六甲氧基甲基三聚氰胺-多元醇-丙烯酸酯混杂聚合体系的研究

六甲氧基甲基三聚氰胺 (HMMM) 多元醇 丙烯酸酯 酸催化剂混杂聚合体系在高温下同时进行缩聚和自由基聚合并表现出协同效应 .体系中的活泼亚甲基在HMMM的催化下被空气氧化成过氧化氢物 ;过氧化氢物在酸催化下分解成自由基进而引发自由基聚合反应 .研究结果表明 ,体系中存在固化加速的协同效应 ;同时体系中还存在热互补效应 ,丙烯酸酯的自由基聚合反应放出的热可以传递给缩聚反应 ,满足缩聚反应吸热的要求 .混杂聚合得到的高分子合金膜具有优良的机械性能和耐溶剂性能 ,这是由于在混杂聚合过程中形成了互穿聚合物网络 (IPN)结构 .使用潜酸催化剂作为酸的来源 ,可以提高体系的储存稳定性 ;交联 引发剂的使用可以拓宽它的使用范围 ;对超枝化聚合物在混杂体系中的应用也进行了初步研究     

六甲氧基甲基三聚氰胺-多元醇-丙烯酸酯混杂聚合过程热互补效应的研究

六甲氧基甲基三聚氰胺（HMMM）－多元醇－丙烯酸酯－酸催化剂的混合体系在较高温度下同时进行缩聚和自由基聚合并表现出协同效应，DSC研究结果表明，丙烯酸酯在HMMM和酸的催化作用下可在较低温度下发生自由基聚合反应，并把反应释放出来的大量的热量有效地传递给缩聚发反应，满足缩聚反应吸热的要求，从而节省固化所需要的能量，为了提高储存稳定性。本文以潜酸催化剂作为酸的来源，对该混杂聚合体系进行了研究，仍有明显的热互补效应。     

密胺-脲甲醛树脂合成工艺放大研究

以密胺－脲甲醛树脂合成的小试工艺条件为依据，完成了放大试验过程的工艺研究。研究结果与小试研究的工艺条件相吻合。     

Demonstration of methylene-ether bridge formation in melamine-formaldehyde resins

¹H and ¹³C NMR have been used for the quantitative determination of methylene-ether bridges in melamine-formaldehyde (MF) resins. The amount of methylene-ether bridges was determined by ¹³C NMR from the number of monomethylolated amino groups consumed in the condensation reactions and is in agreement with that calculated from the condensation water contents. This latter method, which involves a combination of ¹H and ¹³C NMR, is based on the amount of condensation water released during the formation of both methylene and methylene-ether bridges. © 1995 John Wiley & Sons, Inc.     

Optimized Synthesis of Silver Nanoparticles by Factorial Design with Application for the Determination of Melamine in Milk

A colorimetric method based on silver nanoparticles was developed for the determination of melamine in milk. Silver nanoparticles were synthesized without any stabilizer, using sodium borohydride as the reducing agent. Optimization of the variables for the formation of the nanoparticles was performed by factorial design, resulting in stable colloidal silver nanoparticles with a mean diameter of 14.0?±?2.7?nm. Spectrophotometric measurements performed at 475?nm showed a linear range from 0.033 to 1.50?mg?L^?1 of melamine with limits of detection and quantification of 0.009 and 0.031?mg?L^?1, respectively. The method provided highly sensitive determination of melamine in milk.     

A mixed-ligand approach for building a N-rich porous metal-organic framework for drug release and anticancer activity against oral squamous cell carcinoma

Abstract

A new Zn(II) metal-organic framework (MOFs), [Zn(BTC)(HME)]·(DMAc)(H₂O) (1, H₃BTC =1,3,5-benzenetricarboxylic acid, HME?=?protonated melamine, DMAc?=?N,N-dimethylacetamide), has been synthesized under solvothermal conditions. In the structure of 1, the four-coordinate Zn(II) ions are connected by BTC^3? ligands into a 3-D framework with (3)-connected utg-type topology. This MOF shows permanent porosity after lattice solvent removal with a calculated pore size distribution around 0.72?nm. With abundant N-donor sites and suitable pore size, the desolvated 1 (1a) was used as a drug carrier for the loading of anticancer drug 5-fluorouracil (5-Fu) molecules. Moderate 5-Fu loading capacity and long drug release time were observed for 1a. The computational simulation results reveal that strong H-bond interactions between the 5-Fu molecules and the nitrogen sites allow slow release of the drug 1a. In addition, the in vitro cytotoxicity of 1 and 5-Fu loaded 1a were also evaluated using MTT assays against human oral squamous cell carcinoma (SCC-251 and HSC-4).     

Magnetic‐based picolinaldehyde–melamine copper complex for the one‐pot synthesis of hexahydroquinolines via Hantzsch four‐component reactions

A picolinaldehyde–melamine copper complex was loaded on a magnetic Fe₃O₄ core, so that it contained 0.33 mmol of Cu per gram, and was used as an efficient catalyst. The as‐synthesized catalyst was characterized using various techniques, including Fourier transform infrared spectroscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry and thermogravimetric analysis. The catalyst was used to activate the raw materials in the synthesis of hexahydroquinoline derivatives in one‐pot four‐component reactions. Low reaction time (minutes versus half an hour), solvent‐free condition and magnetically separable catalyst are some salient features of the developed catalyst. Also, the optimum amount of catalyst and temperature were determined as 0.07 g and 87.6 °C, respectively, which were obtained using response surface methodology and optimization techniques.     

Poly(vinyl alcohol)/melamine phosphate composites prepared through thermal processing: thermal stability and flame retardancy

Poly(vinyl alcohol)/melamine phosphate composites (PVA/MP) as a novel halogen‐free, flame‐retardant foam matrix were prepared through thermal processing, and then their thermal stability and flame retardancy were investigated by thermo‐gravimetric analysis, micro‐scale combustion calorimeter, cone calorimeter, vertical burning test, and limiting oxygen index (LOI) test. It was found that the thermal stability and combustion properties of the PVA/MP composites could be influenced by the addition of MP. Compared with the control PVA sample (B‐PVA), in the PVA/MP (75/25) composites, the temperature at 5% mass loss (T_5%) decreased about 10°C, the residual chars at 600°C increased by nearly 27%, the temperature at the maximum peak heat release rate (T_P) shifted from 292°C to 452°C, and the total heat released and the heat release capacity (HRC) decreased by 28% and 14%, respectively. Moreover, the PVA/MP composites could reach LOI value up to 35% and UL94 classification V‐0, showing good flame retardancy. At the same time, both Fourier transform infrared and X‐ray photoelectron spectroscopy spectra of the residual chars from the PVA/MP composites demonstrated that the catalytic effect of MP on the dehydration and decarboxylation reactions of PVA, and the chemical reactivity of MP during the chars‐forming reactions could be used to account for the changed thermal stability and flame retardancy of the PVA/MP composites. Copyright © 2012 John Wiley & Sons, Ltd.     

Studies on Melamine Modified Polyesteramide as Anticorrosive Coatings from Linseed Oil: A Sustainable Resource

Melamine modified polyester amide (MPEA) was synthesized by the reaction of linseed oil fatty amide. The resin was further cured at room temperature by polystyrene co‐maleic anhydride (SMA) in different phr (30–80) to obtain MPEA coatings. The probable structure of MPEA was confirmed by FT‐IR, ¹H‐NMR and ¹³C‐NMR spectroscopic techniques. The physico‐chemical characterization of these resins viz. iodine value, saponification value, refractive index, inherent viscosity were carried out by standard methods. MPEA (40 wt%) solution in ethylene glycol monomethyl ether (EGME) was applied on a mild steel strip of standard sizes to study their physico‐mechanical and chemical resistance properties. It was found that coatings of MPEA with 60 parts per hundred of the resin (phr) of SMA showed the best performance in physico‐mechanical and alkali resistance properties. Thermal stability and curing behavior were studied by Thermo Gravimetric Analyses (TGA) and Differential Scanning Calorimetry (DSC), respectively.     

Melamine Trisulfonic Acid (MTSA): A New Efficient Catalyst for the Chemoselective Methoxymethylation of Alcohols

Melamine trisulfonic acid, which is easily prepared by the reaction of melamine with neat chlorosulfonic acid, is able to efficiently catalyze the chemoselective methoxymethylation of alcohols with dimethoxymethane (DMM). All reactions were performed under mild and completely heterogeneous reaction conditions in good to high yields.