苯乙烯－丁二烯－苯乙烯工嵌段共聚物／聚（苯乙烯－甲基丙烯酸盐）热塑性IPN中离子聚集结构的研究

苯乙烯－丁二烯－苯乙烯工嵌段共聚物／聚（苯乙烯－甲基丙烯酸盐）热塑性ＩＰＮ中离子聚集结构的研究韦雨春，袁惠根，潘祖仁（浙江大学化工系杭州３１００２７）关键词互穿聚合物网络，离子聚集，远红外光谱，Ｘ－光散射以苯乙烯－丁二烯－苯乙烯三嵌段共聚物（ＳＢＳ）...     

苯乙烯－丁二烯－苯乙烯／聚（苯乙烯－甲基丙烯酸盐）热塑性互穿聚合物网络的形态和玻璃化转变

使用化学共混法和机械共混法制备了三嵌段苯乙烯－丁二烯－苯乙烯共聚物（ＳＢＳ）／聚（苯乙烯－甲基丙烯酸盐）热塑性互穿聚合物网络（ＩＰＮ）．用透射电镜和动态力学方法研究了它们的形态和玻璃化转变行为．实验结果显示出，由母体形成ＩＰＮ提高了体系的相容性，且化学共混方法明显好于机械共混法．ＩＰＮ样品均呈微观相分离形态，具有两个分属于聚丁二烯相和聚（苯乙烯－甲基丙烯酸盐）相的玻璃化转变温度．通过Ｂｕｄｉａｎｓｋｙ方程和Ｋｅｒｎｅｒ方程对动态模量数据的分析表明，ＩＰＮ样品具有两相连续性，且随ＳＢＳ（聚合物Ⅰ）组分含量的增加，聚（苯乙烯－甲基丙烯酸）（聚合物Ⅱ）的连续程度降低     

聚氨酯／聚（苯乙烯－甲基丙烯酸甲酯－甲基丙烯酸）互穿聚合物网络的研究

研究了（蓖麻油－聚乙二醇）聚氨酯／聚（苯乙烯－甲基丙烯酸甲酯－甲基丙烯酸）（ＰＵ／Ｐ（Ｓｔ－ＭＭＡ－ＭＡＡ））互穿聚合物网络（ＩＰＮ）．动态力学性能及透射电镜结果均表明该体系相分离较严重；ＩＰＮ具有两个玻璃化转变温度，它们有不同程度的内移，形成一定程度分子水平的混合，而ＩＰＮ（５０／５０）其分子混合水平较大，互穿缠结程度较高。形成ＩＰＮ后，其力学性能得以改善。透射电镜结果表明，聚氨酯网的交联密度直接影响ＩＰＮ的相区尺寸。形成ＩＰＮ后热稳定性提高，易于降解断链的Ｓｔ－ＭＭＡ－ＭＡＡ单体起到了自由基消除剂的作用。     

聚环氧氯丙烷聚氨酯／聚（甲基丙烯酸甲酯－苯乙烯）IPN的研究

改变聚（甲基丙烯酸甲酯－苯乙烯）（Ｐ（ＭＭＡ－ｃｏ－Ｓｔ）中甲基丙烯酸甲酯的含量（Ｗ_（ＭＭＡ）），通过一步法合成出聚环氧氯丙烷聚氨酯（ＰＵ（ＰＥＣＨ）／Ｐ（ＭＭＡ－ｃｏ－Ｓｔ）ＩＰＮ．ＤＳＣ、ＴＥＭ和动态粘弹谱研究结果表明：当Ｐ（ＭＭＡ－ｃｏ－Ｓｔ）中Ｗ_（ＭＭＡ）大于０．６时，ＩＰＮ仅有一个Ｔｇ；当Ｗ_（ＭＭＡ）小于０．４时，ＩＰＮ有２个Ｔ_ｇ，ＴＥＭ上出现相区，Ｐ（ＭＭＡ－ｃｏ－Ｓｔ）溶度参数（δ）及δ的氢键作用分量（δｈ）与相态、力学性能有密切关系。     

对－N，N－二甲氨基苯乙烯及其聚合物与碳－60的电荷转移现象

对－Ｎ，Ｎ－二甲氨基苯乙烯及其聚合物与碳－６０的电荷转移现象邱健，尹芊，杨华铨，姚光庆，李福绵（北京大学化学系北京１００８７１）关键词电荷转移复合物，对－Ｎ，Ｎ－二甲氨基苯乙烯，碳－６０，荧光光谱电荷转移现象是备受瞩目的一个研究领域，诸如在电荷转移引...     

聚氨酯改性环氧树脂／聚苯乙烯IPNs的固化动力学：II苯乙烯含量…

用化学滴定、粘度测定等方法，研究了苯乙烯含量对聚醚型聚氨酯改性双酚Ａ型环氧树脂（ＰＵＤＧＥＢＡ／聚苯乙烯（ＰＳｔ）室温同步半－ＩＰＮ’ｓ（简称ＳＩＰＮ’ｓ）体系固化动力学的影响。结果表明，在上述所研究的体系中，苯乙烯含量的变化对凝胶时间有着不可忽略的影响。随苯乙烯含量的增加，凝胶的时间明显延长。随苯乙烯含量的变化，两个组分固化反应反应速度最大值到来的时间可以相对提前或延后，甚至达到刚好同步，对上述     

2，3－二氰基－2，3－二（X－取代苯基）丁二酸二乙酯在苯乙烯中的分解动力学研究

２，３－二氰基－２，３－二（Ｘ－取代苯基）丁二酸二乙酯在苯乙烯中的分解动力学研究齐陈泽，吴靖嘉，段大勇，贾志胜，张斌，杨第伦（兰州大学应用有机化学国家重点实验室，兰州大学化学系，兰州，７３００００）关键词２，３－二氰基－２，３－二（Ｘ－取代苯基）丁二...     

SYNTHESIS OF 4－S－（1＂－ARYL－TETRAZOLE－5＂－YL）－4－DEOXY－4＇－DEMETHYL－EPIPODOPHYLLOTOXIN ANALOGUES

ＳＹＮＴＨＥＳＩＳ ＯＦ ４－Ｓ－（１＂－ＡＲＹＬ－ＴＥＴＲＡＺＯＬＥ－５＂－ＹＬ）－４－ＤＥＯＸＹ－４＇－ＤＥＭＥＴＨＹＬ－ＥＰＩＰＯＤＯＰＨＹＬＬＯＴＯＸＩＮ ＡＮＡＬＯＧＵＥＳ￥ＫｕａｎＫｅＬＵ；ＦａｎｇＭｉｎＬＩＵａｎｄＹａｏＺｕＣＨＥＮ（Ｄ...     

苯乙烯－乙烯共聚物的合成及其结构性能的研究

用负载型钛系催化剂ＭｇＣｌ_２／ＴｉＣｌ_４，ＮｄＣｌ_３／ＡｌＥｔ_３（ＳＮ－１催化剂）制备出组份比例变化的苯乙烯－乙烯共聚产物．共聚产物通过溶剂萃取分离、~１３Ｃ－ＮＭＲ、ＩＲ、动态粘弹谱进行表征，并初步进行了与聚苯乙烯（ａＰＳ）共混作用的研究．结果表明，ＳＮ－１催化剂能有效地催化苯乙烯与乙烯共聚合．共聚产物为含有均聚聚苯乙烯的共聚物复合物，其中的２５ｍｏｌ％的苯乙烯参加了共聚．共聚产物与ａＰＳ共混可明显提高ａＰＳ的冲击强度和断裂伸长率．     

苯乙烯－乙烯共聚物的合成及其结构性能的研究

用负载型钛系催化剂ＭｇＣｌ２／ＴｉＣｌ４，ＮｄＣｌ３／ＡｌＥｔ３（ＳＮ－１催化剂）制备出组份比例变化的苯乙烯－乙烯共聚产物，共聚产物通过溶剂萃取分离，＾１３Ｃ－ＮＭＲ，ＩＲ，动态粘弹谱进行表征，并初步进行了与聚苯乙烯共混作用的研究。结果表明，ＳＮ－１催化剂能有效地催化苯乙烯与乙烯共聚合，共聚产物为含有均聚聚苯乙烯的共聚复合物，其中约２５ｍｏｌ％的苯乙烯参加了共聚。共聚产物与ａＰＳ共混可明显提高ａＰ     

小角X－光散射方法对苯乙烯－丁二烯－苯乙烯三嵌段共聚物／聚（苯乙烯－甲基丙烯酸盐）热塑性IPN共混体系相区尺寸的研究

mall-angle X-ray scattering(SAXS)techniques were applied to measure the phase dimensions of thermoplastic IPN based on SBS and styrene-methacrylate Ionomer via statistical treatment.Correlation lengths of 1.3-3.0nm were found..Specific surface areas ranged from 145000 to 360000m²/kg.The SAXS results corresponded to the lower range of the transmission electron microscopy dimensions.The two techniques have different systematic errors and measure somewhat diffferent aspects of the morphology;therefore,comparisons are useful.     

Investigation of the micellization process of single and gemini surfactants from arginine by SAXS, NMR self-diffusion, and light scattering

We have investigated the aggregates formed by gemini and single-chain cationic surfactants with arginine head groups in dilute solutions by combining SAXS, static and dynamic light scattering, and PGSE NMR techniques. SAXS and NMR spectroscopy indicate that the single-chain homologue forms spheroidal aggregates, whereas the gemini surfactants form cylindrical micelles. The main parameters characterizing the micellar shape, i.e., aggregation numbers and geometrical dimensions, were evaluated from the analysis of the SAXS and NMR data. These structural parameters are in good agreement with those determined previously by surface tension and cryo-TEM studies. Some divergences were obtained using the light scattering technique, in which case the shapes of the aggregates formed by the single-chain surfactant were not in accordance with those obtained by SAXS and NMR spectroscopy.     

An experimental study of gas adsorption on fractal surfaces

The validity of the fractal versions of the FHH and BET theories for describing the adsorption of butane and nitrogen on a variety of partially dehydroxylated silica surfaces has been tested. The fractal dimensions obtained from adsorption data have been compared with those obtained completely independently using SAXS. It was found that the fractal dimensions obtained from butane adsorption isotherms, using both the fractal FHH and fractal BET theories, agreed well with the corresponding values obtained from SAXS over overlapping length scales. However, in general, a systematic deviation between the fractal dimension obtained from nitrogen adsorption and that obtained from SAXS was observed. The fractal dimensions obtained from nitrogen adsorption were consistently larger than those obtained from SAXS, which is the opposite of what has often been found in the literature. It has been suggested that the differences in the suitability of the adsorption theories tested to describe butane and nitrogen adsorption is due to the significant difference between the interaction strengths of these two different molecules with silica surfaces. A modified theory that can account for the discrepancy between the fractal dimensions obtained from nitrogen adsorption and SAXS has been proposed. The implications of the new theory for the accuracy of nitrogen adsorption BET surface areas for silicas are discussed.     

A novel application of small-angle scattering techniques: Quality assurance testing of virus quantification technology

Small-angle scattering (SAS) techniques, like small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS), were used to measure and thus to validate the accuracy of a novel technology for virus sizing and concentration determination. These studies demonstrate the utility of SAS techniques for use in quality assurance measurements and as novel technology for the physical characterization of viruses.     

Relation of Fractal Characteristics with Structural Parameters of Nanosized ZrO2 Determined by Various Methods

Theoretical and Experimental Chemistry - The fractal dimensions of nanodispersed zirconia determined by the BET and SAXS methods are compared. The fractal dimensions were shown to depend on the...     

Structure of AOT reverse micelles under shear

Reverse micelles in the AOT/water/isooctane system, at various water contents (W(0)), were studied using rheometry and small angle X-ray scattering (SAXS) experiments under static conditions and under shear. The SAXS analysis confirmed the spherical shape of the micelles at low water content and revealed a transition into elongated micelles at higher water content. A population of spherical micelles was found to coexist with the cylindrical ones, even above the percolation threshold. The shape transformation was correlated with a viscosity leap observed in the rheometry measurements. Reverse micelles at low water content under shear act as a Newtonian fluid, without any detectable shape changes. In contrast, reverse micelles at high water content behave as a shear thinning fluid. SAXS measurements at high water content under shear force have shown that the shear forces induced alignment of the cylindrical micelles in the flow direction, without any other changes in the micelle dimensions. The anisotropy parameter, a measure of the degree of the spatial order, was found to increase with increasing water content and shear rate.     

Structure characterization of cellulose nanofiber hydrogel as functions of concentration and ionic strength

Carboxylated cellulose nanofibers (CNFs), having an average width of 7 nm and thickness of 1.5 nm, were produced by TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation method. The fiber cross-sectional dimensions were determined using small-angle X-ray scattering (SAXS), transmission electron microscopy and atomic force microscopy techniques, where the rheological properties under different concentration and ionic strength were also investigated. The formation of hydrogel was evidenced by increasing the CNF concentration or ionic strength of the solvent (water), while the gel structure in ion-induced CNF hydrogels was found to be relatively inhomogeneous. The gelation behavior was closely related to the segmental aggregation of charged CNF, which could be quantitatively characterized by the correlation length (ξ) from the low-angle scattering profile and the scattering invariant (Q) in SAXS.     

A SAXS study of a single crack and craze in plasticized polystyrene

Small-angle x-ray scattering (SAXS) was used to study the structure along a single craze that had broken down to form a crack along part of its length. This study was made possible by use of radiation from the synchrotron source CHESS which is sufficiently intense to permit examination of just a single craze. The total scattering from the craze was in excellent agreement with that expected from a knowledge of its dimensions and fibril volume fraction and width. This fact adds confidence to the interpretation of the scattering pattern of the craze as part diffraction, part reflection, and demonstrates that SAXS is a technique that may be used to measure craze volume within a sample. The craze was shown to grow in width by surface drawing with a constant structure, and then the fibrils broke to form a crack. The broken fibrils contracted and their diameters increased but they appeared to stay parallel with a constant fibril-axis radial distribution function.     

A pyrrole-containing surfactant as a tecton for nanocomposite SiO2 films

A surfactant featuring a polymerizable pyrrole head group (dodecyl-dimethyl-(2-pyrrol-1-yl-ethyl)-ammonium bromide, DDPABr) was synthesized. The thermotropic behavior of the surfactant was investigated by differential scanning calorimetry (DSC) and X-ray scattering techniques, with small-angle X-ray scattering (SAXS) analysis revealing a highly ordered lamellar bilayer structure. After full characterization, DDPABr was used in the preparation of mesostructured SiO2 nanocomposite thin films via evaporation-induced self-assembly (EISA). Resulting thin SiO2-DDPABr films were studied by 1D and 2D small-angle X-ray scattering (SAXS) techniques, indicating a lamellar nanocomposite structure. Suitable theoretical SAXS models were applied to fit the experimental 1D SAXS data. The surfactant could be chemically polymerized within the lamellar domains.     

Differential scanning calorimetry,small‐angle X‐ray scattering,and wide‐angle X‐ray scattering on homogeneous and heterogeneous ethylene‐α‐copolymers

The objective of this work was to use both X‐ray and differential scanning calorimetry techniques in a comparative study of the lamellar and crystalline structures of heterogeneous and homogeneous ethylene‐α‐copolymers. The samples differed in the comonomer type (1‐butene, 1‐hexene, 1‐octene, and hexadecene), comonomer content, and catalyst used in the polymerizations. Step crystallizations were performed with differential scanning calorimetry, and the crystallinity and lamellar thicknesses of the different crystal populations were determined. Wide‐angle X‐ray scattering was used to determine crystallinities, average sizes of the crystallites, and dimensions of the orthorhombic unit cell. The average thickness, separation of the lamellae, and volume fractions of the crystalline phase were determined by small‐angle X‐ray scattering (SAXS). The results revealed that at densities below 900 kg/m³, polymers were organized as poorly organized crystal bundles. The lamellar distances were smaller and the lamellar thickness distributions were narrower for the homogeneous ethylene copolymers than for the heterogeneous ones. Step‐crystallization experiments by SAXS demonstrated that the long period increased after annealing. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1860–1875, 2001