Curing of Epoxy-containing Oligomers with Oxidized Carbon Black

The physical properties of polymeric composites based on polydieneurethane-diepoxide and filled with particles of carbon black of various degrees of oxidation were studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 4, 2005, pp. 639-641.Original Russian Text Copyright © 2005 by Imankulova, Kondrashev, Val’tsifer.     

查尔酮环氧树脂的合成及其固化性能

以4,4′-二羟基查尔酮为原料,和环氧氯丙烷反应合成了主链含有双键结构的查尔酮环氧树脂（CER）,其结构经¹H NMR和FT-IR确证。采用非等温DSC法研究了甲基四氢邻苯二甲酸酐和4,4′-二氨基二苯基砜两种固化剂对CER的固化反应热行为,通过动态热机械分析和热失重分析对CER的热性能进行了研究。结果表明：甲基四氢邻苯二甲酸酐体系固化的CER的T_g为152.73 ℃,初始热分解温度为350.6 ℃, 800 ℃时的残碳率为19.29%; 4,4′-二氨基二苯基砜体系固化的CER的T_g为251.94 ℃,初始分解温度为365.7 ℃, 800 ℃时的残碳率为46.44%。     

Design and Synthesis of Aromatic Polyesters Bearing Pendant Clickable Maleimide Groups

A bisphenol bearing pendant maleimide group, namely, N‐maleimidoethyl‐3, 3‐bis(4‐hydroxyphenyl)‐1‐isobenzopyrrolidone (PPH‐MA) was synthesized starting from phenolphthalein. Aromatic (co)polyesters bearing pendant maleimide groups were synthesized from PPH‐MA and aromatic diacid chlorides, namely, isophthaloyl chloride (IPC), terephthaloyl chloride (TPC), and 50:50 mol % mixture of IPC and TPC by low temperature solution polycondensation technique. Copolyesters were also synthesized by polycondensation of different molar proportions of PPH‐MA and bisphenol A with IPC. Inherent viscosities and number‐average molecular weights of aromatic (co)polyesters were in the range of 0.52–0.97 dL/g and 20,200–32,800 g/mol, respectively indicating formation of medium to reasonably high‐molecular‐weight polymers. ¹³C NMR spectral analysis of copolyesters revealed the formation of random copolymers. The 10% weight loss temperature of (co)polyesters was found in the range 470–484 °C, indicating their good thermal stability. A selected aromatic polyester bearing pendant maleimide groups was chemically modified via thiol‐maleimide Michael addition reaction with two representative thiol compounds, namely, 4‐chlorothiophenol and 1‐adamantanethiol to yield post‐modified polymers in a quantitative manner. Additionally, it was demonstrated that polyester containing pendant maleimide groups could be used to form insoluble crosslinked gel in the presence of a multifunctional thiol crosslinker. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 630–640     

Modeling of Nonlinear Optical Activity of Epoxyamine Oligomers with Binary Chromophore Groups

The molecular systems, modeling composite materials, are formed by the epoxy‐amine oligomers with covalently bound chromophore‐containing dendritic fragments ( EAD ) as a host and additional azo‐chromophores as guests. The relationship between the structure and quadratic nonlinear optical characteristics of the model systems is established by atomistic modeling and quantum chemistry. The effect of the chain length of the model systems and the choice of the dendron structure, in particular, the length of the groups tethering chromophores to the branching center, on the values of first hyperpolarizability is studied. Molecular dynamics, performed for the model systems at various temperatures, reveals chromophores local mobility at temperature close to 130 °C; the calculations being fulfilled with the force field MMFF94s modified in terms of the ESP partial charges estimate at B3LYP/6‐31G(d) level.

     

Photoaddition of Iodoform with Norbornene

The reaction of norbornene with iodoform in the inert solvent under irradiation resulted in Kharasch type addition to give endo-3-iodo-exo-2-diiodomethyl-bicyclo[2.2.1]heptane, and a carbene addition to give tricyclic compound, anti-3-iodo-exo-tricyclo[3.2.1.0^2,4]octane. The structural assignments of these adducts are based on elemental analyses, ir, nmr, and mass spectral studies.     

Thermoreactive polymer binders with a predicted level of rheological and deformation properties

This paper describes new polymer binders of different classes with predicted levels of rheological and deformation properties for promising methods of production of polymer composite materials. The technological and functional properties of binders processed by resin-transfer molding are reported.     

Synthesis of New Methylsiloxane Oligomers with Pendant Trialkoxysilylethyl Groups for Preparation of Silicon hard Coatings

For the purpose to prepare precursor materials for the silicon hard coatings, the hydrosilylation reactions of α, ω–bis(trimethylsiloxy)methylhydridesiloxane to trialkoxyvinylsilanes in the presence of platinum hydrochloric acid (0.1 M solution in THF), Karstedt's catalyst (Pt₂[(VinSiMe₂)₂O]₃) and platinum on the carbon (5%) were investigated. Hydrosilylation reactions at different ratios of initial compounds and at various temperatures (40–60 °C) were investigated and methylsiloxane oligomers with pendant trialkoxy fragments have been obtained. It was shown that completely hydrosilylation of all active Si H groups do not take place. The hydrosilylation reaction order, activation energy and rate constants were determined. The synthesized oligomers were characterized by ¹H, ¹³C NMR and FTIR spectra data. Gel-permeation chromatography, differential scanning calorimetric, thermogravimetric and wide-angle X-ray investigations of synthesized oligomers were carried out. Synthesized oligomers together with tetraethoxysilane were used for preparation of silicon hard coatings via sol-gel processes.     

Free-Radical-Initiated Copolymerization of A-Methylstyrene with Maleimide

Alternating copolymers of α-methylstyrene (α-MeSt) and maleimide (MI) were prepared by free-radical initiated polymerization at different monomer-to-monomer concentrations in the feed in CHCl₃, as solvent. The equilibrium constant of -MeSt and MI was determined by the transformed Benesi-Hildebrand NMR method in CDCl₃, and has a value of 0.03 L/mol. From the equation R_p = R_p(f) + R_p(CT) proposed by Shirota and coworkers, R_pf) and R_pCT) were calculated, and it was found that the copolymerization of -MeSt with MI proceeds predominantly through participation of the CT complex. Alternating copolymers have a glass transition temperature of 567 K (DSC method). Alternating copolymer decomposes via a one-step reaction at 350°C.     

Effect of Silicon Oxide Fillers on Photochemical Curing of Compounds Based on Acrylic Monomers and Oligomers

The course of curing of photocurable compounds was studied as influenced by filling with disperse silicon oxide substances. The effect of the filler concentration on the conversion and rate of photopolymerization was examined.     

Syntheses, Confirmation and Properties of Porphyrin Oligomers with Alkoxyl Linkages

A new and general synthesis of a porphyrinK( Ⅰ ) with two alkoxyl linkages is described. The synthesis involves the reaction of dibromopropane with phenolic porphyrin to form ω-bromopropylporphyrin ether. This ether then reacts with another phenolic porphyrin to give the target compounds. The properties of the target compounds were confirmed by means of elemental analysis, UV-Vis, IR, and ^1H NMR spectroscopies. Their spectral properties and thermal stability were also studied.     

Protecting and Leaving Functions of Trimethylsilyl Groups in Trimethylsilylated Silicates for the Synthesis of Alkoxysiloxane Oligomers

The concept of protecting groups and leaving groups in organic synthesis was applied to the synthesis of siloxane‐based molecules. Alkoxy‐functionalized siloxane oligomers composed of SiO₄, RSiO₃, or R₂SiO₂ units were chosen as targets (R: functional groups, such as Me and Ph). Herein we describe a novel synthesis of alkoxysiloxane oligomers based on the substitution reaction of trimethylsilyl (TMS) groups with alkoxysilyl groups. Oligosiloxanes possessing TMS groups were reacted with alkoxychlorosilane in the presence of BiCl₃ as a catalyst. TMS groups were substituted with alkoxysilyl groups, leading to the synthesis of alkoxysiloxane oligomers. Siloxane oligomers composed of RSiO₃ and R₂SiO₂ units were synthesized more efficiently than those composed of SiO₄ units, suggesting that the steric hindrance around the TMS groups of the oligosiloxanes makes a difference in the degree of substitution. This reaction uses TMS groups as both protecting and leaving groups for SiOH/SiO⁻ groups.     

Copolymerization of N-4-Dibenzoylmethane Maleimide with Styrene

0-Diketonecompoundshaveuniquephotochemicalandcoordinationchemicalproperties.Interestinpolymeric0-diketoneanditsmetal-containingpolymershavebeengreatlystimulatedbytheirpotentialuseinphotoresist',catalysis'andfluorescenceandlasertields'.Thustherehasbeenatrendtowardsthedevelopmentofpolymeric0-diketone.However,foemaleimide-basedcopolymercontaining0-diketoneunitshasnotbeenreportedsotar.Inthispaper.a11ovelcopolymeric6-diketonewaspreparedbyradicalcopolynlerizationofp-DBMIwithSt.thestructureandprope…     

Combining Orthogonal Chain‐End Deprotections and Thiol–Maleimide Michael Coupling: Engineering Discrete Oligomers by an Iterative Growth Strategy

Orthogonal maleimide and thiol deprotections were combined with thiol–maleimide coupling to synthesize discrete oligomers/macromolecules on a gram scale with molecular weights up to 27.4 kDa (128mer, 7.9 g) using an iterative exponential growth strategy with a degree of polymerization (DP) of 2ⁿ −1. Using the same chemistry, a “readable” sequence‐defined oligomer and a discrete cyclic topology were also created. Furthermore, uniform dendrons were fabricated using sequential growth (DP=2ⁿ −1) or double exponential dendrimer growth approaches (DP=2 −1) with significantly accelerated growth rates. A versatile, efficient, and metal‐free method for construction of discrete oligomers with tailored structures and a high growth rate would greatly facilitate research into the structure–property relationships of sophisticated polymeric materials.     

Controlled,Stepwise Syntheses of Oligomers with Modified Quinoxaline Backbones

New oligomers based on quinoxaline units were successfully synthesized through multistep reactions using Wittig coupling, affording (E)-(quinoxalin-2-yl)ethene oligomers. Diverse quinoxaline-based phosphonium salts were designed and synthesized, enabling versatility and compatibility regarding the oligomer-building process. The characterization of the oligomers showed excellent stereoisomer specificity, i.e., a fully E-configurated conjugated π -system. The oligomers’ light absorption/emission profiles indicate potential properties for an application in materials science.     

苯乙烯与N-对位取代苯基马来酰亚胺的乳液共聚

合成了苯乙烯(St)与 N-对位取代基马来酰亚胺的3种二元共聚物乳液.在苯乙烯与N-对位取代苯基马来酰亚胺(N-p-RPhMI)的最大共聚比内,通过种子滴加乳液聚合制得高稳定性、高固含量(40%)、低粘度的共聚物乳液.研究了 N-p-RPhMI 苯环对位上取代基团对共聚物乳液的性能以及共聚物热性能影响.结果表明:N-p-RPhMI 的加入提高了乳液的产率,并且随着取代基团极性的增强,乳液产率提高,乳胶粒的平均粒径增大,乳液的表观粘度降低;共聚物的热分解温度随着取代基团极性的增加而提高,但取代基极性对共聚物的玻璃化转变温度(Tg)的影响明显.同时,St/N-对甲氧基马来酰亚胺(N-p-MOPhMI)体系中助溶剂的加入对共聚物乳液性能影响很大,使共聚物的热起始分解温度升高,但对共聚物的 Tg 基本无影响.     

Synthesis of Novel Exocyclic Allenes with a Norbornene Fragment

Russian Journal of Organic Chemistry - N-Substituted amino acids with a norbornene fragment were synthesized by the direct fusion of amino acids with endic anhydride at 150°C. The synthesized...     

ROMP of Functionalized Cyclooctene and Norbornene Derivatives and their Copolymerization with Cyclooctene

In this work, two novel monomers, a cyclooctene and a norbornene derivative, including the trifluoromethylphenyl ester group, are prepared by chemical modification of 1,5-cyclooctadiene and 5-norbornene-2-carboxylic acid, respectively. The ring-opening metathesis polymerization of each one of these monomers, as well as the commercial carboxylic acid, is confirmed in the presence of Grubbs’ second generation catalyst in CH₂Cl₂. The three functionalized monomers are subsequently copolymerized with cis-cyclooctene in order to obtain modified polycyclooctenes. Solubility is enhanced by the incorporation of the functional group. The thermal properties of the obtained homopolymers and copolymers are studied by DSC and TGA, showing that crystalline behavior strongly depends on the cyclooctene content.