高性能自修复微胶囊预聚物组成的研究

为了指导高性能自修复微胶囊的制备研究, 利用偏光显微熔点仪、红外光谱和核磁共振氢谱定量研究了微胶囊预聚物组成随反应条件如反应温度、pH 值和甲醛-尿素物质的量比的变化. 研究结果表明, 升高体系温度和pH 值都会显著促进副反应的发生从而降低产物中二羟甲基脲的产率; 而提高甲醛-尿素的物质的量比, 二羟甲基脲的产率增加,同时三羟甲基脲的产率降低. 此外, 还研究了升温过程中反应体系的温度变化情况. 研究发现: 升温速率一定时, 反应体系的温度变化均匀, 没有温度骤变阶段.     

硫脲甲醛聚合反应中的半结晶沉淀现象

首次报道了硫脲甲醛聚合反应中的半结晶沉淀现象.定量分析结果显示硫脲甲醛之间的聚合反应接近一种线性交替共聚反应过程.红外光谱的结果证明不同硫脲甲醛物质的量比反应条件下产物中始终存在较强的N—H特征振动吸收峰(v=3311cm-1,δ=1541cm-1).当甲醛用量较高和硫脲用量增加时分别在1008和1137cm-1处检测到较强的C—O—C和C=S伸缩振动吸收峰.结合XRD和核磁共振分析结果推测:硫脲甲醛聚合产物中存在着一种氢键导向型结晶结构;分子中含有醚键的聚合产物因具有复杂的氢键作用没有结晶性.扫描电镜分析显示较高硫脲用量反应条件下生成了层状半结晶碎片产物,而高甲醛比例条件得到的产物为细小的层状碎片交联聚集成的球形粒子.     

用红外光谱法对热固性酚醛树脂固化过程的研究

用红外光谱法研究了四种热固性酚醛树脂在固化过程中的化学变化。结果表明热固性酚醛树脂的固化过程,首先是羟甲基发生缩合反应,缩合反应形成醚键是主要的。热固性酚醛树脂在进一步固化时(150—200°)出现了羰基,它的出现不是亚甲基氧化所致,而是部分醚键断裂形成了醛羰基。对热固性酚醛树脂的固化过程的机理进行了讨论。     

一锅法合成二硝基五亚甲基四胺反应机理的研究

二硝基五亚甲基四胺(DPT)是高性能单质炸药奥克托金(HMX)的重要硝化前体.以尿素为起始原料,中间产物不分离,经硝化、水解、Mannich缩合等反应得到DPT,总收率63.2%.通过分离、捕获中间体以及同位素示踪实验研究了一锅法合成DPT的反应机理.分离出了稳定的中间体二硝基脲、硝酰胺和二羟甲基硝酰胺,用苯磺酰氯捕获到了活性中间体1-硝基-六氢均三嗪.以氘代甲醛、二羟甲基硝酰胺和氨缩合得到氘标记的DPT,1HNMR和MS分析结果表明:在反应过程中二羟甲基硝酰胺解离释放出甲醛和硝酰胺,小分子碎片随机组合生成了三嗪化合物,进而生成DPT.     

混合价化合物的研究(Ⅱ)─—电化学及现场光谱电化学方法研究非质子介质中Dawson结构杂多阴离子[HAs_2Mo_(18)O_(62)]~(n-)的电还原性质

以电化学和现场紫外－可见－近红外及现场FTIR光谱电化学方法对Dawson结构杂多阴离子［HAS2Mo18O62］5－在非质子介质（CH3CN）中的电还原过程进行了研究．结果表明，该杂多阴离子在非质子介质中经历4步单电子还原反应，所产生的杂多蓝阴离子在近红外区出现宽广的价间电荷转移吸收带，而红外区Mo＝O端键及Mo—O—Mo桥键的特征吸收峰在还原后均有不同程度的红移．     

36种灵芝产品傅里叶变换红外光谱快速鉴别研究

利用傅里叶变换红外光谱法（FTIR）无损快速鉴别了36种灵芝类产品。灵芝、孢子粉和菌丝体的红外谱图差别较显著;不同厂家所生产的灵芝产品由于所选用灵芝的产地不同、所用辅料的种类以及辅料所添加的多少不同,均引起了谱图的相对峰强度和波数位置的改变。结果表明：36种灵芝产品均可以根据红外的特征谱图进行分类鉴别。该方法快速、不需对灵芝产品进行分离提取。     

聚丙烯表面接枝PNIPAAm膜Ⅰ.光接枝反应和表面形态结构研究

以氧杂蒽酮或二苯甲酮为引发剂 ,通过紫外光引发表面接枝聚合的方法在聚丙烯薄膜表面引入了具有温度敏感特性的聚异丙基丙烯酰胺 (PNIPAAm)接枝聚合物层 .提高紫外光强度和接枝反应温度均有利于接枝率增大 ,而单体浓度对接枝率的影响存在最佳值 ,为 0 1 8mol L .在引发剂预浸渍引发接枝和休眠基引发接枝这两种方式中 ,后者能够实现更高的接枝率 .红外光谱 (FTIR)、X射线光电子能谱化学分析 (ESCA)和扫描电子显微镜 (SEM)等对接枝层组成的表征结果证实了接枝层的存在 .在不同温度下 ,接枝膜的FTIR谱图中酰胺I带和酰胺II带特征吸收峰发生位移 ,表明它具有温度敏感特性 .同时 ,SEM研究发现由于接枝膜的温度敏感特性而导致的球状表面形态结构     

6种燕窝的傅里叶变换红外光谱法原性状快速鉴别

首次利用微钻石ATR探头傅里叶变换红外光谱法（FTIR）无损快速鉴别了6种燕窝。结果表明：印尼燕、越南燕、马来西亚燕、泰国血燕、菲律宾草燕和香港市售燕窝均有自己的红外特征谱,据谱图吸收峰的波数位置和相对峰强度的差异可达到燕窝类同和伪品和鉴别。该方法快速、简便、可靠。     

聚丙烯醛及其共聚物的膦化反应

用游离基聚合法将丙烯醛及其它烯类单体制成丙烯醛均聚物、丙烯醛-苯乙烯共聚物及丙烯醛-二乙烯苯共聚物,从其红外光谱图上,知聚丙烯醛具有羰基、羟基、碳—碳双键和大量的醚键,聚丙烯醛与羟氨盐酸盐反应后,红外光谱图不再显示有羰基和醚键;与氢氧化钠反应后,羰基增高与醚键有所下降,这些特征表明:聚丙烯醛的羰基与醚键是活泼的。 不同组成的丙烯醛—苯乙烯共聚物,其红外光谱有差别,苯乙烯含量低的共聚物,羰基波峰小,醚键波峰高,当苯乙烯量增至与丙烯醛的克分子数约相同时,羰基波峰高,醚键波峰小,这表明苯乙烯与丙烯醛共聚后,可减少聚丙烯醛的成环反应,由于这个缘故,苯乙烯—丙烯醛共聚物及二乙烯苯(含量不能过高)—丙烯醛共聚物的膦化程度比丙烯醛的均聚物高,若苯乙烯及二乙烯苯的含量不太大,甚至共聚物的磷含量及交换量也较均聚物高。 将制成的均聚物、共聚物在不同条件下(改变反应时间、反应温度及不同溶剂)与三氯化磷反应,然后用醋酸分解,得到α-羟基二元磷酸,在室温(20℃)反应24小时,可得稳定的磷含量及交换量;温度升高,(不超过75℃)反应速度加快。用高介电常数溶剂及混合溶剂,能得到较高磷含量及交换量的产品。 由于均聚物及共聚物的磷化反应不完全,同时所存在的羰基能起Cannizzaro反应,故磷化物     

尼龙6升温过程的二维红外相关分析研究

通过二维红外相关分析来研究尼龙6在25～200℃范围内酰胺氢键和碳氢链段的结构变化．结果证明,尼龙6中酰胺氢键的吸收峰和主链上亚甲基的伸缩振动对于温度变化所导致的结构变化是十分敏感的,因此可以通过对二维红外相关谱图的分析,确定尼龙6在升温过程中酰胺氢键的解离和碳氢链段结构变化的先后顺序．     

酸性条件下脲醛树脂中不稳定结构的研究

通过较强酸性介质中尿素和甲醛的反应, 在不同条件下合成了透明的脲醛树脂溶液, 利用液体13C NMR研究了甲醛与尿素摩尔比对最终树脂中不稳定结构的影响.     

Thermal behavior of modified urea–formaldehyde resins

The thermal stability of pure urea–formaldehyde resin (PR) and modified urea–formaldehyde (UF) resins with hexamethylenetetramine-HMTA (Resin 1), melamine-M (Resin 2), and ethylene urea (EU, Resin 3) including nano-SiO₂ was investigated by non-isothermal thermo-gravimetric analysis (TG), differential thermal gravimetry (DTG), and differential thermal analysis (DTA) supported by data from IR spectroscopy. Possibility of combining inorganic filler in a form of silicon dioxide with UF resins was found investigated and percentage of free formaldehyde was determined. The shift of DTG peaks to a high temperature indicates the increase of thermal stability of modified UF resin with EU (Resin 3) which is confirmed by data obtained from the FTIR study. The minimum percentage (6%) of free formaldehyde was obtained in Resin 3.     

Melamine–formaldehyde resins: Constitutional characterization by fourier transform 13C-NMR spectroscopy

The random chemical structures of melamine–formaldehyde resins, including methylated melamine–formaldehyde resins and urea–melamine formaldehyde resins, were investigated by ¹³C-NMR spectroscopy (Fourier transform). All the combined formaldehydes, methylol and methyl ether groups, methylene structures, and dimethylene ether structures were assigned. A ¹³C chemical shift of methylene carbon occurred by substitution of other constituents of the methylene group for a proton of the adjacent monosubstituted nitrogen atom, as shown in a ¹³C-NMR spectrum of urea–formaldehyde resins. It was found that the chemical shift of each corresponding carbon of both melamine resins and urea–melamine resins was almost superimposed with that of urea resins.     

Synthesis and Characterization of Poly（ether amide）s Containing Bisphthalazinone and Ether Linkages

A novel aromatic diacid, 4, 4′-bis[2-(4-carboxyphenyl)phthalazin- 1-one-4-yl]-bisphenyl ether III, containing bisphthalazinone and ether linkages was prepared from nucleophilic substitution of p-chlorobenzonitrile with the bisphenol-like monomer I, followed by alkaline hydrolysis of the intermediate dinitrile II. A series of poly(ether amide)s containing bisphthalazinone and ether linkages derived from diacid III and aromatic diamines were synthesized by one-step solution condensation polymerization using triphenyl phosphite and pyridine as condensing agents. Moreover, the properties of poly(ether amide)s including thermal stability,solubility and crystallinity were also studied.     

Urea-formaldehyde resins characterized by thermal analysis and FTIR method

Urea-formaldehyde (UF) resins are the most used polycondensation resins today, in manufacturing particleboards. UF resins possess some advantages such as fast curing, good performance in the panel, water solubility and low price. However, the main chemical bonds of the UF resins macromolecules are hydrolysis sensitive. This causes low water and mositure resistance performance and subsequent formaldehyde release from the UF-bonded panels. A multitude of pathways have been explored for the improvement of UF resins’ behavior relating either to their synthesis procedure or application parameters during panel manufacture. In this study, two UF resins (a conventional and an innovative one produced at very low pH and temperature conditions) were analyzed for their specifications and characterized with TG-DTA technique in dynamic heating conditions and FTIR measurements both in their pre-polymer and cured state.     

Thermal behaviour of hydroxymethyl compounds as models for adhesive resins

Urea–formaldehyde (UF) and phenol–formaldehyde (PF) resins are the most widely used wood adhesives. The first stage in resin manufacturing is the formation of methylol derivatives which polycondensation leads to building the tridimensional network. Understanding the behaviour of methylol compounds in curing provides useful information for developing appropriate resin structures. Thermal behaviour of N,N′-dihydroxymethylurea, 2- and 4-hydroxymethylphenols, urea and phenol as model compounds for UF, PF and phenol–urea–formaldehyde (PUF) resins was followed by TG-DTA method. The measurements were carried out by the labsys instrument Setaram at 30–450 °C in nitrogen flow. The characteristic signals for model compounds and for some reaction mixtures were measured by high resolution ¹³C NMR spectroscopy.     

木质素对木质素-脲醛共聚树脂的影响及反应机理

通过调控甲醛与尿素摩尔比, 降低脲醛树脂胶黏剂中游离甲醛的含量, 以生物质玉米芯为原材料, 用碱液提取得到的碱木质素溶液与甲醛和尿素进行三元逐步共聚, 弥补降低醛脲比带来的胶合强度的快速下降问题. 以降低游离甲醛含量同时兼顾胶合强度为原则进行探索, 得到最佳实验条件为甲醛与尿素摩尔比(F/U)为0.91∶1, 木质素添加量为20%(质量分数), 在此条件下木质素-尿素-甲醛共聚树脂(LUF)胶合强度为0.99 MPa, 游离甲醛含量为0.26%. 对共聚树脂进行了结构表征, 表明木质素参与到反应中, 并能提高树脂的热稳定性和耐水性, 同时对反应的机理进行了讨论.     

Structural characteristics of p‐t‐Octylphenol formaldehyde resole resins using molecular simulation

p‐t‐Octylphenol formaldehyde resole resins have two linkage types of methylene‐ and dimethylene ether‐linkages and have three terminal types of hydrogen, methylol, and o‐methylene quinone. Variation of structural characteristics of the resins due to different types of linkages and terminals were studied using molecular dynamics and molecular mechanics. The structural characteristics of the methylene‐bridged resins were intramolecular hydrogen bonds between hydroxyl groups of the adjacent p‐t‐octylphenols. In the dimethylene ether‐bridged resin, the intramolecular hydrogen bonds between oxygen atoms of the dimethylene ether‐linkages and hydroxyl groups of the neighboring phenolic units were found. For the resins with both methylol terminals, one of both terminals of the resins was hidden at the center of the molecule when the resin size is large. The number of hydrogen bonds in the resins with the methylol terminal was larger than for the resins with the o‐methylene quinone terminal. Variation of the structural characteristics of the resins by dehydration of the terminal methylol was discussed. Using the calculated results, dissociation of the dimethylene ether linkage and crosslinking reaction of rubber chains by the resin were explained. Copyright © 2002 John Wiley & Sons, Ltd.     

Synthesis and self-assembly of an amino-functionalized hybrid hydrocarbon/fluorocarbon double-chain phospholipid

In this article, we designed and synthesized an amino-functionalized hybrid hydrocarbon/fluorocarbon double-chain phospholipid (ACFPC) containing one chain with the hydrophobic fluorocarbon chain and terminal amino, amide, and ether linkages and one chain with the hydrocarbon chain. The novel reactive phospholipid was fully characterized with Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and mass spectrometry (MS). Then the self-assembly behaviors of the hybrid double-chain phospholipid in aqueous and acidic media were investigated with transmission electron microscopy (TEM), the critical micelle concentration (cmc), dynamic light scattering (DLS), and the hydrocarbon double-chain phospholipid (ACCPC) for comparison. Moreover, their self-assembled structures in aqueous and acidic media were simulated using the dissipative particle dynamics (DPD) method. These results suggest that the fluorocarbon/hydrocarbon hybrid-chain phospholipid can self-assemble into a more stable microstructure compared to the double hydrocarbon chain phospholipid, which will have the potential ability to self-assemble into a more stable minicking biomembrane structure onto material surfaces to inhibit protein adsorption under complicated physiological conditions.     

Introducing flexibility in urea–formaldehyde resins: Copolymerization with polyetheramines

Adhesives obtained by copolymerizing urea, formaldehyde, and difunctional polyetheramine with different molecular weights (230, 600, 900, and 2000 g mol⁻¹) are presented as a more resilient alternative to conventional urea–formaldehyde resins. Urea and polyetheramine contents were varied and the resulting resins characterized by FTIR, ¹³C‐NMR, and TGA. These resins were used for production of agglomerated cork panels, an application that demands that the binder system is flexible. Polyetheramine with molecular weight 900 g mol⁻¹ yielded the most promising agglomerated cork panel, with remarkable flexibility, good tensile strength, and with the E1 formaldehyde content specification for wood‐based panels used in construction, according to European Standard EN 12460‐5. These new thermoset adhesives have demonstrated to be capable of being used in systems where conventional formaldehyde‐based resins do not perform well due to inherent high rigidity. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1834–1843