Al2O3-SiO2(sf)/Al-Si复合材料的界面结构研究

采用ＴＥＭ,ＥＤＳ,ＨＲＥＭ 等测试手段,对液体压力浸渗法制备的Ａｌ２Ｏ３－ ＳｉＯ２（ｓｆ）／ＺＬ１０９复合材料的界面结构以及界面反应机理进行了观察和分析,结果表明：多晶Ａｌ２Ｏ３－ ＳｉＯ２纤维和基体金属在复合材料的高温制备过程中发生了化学反应,产生了尖晶石ＭｇＡｌ２Ｏ４;ＭｇＡｌ２Ｏ４沿复合材料界面呈颗粒状分布,形成了非连续分布的反应结合型界面结构。     

Al2O3—SiO2（sf）／Al—Si复合材料的界面结构研究

采用ＴＥＭ,ＥＤＳ,ＨＲＥＭ等测试手段,对液体压力浸渗法制备的Ａｌ２Ｏ３－ＳｉＯ２（ｓｆ）／ＺＬ１０９复合材料的界面结构以及界面反应机理进行了观察和分析,结果表明：多晶Ａｌ２Ｏ３－ＳｉＯ２纤维和基体金属在复合材料的高温制备过程中发生了化学反应,产生了尖晶石ＭｇＡｌ２Ｏ４;ＭｇＡｌ２Ｏ４沿复合材料界面呈颗粒状分布,形成了非连续分布的反应结果型界面结构。     

反应条件对聚双环戊二烯性能的影响

以ＷＣｌ６／ＷＯＣｌ４－ＡｌＥｔ３为催化剂,采用ＲＩＭ方法完成了双环戊二烯（ＤＣＰＤ）的聚合反应,研究了催化剂的用量,反应温度对聚双环戊二烯（ＰＤＣＰＤ）性能的影响,实验结果表明,在ＤＣＰＤ／Ｗ＝１０００￣３０００／１（ｍｏｌ ｒａｔｉｏ）,Ａｌ／Ｗ＝２／１（ｍｏｌ／ｒａｔｉｏ）,反应温度为７０￣１２０℃,ＰＤＣＰＤ具有优良的性能。     

新型硅氮烷先驱体的合成和表征

采用ＭｅＳｉＨＣｌ２和ＭｅＳｉＶｉＣｌ２共氨解方法制备出了流动性好的含Ｓｉ－Ｈ和Ｓｉ－Ｖｉ的低分子硅氮烷。结果表明，Ｈ２ＨｔＣｌ６（脱水）和ＤＣＰ是合适的硅氢化交联催化剂和双键交联的引发剂，交联产物在程序控温的管式炉中裂解，得到了高的陶瓷产率。     

双环戊二烯聚合反应热力学和动力学研究

研究了ＤＣＰＤ－ＷＯＣｌ４－ＡｌＥｔ３体系前阶段的反应动力学，采用ＧＣ法分析了不同反应条件下的动力学数据，发现ｌｇ（［ＤＣＰＤ］０／［ＤＣＰＤ］）￣ｔ存在线性关系，说明该体系在前段的聚合反应为一链式反应符合二级反应模型。同时还对该体系聚合反应热力学也进行了研究；对聚合反应的ΔＨｐ、ΔＳｐ、ΔＧｐ进行了讨论。     

（Y－ZrO_2）－SiCw－Al_2O_3陶瓷复合材料的摩擦磨损

本文对Ａｌ２Ｏ３基陶瓷复合材料Ａｌ２Ｏ３－ＺｒＯ２－ＳｉＣｗ进行了干摩擦磨损试验，并运用了ＳＥＭ，ＴＥＭ和ＸＲＤ等手段对其显微结构、力学性能及它们与ＧＣｒ１５钢对摩时的摩擦磨损行为进行了系统分析，在此基础上深入探讨了ＳｉＣ晶须（ＳｉＣｗ）增韧补强作用对复合材料的摩擦磨损性能的影响。     

Lewis酸引发的1，3－戊二烯阳离子聚合

以ＡｌＣｌ_３、ＢＦ_３·ＯＥｔ_２、ＴｉＣｌ_４和ＡｌＢｒ_３等Ｌｅｗｉｓ酸为引发剂，在不同溶剂中（正己烷、二氯甲烷、甲苯）于３０℃引发１，３－戊二烯阳离子聚合。实验结果表明，ＡｌＣｌ_３和ＢＦ_３·ＯＥｔ_２显示出较高的催化活性，ＡｌＣｌ_３引发的聚合反应得到的聚合物具有较高的分子量，但聚合反应过程中总是伴随交联产物的生成。用甲苯作溶剂时交联反应可以被抑制。ＩＲ和￣１ＨＮＭＲ结果表明，甲苯作为聚合反应的链转移剂参与了链转移反应。     

LOM技术中的挤制陶瓷片的研究

采用挤出工艺制备了用于ＬＯＭ技术中的Ａｌ２Ｏ３和ＳｉＣ陶瓷片坯件，厚度０．２ｍｍ。有机物载体采用低密聚乙烯，固体粉料占４８ｖｏｌ％，研究了Ａｌ２Ｏ３－ＬＤＰＥ混合物的流变性能，对陶瘊片进行了ＴＧ－ＤＴＡ热分析和ＳＥＭ微观组织分析。     

Lewis酸／SOCl_2复合引发体系α－蒎烯聚合作用研究

研究了由多种Ｌｅｗｉｓ酸（ＦｅＣｌ３、ＡｌＣｌ３、ＴｉＣｌ４、ＢＦ３·ＯＥｔ２等）与ＳＯＣｌ２配制成的一类新型聚合引发剂，比较了它们对α－蒎烯的引发复合性能。结果表明复合引发体系的活性比之单独的Ｌｅｗｉｓ酸均大幅度提高，活性大小顺序为：ＢＦ３·ＯＥｔ２／ＳＯＣｌ２＞ＴｉＣｌ４／ＳＯＣｌ２≈ＡｌＣｌ３／ＳＯＣｌ２＞ＦｅＣｌ３／ＳＯＣｌ２，与它们的配位能力大小顺序一致。系统考察了ＴｉＣｌ４／ＳＯＣｌ２体系的聚合性能，研究了复合引发剂组分比、溶剂、活泼单体苯乙烯、外加Ｌｅｗｉｓ碱以及聚合条件等对α－蒎烯聚合动力学、产物分子量及其分子结构的影响，据之讨论了该复合引发剂的作用机制，提出了活性种本质的看法。     

STUDY FOR MECHANICAL ALLOYING OF Fe─M BY MOSSBAUER SPECTROSCOPY

将Ｆｅ－Ｍ（Ｍ＝Ｃ５ＳｉＯ２Ａｌ２Ｏ３）混合物在Ａｒ中高能球磨５６ｇ后测量Ｍｏｓｂａｕｅｒ谱，结果表明，（Ｆｅ）２－（ＳｉＯ２）１仍为Ｆｅ和ＳｉＯ２的机械混合物：（Ｆｅ）６－（Ｃ）３已完全合金化，生成两种Ｆｅ３Ｃ；（Ｆｅ）２－（Ａｌ２Ｏ３）１则成为Ｆｅ（７３％），尖晶石型的ＦｅＡｌ２Ｏ４）２２％），ｑｑｎｔＦｅ的团聚族（５％）和Ａｌ２Ｏ３的混合物。     

1,3-戊二烯-1-戊烯阳离子共聚反应

研究了ＡｌＣｌ３引发的１,３－戊二烯（ＰＤ）－１－戊（ＰＩ）阳离子共聚反应。在正已烷作介质的ＰＤ阳离子聚合体系中加入ＰＩ可抑制凝胶（交联聚合物）的生成,同时使聚合物总产率下降。随共聚单体中ＰＩ含量的增加,聚合物分子量先呈现上升,并在达到极大值后逐渐下降。在甲苯介质中ＡｌＣｌ３引发的ＰＤ阳离子聚合体系中加入ＰＩ使得聚合物产率呈现下降趋势,聚合物分子量仍随共聚单体ＰＩ含量的增加先呈现上升并在达到极大值     

茂金属化合物合成星状羟基功能化无规聚苯乙烯

采用茂金属化合物(n-BuCp)2TiCl2,还原剂(Sn)及引发剂4,4’-亚甲基二(N,N-二缩水甘油基苯胺(I4))组成的催化体系,引发苯乙烯活性自由基聚合,合成了星状羟基功能化无规聚苯乙烯。考察了聚合温度、时间、投料比等反应条件对苯乙烯聚合的影响。用沸丁酮对所得聚合物进行抽提,并采用凝胶渗透色谱(GPC)和核磁共振(13C-NMR)对沸丁酮可溶部分的结构和性能进行了表征。GPC分析证明催化体系(n-BuCp)2TiCl2/Sn/I4引发苯乙烯聚合属于活性聚合;13C-NMR结果证明所得聚苯乙烯链段为无定型态。实验表明所得聚合物为星状羟基功能化无规聚苯乙烯。     

不同引发剂体系对氧化铝浆料固化过程的影响

研究了引发剂体系对氧化铝浆料固化过程的影响. 通过测试丙烯酰胺(AM)水溶液聚合过程的弹性模量曲线, 考察了引发剂体系对丙烯酰胺(AM)和N,N’-亚甲基双丙烯酰胺 (MBAM)水溶液交联聚合过程的影响. 引发剂体系分别为过硫酸铵(APS)、过硫酸铵-四甲基乙二胺(APS-TEMED)氧化还原体系和2,2’-偶氮[2-(2-咪唑啉-2-基)丙烷]盐酸盐(AZIP·2HCl). 三种引发剂中AZIP\cdot2HCl引发的聚合产物的模量在40～50℃都比较高; 温度对闲置时间影响较大, 更容易控制固化进程. AZIP·2HCl引发的50vol%浆料固化的模量曲线表明温度和引发剂浓度对浆料固化影响较大. 比较了三种引发剂引发的50vol%氧化铝浆料的固化过程模量曲线, 50℃时AZIP·HCl引发的浆料固化后的湿坯的弹性模量达到2.3×10⁶Pa, 比APS(1.58×10⁶Pa,55℃)和APS--TEMED(1.58×10⁶Pa, 25℃)引发的浆料固化后的湿坯模量要高.     

Fracture morphology and mechanical properties of thermocatalytically polymerized MMA-impregnated mortar

Mortar mixes with different water-cement ratios and consistency were impregnated with methyl-methacrylate monomer and polymerized thermally under water using the free radical initiator, -azobis (isobutyronitrile). Results on drying, impregnation and polymerization are presented. It is shown that a considerable amount of polymer remained strongly adhered or chemically inserted in the inorganic matrix. The molecular weight of the inserted polymer is higher than that obtained in the solvent extracted polymer and this is also higher than the polymer molecular weight obtained by bulk polymerization under the same conditions. The compressive and flexural strength of the impregnated mortar were found to be a function of the amount of polymer in the composites. Fracture behaviour under load, and polymer distribution inside the composites were examined by scanning electron microscopic techniques (SEM). It was observed that the polymer acts in two ways, first as a filler of porous and microcrack voids, secondly forming an anisotropic irregular network improving the bond characteristic of the interface between aggregate and matrix. Furthermore, due to the the adhesion of the polymer to both phases, it acts as a reinforcement and improves the mechanical properties, in particular the flexural strength.     

A novel light-cured glass-ionomer system for improved dental restoratives

A novel light-cured glass-ionomer cement (LCGIC) system based on the 4-arm star-shape poly(acrylic acid) (AA) tethered with glycidyl methacrylate has been developed. The 4-arm poly(AA) polymer was synthesized using atom-transfer radical polymerization. The purified polymer was used to formulate with water and Fuji II LC filler to form LCGICs. Compressive strength (CS) was used as a screening tool for evaluation. The effects of grafting ratio, polymer/water (P/W) ratio, filler powder/polymer liquid (P/L) ratio and aging on strengths were investigated. All the specimens were conditioned in distilled water at 37 °C for 24 h prior to testing. The results show that the 4-arm poly(AA) polymer exhibited a lower viscosity as compared to its linear counterpart that was synthesized via conventional free-radical polymerization. This novel LCGIC system was 13% in CS, 86% in diametral tensile strength (DTS) and 123% in flexural strength higher but 93.6% in shrinkage lower than Fuji II LC. Increasing P/W ratio significantly increased both CS and DTS. Upon increasing grafting ratio, the CS was increased from 35% to 50% but not from 50% to 70%. Likewise, when P/L ratio was increased, the CS was increased from 2.2 to 2.7 but not from 2.7 to 3.0. During aging, the ultimate CS (MPa) was significantly increased from 209.2 at 1 h to 329.7 at 1 week. It appears that this novel LCGIC system will be a better dental restorative because it demonstrated improved mechanical strengths as well as little shrinkage and may eliminate cytotoxicity in current LCGICs caused by leached HEMA.     

Synthesis and properties of a water-soluble ionic conjugated polymer with carboxylic acids

A new water-soluble ionic conjugated polymer, poly[N-(carboxymethyl)-2-ethynylpyridinium bromide], was prepared by the activated polymerization of 2-ethynylpyridine by using bromoacetic acid. This polymerization proceeded well in mild reaction conditions without any additional initiator or catalyst. The polymer structure was characterized by various instrumental methods to have a conjugated polymer backbone system with the designed functional groups. The photoluminescence spectrum of polymer showed that the PL peak is located at 603 nm corresponding to the photon energy of 2.06 eV. The cyclovoltammograms of polymer exhibited the irreversible electrochemical behaviors between the oxidation and reduction peaks. The oxidation current density of polymer versus the scan rates is approximately linear relationship in the range of 30 mV/sec-150 mV/sec. It was found that the kinetics of the redox process of polymer is almost controlled by the reactant diffusion process from the oxidation current density of polymer versus the scan rates.     

Preparation and characterization of poly(N-isopropylacrylamide) films on a modified glass surface via surface initiated redox polymerization

A functionalization with 3-aminopropyltriethoxysilane (APTES) monolayer of a hydroxylated glass surface, followed by the surface initiated graft radical polymerization of N-isopropylacrylamide (NIPAm) using amino groups of APTES monolayer chemical bonded with glass surface and Ce⁴⁺ as a redox initiating system. The microstructure of poly(N-isopropylacrylamide) (PNIPAm) film obtained from the redox graft polymerization on the modified glass surfaces was examined by water contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM), and the results showed that about 60 nm thickness of thermosensitive polymer (PNIPAm) film successfully formed.     

梳型丙烯酰胺共聚物在水溶液中的缔合结构

采用荧光探针研究了丙烯酰胺(AM)/4-乙烯苄基辛烷基酚聚氧乙烯(10)醚(VBPOE)/2-丙烯酰胺基-2-甲基丙磺酸钠(NaAMPS)梳型共聚物(PAVA)在水溶液中的疏水缔合微结构。结果发现,在纯水和盐水溶液中,随聚合物浓度的增大,疏水微区的数量和非极性明显增加,但当PAVA浓度高于0.20 g/dL时,疏水微区的非极性趋于恒定,而且0.5 g/dLNaCl的加入对I1/I3值(I1/I3的变化可以表征疏水微区是否形成以及监测疏水缔合微区的变化)的影响极小,这证实了分子链在盐水中的构象仍然较伸展,使得PAVA在盐水中也能形成连续的缔合结构,从而赋予聚合物良好的抗盐和增粘性能。随着盐浓度的增加,缔合微结构的非极性变化不大,但其紧密度和数量增加,Ie/Im值持续增大。     

Surface-confined living radical polymerization for coatings in capillary electrophoresis

Surface-confined living radical polymerization is shown to be a controlled means of covalently bonding both linear and cross-linked polymer films on silica. CuCl/bipyridine initiates radical formation through atom transfer with a self-assembled monolayer of benzyl chloride, onto which polymer then grows. The polymerization is intrinsically confined to the surface, avoiding problems associated with polymer formed in the solution. The surface-confined polymerization scheme is generally applicable to radical polymerization of vinyl monomers and was studied here for the case of acrylamide. Infrared spectroscopy shows that the film growth is controllable, and atomic force microscopy reveals that smooth films are prepared. The surface-confinement polymerization scheme was tested for both linear and cross-linked polyacrylamide. Capillary electrophoresis of strongly basic proteins confirms that the coated capillaries provide the high efficiency expected for polyacrylamide. The cross-linked coating exhibits higher reproducibility with respect to migration time than does the linear coating. Surface-confined living radical polymerization prepares linear and cross-linked polymer films without danger of clogging narrow capillaries and will ultimately facilitate cross-laboratory comparisons by enabling control of film thickness.     

含溴四官能团引发剂引发单电子转移活性自由基聚合

以季戊四醇为原料合成了2,2-二溴甲基-1,3-二溴丙烷(PEBr4),并以此为引发剂,Cu0粉/三-(2-二甲氨基乙基)胺(Me6-TREN)为催化体系,在二甲亚砜(DMSO)中实现了丙烯酸甲酯(MA)的单电子转移活性自由基聚合(SET-LRP),得到了星形PMA。采用1H-NMR对PMA结构进行表征确认并采用GPC测定了PMA的分子量及分子量分布,单体转化率为36.3%时聚合物的分子量为13300,-Mw/-Mn=1.40;考察了水、单体/催化剂(引发剂)配比对聚合反应的影响。结果表明,H2O含量增加到20%(体积分数)导致表观聚合速率常数(kappp)由0.0367 h-1增加到0.2785 h-1;增加催化剂及引发剂用量分别导致kappp增加。