Synthesis of Silicone Modified Acrylic Resin Paint and It's Properties Studies

An acrylic resin coating by itself, shows resistance to weather and color retention, but has poor high-temperature resistance. The silicone resin exhibits excellent weatherability, good heat resistance and strong hydrophobicity. To improve the exterior durability, dirt-pickup resistance and color retention of acrylic resin, a little amount of silicone functional group was introduced into it, taking advantaging of high dissociation energy and low surface tension, good stability to gloss and heat,ultraviolet light resistance of the Si-O bond of polysilonxane^[1,2].     

Reactions of o-aminothiophenol withαβ-unsaturated dicarbonyl systems. Facile synthesis of benzothiazines and benzothiazepines

When treated with maleanilic/fumaranilic acids or esters or the corresponding imides or isoimides, o-aminothiophenol furnishes benzothiazines, whereas treatment of o-aminothiophenol with acrylic acids/esters furnishes benzothiazepines. The orientational preferences in these Michael-type reactions are discussed.     

Thermally stable polymers based on addition-type imidobenzoxazoles; synthesis and characterization of polybismaleimidobenzoxazoles and polybiscitraconimidobenzoxazoles

Four structurally different bisimidobenzoxazole monomers were synthesized, based on the reaction of two isomeric diaminobenzoxazoles, viz., 5-amino-2-(p-aminophenyl) benzoxazole and 5-amino-2-(m-aminophenyl) benzoxazole with maleic and citraconic anhydrides. The diamines were synthesized by a new route. The imides and the amic intermediates were characterized by elemental analysis, IR, NMR, and mass spectra. The imides could be thermally polymerized to crosslinked brittle polybisimidobenzoxazoles. The citraconimides polymerized at a lower temperature than the maleimide. Thermal stability of the cured resins was evaluated by TGA and was correlated to the structure of the polyimide. The polybismaleimidobenzoxazoles were stable up to about 500°C in N₂, leaving 50–60% anaerobic char yield at 800°C, whereas polybiscitraconimidobenzoxazoles were stable up to 420°C. Comparison of the thermal behavior of similar polyimides based on oxydianiline revealed that incorporation of benzoxazole structure enhances the decomposition temperature, lowers the rate of decomposition, and enhances the anaerobic char yield at high temperature. Addition of diamines as chain-extending agents decreased the thermal stability of the resins without any change in the anaerobic char yield.     

Photoreactive UV-crosslinkable solvent-free acrylic pressure-sensitive adhesives containing copolymerizable photoinitiators based on benzophenones

The design and development of new, tailor-made, novel photoreactive acrylic pressure-sensitive adhesives, which can cope with both the technical and ecological demands, is therefore a continuing challenge for industrial research and development. Progress in the coating technology and the development of improved photoreactive acrylic adhesive will open the door for new applications and an extended market penetration of UV-crosslinkable acrylic adhesive raw materials containing unsaturated copolymerizable photoinitiators incorporated into the polymer backbone. They are characterized by good tack, good adhesion, excellent cohesion and very high shrinkage resistance. In this paper it is shown the application of H-abstractor such as 4-acryloyloxy benzophenone to obtain of the UV-crosslinked acrylic PSA.The presented novel UV-crosslinkable acrylic hotmelt PSA combines the economic advantages of the hotmelt coating technology with the high performance characteristics of the acrylic chemistry, including an excellent aging resistance, optical transparency and heat resistance.     

Cyclopolycondensation. XIII. New synthetic route to fully aromatic poly(heterocyclic imides) with alternating repeating units

Fully aromatic poly(heterocyclic imides) of high molecular weight were prepared by the cyclopolycondensation reactions of aromatic diamines with new monomer adducts prepared by condensing orthodisubstituted aromatic diamines with chloroformyl phthalic anhydrides. The low-temperature solution polymerization techniques yielded tractable poly(amic acid), which was converted to poly(heterocyclic imides) by heat treatment to effect cyclodehydration at 250–400°C under reduced pressure. In this way, the polyaromatic imideheterocycles such as poly(benzoxazinone imides), poly(benzoxazole imides), poly(benzimidazole imides) and poly(benzothiazole imides) were prepared, which have excellent processability and thermal stability both in nitrogen and in air. The poly(amic acids) are soluble in such organic polar solvents as N,N-dimethyl-acetamide, N-methylpyrrolidone, and dimethyl sulfoxide, and the films can be cast from the polymer solution of poly(amic acids) (η_inh = 0.8–1.8). The film is made tough by being heated in nitrogen or under reduced pressure to effect cyclodehydration at 300–400°C. The polymerization was carried out by first isolating the monomer adducts, followed by polymerization with aromatic diamines. On subsequently being heated, the open-chain precursor, poly(amic acid), undergoes cyclodehydration along the polymer chain, giving the thermally stable ordered copolymers of the corresponding heterocyclic imide structure.     

Anionic ring-opening polymerization of several N-substituted diphenimides

Five N-substituted diphenimides were prepared from the corresponding N-substituted amic acids. Attempts to polymerize the prepared seven-membered ring imides were partially successful. N-phenyldiphenimide was relatively the best monomer that polymerized anionically using n-butyl lithium or sodium metal as the initiater. The other N-substituted imides were sluggish in anionic polymerization. The resistance of the seven-membered ring imides toward ring-opening polymerization was attributed to the stability of the rings caused by the two phenylene groups adjacent to the carbonyls. © 1993 John Wiley & Sons, Inc.     

New developments in the field of reactive acrylic adhesives and sealing materials

The influence of oligomeric base on the properties of acrylic adhesives and sealants cured by radical mechanism is studied. New anaerobic materials on the basis of oligourethane(meth)acrylates (OUMs) are developed. It is shown that, by adjusting the OUM nature, it is possible to increase the heat and moisture stability of adhesive compositions. As a result of these works, UV-cured adhesive compositions, heat-cured adhesive for bonding untreated aluminum, and two-part adhesive compounds cured at both positive and negative temperatures are developed.     

Crystallization of alkyl-aromatic polyimides (polyalkanimides)

Polyalkane imides based on 3,3′,4,4′-diphenyloxidetetracarboxylic, pyromellitic and 1,4,5,8-naphthalenetetracaboxylic acids, and aliphatic diamines containing 4, 6, 8, 10, or 12 methylene groups have been studied. Relations governing the effect of structure on solubility, heat resistance, density, and crystallizability have been established. Conformation analysis has been carried out and models of the macromolecules have been constructed. The morphology of the crystalline polymers has been studied. For the polymers of the given class, crystallization capability is shown to be associated with the conformational flexibility of the macromolecular unit determining a given acid moiety by the number of methylene groups in the diamine unit.     

Thermomechanical properties and heat resistance of copolymers of methyl methacrylate with acrylic acid

Copolymers with a mole fraction of acrylate units of 0.20 to 0.69 were prepared by radical copolymerization of methyl methacrylate with acrylic acid. The heat resistance and thermomechanical properties of copolymer films formed from dimethylformamide solution were evaluated, and the possibilities of improving these characteristics were demonstrated.     

Acrylic polymer/silica hybrid for electron‐beam resists

An acrylic polymer/silica hybrid resist film was investigated for fabricating a microstructure by electron‐beam (EB) lithography. EB lithography on the hybrid thin film afforded a positive pattern whose depth corresponded to the EB exposure dose; this indicated that the hybrid was an analog resist and could fabricate a three‐dimensional microstructure. The resist film had high heat resistance and compatibility with the underlying quartz plate, probably because of the silica component. The acrylic polymer/(RSiO_1.5)_n hybrid film showed higher EB sensitivity than a film of the crosslinked acrylic polymer and an acrylic polymer/(SiO₂)_n hybrid. Atomic force microscopy observation of the hybrid film surface showed the homogeneous dispersion of the acrylic polymer and the silica components in the hybrid film. The acrylic polymer component was EB‐sensitive, whereas dispersing the acrylic polymer and silica components homogeneously also played an important role in increasing the EB sensitivity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2107–2116, 2006     

Optically active telluronium imides: Optical resolution,absolute configuration,and mechanism of racemization

Thermodynamically and kinetically stabilized asymmetric diaryltelluronium imides were synthesized and optically resolved into their enantiomers on an optically active column using medium‐pressure column chromatography. The relationship between the absolute configuration and the optical properties of the chiral telluronium imides was clarified. The mechanism of the racemization, which involves the formation of telluroxides by the hydrolysis of the telluronium imides, was proposed. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:523–529, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10185     

Preparation of Heteroaromatic (Aryl)iodonium Imides as I−N Bond‐Containing Hypervalent Iodine

Hypervalent iodine(III) compounds containing iodine–nitrogen bonds are very attractive amination reagents in organic synthesis. Heteroaromatic (aryl)iodonium imides containing a iodine–nitrogen bond and a hypervalent iodine(III) atom were prepared from heteroarenes, bis(sulfon)imides and (diacetoxyiodo)arenes under mild conditions. These compounds were stable under air and in organic solvents, and could be easily purified by precipitation. X‐ray crystal structure analysis indicated that the structure of N‐pivaloyl indolyl(phenyl)iodonium bis(tosyl)imides and N‐pivaloyl indolyl(2‐butoxyphenyl)iodonium bis(tosyl)imides was a dimer with a T‐shaped geometry at the iodine atom linked to an indole group and a bis(tosyl)imide by a monomer unit. Moreover, the use of substituted iodoarenes facilitated the purification of some of the heteroaromatic (aryl)iodonium imides.     

Reactive adhesives on the basis of (meth)acrylic oligomers

A review of works carried out at the Academician V.A. Kargin Research Institute of Polymers and literature data on applications and properties of anaerobic, UV-, and thermo-curable, aerobic and modified acrylic adhesives is presented. The primary attention is paid to the possibility of preparation of thermally stable adhesive acrylic materials, modifying an oligomeric backbone and using viscosifiers and additives. Data on the use of efficient stabilizers and curing accelerators are presented. Curing mechanisms of acrylic adhesives are considered.     

Correlation of antithrombogenicity and heat treatment for layer-by-layer self-assembled polyelectrolyte films

Antithrombogenic films with high durability were fabricated in a wet process. Antithrombogenicity was achieved with polyelectrolyte multilayer thin film prepared from poly(vinyl alcohol)-poly(acrylic acid) (PVA-PAA) blends, deposited in alternate layers with poly(allylamine hydrochloride) (PAH). Film durability, assessed by abrasion resistance and water resistance, was enhanced by forming cross-links via amide bonds induced by heat treatment of the film. The film was found to be resistant to protein adsorption, as measured by the amount of fibrinogen adsorbed from an aqueous solution. The antithrombogenic efficacy was assessed in ex vivo experiments by the ability of stainless steel mesh, coated with the polyelectrolyte and inserted into a pig blood vessel, to inhibit thrombus formation. Mesh coated with the polyelectrolyte did not reduce blood flow over a period of 15 min, whereas with uncoated mesh blood flow stopped within 6 min because of blood vessel blockage by thrombus formation.     

Stereospecific hydrogen migration in retro-diels-alder fragmentation of some polycyclic imides

A stereospecific ‘retro-Diels-Alder’ fragmentation followed by hydrogen migration was found in the mass spectra of imides and phenyl imides of decahydroindacene 4,5-dicarboxylic acid. The fragmentation involves a one hydrogen atom rearrangement when the charge is retained on the diene moiety and double hydrogen rearrangement when the charge is on the dienophilic moiety.     

Development of biobased polyurethane‐imides from maleinized cottonseed oil and castor oil

An eco‐friendly coating system, which is largely biobased, has been developed from castor and cottonseed oil. Cottonseed oil was functionalized with maleic anhydride by “ene” reaction to give maleinized cottonseed oil (MACSO); the anhydride groups were reacted with isocyanates to yield –NCO terminated polyurethane prepolymer. The prepolymer was further chain extended with hydroxyl groups of castor oil to give polyurethane‐imides (PUIs). The cross‐linked films thus obtained had good mechanical properties, and the imide groups in the backbone improved the corrosion resistance of PUIs as revealed by potentiodynamic polarization study. With increasing content of MACSO, thermal stability, glass transition temperatures (T_g), tensile strength, and corrosion resistance of resulting PUIs significantly increased.     

Synthesis of new functionalized 3,7-diazabicyclo[3.3.1]nonanes by aminomethylation of the Guareschi imides

The aminomethylation of 4,4-dialkyl-2,6-dioxopiperidine-3,5-dicarbonitriles (Guareschi imides) was studied for the first time. When the Guareschi imides were treated with primary aliphatic amines and an excess of formaldehyde, 2,4-dioxo-3,7-diazabicyclo[3.3.1]nonane-1,5-dicarbonitriles were obtained in varying yields (15–67%). The structure of 9,9-dimethyl-7-(2-methylpropyl)-2,4-dioxo-3,7-diazabicyclo[3.3.1]nonane-1,5-dicarbonitrile was studied by X-ray diffraction analysis.     

红紫素-18的胺解反应及其叶绿素类二氢卟吩衍生物的合成

以红紫素-18甲酯为原料,与脂肪胺或者苯胺在加热回流和微波促进的条件下进行胺解反应,分别得到单酰胺化、双酰胺化和羰基亚胺化产物;同时,沿着N21-N23轴向对所得红紫素-18酰亚胺实施化学修饰,分别得到难以分离的具有阻旋异构和差向异构特征的红紫素-18酰亚胺混合物.新的二氢卟吩类衍生物均经UV,IR,1H NMR光谱、质谱及元素分析证明其结构,并对相应的胺解反应提出了可能的反应机理.     

N-Alkynyl imides (ynimides): synthesis and use as a variant of highly labile ethynamine

This study describes the first reliable synthesis of N-alkynyl imides (ynimides). This was accomplished with a copper-catalyzed coupling reaction between alkynyl(triaryl)bismuthonium salts and five-membered imides. We also found that it was possible to utilize N-ethynyl phthalimide as a variant of the highly labile ethynamine. 4-Amino-1,2,3-triazole was successfully obtained via the CuAAC reaction of N-ethynyl phthalimide with azide followed by hydrazinolysis of the phthaloyl protecting group.     

Effect of polar modifications on cure characteristics, solvent resistance and thermo-mechanical properties of metallocene-based polyolefinic elastomers

Metallocene-based poly(ethylene-octene) and poly(ethylene-butene) elastomers were polar modified through sulfonation and grafting of acrylic acid. The impact of polar modifications on the oil and solvent resistance, curing characteristics and various thermo-mechanical properties of the cured elastomers was thoroughly investigated. Greater solvent resistance was observed due to grafting of acrylic acid in comparison to sulfonation. Thermo-mechanical properties were significantly improved after polar modifications.