氨酯改性聚异氰脲酸酯体系反应动力学

氨酯改性聚异氰脲酸酯体系反应动力学;FTIR; 氨酯; 聚异氰脲酸酯; 反应动力学     

乳酸酯氧化脱氢制备丙酮酸酯的研究进展

生物质资源替代化石资源制取燃料和化学品已成为发展可再生能源化工的重要研究方向之一。本文综述了近年来以生物质平台分子乳酸酯为原料制备丙酮酸酯的研究工作,主要涉及的反应包括气相催化反应、液相催化反应和光催化反应。详细讨论了各种类型的催化剂对反应性能的影响;最后,对乳酸酯催化转化制取丙酮酸酯的发展前景进行了展望。     

薄层扫描法测定蔗糖脂肪酸酯中的各组成酯

 建立了蔗糖脂肪酸酯中一酯～三酯的薄层分离定性及薄层扫描定量方法。以氯仿 甲醇 醋酸 水 (体积比为 80∶1 0∶8∶1 )为展开剂 ,双波长反射法锯齿扫描 ,测定波长为 530nm ,参比波长为 70 0nm ,线性范围为 4μg～60 μg ,相关系数为0 9940～ 0 9980 ,平均回收率为 96 45%～ 98 73% (RSD为 2 8%～ 3 3% ,n =3)。方法可靠 ,数据准确 ,操作简便易行 ,线性范围宽。     

反丁烯二酸酯的自由基共聚反应

<正> 对反丁烯二酸酯(DRPs)类单休的均实反应研究已有许多报道。研究结果表明,所有的正烷基酯基DRFs单体,如反丁烯二酸二王丙酯等,均表现出很低的聚合反应活性,因而得不到高分子量的均聚物;而某些非正烷基酯的DRFs单体,如反丁烯二酸二异丙酯则显示出很高的聚合反应活性并可形成高分子量的聚合物。对反丁烯二酸酯同其他乙烯类单体(如苯乙烯等)的共聚研究曾有一些报道,但对DRFs单体之间的共聚     

新型非酯型拟除虫菊酯的合成

传统拟除虫菊酯类杀虫剂均含有一个酯基^[1,2],近年来,在保持分子整体空间结构不变的情况下,用其它功能基替换酯基,合成了非酯型的拟除虫菊酯^[3],式1所示结构的化合物具有良好的生物活性^[4],其中碳碳键或碳氧键 取代了传统拟除虫菊酯中的酯基,在主链结构上含有偕二甲基和3－苯氧基苯基,二是该结构中决定生物活性的主要基因^[5,6],在此结构的基础上已醚菊酯^[6],烃菊酯^[4]和酮菊酯^[7]等高效低毒,结构简化的除除虫菊酯类杀虫剂,而醚菊酯MTI－800已商品化,作为式1所示结构 新尝试,我们在保留2在性部分外,用环戊烯基取代直链烯烃,合成了一种非酯型的拟除虫菊酯（即1－甲基－1－苯基－1－[3-（3－苯氧基）苯基]环戊烯基－乙烷）（9）,其合成路线如式2。     

氟聚合物改性聚丙烯酸酯乳液的制备

氟聚合物改性聚丙烯酸酯乳液的制备;氟改性;聚四氟乙烯;聚丙烯酸酯乳液     

氢醌单丙酸酯的改进合成

氢醌单丙酸酯的改进合成马美玲（西安地质学院应用化学系，西安７１００５４）邓月松谢明贵（四川大学化学系，成都６１００６４）关键词除色素剂氢醌单羧酸酯氢醌单丙酸酯中图分类号Ｏ６２５．３２３氢醌单脂肪酸酯是一类很好的皮肤去色素剂，其中尤以氢醌单丙酸酯为最佳...     

亚磷酸三月桂醇酯的合成

亚磷酸三月桂醇酯的合成;亚磷酸三月桂醇酯;月桂醇;三氯化磷;吡啶;苯     

超高效液相色谱-串联四极杆质谱法测定葡萄中单咖啡酰酒石酸酯、单香豆酰酒石酸酯和单阿魏酰酒石酸酯

建立了超高效液相色谱-串联四极杆质谱测定葡萄汁、皮和籽中羟基桂皮酒石酰酯类化合物含量的方法。采用的色谱柱为Waters UPLC HSS T3 (150 mm×2.1 mm, 1.7 μm),流动相为含0.1%甲酸的水-乙腈体系,梯度洗脱,流速0.3 mL/min,柱温35 ℃;质谱采用电喷雾离子源、负离子多反应检测模式。对单香豆酰酒石酸酯和单阿魏酰酒石酸酯,其含量以单咖啡酰酒石酸酯当量表示。结果表明,单咖啡酰酒石酸酯在25～2000 μg/L范围内线性关系良好(r2=0.9989);检出限为0.25 μg/L,定量限为25 μg/L;在250、750、1200 μg/L添加水平下单咖啡酰酒石酸酯的平均回收率为97.7%～99.5%,相对标准偏差小于2.5%。实验结果表明,葡萄汁、皮和籽中羟基桂皮酒石酰酯类化合物的含量差异显著。该方法简单快速、灵敏度高、回收率高、准确性好,可用于葡萄产品中单咖啡酰酒石酸酯、单香豆酰酒石酸酯和单阿魏酰酒石酸酯的分析。     

荧光素酯与蒽甲酸酯之间的光致相互作用

我们合成了以不同链长连接的荧光素酯与蒽甲酸酯的四种二元化合物.在溶液中的构象研究表明.链呈不同程度的弯曲.但分子内两个发色团的相互作用是微弱的.激发蒽甲酸酯时,无论是在分子间还是在分子内,其单重态能量几乎都传递给了荧光素酯.激发荧光素酯时,并未观测到分子内的光致电子转移,尽管计算和模型化合物分子间的对照实验都表明它们之间是可以发生这种电子转移的.最可能的原因是这个系列在溶液中,分子内的两个发色平面没有好的匹配,或者说,这些二元化合物在所研究的溶液中,不能满足分子内的光致电子转移对构象的要求.     

淀粉与聚丁二酸己二醇酯的反应及其生物降解性研究

合成了一种新型的完全生物降解型材料－淀粉－聚丁己二醇酯共聚物，对影响聚丁二酸己二醇酯的分子量及淀粉与聚丁二酸己二醇酯反应接枝率的主要因素进行了研究，当聚丁二酸己二醇酯酰氯化物与淀粉投料重量比为４：１时，聚酯的接枝率达到３８．２０％，接枝共聚物用枯草芽孢杆菌和金黄色葡萄球菌降解４０ｄ，其失重率达８９．６０％，在土壤中堆埋９０ｄ，接枝共聚物基本完全被降解。     

新型温度敏感性自组装胶束P(NiPAAm-co-DMAA)-co-P(L-Ala)的合成和性能

通过原子转移自由基聚合(ATRP)合成了一种带有活性—NH2基团的温度敏感性亲水型共聚物P(NiPAAm-co-DMAA), 并将其作为引发剂, 合成了P(NiPAAm-co-DMAA)-co-P(L-Ala), 其分子量分布(PDI)在1.3左右. 聚合物通过自组装形成纳米胶束. 透射电镜(TEM)结果表明, 胶束大小200~300 nm, 具有明显的核壳结构. 共聚物的最低临界溶解温度(LCST)为45.5 ℃. 温度低于LCST时, 聚合物溶解形成胶束; 高于LCST时, 胶束解离, 聚合物不溶. 聚合物对温度的响应是快速而可逆的.     

Hydrolytic degradation of poly(ε‐caprolactone) with different end groups and poly(ε‐caprolactone‐co‐γ‐butyrolactone): characterization and kinetics of hydrocortisone delivery

Asymmetric telechelic α‐hydroxyl‐ω‐(carboxylic acid)‐poly(ε‐caprolactone) (HA‐PCL), α‐hydroxyl‐ω‐(benzylic ester)‐poly(ε‐caprolactone) (HBz‐PCL), and an asymmetric telechelic copolymer α‐hydroxyl‐ω‐(carboxylic acid)‐poly(ε‐caprolactone‐co‐γ‐butyrolactone) (HA‐PCB) were synthesized by ring‐opening polymerization of ε‐caprolactone (CL). CL and CL/γ‐butyrolactone mixture were used to obtain homopolymers and copolymer respectively at 150°C and 2 hr using ammonium decamolybdate (NH₄) [Mo₁₀O₃₄] (Dec) as a catalyst. Water (HA‐PCL and HA‐PCB) or benzyl alcohol (HBz‐PCL) were used as initiators. The three polylactones reached initial molecular weights between 2000 and 3000 Da measured by proton nuclear magnetic resonance (¹H‐NMR). Compression‐molded polylactone caplets were allowed to degrade in 0.5 M aqueous p‐toluenesulfonic acid at 37°C and monitored up to 60 days for weight loss behavior. Data showed that the copolymer degraded faster than the PCL homopolymers, and that there was no difference in the weight loss behavior between HA‐PCL and HBz‐PCL. Caplets of the three polylactones containing 1% (w/w) hydrocortisone were placed in two different buffer systems, pH 5.0 with citrate buffer and pH 7.4 with phosphate buffer at 37°C, and monitored up to 50 days for their release behavior. The release profiles of hydrocortisone presented two stages. The introduction of a second monomer in the polymer chain significantly increased the release rate, the degradation rate for HA‐PCB being faster than those for HBz‐PCL and HA‐PCL. At the pH studied, only slight differences on the liberation profiles were observed. SEM micrographs indicate that hydrolytic degradation occurred mainly by a surface erosion mechanism. Copyright © 2009 John Wiley & Sons, Ltd.     

Bioartificial materials based on blends of dextran and poly(vinyl alcohol-co-acrylic acid)

Bioartificial polymeric materials based on blends of dextran and poly(vinyl alcohol-co-acrylic acid) P(VA-co-AA) were prepared in the form of films and characterised to evaluate the miscibility of the natural component with the synthetic one. The idea of this work was to compatibilise PVA and dextran by introducing carboxylic groups along the PVA chains.The copolymer was synthesised and characterised in our laboratories. The results evidenced that the copolymer had an appropriate molecular weight and the content of PAA in the copolymer was 45% (weight). Then, films with different composition ratios were prepared by solution casting and analysed by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), chemical imaging analysis and mechanical tests. The results obtained indicated that the introduction of carboxylic groups along the PVA chains had a positive effect on the miscibility degree of the synthetic component with the biological one.     

Electrospinning of Hyaluronic Acid (HA) and HA/Gelatin Blends

Summary: In the present study, electrospinning of hyaluronic acid (HA) and hyaluronic acid/gelatin (HA‐GE) blends in N,N‐dimethylformamide (DMF)/water‐mixed solvents have been investigated. When the volume ratio of DMF to water was in the range of 1.5–0.5, HA solutions could be electrospun into fibrous membranes successfully. The average diameter of HA fibers was about 200 nm. The HA‐GE composite nanofibrous membranes with varied HA/GE weight ratio in the range of 100/20–100/100 have also been successfully fabricated. The average diameter of HA‐GE fibers was in the range of 190–500 nm. The decrease in surface tension could promote fiber formation. Thus, an introduction of DMF that could decrease the surface tension distinctively, without significant change or increase in viscosity of the solution, could bypass the use of blowing‐assisted electrospinning. Our postulated picture is that the lower surface tension could help the ejection of stream with relatively high viscosity and reduce or prevent the droplet formation during the spinning process.

HA/GE (100/80) nanofibrous membrane produced by electrospinning.     

具有电活性苯胺四聚体接枝聚谷氨酸的合成与表征

以N-羟基琥珀酰亚胺(NHS)活化聚L-谷氨酸的羧基并与苯胺四聚体的氨基缩合,得到了以可生物降解的聚谷氨酸为主链,具有电活性的苯胺四聚体为侧链的新型接枝聚合物.用1H-NMR、质谱分析、光谱分析的方法确定了化合物的结构.侧链羧基的存在使聚合物可以溶解于碱性的缓冲溶液中.对聚合物的电化学性质进行了紫外及循环伏安的表征,研究结果表明,接枝后的聚合物具有与苯胺低聚体相似的可逆的氧化还原过程并可被质子酸掺杂,表现出良好的电化学活性.同时,以定量紫外吸收及元素分析的方法分别测定了聚合物的接枝率.实验中通过控制反应的投料比可以使苯胺四聚体的接枝率达到40%以上,并对聚合物的自掺杂现象进行了讨论.     

Miscibility of poly(ϵ-caprolactone) and of poly(styrene-co-acrylonitrile) with poly(styrene-co-acrylic acid)

The miscibility of poly (?-caprolactone) (PCL) with poly (styrene-co-acrylic acid) (SAA) and of poly (styrene-co-acrylonitrile) (SAN) with SAA was examined as a function of the comonomer composition in the copolymers. For PCL/SAA blends it was found that PCL is miscible with SAA within a specific range of copolymer compositions. Segmental interaction energy densities were evaluated by analysis of the equilibrium melting point depression and application of a binary interaction model. The results suggest that the intramolecular repulsion in SAA copolymer plays an important role in inducing the miscibility. Additionally, the critical AA content in SAA for the blend to be homogeneous was predicted by correlating the segmental interaction energy densities with the binary interaction model. For SAN/SAA blends, it was also found that SAA is miscible with SAN within a specific range of copolymer compositions. From the binary interaction model, segmental interaction energy denisties between different monomer units were estimated from the miscibility map and were found to be positive for all pairs, indicating that the miscibility of the blends is due to the strong repulsion in the SAA copolymers.     

Mechanochemical synthesis of poly(butadiene-b-acrylic acid)

The preparation of block copolymer with polybutadiene, respectively poly(acrylic acid) sequences, using mechanochemical methods was investigated. The synthesis involves the generating of polybutadiene macroradicals, by ultra-high speed stirring of the polymer in toluene solution. The macroradicals are capable to initiate the polymerization of acrylic acid present in the reaction medium, leading to block copolymer formation. The influence of different parameters, such as temperature, duration, acrylic acid/polybutadiene molar ratio, on the yield and composition of the synthesized copolymer was studied.     

模板聚合法合成P(AM/AA)多嵌段共聚物的溶液性质和自缔合作用

研究了模板法合成多嵌段状丙烯酰胺(AM)和丙烯酸(AA)共聚物(简称模板共聚物TP)在水溶液中的溶液性质和缔合作用.结果表明,模板共聚物具有明显的结构效应.不同于无模板参与聚合的无规共聚物(CP),模板共聚物随着溶液pH的降低或加入多价金属离子容易发生相分离.透射电子显微镜(TEM)表明,加入Ca2+离子后,聚合物形成了大的分子间交联体,且随着Ca2+离子浓度的增加,交联程度增加,致使溶液产生相分离.随着溶液pH的升高,模板共聚物溶液粘度变化与丙烯酸均聚物具有相同的规律,都是先增大后减小,粘度有一个最大值,但模板共聚物溶液粘度升高幅度更大.TEM表明在粘度最大处形成了带状分子间缔合体.     

Characterisation of Hyaluronic Acid Blends Modified by Poly(N-Vinylpyrrolidone)

The viscosity behaviour and physical properties of blends containing hyaluronic acid (HA) and poly(N-vinylpyrrolidone) (PVP) were studied by the viscometric technique, steady shear tests, tensile tests and infrared spectroscopy. Viscometric and rheological measurements were carried out using blends of HA/PVP with different HA weight fractions (0, 0.2, 0.5, 0.8 and 1). The polymer films and HA/PVP blend films were prepared using the solution casting method. The study of HA blends by viscometry showed that HA/PVP was miscible with the exception of the blend with high HA content. HA and its blends showed a shear-thinning flow behaviour. The non-Newtonian indices (n) of HA/PVP blends were calculated by the Ostwald–de Waele equation, indicating a shear-thinning effect in which pseudoplasticity increased with increasing HA contents. Mechanical properties, such as tensile strength and elongation at the break, were higher for HA/PVP films with w_HA = 0.5 compared to those with higher HA contents. The elongation at the break of HA/PVP blend films displayed a pronounced increase compared to HA films. Moreover, infrared analysis confirmed the existence of interactions between HA and PVP. The blending of HA with PVP generated films with elasticity and better properties than homopolymer films.