光致聚合物中单体及粘结剂对全息性能的影响

研究了单体及粘结剂等成份对全息光致聚合物薄膜光存储性能的影响。在相同引发条件下．以丙烯酰胺作为单体时，光聚物的衍射效率明显高于以丙烯酸和N羟甲基丙烯酰胺作为单体时光聚物的衍射效率。向丙烯酰胺中加入少量N-羟甲基丙烯酰胺，可以改善膜表面的光学质量．降低散射光强度，并提高膜的保存时间。在聚乙烯醇膜中单体聚合程度明显优于在聚乙烯吡咯烷酮中的程度，在大分子量的聚乙烯醇中的衍射效率及感光灵敏度高于在小分子量中的衍射效率和感光灵敏度，而且大分子量的聚乙烯醇能够制备厚膜，这是实现全息海量存储的一个重要因素。

Spectroscopic and structural properties of YbF3-doped fluorophosphate glasses

Compositional influences on the spectroscopic properties of Yb3+ and the structural variations with the introduction of YbF3 were studied in fluorophosphate glasses. Emission cross-section (sigma(emi)) and gain coefficient (sigma(emi) x tau(f)) were calculated which exhibit maximum at RF2 = 33 mol%. YbF3 has an important effect on the glass forming ability of fluorophosphate glasses when RF2 is over 36 mol%. The study of Raman spectra showed big differences on the glass structure between non-Yb3+ and Yb3+ -doped glasses. The main building units in Yb3+-doped samples are metaphosphate groups, pyrophosphate groups (P-2(O,F)(7), PO3F), Al[F-6] +Al[O,F](6) and F3Al-O-AlF3 while those of the non-Yb3+-doped glasses are monophosphate group P(O,F)(4), little pyrophosphate group, Al[F-4] + Al[F-6] + Al[O,F](4) + Al[O,F](6) and F3Al-O-AlF3, which means Yb3+ ions contribute to a better glass polymerization and network uniformity. (C) 2004 Elsevier B.V. All rights reserved.

Special effects of YbF3 on the structural changes for fluorophosphate glass

From Raman and IR spectra, obvious differences of the glass structure were observed in non-Yb3+-doped and Yb3+ -doped fluorophosphate glasses. Results showed that Yb3+ ions can induce, in a better glass, polymerization and network uniformity. Compared with the monophosphate-mastered Yb3+-free glass, Yb3+-doped glass has a pyrophosphate environment. The main building blocks in Yb3+ -doped samples are metaphosphate groups, pyrophosphate groups (P-2(O,F)(7),PO3F), Al[F-6]+Al[O,F](6) and F3Al-O-AlF3 while those of the Yb3+ -free glasses are monophosphate groups P(O,F)(4), little pyrophosphate groups, Al[F-4]+Al[F-6]+Al[O,F](4)+Al[O,F](6) and F3Al-O-AlF3. The DSC analysis also showed a slight increase in crystallization stability. (c) 2005 Elsevier B.V. All rights reserved.

Extraction of genomic DNA using a new amino silica monolithic column

A new amino silica monolithic column was developed for DNA extraction in a miniaturized format. The monolithic column was prepared in situ by polymerization of tetraethoxysilane (TEOS) and N-(beta-aminoethyl)-gamma-aminopropylmethyldimethoxysilane (AEAPMDMS). DNA was loaded in 50 mM tris(hydroxylmethyl)aminomethane-EDTA buffer at pH 7.0 and eluted with 300 mM potassium phosphate solution at pH 10.0. Under optimal condition, a 6.0-cm monolithic column provided a capacity of 56 ng DNA with an extraction efficiency of 71 +/- 5.2% (X +/- RSD). When the amino silica monolithic column was applied to extract genomic DNA from the whole blood of crucian carp, an extraction efficiency of 52 +/- 5.6% (X +/- SD) was obtained by three extractions. Since the chaotropic-based sample loading and organic solvent wash steps were avoided in this procedure, the purified DNA was suitable for downstream processes such as PCR. This amino silica monolithic column was demonstrated to allow rapid and efficient DNA purification in microscale.

Effects of cell-cycle arrest agents on cleavage and development of loach (Misgurnus anguillicaudatus) embryos

The aim of this study was to determine the lowest concentration of nocodazole and colchicine to arrest blastomere division during the cleavage stage of loach embryos and to assess the reversibility and toxicity of the treatments in the treated embryos. Eight-cell loach embryos were incubated for 4, 8, 12, or 16 h in 1/10x Holtfreter supplemented with either nocodazole, an inhibitor of tubulin polymerization, or colchicine, an inhibitor of tubulin assembly. Complete arrest of cell cycle was observed, at a colchicine concentration of 0.996 mM and at a nocodazole concentration of 0.275 muM, respectively (the lowest effective concentration). No major morphological alteration in chromatin was observed. Reversibility and toxicity of both agents were dose and exposure period dependent. For both agents, prolonging cleavage arrest for more than 4 h (at the effective concentrations) is detrimental to development of embryos. Nocodazole treatment was less cytotoxic, whereas the concentrations of colchicine which induce cleavage arrest were detrimental to development beyond the blastula stage. Toxic effects beyond the blastula stage could be minimized for both agents by reducing the period of treatment and concentration.

Assembly of side-functional monomers with inorganic nanometer particles

Monomers of methacrylate with various pi -conjugated pendants were designed and prepared in our laboratory, The monomer with suitable end-group was successfully assembled with nano-scale inorganic particles to form an orderly-aligned structure that showed special optical properties, both absorption and emission band were much red-shifted compared with the monomer, A new type of organic/inorganic hybrid materials was obtained by in situ polymerization of the assembly, The hybrid materials could also show special optical properties as the assembly, This might open a new route to tune the emission color.

Synthesis and characterization of an active styrlthiophene monomer and its polyurethane with second-order optical nonlinearity

A novel monomer, (trans)-7-[4-N,N-(di-beta-hydroxyethyl) amino-benzene]-ethenyl-3,5-dinitrothiophene (HBDT), and the corresponding prepolymer, polyurethane were synthesized and characterized. The details of synthesis of the monomer and its further polymerization were presented. The prepolymer and polyurethane exhibited good thermal stability and good solubility in common organic solvents. The d(33) coefficient of the poled films was determined to be 40.3 pm/V. (C) 2000 Kluwer Academic Publishers.

On the acid-base stability of Keggin Al-13 and Al-30 polymers in polyaluminum coagulants

The acid-base stabilities of Al-13 and Al-30 in polyaluminum coagulants during aging and after dosing into water were studied systematically using batch and flow-through acid-base titration experiments. The acid decomposition rates of both Al-13 and Al-30 increase rapidly with the decrease in solution pH. The acid decompositions of Al-13 and Al-30 with respect to H+ concentration are composed of two parallel first-order and second-order reactions, and the reaction orders are 1.169 and 1.005, respectively. The acid decomposition rates of Al-13 and Al-30 increase slightly when the temperature increases from 20 to ca. 35 A degrees C, but decrease when the temperature increases further. Al-30 is more stable than Al-13 in acidic solution, and the stability difference increases as the pH decreases. Al-30 is more possible to become the dominant species in polyaluminum coagulants than Al-13. The acid catalyzed decomposition and followed by recrystallization to form bayerite is one of the main processes that are responsible for the decrease of Al-13 and Al-30 in polyaluminum coagulants during storage. The deprotonation and polymerization of Al-13 and Al-30 depend on solution pH. The hydrolysis products are positively charged, and consist mainly of repeated Al-13 and Al-30 units rather than amorphous Al(OH)(3) precipitates. Al-30 is less stable than Al-13 upon alkaline hydrolysis. Al-13 is stable at pH < 5.9, while Al-30 lose one proton at the pH 4.6-5.75. Al-13 and Al-30 lose respective 5 and 10 protons and form [Al-13] (n) and [Al-30] (n) clusters within the pH region of 5.9-6.25 and 5.75-6.65, respectively. This indicates that Al-30 is easier to aggregate than Al-13 at the acidic side, but [Al-13] (n) is much easier to convert to Alsol-gel than [Al-30] (n) . Al-30 possesses better characteristics than Al-13 when used as coagulant because the hydrolysis products of Al-30 possess higher charges than that of Al-13, and [Al-30] (n) clusters exist within a wider pH range.

Guiding mode in elliptical core microstructured polymer optical fiber

A kind of microstructured polymer optical fiber with elliptical core has been fabricated by adopting in-situ chemical polymerization technology and the secondary sleeving draw-stretching technique. Microscope photography demonstrates the clear hole-structure retained in the fiber. Though the holes distortion is visible, initial laser experiment indicates that light can be strongly confined in the elliptical core region, and the mode field is split obviously and presents the multi-mode characteristic. Numerical modeling is carried out for the real fiber with the measured parameters, including the external diameter of 150 pin, the average holes diameter of 3.3 mu m, and the average hole spacing of 6.3 mu m. by using full-vector plane wave method. The guided mode fields of the numerical simulation are consistent with the experiment result. This fiber shows the strong multi-mode and weak birefringence in the visible and near-infrared band, and has possibility for achieving the fiber mode convertors, mode selective couplers and so on.

Casting preforms for microstructured polymer optical fibre fabrication

A monolithic structured polymer preform was formed by in-situ chemical polymerization of high-purity MMA monomer in a home-made mould. The conditions for fabrication of the preforms were optimized and the preform was drawn to microstructured polymer optical fibre. The optical properties of the resultant elliptical-core fibre were measured. This technique provides advantages over alternative preform fabrication methods such as drilling and capillary stacking, which are less suitable for mass production. (c) 2006 Optical Society of America.

RAFT调控的丙烯腈可控/活性自由基聚合研究

可逆加成裂解链转移(RAFT)聚合已经成为高分子合成的研究热点之一，这是因为它同时具有自由基聚合和活性聚合的优点，能够有效控制分子量和分子量分布，反应条件温和，可用于本体、溶液、悬浮、乳液等体系，单体范围广，能够合成嵌段、接枝、支化等复杂结构的聚合物。在已经报道的丙烯腈RAFT聚合研究中，所得聚合物具有较窄的分子量分布，分子量接近理论预测值，然而，最高值只达到5000左右。本论文的研究工作正是从这一个基本问题展开的。 1. 利用三硫代碳酸二苄基酯代替二硫代羧酸酯作为链转移剂，降低中间态自由基断裂反应的活化能，保证活性态与休眠态之间的平衡以一较快的交换速率进行，聚合结果表明，在文献报道的反应条件下，聚合速率有了明显的提高，同时聚合以一种可控的方式进行，所得聚合物分子量最高达8000，且分子量分布较窄。 2. 将二硫代苯甲酸异丙腈酯调控的丙烯腈聚合实验参数优化，提高反应温度降低缓聚，选择碳酸乙二酯作为溶剂减小链转移反应，导致中间态自由基断裂反应的效率大大提高，以一种可控/活性自由基聚合方式进行，首次合成了分子量高达32800、分子量分布指数小于1.3的聚丙烯腈。 3. 由于RAFT试剂很难制备和长期保存，当以二硫代物作为替代的调控试剂, 偶氮二异丁腈作为引发剂，可以在“原位”合成RAFT聚合所需的链转移剂，直接调控丙烯腈的自由基聚合，得到高分子量、分子量分布指数比较小的丙烯腈均聚物和共聚物。 4. 将不对称的双乙烯基单体作为支化剂引入到丙烯腈聚合体系中，同时采用RAFT技术来抑制交联反应，单体转化率增加至较高值而不形成凝胶，1H NMR和凝胶渗透色谱证明了合成的聚合物具有支化结构，并且聚合物的特性粘数低于相近分子量的线性聚合物的对应值。

含氮氧磷多齿配体稀土烷基配合物的合成、表征及催化丙交酯聚合

1. 合成了三齿水杨醛稀土配合物，发现配体中含有柔性取代基易生成均配物，而刚性较强的配体生成单烷基配合物。考察了单体浓度、聚合时间等因素对配合物催化丙交酯聚合活性的影响。 2. 以含二苯基膦苯胺的β-二酮单亚胺三齿配体合成了双配体单烷基稀土配合物，空间位阻比较大，因而引发丙交酯聚合的速度比较快。 3. 合成了含甲氧基侧基的芳氧胺四齿双烷基配合物，并合成了芳氧胺与茂（茚）混配的稀土单烷基配合物。首次将它们用于丙交酯的聚合，实验结果发现，双烷基配合物中的双烷基是作为双活性中心起作用的。 4. 合成了含双吡咯烷的稀土烷基配合物，将之应用于丙交酯的聚合，发现位阻大的配合物催化聚合可控性好。并应用双吡咯烷配合物进行了丙交酯和己内酯的共聚合研究。

外消旋丙交酯的立体选择性聚合催化剂

聚丙交酯又称聚乳酸(PLA)，是目前最重要的合成生物降解高分子之一。丙交酯有L,L-丙交酯（LLA）、D,D-丙交酯（DLA）和内消旋丙交酯（meso-LA）三种立体异构体。PLA包括全同立构、间同立构、无规立构、不均匀有规立构和嵌段立构等构型。 PLA的微观链结构在很大程度上决定了PLA的理化性质。无规立构和不均匀有规立构聚丙交酯是非晶聚合物，它们可以由meso-LA或者rac-LA（LLA和DLA的等物质的量混合物）的聚合得到；而全同立构、间同立构和嵌段立构的聚丙交酯都是可以结晶的；全同立构的聚丙交酯可由纯的DLA或者LLA聚合而成，高分子量的全同立构PLA（PLLA或者PDLA）的熔点约180ºC；但是，有趣的是，等量PDLA和PLLA形成的外消旋混合物的熔点约230ºC，这与无规的poly(rac-LA)（聚外消旋丙交酯）形成强烈对照；间同和嵌段立构聚丙交酯只是最近几年才被合成出来，目前，只能通过丙交酯的立体选择性聚合才能得到，它们的结晶性和熔点随催化剂的选择性不同变化范围很大；而就降解性能而言，非晶聚丙交酯的降解速率要高于结晶性的聚丙交酯。因为序列结构对聚丙交酯的性质有很大的影响，而聚丙交酯的序列结构可以通过丙交酯的立体选择性聚合来控制，所以，近年来，丙交酯的立体选择性聚合催化剂的开发成为了一个研究热点。 我们设计合成了一系列非手性烯醇式席夫碱－铝/锌化合物，详细的表征了它们的结构，阐明了配体取代基团与催化剂构型之间的关系；将这一系列化合物用于丙交酯的开环聚合，系统的研究了不同结构的催化剂与丙交酯的聚合动力学、立体规整度之间的关系。

原位聚合制备聚乙烯多相材料的微结构调控

聚合物多相材料的制备作为丰富材料品种，扩展材料用途的重要手段受到了广泛地关注和深入地研究。传统的熔融共混法制备聚合物多相材料时，一般需要加入增容剂来改善各相之间的相容性，从而使多相材料的性能达到预期的目标。但是由于增容剂本身也存在分散状态的问题，所以它的加入对多相材料的性能的影响比较复杂。因此，本论文致力于用原位共聚接枝的方法和粒子破碎的方法解决多相材料的界面结合和相分散问题。首先，采用对分散相进行共聚功能化改性的方法，使分散相与乙烯共聚，聚合过程中原位生成聚乙烯接枝物，这种聚乙烯接枝物能起到增容两相的作用，提高两相界面的粘结性，将这种方法应用到有机聚苯乙烯粒子和无机磁性钴粒子体系中，并分别进行了详细的研究；其次，通过聚苯乙烯载体的结构设计，使聚苯乙烯载体催化剂具有较高并且可控的活性，在较高的活性下，聚苯乙烯载体可以破碎，破碎后的聚苯乙烯均匀地分散到乙烯聚合产物中，并且碎片达到纳米级，用这种方法可以改善多相材料的相分散。 本论文的主要工作和研究结果总结如下： 1、采用悬浮聚合制备了交联聚苯乙烯粒子（c-PS），并且在聚苯乙烯粒子的表面引入了双键；c-PS粒子在乙烯填充聚合时，可以与乙烯共聚，从而制备了表面接枝聚乙烯的聚苯乙烯微球（PS-g-PE）；PS-g-PE微球上的聚乙烯的结晶温度与纯聚乙烯的结晶温度相比提高了6℃，说明聚乙烯与聚苯乙烯间的化学连接促进了PE的结晶；PS-g-PE与PE共混后，聚苯乙烯粒子与聚乙烯基体间的界面粘结增强。 2、采用乳液聚合制备了共聚型和不可共聚型交联聚苯乙烯乳胶粒子；将两种聚苯乙烯粒子用于乙烯填充聚合制备了聚苯乙烯/聚乙烯纳米共混材料，结果发现，共聚型聚苯乙烯/聚乙烯的断面上，两相间的界面模糊，并且拉伸断面上也没有不可共聚聚苯乙烯体系中由于拉应力作用而产生的空穴，超薄切片的透射电镜结果同样说明了可共聚型聚苯乙烯体系中界面粘结性的提高；当共聚型聚苯乙烯乳胶粒子的填充量较大（20 wt%）时，聚乙烯共混材料的凝胶含量比较高，说明有更多的共聚型聚苯乙烯在聚乙烯中充当交联点。总之，共聚型聚苯乙烯的填充量在非常少时（0.1 wt%）就能达到很好的改性效果。 3、采用阴离子共聚制备了两亲性的聚苯乙烯-b-聚-2-乙烯基吡啶嵌段共聚物（PS-b-P2VP）和聚4-（3-丁烯基）苯乙烯-聚苯乙烯-聚2乙烯基吡啶的三嵌段共聚物（PBSt-b-PS-b-P2VP）；两个嵌段共聚物在甲苯中均能自组装形成以PVP为核、PS为壳的胶束；Co2(CO)8在PS-b-PVP和PBSt-b-PS-b-P2VP甲苯胶束中热分解得到了由胶束稳定分散的Co磁流体；无水无氧的钴磁流体与乙烯填充聚合后得到了磁性聚乙烯纳米复合材料；钴纳米粒子在聚乙烯中稳定分散，不会发生聚集；PBSt-b-PS-b-P2VP与乙烯共聚后，纳米粒子与聚乙烯基体的相容性进一步提高，从而解决了金属纳米粒子在聚合物中的分散以及界面增强的问题。 4、采用悬浮聚合制备了三种溶胀能力不同的聚苯乙烯交联粒子，研究了溶胀时间对聚苯乙烯载体溶胀程度的影响，以及溶胀程度对乙烯聚合和产物聚乙烯形态的影响；实验结果发现溶胀程度较大、溶胀能力较强的聚苯乙烯载体的负载量和活性都较高；通过提高载体的溶胀程度可以增加催化剂对乙烯聚合的催化活性，最终使载体充分破碎分散到乙烯聚合产物中，原位形成纳米级聚乙烯共混物；乙烯聚合的动力学研究表明载体的破碎是一个由外向内逐步发生的过程；适当的活性可以控制载体破碎的速度，从而得到颗粒形态较好的聚乙烯产物。

噻吩胺基稀土配合物的合成、表征

本论文共合成了两种类型12个稀土金属配合物和一个硅化合物,分别对它们进行了红外、核磁等表征，对其中的9个配合物进行了晶体结构的测定。考察了配体结构和反应条件对所生成的配合物结构的影响，研究了稀土单烷基配合物的反应性，以及稀土双烷基配合物在烷基铝和有机硼盐的共同作用下对丁二烯聚合的催化活性和选择性。主要工作内容和结论如下： (1) 合成了噻吩苯胺配体(HL1)，该配体与(Lu，Y)稀土三烷基化合物反应，通过C–H活化和烷基消除反应制备了稀土(Lu，Y)单烷基配合物1和2，配体以少见的C，N模式配位，S原子并不参与配位。配体(HL1)与Sc三烷基化合物反应制备了配体分别以C, N和N, S配位的双配的Sc配合物5。 (2) 通过改变反应时间和溶剂体系，HL1与稀土钇三烷基化合物反应可得到罕见的由稀土烷基化物和胺化物两部分组成的配合物3，它们通过噻吩环上活化的C原子连接在一起。HL1和Lu(CH2SiMe3)2(THF)2LiCH2SiMe3在甲苯和正己烷溶剂中反应可得到以L12Lu(CH2SiMe3)2为阴离子，Li(THF)4为阳离子的离子对4。 (3) 研究配合物1和2的反应性。1和2与过量的PhSiH3反应得到中心金属与Si元素交换的Si化合物。 (4) 合成了噻吩苯基膦胺配体(HL2-4)和苯基膦胺配体(HL5)配体。HL2-5与稀土(Y, Lu和Sc)三烷基化合物反应制备了稀土双烷基配合物6，7，8，9，10，11和12。进一步研究了稀土金属双烷基配合物6–12对丁二烯的催化特性，发现该系列催化剂具有独特的催化性质，能够催化丁二烯高反1，4-聚合（91.3%），得到的聚合物分子量在1到2万之间，分子量分布较窄(1.4–1.6)。 (5) 研究了金属钇(Y)，镥(Lu)，钪(Sc)三种中心金属对丁二烯聚合活性和反式1，4选择性的影响，发现催化剂对丁二烯聚合活性和反1，4选择性取决于配合物的中心金属原子，其中选择性最高为钪配合物，催化活性最佳的为钇配合物。 (6) 研究了配体HL2-4的N-芳环上的取代基分别为甲基，乙基，异丙基时催化体系对丁二烯反式1，4聚合活性和选择性的影响，发现随着N-芳环上取代基空间位阻的增大，催化剂活性逐渐下降，选择性逐渐增加，但当其取代基为异丙基时，过大的空间位阻导致活性和选择性同时有明显的下降。我们通过改变噻吩基为苯基，比较了相同聚合条件下含噻吩基的稀土双烷基配合物和含苯基的稀土双烷基配合物对丁二烯聚合活性和选择性的影响，发现噻吩环的存在对催化剂的活性和选择性有较大的影响。 (7) 在相同催化剂条件下，研究了不同聚合条件(不同类型的AlR3，不同类型的Borate，Al/Ln比等)对丁二烯反1，4聚合活性和选择性的影响。 我们发现，在AlR3和Borate这两种影响因素中，以烷基铝的类型对催化剂催化活性和选择性的影响最大，而有机硼盐的影响则比较轻微，其中以烷基铝为AliBu3，Borate为[B(C6F5)4][Me2NHPh]时，反1，4选择性为最佳。Al/Ln增大并不能够显著增加催化剂的活性，对选择性的影响也并不明显，相反，随着铝比的增加，聚合过程中的链转移增加，导致分子量下降，对于该系列稀土烷基催化剂，最佳Ln/Al 为10。