Identification of the preferentially targeted proteins by carbamylation during whole lens incubation by using radio-labelled potassium cyanate and mass spectrometry

AIMTo attempt to identify the primary targets of carbamylation in bovine lenses incubated under physiological condition.

A Study on the Properties of Resin Transfer Molding Cyanate Ester and Its T800 Grade Carbon Fiber Composites

The properties of resin transfer molding(RTM)cyanate ester and its T800 grade carbon fiber composites were studied with the rheometer,differential scanning calorimetry(DSC),FT-IR,dynamic mechanical analyzer(DMA),thermal gravimetric analysis(TGA),mechanical property testing,and scanning electron microscopy(SEM).The results showed that the temperature of cyanate ester suitable for RTM process was 70℃.Curing process of the resin was 130℃/2 h+160℃/2 h+200℃/2 h+220℃/4 h.Glass transition temperature and heat decomposition temperature of the cured resin are 289℃and 415℃,respectively.Mechanical properties of T800/RTM cyanate composites are 13.5%higher than that of T700/RTM cyanate composites and equal to that of T800/Prepreg cyanate composites.Tg of T800/RTM cyanate composites was proved to be 291℃.Fracture pattern of the composites was flat,which proved excellent interface properties between fiber and resin in this composite.

Thermal Polymerization of Cyanate Ester-Benzoxazine:Study of a Functional Model Compound

A novel benzoxazine(BOZ)monomer is synthesized by a pot method with solvent-free to blend with cyanate ester(CE).A soluble intermediate is obtained after being cured for 20 h at 80℃.The two model compound and the blends are analyzed with the infrared radiation(IR),nuclear magnetic resonance(NMR)spectroscopy,and differential scanning calorimetry(DSC).The results show that an intermediate of the iminocarbonate and BOZ structures is formed by the ring-open BOZ reacting with the cyanate groups and ring-unopened BOZ.Moreover,rearrangement and ring-opening occur in the postcure of the intermediate to form the alkyl isocyanurate structure with polybenzoxazine.

Investigation on Thermal and Dimensional Stability of Epoxy Resin In-Situ Modified by Cyanate Ester Resin and Polydimethylsiloxane

The thermal and dimensional stability of epoxy resin(EP)in-situ modified by cyanate ester(CE)and polydimethylsiloxane(PDMS)are investigated by means of experiments and numerical simulation.Thermal gravimetric analysis(TGA)and differential scanning calorimeter(DSC)are used to analyze the heat resistance of the modified EP.The dimensional stability is characterized by the volume shrinkage of the series PDMS/CE/EP obtained by the density method.The chemical structure of the PDMS/CE/EP is analyzed by Fourier transform infrared spectroscopy(FTIR).The results of TGA and DSC indicate that the thermal stability of PDMS/CE/EP decreases firstly and then increases with the increase in the amount of CE.The addition of PDMS shows a slight effect on the thermal stability.The 40%CE makes the blending system exhibit the lowest initial decomposition temperature,which reduces by 15.5%and 40.8%compared with pure EP and CE,respectively.The FTIR results suggested that the influence of CE on the thermal stability of the modified EP is mainly ascribed to the generation of oxazolidinone ring with low thermal stability and the increase in the triazine ring with high thermal stability.The volume shrinkage measurement results show that the introduction of CE and PDMS are both beneficial to the improvement of the dimensional stability of the blending systems.The in-situ addition of 80%CE shows the lowest volume shrinkage of6.11%.The thermal stress distribution of PDMS/CE/EP generated during the solidification process is simulated by the finite element analysis.The results suggested that the introduction of 80%CE into EP results in the lowest thermal stress in the blending system,which indicates that the system has the lowest volume shrinkage,which agrees well with the experimental results.

A Dielectric Ink Combining Acrylate and Cyanate Moieties for Inkjet 3D Printing with Good Thermal Stability

Inkjet 3D printing has potential in the additive manufacturing of electronic circuits and devices.However,inks that can be used for printing layers with T5%>300℃ or hardness>200 MPa have been rarely reported.Cyanate ester(CE)polymers have excellent thermal stability,high strength,and low shrinkage compared to other common dielectric inks for inkjet 3D printing,but cannot be quickly shaped by ultraviolet(UV)irradiation or thermal treatment.Combining CEs with UV-curable monomers may be a possible way to accelerate crosslinking,but there are challenges from the adverse effects of the dilution of both monomers.In this study,dielectric inks with acrylate and cyanate moieties were developed.The low viscosity and surface tension of the CE precursor(Bisphenol E cyanate ester)were combined with photocurable acrylate diluent monomers and cross-linker to realize an ink suitable for inkjet 3D printing.An internal dual three-dimensional cross-linked network structure resin was prepared by a combination of photocuring and thermal curing with T5%up to 326.69℃,hardness up to 431.84 MPa,dielectric constant of 2.70 at 8 GHz,and shrinkage of 1.64%.The developed dielectric inks can be applied to the 3D printing of printed circuit boards and other electronic devices that require dielectric properties.

Tribological behavior of shape memory cyanate ester materials and their tunable friction mechanism

High-performance polymer friction materials with tunable tribological behavior to fit varied work conditions remain a challenge of widespread interest for a variety of applications.Shape memory polymer exhibits morphing and modulus changing over temperature changing provides a promising material to adjust the friction process.Herein,we investigated the tribological properties of shape memory cyanate ester(SMCE)under different conditions.The SMCE exhibits the tribological behavior of good friction material with stable high coefficient of friction(COF)and a low wear rate.Besides,the COF increases and wear rate decreases with the temperature increasing show the tunable friction property of the SMCE.We propose a new model of wear-compensation through shape recovery to explain the adjustable friction behavior of thermal-responsive polymer from the aspect of shape recovery and energy conversion.This study provides a high-performance friction material and paves the route for the application of shape memory polymer(SMP)in tribology field with tunable property.

Random copolymer membrane coated PBO fibers with significantly improved interfacial adhesion for PBO fibers/cyanate ester composites

Poly(p-phenylene-2,6-benzobisoxazole)(PBO) fibers possess excellent dielectric, mechanical properties and heat resistance. However, the surface of PBO fibers is smooth and highly chemical inert, resulting in poor interfacial compatibility to polymer matrix, which severely limits its wider application in high-performance fiber-reinforced resin matrix composites. In this work, random copolymers(P(S-co-BCB-co-MMA)) containing benzocyclobutene in the side-chain were synthesized by reversible addition-fragmentation chain transfer(RAFT) polymerization, which were then utilized to form dense random copolymer membrane on the surface of PBO fibers by thermally cross-linking at 250 °C(PBO@P fibers). Four kinds of synthesized P(S-co-BCB-co-MMA) with different number-average molar mass(Mn) were well controlled and possessed narrow dispersity.When the Mnwas 32300, the surface roughness of PBO@P fibers was increased from 11 nm(PBO fibers) to 39 nm. In addition, PBO@P fibers presented the optimal interfacial compatibility with bisphenol A cyanate(BADCy) resins. And the single fiber pull-out strength of PBO@P fibers/BADCy micro-composites was 4.5 MPa, increasing by 45.2% in comparison with that of PBO fibers/BADCy micro-composites(3.1 MPa). Meantime, PBO@P fibers still retained excellent tensile strength(about 5.1 GPa). Overall, this work illustrates a simple and efficient surface functionalization method, which would provide a strong theoretical basis and technical support for controlling the surface structure & chemistry of inert substrates.

Electroactive Shape Memory Cyanate/Polybutadiene Epoxy Composites Filled with Carbon Black

Electroactive shape memory composites were synthesized using polybutadiene epoxy （PBEP） and bisphenol A type cyanate ester （BACE） filled with different contents of carbon black （CB）. Dynamic mechanical analysis （DMA）, scanning electron microscopy （SEM）, electrical performance and electroactive shape memory behavior were systematically investigated. It is found that the volume resistivity decreased due to excellent electrical conductivity of CB, in turn resulting in good electroactive shape memory properties. The content of CB and applied voltage had significant influence on electroactive shape memory effect of developed BACE/PBEP/CB composites. Shape recovery can be observed within a few seconds with the CB content of 5 wt% and voltage of 60 V. Shape recovery time decreased with increasing content of CB and voltage. The infrared thermometer revealed that the temperature rises above the glass transition temperature faster with the increase of voltage and the decrease of resistance.

PREPARATION AND PROPERTIES OF FUMED SILICA/CYANATE ESTER NANOCOMPOSITES

Fumed silica/bisphenol A dicyanate ester （BADCy） nanocomposites were prepared by introducing different contents of nano-sized fumed SiO2 into the BADCy matrix. Two different average primary particle diameters of 12 and 40 nm were chosen. Dibutyltindilaurate （DBTDL） catalyst was chosen to catalyze the cyanate ester group into triazine group via cyclotrimerization reaction. The SEM micrographs indicated that the fumed SiO2 particles were homogeneously dispersed in the poly（bisphenol A dicyanate） matrix by means of ultrasonic treatment and the addition of a coupling agent. The FTIR spectroscopy shows that, not only DBTDL catalyzes the polymerization reaction but also --OH groups of the SiO2 particles surface help the catalyst for the complete polymerization of BADCy monomer. The thermal stability of the cured BADCy can be improved by adequate addition of fumed SiO2. A slight increase in the dielectric constant and dielectric loss values were identified by testing the dielectric properties of the prepared nanocomposite samples. By increasing the SiO2 content, there was a slight increasing in the thermal conductivity values of the tested samples. The obtained results proved that the fumed silica/BADCy nanocomposites had good thermal and dielectrieal properties and can be used in many applications such as in the thermal insulation field.

Preparation and Properties of Nano-SiO_2/TDE-85/BMI/BAD Cy Composites

A new type of the nanometer particles and epoxy/bismaleimide-triazine nanocomposites were prepared using a nanometer silica （nano-SiO2）, a 4,5-epoxycyclohexane 1,2-dicarboxylic acid dilycidyl （TDE-85） epoxy resin, a 4,4＇-bismaleimidodiphenymethane （BMI） and a bisphenol a dicyanate （BADCy）. The properties of nano-SiOJTDE-85/BMI/BADCy composites, such as mechanical and thermal properties, were systemically investigated in detail by mechanical measurement, scanning electron microscope （SEM）, dynamic mechanical analysis （DMA） and thermogravimetric analysis （TGA）. The experimental results showed that the addition of the appropriate amount of nano-SiO： could improve the impact strength and the flexural strength of the nano- SiO2/TDE-85/BMI/BADCy composites. Simultaneously, the thermal stability of the blends was found to be higher than that of the TDE-85/BMI/BADCy copolymers.

Adsorption and Reaction of CN +O→OCN on Cu(100) Surface: A Density Functional Theory Study

The adsorption and reaction of O ＋ CN → OCN on Cu（100） are studied by using density functional theory and cluster model. Cu14 cluster model is used to simulate the surface. The calculated results show that the OCN species with the molecule perpendicular to the surface via N atom （N-down） is more favorable than other adsorption models, and the N-down at the bridge site is the most favorable. For N-down, calculated OCN symmetric and asymmetric stretching frequencies are all blue-shifted compared with the calculated values of free and in good agreement with the experiments. The charge transfer from the surface to the OCN species leads to that the bonding of OCN to the metal surface is largely ionic. The present studies also show that CN with the molecule perpendicular to the surface via C atom （NC-down） at the top site is the most stable. Except NC-down at the top site, the calculated CN stretching frequencies are all red-shifted. With O coadsorbed at the hollow site, the adsorption of NC-down at the next nearest bridge or top site is energetically more favorable than that at the adjacent hollow site. The reaction of O ＋ CN → OCN on Cu（100） has no energy barrier via both Eley-Rideal and Langmuir-Hinshelwood processes.

Progress in Recycling of Composites with Polycyanurate Matrix

Thermoset based composites are used increasingly in industry for light weight applications, mainly for aircraft, windmills and for automobiles. Fiber reinforced thermoset polymers show a number of advantages over conventional materials, like metals, especially their better performance regarding their strength-to-weight ratio. However, composite recycling is a big issue, as there are almost no established recycling methods. The authors investigate the recyclability of polycyanurate homo- and copolymers with different recycling agents under different conditions. Also the influence of the recycling process on the most important reinforcement fibers, i.e. carbon-, glass-, aramid-, and natural-fiber is investigated. The authors find that: the recycling speed is not only dependent on the temperature, but also is significantly influenced by the particular recycling agents and the polycyanurate formulation. Hence, the stability against the recycling media can be adjusted over a broad range by adjusting the polymer composition. Furthermore, the authors find that the inorganic reinforcement fibers (carbon and glass) are almost unaffected by neither recycling agent at either temperature. Aramid-fibers degrade, depending on the particular recycling agent, from slightly up to extremely strong. This leaves one with the possibility to find a combination of matrix resin and recycling agent, which does not affect the aramid-fiber significantly. In the case of natural fibers, the dependence on the particular recycling media is very strong: some media do not affect the fiber significantly;others reduce the mechanical properties (tensile strength and elongation at break) significantly, and still others even improve both mechanical properties strongly. From the Recyclate, the authors synthesize and subsequently characterize a number of new polyurethane thermosets (foamed and solid samples) with different contents of recyclate, exhibiting Tg in the range of 60°C to 128°C.

Formation of Hybrid Ring Structure of Cyanurate/Isocyanurate in the Reaction be-tween 2,4,6-Tris(4-Phenyl-Phenoxy)-1, 3,5-Triazine and Phenyl Glycidyl Ether

Reaction products of 2,4,6-tris(4-phenyl-phenoxy)-1,3,5-triazine derived from 4-phenylphenol cyanate ester and phenyl glycidyl ether were analyzed. In addition to an isocyanurate compound and an oxazolidone compound which were well known as reaction products of cyanate esters and epoxy resins, compounds with hybrid ring structure of cyanurate/isocyanurate were determined. Gibbs free energies of the compound having hybrid ring structure of cyanurate/isocyanurate with two isocyanurate moiety were found to be lower than that of the compound with cyanurate ring structure through calculations. Calculation data supported the existence of hybrid ring structure of cy-anurate/isocyanurate. It was revealed that isomerization from cyanurate to isocyanurate occurs via hybrid ring structure of cyanurate/isocyanurate in the reaction of aryl cyanurate and epoxy.

Recent developments in electrosynthesis of nitriles and electrocatalytic cyanations

Nitrile compounds are a class of high-value chemicals and versatile intermediates which can easily be transformed into a variety of useful products bearing functional groups such as carboxyl, carbamoyl, aminomethyl, ketyl and heterocyclic derivatives. Various thermal catalytic cyanation procedures have been devised and scaled up industrially while developing alternative methods are actively pursued. The access to these classes of molecules electrochemically offers greener alternatives to their preparation. The development of electrochemical synthesis of cyano-containing compounds under mild conditions with low energy consumption will imminently become indispensable approaches for industrial production of nitriles. The electrochemical cyanation presents many challenges from the toxicity of cyanide to the development of catalysts and the design of electrochemical cells. Electrochemical cyanation reaction offers promise to conveniently accessing nitriles but still requires efficient electro-catalysts, safe protocols and scale up considerations. This review discusses recent progress in the field of electrochemical synthesis of nitrile compounds placing emphasis on electro-synthetic and electro-catalytic mechanism aspects while making reference to original works to highlight the progress in this area.

Improved Electrochemical Synthesis of Nitro-substituted 1-Aryl-2-pyrrolidinecarbonitriles

In this paper, we described an improved electrochemical method for synthesis of some 1-aryl-2-pyrrolidinecarbonitrile derivatives bearing an electron-withdrawing group （NO2）. The electrochemical synthesis of titile compounds has been successfully performed in an undivided cell in reasonable yields.

Anodic Cyanation of 1-(1-Methoxycarbonyl ethyl) piperidine

Aminonitriles were prepared efficiently from anodic cyanation of ?amino ester. The effect of different solvents and electrolytes was studied. The other byproducts were analyzed.

硅胶功能化的N-丙哌嗪固载钯纳米粒子作为有效的多相催化剂用于氰化反应(英文)

An efficient heterogeneous Pd catalytic system has been developed, based on immobilization of Pd nanoparticles (PNPs) on a silica-bonded N-propylpiperazine (SBNPP) substrate. The SBNPP substrate effectively stabilizes the PNPs and improves their stability against aggregation. The catalytic activity of this catalyst was investigated in the cyanation of aryl halides with K4[Fe(CN)6 ] as the cyanide source. The catalyst could be recycled several times without appreciable loss of catalytic activity.

Reactions with Aminobenzoic Acids via Diazonium Salts Open New Routes to Bio-Derived Aromatics

Aromatics have a broad application in our everyday life ranging from plastics, coatings and fibres, to food and pharmaceuticals. To date the bulk of these aromatics is derived from naphtha-based pet-rochemistry. However, recent progress in the fermentative production of metabolites using renew-able resources and engineered microbes has enabled the production of bio-precursors, such as 4-amino benzoic acid (pABA) and 2-amino benzoic acid (oABA). In this work we explored the feasibility of Sandmeyer reactions for the conversion of pABA to terephthalic and oABA salicylic acid, providing two very important platform chemicals for the chemical and pharmaceutical industries. We could demonstrate that both acids can be obtained from the amino benzoic acids derived from the shikimate pathway in microbes and plants. Good conversions could be achieved using Sandmeyer reactions at mild conditions with biodegradable reagents and without organic solvents.

A facile and convenient approach for the one-pot synthesis of 2,4(1H,3H)-quinazolinediones

A fast and efficient method is described for the one-pot synthesis of 2,4（1H,3H）-quinazolinediones by cyclization reaction of anthranilic acid derivatives with potassium cyanate and acetic acid in PEG.Good to high yields of the products obtain in short reaction times with simple work-up.

PEN/BADCy Interlayer Dielectric Films with Tunable Microstructures via an Assist of Temperature for Enhanced Frequency Stability

Low dielectric in terlayer films have become an important element to ensure the development of the microelectr onics industry.A kind of flexible interlayer dielectrics,polyarylene ether nitrile/bisphenol A cyanate ester(PEN/BADCy)film,with good thermal stability and low frequency dependence,has been developed by solution casting method.Herein,materials were designed to incorporate bisphenol A cyanate ester as a part of blend,contributing to the frequency stability and structural integrity.The morphological study combined with electron microscopy revealed the uniform and flexible microstructure information with controllable morphology through self-polymerization of cyanate esters with different prepolymerization time and curing temperatures.The dielectric films could present high thermal stability with Tg>180℃.Significant improvement in the dielectric properties was achieved for the dielectric constant and loss was much stabler than neat PEN over the frequency range from 100 Hz to 5 MHz.When the prepolymerization time was 3h and final curing temperature reached 230℃,the dielectric constant and dielectric loss of the films were 3.36 and 0.013 at 100 kHz,respectively.The dimensional stability(CTE=53.67×10^-6 K^-1)was confirmed and con sidered beneficial to use as an in terlayer dielectrics.