SPan80-Tween60/白油/丙烯酰胺/丙烯酸钠/H2O体系形成反相微乳液的研究

采用电导法和相体积法相结合，并借助相图、黏度、光学显微镜，研究了Span80-Tween60／白油／丙烯酰胺／丙烯酸钠／H2O体系形成反相微乳液的过程，以及表面活性剂Span80与Tween60质量比、温度、乙酸钠对体系形成反相微乳液区的影响。结果表明，体系中表面活性剂质量分数小于20％时，电导法与相体积法确定的反相微乳液区边界基本一致；表面活性剂质量分数大于20％时，两方法确定的反相微乳液区边界相差甚远。说明仅由电导率突变不能准确确定反相微乳液区的边界，必须与相体积法相结合来共同确定相区的边界。当质量比m(Span80)：m(Tween60)=13：7、温度为25～30℃、乙酸钠质量分数为2％时，体系能形成比较大的反相微乳液区，适合进行微乳液聚合。     

几种阳离子度PDA共聚物的合成

以丙烯酰胺(AM)和工业单体二甲基二烯丙基氯化铵(DMDAAC)为原料,过硫酸铵(APS)和亚硫酸氢钠(RH)复合物为引发体系,采取一次性加料方法,以特征黏度为考核指标,对几种阳离子度二甲基二烯丙基氯化铵与丙烯酰胺的共聚物PDA进行了制备工艺研究。通过正交优化等实验方法考察了单体起始质量分数、引发剂用量和聚合反应温度3个因素对选定的每一种阳离子度PDA共聚合反应结果的影响,得到了制备系列化具不同阳离子度PDA的各自最佳点的制备工艺条件,比较了在各阳离子度条件下,最佳制备工艺点时单体起始质量分数、引发剂用量和聚合反应温度的变化规律。结果表明,对于制备5%、10%、20%、30%和50%阳离子度的PDA产物,当单体起始质量分数分别为16%、18%、25%、35%和65%,引发剂用量占单体的质量分数分别为8.62×10-5、8.82×10-5、7.35×10-5、5.40×10-5和9.19×10-5,聚合反应温度分别为25、30、30、30℃和25℃时,特征黏度可分别达到17.0、15.0、11.6、9.0 dL/g和6.2 dL/g。此外还对共聚产物PDA进行了红外光谱结构表征。该工艺简单方便、清洁安全,适合于工业化生产。     

Synthesis of novel superabsorbing copolymers for agricultural and horticultural applications

A series of novel superabsorbent copolymers (SAPs) based on monomers acrylamide, calcium acrylate and sodium acrylate have been prepared using ammonium persulfate as initiator and N,N‐methylene‐bis‐acrylamide (MBA) as crosslinking agent; the monomer concentration, MBA concentration and initiator concentration were varied. The experimental results show that the SAPs have good absorbency both in water and NaCl solutions. The copolymers were characterized by IR spectroscopy. Water retention in soil is enhanced by use of these superabsorbents. The effect of SAPs on the growth of bean plants is reported. SAPs may be of use as water management materials for agricultural and horticultural purposes in desert and drought‐prone areas. © 2001 Society of Chemical Industry     

Atmospheric Photopolymerization of Acrylamide Enabled by Aqueous Glycerol Mixtures: Characterization and Application for Surface‐Based Microfluidics

Polyacrylamide usually is the material of choice for electrophoretic separation in slab gels, capillaries, and microfluidic devices. So far its polymerization requires anaerobic environments because oxygen impurities inhibit or even terminate the polymerization reaction of acrylamide. Here, it is demonstrated that gel precursor solutions with glycerol contents above 20 vol% enable direct atmospheric photopolymerization of acrylamide with no need for sealing or degassing the solution in advance. The positive effect of glycerol on the polymerization reaction is proven by simulation‐validated electron paramagnetic resonance measurements. Nuclear magnetic resonance reveals that glycerol does not interfere with the reaction indicating that the observed enhancement in polymerization is owed to the low oxygen solubility of aqueous glycerol mixtures. Glycerol concentrations of >60 vol% in the gel precursor solution enable complete polymerization of volumes down to 5 nL within less than 5 s. This enables using liquid handling robots to fabricate channel‐free open microfluidic structures of solid polyacrylamide hydrogel in a low‐cost automated manner in a standard lab environment.     

Homogeneous complex solution formed through interactions of poly(acrylamide‐co‐acrylic acid)/poly(acrylamide‐co‐dimethyldiallylammonium chloride) complex with M n+ hydration metal ions in aqueous media

A homogeneous complex solution, formed through inter‐polyelectrolyte complexation of poly(acrylamide‐co‐acrylic acid) (P(AM‐AA)) with poly(acrylamide‐co‐dimethyldiallylammonium chloride) (P(AM‐DMDAAC)) and interaction of the P(AM‐AA)/P(AM‐DMDAAC) complex with M ⁿ⁺ hydrated metal ion, was prepared and the structure and properties of the P(AM‐AA)/P(AM‐DMDAAC)/M ⁿ⁺ homogeneous complex solution were studied by UV spectrometry, dynamic light scattering and viscometry. The experimental results show that the homogeneous complex solution can be obtained by controlling the composition of the P(AM‐AA)/P(AM‐DMDAAC) complex and the M ⁿ⁺ metal ion content. Compared to the constituents, ie the P(AM‐AA) solution, the P(AM‐DMDAAC) solution and the P(AM‐AA)/P(AM‐DMDAAC) complex solution, the P(AM‐AA)/P(AM‐DMDAAC)/M ⁿ⁺ complex solution has a new peak at 270 nm in its UV spectrum, a larger hydrodynamic radius, and hence a higher solution viscosity, all of which indicate that there exist specific interactions between polymers and M ⁿ⁺ metal ions. These interactions lead to the formation of a network structure and hence an obvious increase not only in solution viscosity but also in resistance of the polymer solution to simple salts, to temperature changes and to shearing. © 2001 Society of Chemical Industry     

Photon transmission technique for monitoring drying processes in acrylamide gels formed with various crosslinker contents

In situ photon transmission experiments were performed using UV‐visible (UVV) spectrometer during the drying of polyacrylamide (PAAm) gels. These gels are formed from acrylamide (AAm) with various N,N′‐methylenebis(acrylamide) (Bis) contents by free radical crosslinking copolymerization (FCC) in water. The transmitted light intensity, I_tr increased continuously as PAAm gels are dried. Increase in I_tr was attributed to the decrease in the scattered light intensity, I_sc, which might be originated from the contrast between “frozen blob clusters” and holes in the drying gel. Decrease in I_sc was modeled using Rayleigh's equation, where drying times with various exponents were found to be proportional to the volume of frozen blob clusters. It was observed that the radius of frozen blob cluster (correlation length), ξ_c increased in various power of time, depending on Bis contents during drying of gels. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1898–1906, 2001     

Poly(acrylamide) functionalized chitosan: An efficient adsorbent for azo dyes from aqueous solutions

In the present communication we report on the optimization of persulfate/ascorbic acid initiated synthesis of chitosan-graft-poly(acrylamide) (Ch-g-PAM) and its application in the removal of azo dyes. The optimum yield of the copolymer was obtained using 16 × 10⁻² M acrylamide, 3.0 × 10⁻² M ascorbic acid, 2.4 × 10⁻³ M K₂S₂O₈ and 0.1 g chitosan in 25 mL of 5% aqueous formic acid at 45 ± 0.2 °C. Ch-g-PAM remained water insoluble even under highly acidic conditions and could efficiently remove Remazol violet and Procion yellow dyes from the aqueous solutions over a pH range of 3–8 in contrast to chitosan (Ch) which showed pH dependent adsorption. The adsorption data of the Ch-g-PAM and Ch for both the dyes were modeled by Langmuir and Freundlich isotherms where the data fitted better to Langmuir isotherms. To understand the adsorption behavior of Ch-g-PAM, adsorption of Remazol violet on to the copolymer was optimized and the kinetic and thermodynamic studies were carried out taking Ch as reference. Both Ch-g-PAM and Ch followed pseudo-second-order adsorption kinetics. The thermodynamic study revealed a positive heat of adsorption (ΔH°), a positive ΔS° and a negative ΔG°, indicating spontaneous and endothermic nature of the adsorption of RV dye on to the Ch-g-PAM. The Ch-g-PAM was found to be very efficient in removing color from real industrial wastewater as well, though the interfering ions present in the wastewater slightly hindered its adsorption capacity. The data from regeneration efficiencies for ten cycles evidenced the high reusability of the copolymer in the treatment of waste water laden with even high concentrations of dye.     

Spectroelectrochemical study of N‐ethyl‐carbazole in the presence of acrylamide

Polymerization of N‐ethylcarbazole (NECz) in the presence of acrylamide (AAm) has been investigated by in situ and ex situ UV–visible spectrophotometric measurements to obtain information about the reaction pathway, because NECz gives soluble oligomeric species allowing such measurements. A tentative mechanism is proposed in the light of these results. The redox properties of the new polymers have been studied for possible sensor application. © 2001 Society of Chemical Industry     

Interpolymer radical coupling: A toolbox complementary to controlled radical polymerization

The current review focuses on the relevance and practical benefit of interpolymer radical coupling methods. The latter are developing rapidly and constitute a perfectly complementary macromolecular engineering toolbox to the controlled radical polymerization techniques (CRP). Indeed, all structures formed by CRP are likely to be prone to radical coupling reactions, which multiply the available synthetic possibilities. Basically, the coupling systems can be divided in two main categories. The first one, including the atom transfer radical coupling (ATRC), silane radical atom abstraction (SRAA) and cobalt-mediated radical coupling (CMRC), relies on the recombination of macroradicals produced from a dormant species. The second one, including atom transfer nitroxide radical coupling (ATNRC), single electron transfer nitroxide radical coupling (SETNRC), enhanced spin capturing polymerization (ESCP) and nitrone/nitroso mediated radical coupling (NMRC), makes use of a radical scavenger in order to promote the conjugation of the polymer chains. More than a compilation of macromolecular engineering achievements, the present review additionally aims to emphasize the particularities, synthetic potential and present limitations of each system.     

甲基丙烯酰氧乙基三甲基氯化铵/丙烯酰胺反相乳液的聚合及表征

以Span 80、OP 10为乳化剂,K2S2O8、Na2S2O4、V 044为引发剂,以汽油为分散介质, 用反相乳液聚合法制备出甲基丙烯酰氧乙基三甲基氯化铵 /丙烯酰胺共聚物,并且用粒度分布仪及红外光谱进行了分析表征。结果显示,随乳化剂用量及引发剂用量增加,共聚物相对分子质量下降;乳胶粒子大小受引发剂、乳化剂、交联剂的加量及放置时间等条件的影响而变化。