定量分析丙烯酰胺水溶液中微量有机杂质

本文采用ＸＥ－６０毛细管单柱色谱法，快速、准确测定了丙烯酰胺水溶液中的有机杂质，定量测定结果的重现性良好。     

阳离子聚丙烯酰胺的重要研究技术进展

聚丙烯酰胺(PAM)在许多领域均得到了广泛的应用,而其中很重要的一部分——阳离子聚丙烯酰胺(CPAM)在日常生活和工业生产中,特别是在污水处理中所发挥的作用则尤为显著。本文综合论述了阳离子聚丙烯酰胺的主要用途和作用机理,重点列举了几种较为热门的阳离子聚丙烯酰胺合成技术的特点和研究进展,展示了阳离子聚丙烯酰胺的国内外研究进展,并对国内阳离子聚丙烯酰胺的今后发展进行了展望,为日后对阳离子聚丙烯酰胺的进一步开发研究提供重要参考和依据。     

丙烯酰胺中痕量杂质色谱分析

In this work traces of acrolein,acrylonitril,acetonitrile and cyanoethanol in 30%aqueous solution of acry-lamide has been analyzed by gas chromatography.The analysis was performed on a T-programmed quartz capilfary column XE-60 with the dimension of 50m×0. 25mm i.d.     

聚丙烯酰胺/聚异丙基丙烯酰胺互穿网络水凝胶的制备与性能

采用分步法用电子加速器辐射合成了聚丙烯酰胺(PAAm)/聚异丙基丙烯酰胺(PNIPAAm)互穿网络水凝胶,并考察了温度、pH值、离子强度对其溶胀性能的影响.研究表明:互穿水凝胶具有温度敏感性,且其体积相变与互穿网络中PAAm和PNIPAAm含量有关,随着网络中PAAm含量的增加水凝胶的体积相变趋于平缓,可以通过改变PAAm和PNIPAAm的组成比来控制水凝胶的体积相变行为.此外,互穿水凝胶还具有pH敏感性和一定的抗盐性.     

聚丙烯酰胺的形态结构研究

本文用电子显微镜深入的研完了部分水解聚丙烯酰胺在水溶液中的形态。给出大分子的伸展网状结构是其稀溶液高粘度的结构本质。并详细讨论了聚合物的水解度、分子量、外加盐种类及波度与分子聚集状态的关系。     

超高分子量聚丙烯酰胺的表征

采用环己烷及乳化剂ＥＡ合成了分子量（■≥１２００万）的速溶型、粉状聚丙烯酰胺（ＰＡＡ），采用扫描电镜及透射电镜观察了其微细结构，对其速溶性作出了解释。给出了该产品的综合性能数据，与进口样品进行了对比。     

丙烯酰胺水溶液聚合──添加Na_2CO_3制取高分子量阴离子型速溶聚丙烯酰胺的研究

本文建立了丙烯酰胺水溶液聚合的潜在型引发体系；研究了在碳酸盐法聚合体系中，添加不同量氨、尿素、ＥＤＴＡ—２Ｎａ，以及聚合体系ｐＨ、单体浓度、聚合水浴温度对聚合产物分子量及其溶解性能的影响规律和原因；解决了产物高分子量与产生不溶聚合物之间的矛盾；指出了获得高分子量阴离子型速溶粉末产品的关键．从而，用碳酸盐法得到了溶解性能优异的［η］高达２８ｄｌ／ｇ的胶体产品和［η］高达２２ｄｌ／ｇ的速溶粉末产品．     

食品中的丙烯酰胺及其形成机制

2002年瑞典国家食品管理局和一个科研小组共同指出淀粉性食品在高温烹调过程中会产生有毒化合物--丙烯酰胺,并提出了几种可能的形成机制.围绕这个课题,世界各国的科学家们进行了大量的研究工作,本文即对食品中的丙烯酰胺研究进行了综述.     

交联聚丙烯酰胺吸水凝胶的强度

高吸水材料是一类新型的功能高分子材料,已有广泛开发和应用。本文讨论了含大量无机填料膨润土的阴离子型交联聚丙烯酰胺(JSWAM)吸水凝胶的强度及其形态结构。 吸水材料JSWAM的制备:将填料搅拌分散于丙烯酰胺水溶液中,同时加入规定量的甲叉基双丙烯酰胺、过硫酸铵、碱,而后聚合并水解。将聚合物胶块造粒、烘干、粉碎。凝胶强度     

光敏引发合成聚丙烯酰胺

采用紫外光照射下光敏引发聚合技术,以丙烯酰胺(AM)为单体,以水溶性光敏剂为引发剂,合成了分子量较高的聚丙烯酰胺(PAM)。探讨了光敏引发剂浓度、单体浓度、Na2CO3浓度、pH、络合剂乙二胺四乙酸二钠盐(EDTA)浓度等因素对PAM分子量的影响,通过红外光谱对产物结构进行了表征。结果表明:光敏引发合成的PAM黏均分子量可以达到1.7×107,溶解性能良好,纯度较高。     

Characterization of inhomogeneous polyacrylamide hydrogels

The physical and structural properties of acrylamide gels have been characterized by osmotic deswelling, mechanical compression, and x-ray scattering. These properties vary considerably with the concentration of the crosslinking agent bisacrylamide, at fixed total monomers concentration (10% wt/wt water). In particular, changes in the properties appear more prominent at a crosslinking level of about 5-6% (wt bisacrylamide/wt monomers). The compression modulus of as-prepared and swollen gels passes through a maximum at this level of crosslinking. The swelling pressure curves can be separated into osmotic and elastic contributions of the gel network. The elastic part exhibits similar behavior to the compression modulus. The scaling of the osmotic part with the gel concentration varies with the degree of crosslinking, changing from 2.33 to 3.09. This indicates that the solvent power of water decreases with increasing crosslinking level, towards Φ conditions. The scattering patterns from the gels have been analyzed as arising from additive contributions from a homogeneous gel matrix, and embedded heterogeneities having a higher crosslinking density. These heterogeneities become much more prominent at the same level of crosslinking about 5-6%. Hysteresis observed in the sorption/desorption behavior of polyacrylamide gel suggests that further irreversible structural changes may occur at water activities lower than probed by osmotic deswelling. © 1992 John Wiley & Sons, Inc.     

Thermogravimetric study of polyacrylamide with evolved gas analysis

Dried samples of polyacrylamide in an He atmosphere have been subjected to thermogravimetric analysis in the 30–600°C range, and the evolved gases were monitored by FTIR. Water, ammonia, and small quantities of carbon dioxide are released in the first stages of decomposition (220–340°C), where the polymer chains remain intact and the reaction occurs on the pendant amide groups. In the second stage of decomposition (340–440°C), the majority of the weight loss occurs, and main chain breakdown occurs, releasing carbon dioxide, water, nitrile compounds, and imides. Trapping of the gases in this stage and analysis by GC–FTIR and GC–MS reveals the presence of more than 20 decomposition products, and confirms that a large proportion of these can be assigned to glutarimide and its substituted analogs. Imidization and dehydration reactions on the amide groups, as well as free radical breakdown of the main chains, with inter- and intramolecular hydrogen transfer, can account for many of the products of the decomposition. © 1993 John Wiley & Sons, Inc.     

高纯氯化铷的制备及其杂质含量的测定

随着原子能工业、航天航空技术、生物工程技术及含能材料等的飞速发展,铷的研究越来越引起人们的关注,需要量与日俱增。本文以江锂华翔实业责任公司生产的工业碳酸铷为原料,利用溶解温度效应和氯化氢盐析效应等提出了一种制备高纯氯化铷的新工艺,方法简便有效,并相应建立     

Swelling of polyacrylamide gels in polyacrylamide solutions

Swelling behavior of polyacrylamide (PAAm) and polyacrylamide-co-polyacrylic acid (PAAm-co-PAAc) gels was investigated in aqueous solutions of monodisperse PAAms with molecular weights (M_w) ranging from 1.5 × 10³ to 5 × 10⁶ g/mol. The volume of the gels decreases as the PAAm concentration in the external solution increases. This decrease becomes more pronounced as the molecular weight of PAAm increases. The classical Flory–Huggins (FH) theory correctly predicts the swelling behavior of nonionic PAAm gels in PAAm solutions. The polymer–polymer interaction parameter χ₂₃ was found to decrease as the molecular weight of PAAm increases. The swelling behavior of PAAm-co-PAAc gels in PAAm solutions deviates from the predictions of the FH theory. This is probably due to the change of the ionization degree of AAc units depending on the polymer concentration in the external solution. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1313–1320, 1998     

Silver staining of DNA in polyacrylamide gels

Nucleic acids can be detected at the picogram level using a quick and simple silver staining method (2). Using very thin polyesterbacked polyacrylamide gels, a further simplified protocol was compared to other widely used silver staining procedures. The improved protocol described here was the most sensitive, the fastest to perform, and had relatively few steps and reagents. This method also produced the least number of staining artifacts and offered images of high contrast.     

Enthalpy of adsorption and adsorption isotherms of polyacrylamide on sea sand

The enthalpy of dilution of polyacrylamide 3530s (HPAM) solution, the enthalpy of adsorption of the polymer on sea sand, and the adsorption isotherms, were determined at 298. 15 K. The effect of NaCl on these properties were also determined. From the experimental results and certain assumptions, it was deduced that, for an adsorbedHPAM molecule, a large number of segments are in contact with the surface of the solid, some of them forming hydrogen-bonds, most of them belonging to Van der Waals interactions, which are much weaker than hydrogenbonds, and theHPAM molecules adsorbed on the surface of the solid are spread out.     

“水包水”型阳离子聚丙烯酰胺乳液的合成

The emulsion of cationic polyacrylamide was prepared by a soap-free polymerization,using water as media,the oligomer that prepared by myself as emulsifier and stabilizer,(NH_4)_2S_2O_8 as initiator.The effect of the amount of isopropanol,oligomer and the ratio of DMC/AM on the molecular weight of cationic polyacrylamide were all studied.The best amount of isopropanol,oligomer are 25%,20% of the total monomer and the ratio of DMC/AM is 3/7.     

低分子量聚丙烯酰胺研究进展

综述了低分子量聚丙烯酰胺的合成方法及应用研究进展,同时对其未来的发展方向进行了展望.     

A simple polyacrylamide gel electrophoresis procedure for separation of polyamidoamine dendrimers

A simple, inexpensive, and rapid electrophoresis technique was developed for use as a routine tool for evaluating purity of polyamidoamine (PAMAM) dendrimers. A variety of factors influencing migration of generations 0-7 dendrimers on nongradient polyacrylamide gels were evaluated. The low generation dendrimers were found to be very sensitive to diffusion during or after electrophoresis. The proposed method incorporates steps that minimize diffusion, in order to obtain improved resolution and sensitivity, especially for the lower-molecular-weight dendrimers. This was accomplished by inclusion of a dendrimer fixation step with glutaraldehyde and performing the electrophoresis separation, fixation, staining, and destaining at 4 degrees C. PAMAM dendrimer separation was studied under basic and acidic conditions. Electrophoresis under acidic conditions gave increased resolution and sensitivity over separation at alkaline pH. Oligomers and trailing generations could be clearly separated and visualized under these conditions. The smallest PAMAM dendrimer, generation 0, was visible at 1.5 microg under the optimized acidic conditions. With slight modifications, this technique should be applicable to separation of other water-soluble dendrimers.     

Chiral detection of entecavir stereoisomeric impurities through coordination with R‐besivance and ZnII using mass spectrometry

In this study, a mass spectrometry (MS)‐based kinetic method (KM) is shown to be successful at analyzing a multichiral center drug stereoisomer, entecavir (ETV), both qualitatively and quantitatively. On the basis of the KM, the bivalent complex ion [M^II(A)(ref*)₂]²⁺ (M^II = divalent metal ion, A = analyte, and ref* = chiral reference) was set as precursor ion in MS/MS. The experiment results suggest strong chiral selectivity between ETV and its isomers when using Zn^II coordinated with the chiral reference R‐besivance (R‐B). The logarithm of the fragment ion abundance ratio and the enantiomeric percentage (%) exhibits a strong linear relation because of the competitive loss of the reference and analyte. The product ion pair [Zn^II(R‐B)A‐H]⁺ (m/z 733) and [Zn^II(R‐B)₂‐H]⁺ (m/z 849), together with [R‐B + H]⁺ (m/z 394) and [A + H]⁺ (m/z 278), can realize the identification of ETV and all of its chiral isomers. Theoretical calculation were also performed using the B3LYP functional with the 6‐31G* and LanL2DZ basis set to clarify the mechanism of structural difference of these bivalent complex ions. The results reveal that MS‐KM can be used to detect optical impurities without a chiral chromatographic column and fussy sample pretreatment. The established method has been used to determine stereoisomeric impurities of less than 0.1% in ETV crude drug, a demonstration of its simple and effective nature for rapid detection of stereoisomeric impurities.