磺基甜菜碱型两性离子聚合物的合成

以甲基丙烯酰氧乙基二甲基胺(DM)和1,3-丙基磺内酯为原料,在55℃下反应20 h,合成了3-(2-甲基丙烯酰氧乙基二甲胺基)丙磺酸盐(DMAPS);并在盐溶液中与丙烯酰胺(AM)单体进行自由基共聚合反应,获得了净电荷为零的磺基甜菜碱型两性离子共聚物P(AM-DMAPS);采用红外光谱对共聚物进行表征;考察了总单体的质量分数、单体摩尔分数、引发剂用量、反应时间、反应温度、c(NaCl)以及氧化剂与还原剂的物质的量比等因素对聚合反应的影响;获得最佳反应条件:总单体的质量分数25%,x(DMAPS)=5%,w(引发剂)=0.03%,反应时间10 h,反应温度25℃,c(盐)=0.5 mol/L,n(氧化剂)∶n(还原剂)=1.4∶1。在此条件下获得的共聚物特性粘数为18.5 mL/g。     

Synthesis and solution properties of a new sulfobetaine/sulfur dioxide copolymer and its use in aqueous two-phase polymer systems

The zwitterionic monomer, 3-(N,N-diallylammonio)propanesulfonate, was copolymerized with sulfur dioxide in dimethyl sulfoxide using azo-bis-isobutyronitrile (AIBN) to afford the polysulfobetaine (PSB) copolymer in excellent yields. The PSB was converted into the corresponding anionic polyelectrolyte (APE) by treatment with 1 equiv. of sodium hydroxide. The solution properties of PSB and APE were investigated by potentiometric and viscometric techniques. The critical (minimum) salt concentrations (CSC) required to promote water solubility for the PSB at 23 °C have been measured. Basicity constant of the amine functionality in APE is found to be ‘apparent’ and as such follow the modified Henderson-Hasselbalch equation. The composition and phase diagram of the aqueous two-phase polymer systems of PSB (treated with 0.60 equiv. sodium hydroxide) and poly(ethyelene glycol) (PEG) in 0.1N KCl has been studied for the first time for this class of PSB copolymer.     

Carboxybetaine,sulfobetaine, and cationic block copolymer coatings: A comparison of the surface properties and antibiofouling behavior

Two different zwitterionic block copolymers (BCs) and a cationic BC were synthesized from the same BC precursor, which consisted of a polystyrene (PS) block and a poly[N‐(3‐dimethylamino‐1‐propyl)acrylamide] block. The zwitterionic BCs contained the dimethylammonioacetate (carboxybetaine) and dimethylammoniopropyl sulfonate (sulfobetaine) groups. Thin films cast from these polymers were investigated for surface wettability, surface charge, and protein adsorption. Surface‐energy parameters calculated with advancing contact angle (θ_a) and receding contact angle (θ_r) of different probe liquids showed that it was θ_r and not θ_a that was representative of the polar/ionic groups in the near‐surface regions of the coatings. Electrophoretic mobility was used to characterize the influence of pH on the net surface charge. In aqueous dispersions, the carboxybetaine polymer showed an ampholyte behavior with an isoelectric point of 6, whereas the sulfobetaine polymer was found to be anionic at all pH values between 2 and 10. Protein adsorption on the carboxybetaine BC was relatively independent of the net charges on the protein or the polymer, but the negatively charged sulfobetaine polymer showed a higher adsorption of positively charged protein molecules. Regardless of the net protein charge, both zwitterionic coatings adsorbed less protein compared to the PS and poly(2,3,4,5,6‐pentafluorostyrene) controls. The sulfobetaine and cationic BCs adsorbed higher amounts of oppositely charged protein molecules than like‐charged protein molecules. However, the adsorption of oppositely charged protein was much higher on the cationic surface than on the sulfobetaine surface. The zwitterionic BCs, particularly the carboxybetaine polymer, from this article are expected to function as stable, low‐fouling surface modifiers in different biological environments. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A suspension of spheres in a dilute polymer solution

The Hookean dumbbell model of a macromolecule predicts non‐uniform density and pressure fields surrounding a sphere buoyant in a dilute polymer solution when the size of the sphere is of the same order of magnitude as the size of the macromolecules. Using this prediction, the root mean square separation distance of a suspension of spheres buoyant within a dilute polymer solution is found to be inversely proportional to both the square of the radius of a sphere and the density of the polymer solution. The phase space distribution function for an ensemble of spheres immersed at equilibrium within a dilute polymer solution is found and used to define the magnitude of the ensemble average peculiar acceleration of the spheres. The peculiar acceleration results from changes in direction of the peculiar velocity. It is found to be directly proportional to the temperature, polymer density, and square of the radius of a sphere and inversely proportional to the mass of a sphere. The self‐ diffusivity of the particles varies directly with the square root of the temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Conformational and visometric behavior of quaternized polysulfone in dilute solution

Some properties of polysulfone, chlorometylated polysulfone and quaternized polysulfone were studied by viscometry, interferometry and dialysis equilibrium. Modification of intrinsic viscosity, preferential and total adsorbtion coefficients explained the changes of the hydrodynamic dimensions with solvent quality. POLYM. ENG. SCI., 46: 827–836, 2006. © 2006 Society of Plastics Engineers     

Excluded volume effect on the self-assembly of amphiphilic AB diblock copolymer in dilute solution

The self-assembly of amphiphilic AB diblock copolymer in solution with different molecular size was investigated by using the self-consistent field theory (SCFT). By continuously varying the solvent size and the polymer concentration, the phase diagram is constructed. The aggregate concentration of the amphiphilic AB diblock copolymer decreases in solution with larger solvent size. The phase will transit in solution with different solvent size due to the excluded volume interaction effect. This widely existing excluded volume effect is very useful for the separation of polymers and helpful for understanding the crowding effect in bio-molecules.     

丙烯腈共聚物溶液的流变性和相分离性能研究

通过红外光谱和核磁共振分析,对不同丙烯腈共聚物(PAN1,PAN2)分子结构进行表征。通过哈克流变仪测定溶液流变性,结果表明共聚物的相对分子质量和第二单体含量对溶液流变性有影响。通过扫描电镜观察膜的形态,并通过热力学和动力学对膜形态进行了讨论。PAN2相对分子质量与第二单体含量较高造成相互作用参数偏高,相对PAN1表现出更易分相特征,分相过程中聚合物贫相所占膜的体积分数偏高,形成的膜孔洞较大。     

The grain-boundary resistance of CeO2 ceramics: A combined microscopy-spectroscopy-simulation study of a dilute solution

Weakly acceptor-doped ceria ceramics were characterized structurally and compositionally with advanced transmission electron microscopy (TEM) techniques and electrically with electrochemical impedance spectroscopy (EIS). The grain boundaries studied with TEM were found to be free of second phases. The impedance spectra, acquired in the range 703 ≤ T/K ≤ 893 in air, showed several arcs that were analyzed in terms of bulk, grain-boundary, and electrode responses. We ascribed the grain-boundary resistance to the presence of space-charge layers. Continuum-level simulations were used to calculate charge-carrier distributions (of acceptor cations, oxygen vacancies, and electrons) in these space-charge layers. The acceptor cations were assumed to be mobile at high (sintering) temperatures but immobile at the temperatures of the EIS measurements. Space-charge formation was assumed to be driven by the segregation of oxygen vacancies to the grain-boundary core. Comparisons of data from the simulations and from the EIS measurements yielded space-charge potentials and the segregation energy of vacancies to the grain-boundary core. The space-charge potentials from the simulations are compared with values obtained by applying the standard, analytical (Mott–Schottky and Gouy–Chapman) expressions. The importance of modelling space-charge layers from the thermodynamic level is demonstrated.     

两亲高分子驱油剂体系的增粘性能和分子聚集行为

通过氧化-还原体系、采用水溶液胶束共聚法制得了一种两亲高分子(FPAM),研究了电解质、温度、表面活性剂等对两亲高分子在水溶液中的聚集体形态以及对水溶液宏观性质的影响。结果表明,高分子在水溶液中存在着特殊分子聚集体,这种聚集体能使高分子具有较强的耐盐抗温性能;在4%的NaCl溶液中,FPAM(1500 mg/L)体系粘度超过100 mPa.s;加入Gemini型表面活性剂(150 mg/L)的FPAM(1500 mg/L)二次水溶液粘度可达2 700 mPa.s。     

Molecular size and aggregation behavior of Erwinia gum in aqueous solution

Erwinia (E) gum, a stabilizer and thickening agent of food, is composed of glucose, fucose, galactose, and glucuronic acid (1 : 0.1 : 0.05 : 0.3 by molar ratio). The apparent weight‐average molecular weight M_w and intrinsic viscosity [η] in 0.2 M NaCl aqueous solution were measured to be 7.83 × 10⁵ and 268 mL g⁻¹, respectively, by light scattering and viscometry. The aggregation behavior of E gum in aqueous solution was investigated by gel permeation chromatography (GPC) and dynamic light scattering. The results showed that 7.5% E gum exists as an aggregate, whose diameter is 12 times greater than single‐stranded chain, in aqueous solution at 25°C, and the aggregates' content decreased with increasing temperature or decreasing polymer concentration. The aggregates at higher temperature were more readily broken than in exceeding dilute solution. GPC analysis proved that a significant shoulder, corresponding to a fraction of higher molecular weight due to chain aggregation, appeared in the chromatogram of E gum in 0.05 M KH₂PO₄/5.7 × 10⁻³ M NaOH aqueous solution (pH 6.0) at 35°C, and decreased with increasing temperature, finally disappeared at 90°C. The disaggregation process of E gum in aqueous solution can be described as follows: with increasing temperature, large aggregates first were changed into the middle, then disrupted step by step into single‐stranded chains. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1083–1088, 2000     

Continuous deionization of a dilute nickel solution

This paper describes the continuous removal of nickel ions from a dilute solution using a hybrid ion-exchange/electrodialysis process. Emphasis was placed on the ionic state of the bed during the process, and the mass balance of ions in the system. Much of this information was obtained by analysing the current distribution across the cell. The effects of temperature, feed nickel concentration and feed solution flow rate were ascertained. It was found that a steady, continuous process can be achieved.     

Diffusion in dilute polytetrahydrofuran solution

The diffusion coefficients of four polymer-solvent mixtures at 34.0‡C were measured using a Mach-Zehnder diffusiometer. Monodisperse (M_w/M_n <1.05) polytetrahydrofuran (PTHF) with and without OH-end group were chosen for this work to study the effects of association of polymer molecules on the diffusion coefficient. In order to minimize the interaction between solvent and polymer molecules, bromobenzene having no hydrogen bond-forming capability was employed as a solvent. The experimental results showed that the OH end group indeed affected diffusion property of dilute polymer solution. An association model was developed in this work and the experimental results were interpreted based on the model.     

Phase transition in a polymer chain in dilute solution

Some general theoretical arguments are advanced to help in an understanding of the behaviour of a single molecular chain with intramolecular forces of van der Waals type. Analogy with a fluid suggests that as N→∞ a first-order phase transition takes place at a unique condensation temperature and this defines a unique ?-temperature. However, for finite N the transition becomes rounded and hence the ?-temperature is dependent on N. Instead of a ?-temperature one should now talk of a ?-region, an idea already put forward by Mazur et al. from an analysis of Monte Carlo data. Evidence for this pattern of behaviour is adduced from a lattice model of a self-avoiding walk with near-neighbour attractive forces using ideas which have proved useful in critical phenomena. Attention is drawn to a ferroelectric model which shows some similarities in behaviour.     

Ultrasonic disassociation of EVA random copolymer in dilute solutions

Ultrasonic disassociation of the ethylene–vinyl acetate (EVA) random copolymer in 1,2‐dichloroethane (DCE), cyclohexane (CYH), and their solvent mixtures was investigated using viscometry and dynamic laser light scattering (DLLS). It was found that the disassociation of the EVA aggregates in solutions increases with increasing the time and intensity of ultrasonic shearing and approaches invariant finally. This phenomenon is especially marked for the EVA copolymer with low vinyl acetate (VA) content in the polar solvent of DCE at higher concentration and lower temperature. This is attributed to disassociation of the ethylene segment of the EVA random copolymer in dilute solutions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2798–2802, 2001     

In situ synchrotron study of the solution crystallization of ultralong alkanes from dilute solution

The crystallization from dilute solution of two long n-alkanes (C₂₄₆H₄₉₄ and C₁₆₂H₃₂₆) has been followed in real time using synchrotron X-ray diffraction techniques at the European Synchrotron Radiation Source (ESRF) at Grenoble.The data confirm the existence of minima in crystallization and nucleation rates in C₂₉₄H₅₉₀. Further, the ability to record data very rapidly has allowed us to see the minimum in crystallization rate in C₁₆₂H₃₂₆ for the first time.Small changes in lattice spacing were seen during and after crystallization in all samples. These indicate that there is some perfectioning of crystals—for example the removal of cilia at the surfaces, etc.     

Long-term corrosion of copper in a dilute anaerobic sulfide solution

The mechanism of corrosion of oxygen-free copper has been studied in stagnant aqueous sulfide solutions using corrosion potential and electrochemical impedance spectroscopy (EIS) measurements. Film structure and composition were examined on surfaces and on cross-sections prepared by focused ion beam (FIB) milling using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Experiments were conducted in anaerobic 5 × 10⁻⁵ mol dm⁻³ Na₂S + 0.1 mol dm⁻³ NaCl solutions for exposure periods up to 4000 h (∼167 days) to mimic (at least partially) the conditions that could develop on a copper nuclear fuel waste container in a deep geologic repository. The corrosion film formed was a single cellular Cu₂S layer with a non-uniform thickness. The film thickness increased approximately linearly with immersion time, which implied that the sulfide film formed on the Cu surface is non-protective under these conditions up to this exposure time. The film growth process was controlled by HS⁻ diffusion partially in the aqueous solution in the pores in the cellular sulfide film and partially in the bulk of the aqueous solution.     

溴代苝二酰亚胺衍生物的光谱及其在溶液中的聚集

设计合成了一种新型的苝二酰亚胺衍生物1,6,7,12-四溴代-N,N-丙酸2-(2-氨基乙氧基)乙醇酯苝四羧酸酐.研究了在不同有机溶剂中的紫外、荧光光谱性能以及相应的聚集行为.光谱研究表明,在4种不同的溶剂中,临界聚集浓度不同.随着溶液浓度的增加,化合物分子呈斜线发生面-面堆积.SEM观察了在有机溶液中的聚集形貌,受分...     

表面活性离子液体的表面性能及在水溶液中聚集行为的研究进展

综述了表面活性离子液体的表面活性及在水溶液中聚集行为的主要研究成果,重点介绍了影响表面活性离子液体表面活性的因素及表面活性离子液体在水溶液中形成的有序聚集体。在此基础上,分析了表面活性离子液体的表面活性及在水溶液中的聚集行为研究存在的问题和未来的发展方向。