG–TDI–BD polyurethane networks was discussed.     

Oxygen binding and activation by the complexes of PY2- and TPA-appended diphenylglycoluril receptors with copper and other metals

The copper(I) complexes of diphenylglycoluril basket receptors and , appended with bis(2-ethylpyridine)amine (PY2) and tris(2-methylpyridine)amine (TPA), respectively, and their dioxygen adducts were studied with low-temperature UV-vis and X-ray absorption spectroscopy (XAS). The copper(I) complex of, [.Cu(I)2] or, forms a micro-eta2:eta2 dioxygen complex, whereas the copper(I) complex of, [.Cu(I)2] or, does not form a well defined dioxygen complex, but is oxidized to Cu(II). Dioxygen is bound irreversibly to and the formed complex is stable over time. The coordination geometries of the above complexes were determined by XAS, which revealed that pyridyl groups and amine N-donors participate in the coordination to Cu(I) ions in the complexes of both receptors. The catalytic activities of various metal complexes of and , that were designed as mimics of dinuclear copper enzymes that can activate dioxygen, were investigated. Phenolic substrates that were expected to undergo aromatic hydroxylation, showed oxidative polymerization without insertion of oxygen. The mechanism of this polymerization turns out to be a radical coupling reaction as was established by experiments with the model substrate 2,4-di-tert-butylphenol. In addition to Cu(II), the Mn(III) complex of and the Fe(II) complex of were tested as oxidation catalysts. Oxidation of catechol was observed for the Cu(II) complex of receptor but the other metal complexes did not lead to oxidation.     

TMA characterization of urethane elastomers,with the structure varying from chain to network

TMA has been used to investigate the thermomechanical behaviour of six series of elastomers in connection with their chemical constitution and physical structure. The elastomers, were synthesized from an NCO-terminal pre-polymer, based on oligo (ethylene adipate), 1,4-butanediol and 2,4-toluylene diisocyanate, by curing with systems of two agents: a bifunctional one (1,4-butanediol, bistethylene glycol)terephthalate, or monoethanolamine), and a trifunctional one (1,1,1-trimethylolpropane or diethanolamine). The TMA results are presented as due to the superposition of the chemical cross-linking and the physical network, formed through microphase segregation. The TMA suggests that diethanolamine unexpectedly acts as a chain extender, rather than a cross-linking agent.     

Carboxylic acid functionalized ortho-linked oxacalix[2]benzene[2]pyrazine: synthesis, structure, hydrogen bond and metal directed self-assembly

Cyclooligomerization of 2,6-dichloropyrazine 4 and benzyl 2,3-dihydroxybenzoate 5 under microwave irradiation resulted in a racemic pair of ester functionalized ortho-linked oxacalix[2]benzene[2]pyrazine 6, which was further transformed to the corresponding racemic carboxylic acid functionalized ortho-linked oxacalix[2]benzene[2]pyrazine 3. Both enantiomers of 3 adopt 1,3-alternate conformations with their two carboxylic acid groups pointing to opposite directions in the solid state. Enantiomers of 3 form a step-like one-dimensional supramolecular polymer via intermolecular hydrogen bond interactions between the carboxylic acids for crystals obtained in methanol. No hydrogen bonds were formed between the carboxylic acids for crystals of 3 obtained in pyridine and aqueous guanidine solutions; instead, intermolecular hydrogen bonds between the carboxylic acid groups of 3 and pyridine, as well as guanidinium ions were formed. Under metal-mediated self-assembly conditions, the pyrazinyl nitrogen atoms in 3 interacted with transition metal ions, such as Ag(I), Cu(II) and Zn(II), and resulted in the formation of four new metal-containing supramolecular complexes. Metallomacrocycles 7, 8 and 9 were formed by reactions of 3 with Ag(I) or Cu(II) ions by bridging two ligands 3 in the equatorial region via M-N coordination bonds. A one-dimensional coordination polymer 10 was generated by reaction between ligand 3 and Zn(II) ions, and a cage-based structure is presented in 10 by bridging of the cyclophane units by Zn(2+) ions via Zn-N and Zn-O bonds.