一种带疏水长链的水溶性偶氮引发剂的合成及端基疏水聚合物疏水缔合效应研究

以偶氮二异丁腈、十二胺为主要原料,通过Pinner反应制备了一种两端各带有12个碳烷基链的水溶性偶氮引发剂——2,2'-偶氮二异丁基十二脒盐酸盐AIBL.采用核磁氢谱、元素分析及液相色谱对AIBL进行了结构及纯度表征,采用TGA、DSC和紫外分光光度计研究了其热分解现象和热分解动力学,采用表面张力仪对其表面活性进行了测定.结果表明,所合成的引发剂AIBL具有预想的结构和较高的纯度,其热分解反应属于一级反应,热分解活化能为134.80 k J/mol,70℃下水中的半衰期约为4 h;AIBL在水溶液中具有表面活性,其临界胶束浓度为0.13 g/L,对应的表面张力为33.57 m N/m.以丙烯酰胺为单体、AIBL为引发剂制备了水溶性端基疏水聚合物SPAM.采用溴化法研究其转化率,应用乌氏黏度法、零切黏度法以及荧光探针对其缔合作用进行了研究.结果表明,AIBL具有良好的引发丙烯酰胺聚合的能力;相对于不带疏水长链的引发剂所合成的聚合物PAM,SPAM具有明显的疏水缔合效应,这说明AIBL成功地将疏水长链引入到聚合物的端基中,从而形成端基疏水聚合物.     

Control of Batch Polymerizations by Continued Feed

The conventional kinetic scheme for a free-radical homopolymerization is modified to incorporate dilution by a feed stream and the effect of propagation on solution density. Neglect of the volume change can result in prediction of erroneously high conversions. The distribution of average molecular weight fractions is evaluated. In the absence of gelation and transfer reactions, the broadening, which is usually thought to arise from varying composition, is found to be small compared to that which is intrinsic to the addition mechanism.     

醋酸乙烯酯种子乳液聚合动力学研究

用装有红外跟踪器和计算机记录监控系统的膨胀计进行了醋酸乙烯酯的种子乳液聚合。聚合直接从乳液聚合的阶段Ⅱ开始，避开了复杂的成核阶段和成核阶段粒度变化对动力学参数的影响。在引发剂浓度５．０３０×１０＾－５￣１．００２×１０＾－３ｍｏｌ／Ｌ范围内，依据转化率随时间的变化关系，求出了准稳态聚合速率、自由基进入乳胶粒子的速率、自由基从乳胶粒子解吸的速率和ｋｐｎ＾－。结果表明：聚合速率、自由基进入乳胶粒子的速     

Unsymmetrically substituted ethane as a new and efficient initiator for the polymerization of methyl methacrylate and styrene

In this paper, we present a compound, 2,3-diphenyl butyronitrile (DPBN), which can be used as a new and efficient radical initiator for the polymerization of methyl methacrylate (MMA) and styrene (St). Very different from other compounds as a carbon-carbon initiator, DPBN is an unsymmetrically substituted ethane and works with high initiation reactivity at lower temperatures. This new compound as an initiator exhibits various advantages, such as easy preparation, high initiation reactivity, safe use and storage, and convenient handling.     

光缆弯曲对激光能量传输效率的影响

研究了激光火工品系统中光缆弯曲对激光能量传输效率的影响.对7种不同规格光缆在弯曲半径R为2.5~175 mm范围内的弯曲传输特性进行了试验研究.结果表明,R/2a＜50 时,透光量已开始下降;R/2a≈20 时,激光能量传输效率明显下降.根据实验结果,通过数据拟合处理得出了7种规格光缆弯曲损耗的半经验公式,该公式可以直接用于激光火工品系统光缆的传输设计.     

How the interplay of different control mechanisms affects the initiator efficiency factor in controlled radical polymerization: An investigation using organometallic Mo-based catalysts

Compound CpMoI₂(iPr₂dad) (iPr₂dad = iPrNCHCHNiPr), obtained by halide exchange from CpMoCl₂(iPr₂dad) and NaI, has been isolated and characterized by EPR spectroscopy, cyclic voltammetry, and X-ray crystallography. Its action as a catalyst in atom transfer radical polymerization (ATRP) and as a spin trap in organometallic radical polymerization (OMRP) of styrene and methyl acrylate (MA) monomers has been investigated and compared with that of the dichloro analogue. Compound CpMoCl₂(iPr₂dad) catalyzes the ATRP of styrene and MA with low efficiency factors f (as low as 0.37 for MA and ethyl 2-chloropropionate as initiator), while it irreversibly traps the corresponding growing radical chains under OMRP conditions. On the other hand, compound CpMoI₂(iPr₂dad) has a greater ATRP catalytic activity than the dichloro analogue and yields f = 1 for MA and ethyl 2-iodopropionate as initiator. Under OMRP conditions, it does not irreversibly trap the growing radical chains. This comparison serves to illustrate the general principle that low initiator efficiency factors, sometimes observed in ATRP, may result from the interplay of the ATRP and OMRP mechanisms, when the latter ones involves an irreversible radical trapping process.     

双官能度引发剂引发苯乙烯聚合微观动力学

采用 2 ,5 二甲基 2 ,5 二己酰基过氧化己烷 (DMDEHPH)为引发剂 ,在 5 5～ 80℃下引发苯乙烯聚合 .通过研究影响聚合速率的各种因素 ,得出了聚合速率对单体浓度和引发剂浓度的级数分别为 1 0和 0 5次、聚合活化能为 92 0kJ mol、引发效率为 0 5 5± 0 0 3.温度一定 ,引发效率随引发剂浓度的增加而减小 .求得 6 0和70℃下DMDEHPH向引发剂的链转移常数分别为 0 0 37和 0 0 4 8、向单体的链转移常数分别为 0 5 9× 10 - 4和0 75× 10 - 4.     

二苯甲酮／胺：紫外光固化涂料中的新型引发剂

通过三羟甲基丙烷三丙烯酸酯与二乙胺的迈克尔加成反应,合成了一种新型叔胺衍生物,利用＾１Ｈ ＮＭＲ对其进行了验证。当该叔胺与二苯甲酮配合使用时,表现出很好的固化速度并能代替昂贵的光引发剂１１７３,使紫外光固化涂料的成本显著降低。同时,对该二苯安双分子引发剂的作用机理进行了探讨。     

腐植酸对丙烯酰胺溶液聚合的影响

<正> 六十年代以来,苏联发表了一系列文献,涉及乙烯基单体与腐植酸聚合制造土壤改良剂和钻井泥浆处理剂,但就一些基本问题未见阐述,诸如:(1)腐植酸中的多官能及含有的自由基对烯类单体自由基聚合的影响;(2)腐植酸与单体的接枝效率及腐植酸与单体接枝聚合机理;(3)接枝共聚物与共混物在性能上的差异,本文针对上述第一个问题进行了研究。采用膨胀计法研究了在不同类型煤炭腐植酸存在下,过硫酸钾引发丙烯酰胺溶液的聚合反应动力学。     

Characteristic shrinkage evaluation of photocurable materials

Photocurable materials have many advantages such as rapid curing, low energy consumption and a broad variety of favorable characteristics; as a result, their application areas are currently expanding. In order to fully utilize the properties of these materials, the related “shrinkage” problem (corresponding to the specific volume reduction due to the reaction between monomer species) must be resolved first. In this study, we investigated the dependence of the linear shrinkage of a monomer in the axial direction on various internal and external factors. In addition, a complementary relationship describing the photocuring behavior of a polymer was studied by photo-differential scanning calorimetry (photo-DSC). The observed shrinkage characteristics depend on the monomer size and structure, UV radiation intensity and photoinitiator concentration. In contrast to the photo-DSC results, the monomer shrinkage parameters are related to the bulk properties of a material. Hence, the dependence of the material depth profile on external factors was evaluated.