羧甲基壳聚糖/海藻酸钠半互穿网络水凝胶的制备及性能研究

以羧甲基壳聚糖(CMC)和海藻酸钠(SA)为原料,京尼平(GP)为交联剂,制备具有pH敏感性的CMC/SA半互穿网络(semi-IPN)水凝胶.利用特性黏数、红外光谱对CMC/SA水凝胶的半互穿网络结构及形成机理进行了分析与表征;对水凝胶的力学性能进行了测试;探讨了pH值及交联剂含量对水凝胶溶胀性能的影响.结果表明,京尼平交联的CMC/SA水凝胶具有半互穿网络结构.当w(CMC)∶w(SA)=5∶5时,CMC/SA水凝胶的断裂强度达到最大值(59 MPa),分别比纯的CMC(40 MPa)和SA(36 MPa)提高了47.5%和63.9%;当SA含量为60%时,CMC/SA水凝胶的断裂伸长率达到最大值(13.0%).当pH3.0时,溶胀率随pH值的增大而减小,pH=3.0时,溶胀率最小(186%);当pH3.0时,溶胀率随pH值的增大而增大,pH=9.0时,溶胀率最大(886%).京尼平交联的CMC/SA半互穿网络水凝胶具有明显的pH敏感性、溶胀可逆性及对pH的快速响应性.     

键阻断原理构建中孔A型沸石

采用不同类型的有机硅烷化SiO₂作为基本合成单元, 制备了具有晶内中孔的A型沸石。考察了反应碱度、Si/Al比、晶化时间等合成条件对产品的影响。结果表明, 甲氨基丙基三甲氧基硅烷是合成中孔A型沸石的最佳硅烷化试剂;硅烷化试剂的应用, 使中孔沸石晶化过程可以通过“键阻断原理”有效控制;沸石的中孔尺寸可以通过不同类型的有机硅烷化试剂进行调控; 一定范围内, 其外比表面积、中孔体积随SiO₂表面硅烷化度的增加而增加。通过沸石晶化过程中的“键阻断”, 可以制备具有晶内中孔的A型沸石。     

键阻断原理构建中孔A型沸石

采用不同类型的有机硅烷化SiO2作为基本合成单元,制备了具有晶内中孔的A型沸石。考察了反应碱度、Si/Al比、晶化时间等合成条件对产品的影响。结果表明,苯胺基丙基三甲氧基硅烷是合成中孔A型沸石的最佳硅烷化试剂;硅烷化试剂的应用,使中孔沸石晶化过程可以通过"键阻断原理"有效控制;沸石的中孔尺寸可以通过不同类型的有机硅烷化试剂进行调控;一定范围内,其外比表面积、中孔体积随SiO2表面硅烷化度的增加而增加。通过沸石晶化过程中的"键阻断",可以制备具有晶内中孔的A型沸石。     

一类新型硅烷基Schiff碱亚胺络合过渡金属催化剂的合成及催化乙烯性能研究

以γ-氨丙基三乙氧基硅烷和水杨醛为原料,通过席夫碱反应合成一类硅烷基Schiff碱亚胺配体;分别以六水氯化镍和六水氯化钴为络合试剂,通过络合反应合成两类硅烷基Schiff碱亚胺络合过渡金属催化剂.元素分析、FT-IR、~1H NMR和ICP证实合成的硅烷基Schiff碱亚胺配体及其相应的过渡金属催化剂的结构与其理论结构相符.两类硅烷基Schiff碱亚胺络合过渡金属催化剂具有良好的催化乙烯齐聚活性,且其催化性能不仅受助催化剂结构和主催化剂活性中心种类的影响,而且还受聚合反应参数的影响.甲基铝氧烷(MAO)为助催化剂,环己烷为溶剂时,聚合活性和齐聚产物中C_8以上烯烃的含量较高;当Al/Co物质的量比为500、反应温度为25℃、反应压力为0.5 MPa和反应时间为30 min时,硅烷基Schiff碱亚胺络合钴催化剂催化乙烯齐聚的活性为1.13 g·μmol~(-1)·h~(-1),齐聚产物中C_8以上烯烃含量为52.70%.受电子云密度的影响,硅烷基Schiff碱亚胺络合镍催化剂的催化活性高于相应的钴催化剂.     

在线双毛细管-氢化物火焰原子吸收光谱法测定砷、锑、铋、汞、硒和锡

1引言使用氢化物原子吸收光谱(HG-AAS)法测定As、Sb、B、iHg、Se和Sn已有报道。但将氢化物在线引入空气乙炔焰,用火焰法快速测定这些元素的方法少见报道。本实验利用双毛细管装置,建立了在线HG-AAS测定As、Sb、B、iHg、Se和Sn的方法,该方法具有简便、快速、灵敏度高,干扰少和KBH4用量少的优点。2实验部分2.1仪器及试剂GGX-9型原子吸收分光光度计;微型多功能进样装置(自制专利产品);空心阴极灯;盐酸(1 1);硫脲溶液(5%);抗坏血酸溶液(5%);KBH4溶液(1%,2%);邻二氮菲溶液(1%);As、Sb、B、iHg、Se、Sn的标准溶液;蒸馏水;其余试剂…     

不同有机体系中3种烷基膦酸类化合物的硅烷化衍生方法研究

应用人工神经网络原理,考察了吡啶-甲苯、乙腈-甲苯和四氢呋喃(THF)3种体系中,温度、时间、衍生化试剂及其用量对甲基膦酸(MPA)硅烷化衍生效率的影响,确定主要影响因素为衍生化试剂及其用量;在此基础上建立了MPA、异丙基膦酸(IPA)和甲基膦酸频哪酯(PMPA)的三甲基硅(TMS)衍生法和特丁基二甲基硅(TBDMS)衍生法;在3种体系中,选用N,O-双(三甲基硅烷基)三氟乙酰胺(BSTFA)或N-甲基-N-叔丁基二甲基硅烷基三氟乙酰胺(MTBSTFA)作衍生化试剂,选用体积分数为10%的衍生化试剂.稳定性实验表明:3种化合物的TBDMS衍生产物均比其TMS衍生产物稳定.采用核磁共振氢去耦磷谱技术(31P{1H} -NMR)对TBDMS衍生法进行了评价,衍生接近完全.     

Ⅳ.硅烷与烯腈结构对硅氢加成反应的影响

在三组分催化剂——三正丁胺、四甲基乙二胺、氯化亚铜作用下,进行不同硅烷(三氯硅烷、苯基二氯硅烷、甲基二氯硅烷、二苯基氯硅烷、甲基苯基氯硅烷、二乙基氯硅烷、三乙基硅烷)与丙烯腈的加成反应。在相同的反应条件下,对于七种硅烷的活性作定量的比较,发现加成产率百分数与相应的硅烷基团的诱导效应指数间形成一正 S 型曲线。改变烯腈结构(α-氰基丙烯酸乙酯、丙烯腈、α-甲基丙烯腈、α-乙基丙烯腈、丁烯腈),研究其在三氯硅烷加成反应中的影响,同样也得到产率百分数的正 S 型曲线。基于与 Grignard 试剂的反应和碱性水解作用,确定加成产物的结构。实验表明,硅原子系加在烯腈的β-碳上(β-加成)。根据结构活性关系的 S 型曲线讨论加成反应的机理。     

半互穿海藻酸钠/聚丙烯酰胺凝胶吸附结晶紫动力学/热力学行为和吸/脱附机理

将含有大量—COO-的聚阴离子海藻酸钠(SA)引入聚丙烯酰胺(PAM)凝胶网络中,采用自由基溶液聚合法制备半互穿网络结构的SA/PAM水凝胶.采用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和傅里叶变换红外光谱(FTIR)分析了SA/PAM水凝胶吸附结晶紫(CV)前后的孔洞形态和化学组成变化,采用多种模型研究了SA/PAM水凝胶对CV分子的吸附动力学和热力学行为,并探讨了脱附效率,提出了吸脱附机理.研究结果表明,SA的引入降低了孔径尺寸,增加了孔洞数量;SA/PAM-10凝胶对CV分子吸附量最大,达到13.5838 mg/g,符合伪一级吸附动力学模型,吸附速率受膜扩散和粒子内扩散过程共同影响;等温吸附过程符合Temkin和D-R模型,属于微孔多层吸附;热力学分析结果表明,吸附过程由熵驱动引起,非化学诱导因素影响所致;采用HCl进行脱附,最大脱附率高达94.18%,加入Na OH可实现SA/PAM水凝胶的可逆吸附;较高的吸附量主要源于SA分子链上的COO-与CV分子的—C N+—存在的静电作用,低pH值时由于—COO-和—NH2质子化导致与CV分子的静电斥力增大,脱附率随之增加.     

[Eu（Bipy）2]Cl3和[Tb（Bipy）2]Cl3在有机功能化剥层水滑石表面上的组装及光致发光性质

以乙酰基丙氨基三乙氧基硅烷对剥层镁铝水滑石进行了表面硅烷化修饰,得到了表面硅烷化修饰的剥层水滑石复合材料.然后在该复合材料表面进行了[Eu(Bipy)2]3+和[Tb(Bipy)2]3+分子组装,得到了剥层水滑石复合稀土发光体.组装体的紫外激发发射光谱表明,稀土配合物被组装到经硅烷化试剂修饰的剥层水滑石表面后,其电偶极跃迁较原配合物有很大提高,热稳定性也有提高.从主客体材料相互作用角度对稀土配合物电偶极跃迁的提高进行了解释.     

LY12铝合金表面电化学沉积制备DTMS硅烷膜及其耐蚀性研究

采用电化学技术在LY12铝合金表面沉积制备了十二烷基三甲氧基硅烷(DTMS)膜. 反射吸收红外光谱表明, DTMS硅烷试剂与铝合金基体表面发生了化学键合作用, 生成—SiOAl键实现成膜. 通过对膜覆盖电极在质量分数为3.5%的NaCl溶液中的电化学阻抗谱(EIS)测试结果表明, 与开路电位下相比, 采用阴极电位沉积方法得到硅烷膜的耐蚀性能有明显提高, 且存在一个最佳“临界电位”, 在此电位下沉积得到的硅烷膜具有最高的耐蚀性. 扫描电镜观察结果表明, 在“临界电位”下制备得到的硅烷膜的结构最致密. 给出了硅烷膜覆盖电极的阻抗模型及相关参数的拟合结果.     

Scanning angle Raman spectroscopy measurements of thin polymer films for thickness and composition analyses

Scanning angle (SA) Raman spectroscopy was used to measure the thickness and composition of polystyrene films. A sapphire prism was optically coupled to a sapphire substrate on which 6–12% (w/v) polystyrene in toluene was spin coated. Raman spectra were collected as the incident angle of the p-polarized, 785-nm excitation laser was varied from 56 to 70°. These angles span above and below the critical angle for a sapphire/polystyrene interface. The thickness of the polystyrene film was determined using a calibration curve constructed by calculating the integrated optical energy density distribution as a function of incident angle, distance from the prism interface and polymer thickness. The calculations were used to determine the incident angle where waveguide modes are excited within the polymer film, which is the angle with the highest integrated optical energy density. The film thicknesses measured by SA Raman spectroscopy ranged from less than 400 nm to 1.8 μm. The average percent uncertainty in the SA Raman determinations for all films was 4%, and the measurements agreed with those obtained from optical interferometery within the experimental uncertainty for all but two films. For the 1270-nm and 580-nm polystyrene films, the SA Raman measurements overestimated the film thickness by 5 and 18%, respectively. The dependence of the calibration curve on excitation polarization and composition of the polymer and bulk layers was evaluated. This preliminary investigation demonstrates that scanning angle Raman spectroscopy is a versatile method applicable whenever the chemical composition and thickness of interfacial polymer layers needs to be measured.     

Construction and corrosion behaviors of a bilayer superhydrophobic film on copper substrate

A novel bilayer superhydrophobic film was constructed on Cu substrate by a simple multi‐step process. First, (3‐mercaptopropyl) trimethoxysilane (MPTMS) molecules were self‐assembled onto the pre‐etched Cu surface via covalent bonding followed by hydrolysis and condensation, then 1H, 1H, 2H, 2H‐perfluorodecyltrichlorosilane (PFDTS) were grafted onto the resultant hydroxyl terminated surface via the Si‐O‐Si bonding. The so‐prepared sample was defined as Cu‐MPTMS‐PFDTS. The structure and morphology of the samples were characterized by means of contact angle measurement, X‐ray photoelectron spectroscopy and scanning electron microscopy. The corrosion behaviors of the films were evaluated by Tafel plot and electrochemical impedance spectroscopy on an electrochemical work station. The results indicated that the bilayer superhydrophobic film possessed better corrosion protection as compared with the control samples. The superiority of the corrosion protection was mainly ascribed to the following two aspects: the superhydrophobicity and polysiloxane micro‐structures of the Cu‐MPTMS‐PFDTS. Copyright © 2012 John Wiley & Sons, Ltd.     

In situ investigation of the adsorption of alkyltrimethoxysilanes on iron surfaces

Summary The adsorption of methyl and butyl-trimethoxysilane onto iron surfaces from the gas phase at different humidity levels has been investigated in situ with a quartzcrystal micro-balance and with ATR-IR spectroscopy. The thickness of the resulting siloxan polymer depends on the humidity during the film preparation. The polymer coating inhibits the corrosion of iron in an SO₂-containing atmosphere.     

Surface hydration and its effect on fluorinated SAM formation on SiO2 surfaces

Substrate hydration is demonstrated to be crucial to film quality during self-assembled (SA) film deposition of tridecafluoro-1,1,2,2,-tetrahydrooctyltrichlorosilane (FOTS) from the vapor phase. The surface hydration was studied by thermogravimetric analysis, and a model was developed to predict the conditions necessary to desorb all of the water adsorbed on a fused silica surface without significantly altering the concentration of the surface hydroxyl groups. The nature of the SA film was investigated as a function of the degree of rehydration of the dehydrated silica surface. The wettability and microstructure of the SA films were examined by water contact angle, ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscopy. There is an optimum degree of substrate hydration, on the order of 1-1.2 monolayers of adsorbed water, required to produce a dense, durable and uniform FOTS film with high water repellency and a smooth surface.     

Q235钢在假单胞菌和铁细菌混合作用下的腐蚀行为

采用腐蚀失重法、电化学阻抗谱(EIS)和表面分析技术研究了Q235钢在假单胞菌和铁细菌共同作用下的腐蚀行为.结果表明:与单种菌相比,两种菌混合作用下Q235钢腐蚀受到了抑制.混菌体系中金属电极自腐蚀电位升高,腐蚀电流密度减小,交流阻抗值随时间增大.扫描电子显微镜(SEM)分析结果表明混合菌体系中Q235钢表面形成了均匀致密的腐蚀产物膜.     

An Electrochemical Study on the Corrosion Inhibition of Stainless Steel by Polyaniline Film

Polyaniline(PANI)film was electrosynthesized on 304 stainless steel by cyclic voltammetry using aqueous oxalic acid as supporting electrolyte.The potential sweep rates were changed to achieve the PANI film with different thickness and structures.Protective properties of the PANI film for corrosion of stainless steel in 3% NaC1 aqueous solution were investigated by monitoring potentiodynamic polarization curves and electrochemical impedance spectroscopy(EIS).The results showed that the PANI film which was formed with lower sweep rate led to more positive shift of corrosion potential and greater charge transfer resistance,reflecting higher inhibition for corrosion of the stainless steel.     

Effect of molecular weight and substrate on silicone segregation from UV resin at plasma polymerized mold interface

Pristine‐, poly(octafluorotoluene)‐ (POFT), and polyacetylene (PAc)‐coated Si wafers were used as substrates for the study of segregation of silicone diacrylate (SA) from a formulation containing other oligomeric and monomeric acrylates. POFT and PAc were microwave plasma polymerized on the Si wafers. Three SAs with molecular weights ranging from 700 to 6000 Da were synthesized and characterized. Formulations with 2 wt % SA were ultraviolet cured on the silicon wafers. The surface composition of formulation‐substrate side of the cured film was analyzed with X‐ray photoelectron spectroscopy, and the depth profile was analyzed with time of flight‐secondary ion mass spectrometry. The analysis results indicated that SA aggregated on all three types of Si surfaces. However, SA segregation is highest on the low surface energy POFT‐coated Si substrate, and low‐molecular‐weight SA is favorable to the segregation. For high‐molecular‐weight SA, the different Si substrates do not affect the degree of aggregation at the formulation‐substrate interface. The observed SA aggregation trend can be predicted by the Gibbs‐adsorption equation correlated to the resin surface tension and contact angle on substrates. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 442–450, 2010     

计算机硬盘基片CMP中表面膜特性的分析研究

目前,普遍采用化学机械抛光(Chemical-mechanical polishing,CMP)技术对计算机硬盘基片(盘片)表面进行原子级平整。CMP加工中,盘片表面膜及其特性对CMP过程及CMP性能具有关键作用。本文分别采用俄歇能谱(AES)、X射线光电子能谱(XPS)、扫描电镜(SEM)、纳米硬度计、电化学极化法等分析手段对盘片表面物理、化学及机械特性进行了研究,发现盘片CMP后表面发生了氧化,氧化膜在盘片的表层,厚度在纳米量级,氧化产物为Ni(OH)₂;氧化膜为较软的、疏松的、粗糙的多孔结构;氧化膜的存在加快了盘片表面的腐蚀磨损。结合盘片CMP试验结果,推测盘片的CMP机理为盘片表面氧化生成机械强度较低的Ni(OH)₂氧化膜及随后氧化膜的机械和化学去除,二者的不断循环实现表面的全局平面化。     

弱碱性介质中氯离子对铜电极腐蚀行为的影响

应用循环伏安法、X射线光电子能谱法、电化学阻抗谱法以及现场椭圆偏光法研究了在弱碱性介质中添加Cl－对铜电极腐蚀行为的影响.结果表明, Cl－的加入能加剧铜电极的腐蚀,使腐蚀电流以及现场椭圆偏振参数Δ的变化范围都增大1个数量级, Cl－对Cu2O的掺杂将使铜电极的表面膜变得疏松,膜的耐蚀性变差.椭圆偏光实验不仅与电化学和能谱实验的结果一致,而且还能定性地、清楚地分辨出铜电极腐蚀过程中Cu2O的生成、Cl－对Cu2O的掺杂、CuO的生成等不同阶段;同时,利用恰当的模型还能定量地确定各个阶段铜电极表面膜的组成、厚度的变化,从而为研究铜电极的腐蚀与防护机理提供更多有用信息.     

Quantitative assessment of the enzymatic degradation of amorphous cellulose by using a quartz crystal microbalance with dissipation monitoring

The systematic evaluation of the degradation of an amorphous cellulose film by a monocomponent endoglucanase (EG I) by using a quartz crystal microbalance with dissipation monitoring (QCM-D) identified several important aspects relevant to the study the kinetics of cellulose degradation by enzymes. It was demonstrated that, to properly evaluate the mechanism of action, steady state conditions in the experimental set up need to be reached. Rinsing or diluting the enzyme, as well as concentration of the enzyme, can have a pronounced effect on the hydrolysis. Quantification of the actual hydrolysis was carried out by measuring the film thickness reduction by atomic force microscopy after the enzymatic treatment. The values correlated well with the frequency data obtained by QCM-D measurement for corresponding films. This demonstrated that the evaluation of hydrolysis by QCM-D can be done quantitatively. Tuning of the initial thickness of films enabled variation of the volume of substrate available for hydrolysis which was then utilized in establishing a correlation between substrate volume and hydrolytic activity of EG I as measured by QCM-D. It was shown that, although the amount of substrate affects the absolute rate of hydrolysis, the relative rate of hydrolysis does not depend on the initial amount of substrate in steady state system. With this experimental setup it was also possible to demonstrate the impact of concentration on crowding of enzyme and subsequent hydrolysis efficiency. This effort also shows the action of EG I on a fully amorphous substrate as observed by QCM-D. The enzyme was shown to work uniformly within the whole volume of swollen film, however being unable to fully degrade the amorphous film.