DSC研究高吸水树脂吸水性能与分子结构的关系

以丙烯酸(AA)、丙烯酰胺(AM)和2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为共聚单体合成了聚丙烯酸-丙烯酰胺-2-丙烯酰胺基-2-甲基丙磺酸(PAA-AM-AMPS)三元共聚物高吸水树脂.利用茶叶袋法测定了其最大吸水倍率,通过差示扫描量热仪(DSC)测定并比较了含水量为50%,75%和91%的各种水凝胶的自由水和结合水含量.结果表明在蒸馏水和生理盐水中高吸水树脂的最大吸水倍率分别为1900g/g和185g/g,共聚物的结合水含量随着AMPS和AA含量增加及AM含量的减少而增大;在0.9%生理盐水中,结合水含量随着AMPS和AM含量增加及AA含量的减少而增大,共聚物和均聚物高吸水树脂的最大吸水倍率呈现出与结合水含量相同的变化规律.     

The relationship between polymer/substrate charge density and charge overcompensation by adsorbed polyelectrolyte layers

This work examines polyelectrolyte adsorption (exclusively driven by electrostatic attractions) for a model system (DMAEMA, polydimethylaminoethyl methacrylate, adsorbing onto silica) where the adsorbing polycation is more densely charged than the substrate. Variations in the relative charge densities of the polymer and substrate are accomplished by pH, and the polycation is of sufficiently low molecular weight that the adsorbed conformation is generally flat under all conditions examined. We demonstrate, quantitatively, that the charge overcompensation observed on the isotherm plateau can be attributed to the denser positive charge on the adsorbing polycation and that the ultimate coverage obtained corresponds to the adsorption of one oligomer onto each original negative silica charge, when the silica charge is most sparse, at pH 6. This limiting behavior breaks down at higher pHs where the greater silica charge density accommodates single chains adsorbing onto multiple negative sites. As a result of the greater substrate charge density and reduced polycation charge at higher pHs, the extent of charge overcompensation diminishes while the coverage increases on the plateau of the isotherm. Ultimately at the highest pHs, a regime is approached where the coil's excluded surface area, not surface charge, limits the ultimate coverage. In addition to quantifying the crossover from the charge-limiting to the area-limiting behaviors, this paper quantitatively reports adsorption-induced changes in bound counterion density and ionization at the interface, which were generally found to be independent of coverage for this model system.     

硫醇和硫醚的沸点与分子结构之间关系的拓扑化学研究

根据分子拓扑学原理, 用染色因子标识原子性质的差异, 发展了一种适用于含原子分子体系结构性能关系研究的新方法。据此探讨了硫醇和硫醚的沸点与分子结构之间的关系, 提出一个既能合理表征结构性能关系, 又能预测沸点的定量关系式。     

三氮烯试剂的结构与性能关系的研究

为建立三氮烯试剂结构与性能的关系, 我们研究了在非离子型表面活性剂TritonX-100存在下, 上述试剂亚氨基氢的酸性离解常数及镉(II)与上述试剂的显色反应。研究结果表明: (1)三氮烯试剂亚氨基氢的酸性离解常数遵循Hammett方程式, 其反应常数ρ=2.23; (2)试剂的亚氨基氢的酸性离解常数(pKa)与试剂和镉(II)显色反应的最佳酸度(pH最佳)之间的经验关系式为pH最佳=pKa-(1.70±0.20)。     

卤代烷烃结构与折光指数关系的拓扑化学研究

本文根据分子拓扑学原理, 用色图方法探讨了卤代烷烃结构与折光指数的关系。提出一个普遍适用于卤代烷烃折光指数的定量关系式。应用这一定量关系, 不仅能够描述卤代烷烃折光指数的变化规律、预测卤代烷烃的折光指数。而且能够合理表征物质结构与性能之间的关系。     

Studies of relationship between polymer structure and hydration environment in amphiphilic polytartaramides

The relationships between the chemical structures and hydration environment of the polymers can provide significant insight into the water‐amphiphilic polymer interactions. Here, the hydrophobicity of amphiphilic block copolymers poly(ethylene tartaramide‐b‐alkyl isocyanate) is gradually tuned by using of a series of pendant alkyl (isopropyl, n‐butyl, cyclopentyl, and cyclohexyl) groups. Dynamics of hydration probed by low‐field NMR relaxometry exhibits a heterogeneous environment of water molecules, corresponding to tightly bound water with slow re‐orientational mobility and loosely bound water with fast re‐orientational mobility. Progressively larger amounts of bound water are present in the copolymers, ongoing from pendant isopropyl, n‐butyl, cyclopentyl, and finally to cyclohexyl group. Water in the copolymer bearing the cyclohexyl group has a significantly high partial specific heat capacity. Therefore, hydrophobic interaction between the polymer and water is enhanced when the hydrophobicity of the polymer is increased, resulting in considerable hydrophobic hydration with decreased mobility of the bound water. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 138–145     

Synthesis and biocompatibility of phosphoryl polymer and relationship between biocompatibility and water structure

A series of copolymers, poly(methylmethacrylate-co-2-methacryloyloxyethyl phosphorylcholine), with various compositions of methyl methacrylate (MMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) were synthesized by radical copolymerization in a mixed solvent of ethanol and chloroform. The structures of the copolymers were confirmed by proton nuclear magnetic resonance and elemental analysis. The properties and morphologies of the copolymers were characterized by differential scanning calorimeter, scanning electron microscopy, and optical microscope. The adsorption of bovine serum albumin (BSA) and the adhesion of platelet on the surfaces of the copolymer membrane significantly decreased with increasing the MPC composition. The copolymers containing MPC above 18% showed excellent biocompatibility. Moreover, the relationship between the water structure and the biocompatibility was illustrated by changing quantity of the MPC in copolymers. The result showed that the amount of free water affected the platelet compatibility of the copolymer.     

The relationship between the chemical structure of nematic liquid crystals and their pretilt angles

About 50 different additives in one or more of three different nematic mixtures have been investigated to clarify the relationship between the chemical structure of the liquid crystal and the pretilt angle on a polyimide surface. The pretilts found for cells have been explained within our recently proposed population distribution model. For compounds with cyano-groups at one end, we find that the in-plane order is governed both by the surface-mesogen interaction and by the relative strength of the intermolecular interactions in the nematic phase. This strength is nearly linear in alkyl chain length for the compounds investigated. Changes in the strength due to variations in the core of the molecules can be calculated easily by using group contributions from the known Parachors. The in-plane order can be treated as a simple product of the contributions from the liquid crystal and from the polyimide. Different polar end groups will give different angles between the surface and the optical axis of the individual mesogens in the first monolayer. The cyano-group gives the highest angle and alkyl groups the lowest. For nitro-compounds the dimers formed are so strongly bound that they do not break up at the surface. Nitro-compounds will thus act as dialkyl compounds. For dialkyl compounds the pretilt angles are dominated by the difference between the chain lengths at the two ends of the molecule.     

Study on the relationship between chromatographic retention behaviour and molecular structure

Summary With the molecular hydrophobic feature represented by Van der Waals molecular volume, the-hydrophilic parameter of substituting groups in mono-substituted benzenes was determined, in order to predict the retention of substituted benzenes in RP-HPLC. Thus it is possible to predict the retention of multi-functional substituted benzenes. The agreement between the calculated and the measured retention values shows that the proposed model to deal with retention of solutes is reasonable.     

Empirical relationship between structure and molecular optical rotation in six-membered cyclic compounds

The molecular optical rotation of a six-membered series of cyclic compounds has been calculated with a simple method which relates the sign and magnitude of the molecular optical rotation to the geometry, conformation and absolute configuration of the studied compounds. The optimised geometry of each conformer was calculated by molecular mechanics calculations. The values obtained seem to confirm the existence of a close relationship between the value of molecular optical rotation of a compound and its geometry.     

硅烷摩尔折射度与其分子结构之间关系的探讨

本文首次用图论方法探讨了硅烷的摩尔折射度与其分子结构之间的关系, 提出了一个结构基础明确的定量关系。应用本文定量关系，不仅能够预测硅烷的摩尔折射度, 而且可以合理表征物质结构与性能之间的关系。     

The relationship between membrane cleaning efficiency and water quality

Impurities such as particulates and some dissolved salts present in the water used for cleaning of a polysulphone ultrafiltration membrane have been found to affect the efficiency of the cleaning. A cationic surfactant, CTAB (cetyl-trimethyl-ammonium bromide), was used for membrane cleaning after ultrafiltration of a 0.1 wt% reconstituted whey protein solution. Colloidal-free water used for cleaning was doped with a known amount of the ions: calcium, sodium, chloride, nitrate and sulphate. The presence of calcium in water, at the usual concentrations found in tap water, did not greatly affect cleaning efficiency while chloride was found to reduce cleaning efficiency. Sodium, nitrate and sulphate appeared to improve the flux recovery during membrane cleaning. The cleaning efficiency was also improved at higher ionic strengths. Calculations were carried out to demonstrate that the differences were statistically significant.     

The relationship between crystal structure and NMR relaxation in molecular solids with tert-butyl groups

We correlate an X-ray determination of the molecular and crystal structures of 2-tert-butylanthracene and 2-tert-butylanthraquinone reported here with the previously reported dynamical nuclear magnetic resonance determination of the motions of the tert-butyl groups and their resident methyl groups in the solid state [P.A. Beckmann, K.S. Burbank, M.M.W. Lau, J.N. Ree, T.L. Weber, Chem. Phys. 290 (2003) 241].     

Prediction of RO membrane performances by use of artificial neural network and using the parameters of a complex mathematical model

Some mathematical models have properly predicted the RO membrane performances. The equations of these models which were usually complex and time consuming were solved algebraically and numerically. The modified surface force-pore flow model is one of the best models which has predicted the RO membrane performances, for example separation factor (f), pure solvent flux (N _P) and total flux (N _T), better than the others. In this study, these performances were computed by use of an artificial neural networks technique by applying the parameters of this model and the physical properties of the membrane. A back-propagation feed-forward network with three layers including 9 neurons in the first layer and one neuron in the output layer was used. Minimum error was found with 20 neurons in the second layer, by trial and error. Some experimental data were used for simulating the network. The network was trained in two subsequent steps including feed-forward and error back-propagation. The datasets were randomly divided into three parts: 70 % of them were applied for training, 15 % were used for validating, and the remaining 15 % were applied for testing. The predicted values of the network were compared with experimental data existing for RO membrane performances (f, N _P, and N _T). A mean square error less than 0.0007 was achieved and a correlation coefficient with more than 0.99 was derived for the test datasets.     

The relationship between molecular structure and mesomorphic properties of 2,2'- and 3,2'-difluoroterphenyls synthesized by palladium-catalysed cross-couplings

Several homologues of two structurally different types of mesogenic difluoroterphenyls have been prepared. One set of compounds contains two inner-core fluoro-substituents and the other set possesses both an inner-core and an outer-core fluoro-substituent. The use of various types of palladium-catalysed cross-coupling reactions was invaluable in the synthesis (for example, selective couplings, and couplings to trifluoromethanesulphonate derivatives). Additionally, a novel selective lithiation is reported. The mesogenic materials are all low melting and the types of mesophase generated are considerably structure dependent. However, most of the materials support the tilted S_c phase which is required of ferroelectric host materials. The mesomorphic behaviour of these novel materials is discussed in terms of the molecular structure and the structure/property relationships are compared with those for difluoroterphenyls with different arrangements of lateral fluoro-substitution.     

Phase behavior of polymer/diluent/diluent mixtures and their application to control microporous membrane structure

Rechargeable battery separators containing controlled pores were fabricated via the thermally-induced phase separation (TIPS) process. Based on the idea that pores could be manipulated by controlling the liquid–liquid phase separation temperature in the TIPS process, phase boundaries of the polymer–diluent systems were controlled by using diluent mixtures. Phase behaviors of the polymer/diluent/diluent ternary blends consisting of polyethylene (PE) as polymer, and soybean oil (SBO) and dioctyl phthalate (DOP) as diluents were explored. PE/SBO and PE/DOP binary blends, and PE/SOB/DOP ternary blends exhibited typical upper critical solution temperature (UCST) type phase behaviors, and the phase separation temperatures of the PE/SBO blends were higher than those of the PE/DOP blends. When the mixing ratio of the polymer and diluent-mixture was fixed, the phase separation temperature of the PE/SBO/DOP blend initially increased with increasing SBO content in the diluent-mixture passing through a maximum centered at about 80 wt% SBO and decreased beyond this point. Furthermore, the phase separation temperature of the PE/diluent-mixture blend was always higher than that of the PE/SBO blend when the diluent-mixture contained more than or equal to 50 wt% SBO. To understand the observed phase behavior of the blends, thermodynamic analyses based on the lattice-fluid theory were performed. Larger pore membranes were fabricated from the blend when higher phase separation temperatures of the blend were exhibited.     

烷基苯凝聚型性能与分子结构之间关系的探讨

本文根据分子结构的特点，用图论方法探讨了烷基苯的凝聚型性能与其分子结构之间的关系，用四个结构信息指数描述了分子的大小和形状、烷基的大小和数目及烷基在苯环上的位置对凝聚型性能的影响，据此提出一个具有一定结构基础的定量关系式。应用这一定量关系，不仅能够预测烷基苯的沸点、密度和折光指数，而且有助于揭示物质结构与性能之间的奥秘。计算结果表明计算值与实验值的一致性令人满意。