丙烯酰胺水溶液聚合反应的研究

探讨了聚乙二醇作为分散剂时丙烯酰胺水溶液聚合体系中单体含量、还原剂用量对聚合物分子量的影响，并探讨了聚合时间与转化率、单体含量与聚合体系粘度之间的关系。结果表明，在保持聚合体系能够流动的前提下，单体含量可提高到２０％，聚合物的分子量可达３００万以上。     

蛋白质分子在聚丙烯酰胺凝胶中扩散和分配特性的研究

利用凝胶内溶质分子向缓冲溶液中扩散的方法,测定了溶菌酶、β－乳球蛋白、卵清蛋白、牛血清白蛋白和γ－球蛋白５种蛋白在聚丙烯酰胺凝胶中的有效扩散系数和分配系数,研究了单体质量浓度、交联度和蛋白分子粒径等因素的影响,讨论了聚丙烯酰胺凝胶中蛋白分子的扩散和分配机制,发现不能用Ｏｇｓｔｏｎ理论解释聚丙烯酰胺凝胶中蛋白分子的扩散和分配特性     

聚乙二醇／聚丙烯酰胺共混物的制备及性能研究

通过微波加热法制备聚丙烯酰胺,将其与聚乙二醇共混制备聚乙二醇／聚丙烯酰胺（PEG,PAM）共混物,采用傅立叶变换红外线光谱（FTIR）,差示扫描量热仪（DSC）,X射线粉末衍射仪（XRD）,熔点偏光显微镜等测定共混物的性能。结果显示共混物中PEG与PAM形成氢键,共混物的升降温过程中具有吸热和放热峰,相变温度和相变焓随共混物中PAM含量的增加,逐渐降低。PAM的存在对PEG的结晶过程造成了破坏,共混使PEG难以形成均匀球晶,结晶粒子变大。     

双丙酮丙烯酰胺在聚丙烯酰胺改性中的应用

以双丙酮丙烯酰胺(DAAM)和丙烯酰胺(AM)为原料,K2S2O8-NaHSO3氧化还原体系为引发剂,采用水溶液聚合法合成了P(AM-DAAM)二元共聚物,用红外光谱、核磁共振氢谱进行了表征。研究了原料中单体配比、反应时间、引发剂用量对共聚物的特性粘数的影响。结果表明,当DAAM在共聚物中的含量为33.64%时,聚合物的特性粘数比相同条件下合成的聚丙烯酰胺(PAM)提高9.9倍;通过对各种组成共聚物在不同盐溶液中的特性粘数的测定表明,该共聚物具有良好的耐盐性能。     

一种双水相亲和分配配基的制备过程优化--亚氨基二乙酸-聚乙二醇

考察了不同亚氨基二乙酸(IDA)取代度的亚氨基二乙酸-聚乙二醇(IDA-PEG)的制备,并进行了条件优化(BF3浓度,NaOH浓度,反应时间,IDA结合条件等)。通过控制环氧氯丙烷与聚乙二醇的摩尔配比,得到了不同Cu( )含量的固定化金属亲和配基:Cu( )-IDA-PEG(A)(0.24molCu2 /molPEG)、Cu( )-IDA-PEG(B)(0.51molCu2 /molPEG)、Cu( )-IDA-PEG(C)(0.75molCu2 /molPEG),并初步探讨了固定化金属亲和配基的添加对PEG4000-(NH4)2SO4-H2O双水相系统相图的影响。     

非离子聚丙烯酰胺水包水乳液的制备与研究

以丙烯酰胺(AM)单体为原料,通过分散聚合的方法制备了中等固含量、低黏度、稳定的聚丙烯酰胺乳液.分别考察了分散剂类型、引发剂浓度、单体含量等因素对最终产品的表观黏度和特性黏数的影响,并确定了最佳工艺条件.通过红外光谱表征了产品的化学结构.     

聚乙二醇/硫酸铵双水相体系萃取猪胰蛋白酶

采用聚乙二醇(PEG)/硫酸铵[(NH4)2SO4]双水相体系对猪胰蛋白酶分离进行了研究。通过综合考察酶分配系数、蛋白质分配系数、相比和回收率,探讨了PEG400质量分数、(NH4)2SO4质量分数、NaCl质量分数以及pH值对胰蛋白酶萃取的影响,并通过正交实验进一步优化实验条件,结果表明(NH4)2SO4质量分数和PEG浓度对胰蛋白酶的萃取影响大,在PEG400质量分数为24%、(NH4)2SO4质量分数为21%、pH值为4.2所组成的双水相体系下,可获得酶的高分配系数8.48,提取的胰蛋白酶活力达到1780 U/mL。     

聚丙烯酰胺在水介质中的低温化学降解

以聚丙烯酰胺（ＰＡＭ）相对分子质量和ＰＡＭ溶液粘度为指标,讨论了聚丙烯酰胺的低温化学降解在水介质中,在过氧化物的作用下,由于化学降解反应,使得聚丙烯酰胺的相对分子质量明显下降。过氧化物的性质和浓度、降解温度和降解时间等降解条件均极大地影响聚丙烯酰胺的降解速度和降解产物的相对分子质量。对聚丙烯酰胺的水解和相应水溶液粘度的研究结果表明,在本试验条件范围内聚丙烯酰酰胺在降解过程中的水解程度很小,且少量的水解对聚丙烯胺水溶液粘度的影响不大。     

水解聚丙烯酰胺盐水溶液表观粘度的数学模拟(Ⅰ)──通用Mark-Houwink-Sakurada方程式

针对水解聚丙烯酰胺修正了Fixman的聚电解质静电扩张理论式,确定了式中各常数,得到一关联水解度h和盐浓度c_s的通用MHS方程式.经验证该方程有好的精确度和宽的适用范围：30℃,母体相对分子质量10~5～1.3×10~7,水解度4％～40％,NaCl浓度0.02～0.5mol·L~-1.     

水溶液聚合高分子聚丙烯酰胺的研究

采用复合氧化还原引发体系,以丙烯酰胺(AM)为单体水溶液自由基共聚合,合成了高相对分子质量的聚丙烯酰胺。研究了pH值等因素对聚丙烯酰胺相对分子质量的影响,并确定了最佳的反应条件:聚合温度55℃,单体质量分数7.5%,pH值为8,引发剂为C(过硫酸铵量)=12×10-4mol/L、C(亚硫酸氢钠量)=9.6×10-4mol/L的复合体系,聚合时间为3h,此条件下可获得相对分子质量高达3.05×106的聚丙烯酰胺产物。     

Modeling of two‐phase polymerization of acrylamide in aqueous poly(ethylene glycol) solution

Two‐phase polymerization of acrylamide (AM) has been successfully carried out in aqueous poly(ethylene glycol) (PEG) solution with 2,2′‐azobis[2‐(2‐imidazolin‐2‐yl)propane] dihydrochloride (AIBI) as the initiator. A new heterogeneous kinetic model has been developed based on the partitioning of components between the two phases. It was found that polymerization proceeded in both the continuous and dispersed phases, even though the latter was the dominating polymerization locus. Besides the initiator, monomer concentration, and polymerization temperature, the PEG concentration also significantly influences the polymerization rate. With increasing concentration of PEG, gel effects in the aqueous PAM droplets were enhanced and more monomer preferred to polymerize inside the droplets, hence, the polymerization kinetics accelerated. The proposed model can successfully predict the composition of each phase and the polymerization kinetics during the aqueous two‐phase polymerization over a wide range of various reactions conditions. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

RAFT polymerization of acrylamide manipulated with trithiocarbonates in poly(ethylene glycol) solution

The reversible addition fragmentation chain transfer (RAFT) polymerization of acrylamide (AM) in aqueous two‐phase system was successfully carried out in polyethylene glycol (PEG) aqueous solution. Because of phase transition involved in the polymerization process, the ln([M]₀/[M])‐time plots were indicated in two‐stages significantly. Both the initial homogeneous polymerization and the subsequent heterogeneous polymerization were under good control. The effects of various synthesis parameters such as polymerization temperature, concentration of CTA, and initiator on RAFT polymerization behaviors have been investigated. Furthermore, the evolution process of the droplet morphologies after separation was examined by transmission electron microscope. The results showed that the nuclei were formed throughout the whole heterogeneous polymerization and stable sphere particles with an average size of about 1 μm were produced finally. More importantly, it was also found that the viscosity played a significant role in the stabilization of the dispersion of polymer particles. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43000.     

Intermolecular interaction in aqueous solution of binary blends of poly(acrylamide) and poly(ethylene glycol)

The interaction between poly(acrylamide) (PAM) and poly(ethylene glycol) (PEG) in their solid mixture was studied by Fourier transform infrared spectroscopy (FTIR); and their interaction in aqueous solution was investigated by nuclear magnetic resonance spectroscopy (NMR). For the solid PAM/PEG mixtures, an induced shift of the >C?O and >N? H in amide group was found by FTIR. These results could demonstrate the formation of intermolecular hydrogen bonding between the amide group of PAM and the ether group of PEG. In the aqueous PAM/PEG solution system, the PAM and PEG associating with each other in water, i.e., the amide group of PAM interacting with the ether group of PEG through hydrogen bonding was also found by ¹H NMR. Furthermore, the effects of different molecular weight of PAM on the strength of hydrogen bonding between PAM and PEG in water were investigated systemically. It was found that the hydrogen bonding interaction between PAM and PEG in water did not increase with the enlargement of the PAM molecular weight as expected. This finding together with the viscosity reduction of aqueous PAM/PEG solution with the PAM molecular weight increasing strongly indicated that PAM molecular chain, especially having high molecular weights preferred to form spherical clews in aqueous PEG solution. Therefore, fewer amide groups in PAM could interact with the ether groups in PEG. Based on these results, a mechanism sketch of the interaction between PAM and PEG in relatively concentrated aqueous solution was proposed. The fact that the phase separation of aqueous PAM/PEG solution occurs while raising the temperature indicates that this kind of hydrogen bonding between PAM and PEG in water is weak and could be broken by controlling the temperature. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Droplet size and morphology for the aqueous two‐phase polymerization of acrylamide in an aqueous poly(ethylene glycol) solution

A kind of polyacrylamide (PAM) latex product dispersed in an aqueous solution was successfully prepared through the aqueous two‐phase polymerization of acrylamide in an aqueous solution of poly(ethylene glycol) (PEG). The effects of various polymerization parameters on the size and morphology of droplets rich in PAM were systematically investigated. The droplet size and morphology was significantly influenced by the polymerization rate. The high polymerization rate caused the formation of stripe‐shaped droplets because of the aggregation of more droplets rapidly separated from the continuous phase. At the same time, the monomer partition behavior mainly relied on the temperature, and the PEG concentration also dramatically affected the droplet size and morphology. The increase in PEG concentration not only changed the monomer partition behavior and restrained droplet aggregation but also shortened the critical PAM radical chain length and accelerated the droplet formation. Furthermore, the stirring speed was also recognized as the correlative factor that affected the droplet stability and monomer diffusion rate from the continuous phase into the droplets. The addition of salt and alcohol altered the droplet stability and the final droplet size and morphology. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

On the polymerization of acrylamide in methanol in presence of poly(ethylene glycol)

Acrylamide was polymerized in presence of poly(ethylene glycol)-200 (PEG), with persulphate as initiator, in methanol as reaction medium, with varying monomer concentrations. The polymers obtained were finely divided powders and readily soluble in water, unlike pure polyacrylamide. The incorporation of PEG into the polymers was demonstrated by nitrogen determination, IR, and NMR studies. PEG does not covalently link to the polyacrylamide chains, but forms a blend with the polymer.     

Synthesis of cationic polyacrylamide by aqueous two‐phase polymerization in poly(ethylene glycol) chloride solution

Aqueous two‐phase copolymerization of acrylamide(AM) and acryloyloxyethyl trimethyl ammonium chloride (DAC) was performed in poly(ethylene glycol) (PEG) solution and in PEG chloride(Cl‐PEG) solution, respectively. Series of cationic polyacrylamide(CPAM) aqueous dispersion were prepared using potassium persulfate (KPS) as initiator. The effect of total amount of monomers, the dosage of initiator, the content of dispersant, the mass ratio of AM to DAC, and the temperature on the conversion, molecular weight, cationic degree, and stability of aqueous dispersion were studied in detail. It is found that the increase of initiator and reaction temperature resulted in the increase of the final conversion, whereas the increase of DAC and PEG concentration resulted in the decrease of the final conversion. The optimum reaction conditions of synthesis were as follows: (1) PEG‐H₂O system: PEG 7.5 g, AM 8 g, DAC 2 g, KPS 0.05 g, H₂O 100 mL, 70°C. In this process conditions, the molecular weight of CPAM was 3.21 × 10⁶, the cationic degree of CPAM was 24.4%, the storage stability of the aqueous dispersion was over 3 months. (2) Cl‐PEG‐H₂O system: Cl‐PEG 7.5 g, AM 8 g, DAC 2 g, KPS 0.05 g, H₂O 100 mL, 65°C. In this process conditions, the molecular weight was 3.68 × 10⁶, the cationic degree was 23.3%, and the storage stability of the aqueous dispersion was over 6 months. In general, the stability of CPAM aqueous dispersion in Cl‐PEG system is much better than in PEG system. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Swelling behavior of poly(acrylamide)/clay nanocomposite hydrogels in acrylamide aqueous solution

The swelling behaviors of poly(acrylamide) (PAAm)/clay nanocomposite hydrogels (hereinafter abbreviated as NC gels) in acrylamide (AAm) aqueous solution have been investigated. As‐prepared PAAm/clay hydrogels (S‐M gels) were posttreated by immersing them in AAm aqueous solution. It was found that the swelling ratio of the NC gels increased greatly when the concentration of the solution is below a critical concentration (c*), whereas the gels were disintegrated in the solution when the concentration of the solution is above the c*. Some disc‐like particles were found in the AAm solution accompanying with the unusual swelling behaviors. This unusual swelling behavior is resulted from the change of network structure of the NC gels in AAm aqueous solution, which was further convinced by transmission electron microscopy and element analyses. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of end-branched poly(ethylene glycol)s by aqueous atom transfer radical polymerization

Summary This article reports the synthesis of novel hydrophilic end-branched poly(ethylene glycol)s, in aqueous media by atom transfer radical polymerization (ATRP). Poly(ethylene glycol)s with molecular weights 10,000 and 16,000 were end-functionalized and used as bifunctional initiators for the polymerization of a poly(ethylene glycol) macromonomer with a molecular weight of 2,000 (PEGMA), either by aqueous ATRP or in a watedmethanol (l/l V/V) mixture. For both macroinitiators a DP of 10 was the target, giving an average of 5 branches in each end. The rates of polymerization were of the same order of magnitude when the polymerizations were initiated by either of the two macroinitiators in watedmethanol (l/l V/V). When a bifunctional oligo(ethy1ene glycol) initiator (M_n = 600) was used to study the polymerization of PEGMA in water/methanol a reduction in the rate of polymerization was observed indicating an influence of the molecular weight of the initiator on the rate of polymerization. Received 25 Maich 2002/Revised 8 November 2002/Accepted 8 November 2002 Correspondence to Jorgen Kops     

Effect of surface active additives on partitioning of proteins and enzymes in poly(ethylene glycol)/dextran aqueous two-phase systems

The effect of anionic (sodium butylbenzene sulfonate, sodium butylmonoglycol sulfate), cationic (tetrabutyl ammonium bromide), nonionic(Tween 20) and amphoteric (proline) surface active additives on the partitioning of proteins and enzymes, such as BSA, lysozyme, glucose oxidase and β-lactoglobulin, in a bipolymeric aqueous two-phase system of polyethylene glycol and dextran has been studied. The partitioning of proteins and enzymes in the aqueous two-phase system is influenced by surface active additives depending upon their structure and charge. The amphiphiles themselves partition unevenly between the two phases. Their effect on protein partitioning can be explained on the basis of electrostatic and hydrophobic interactions. In the presence of ionic amphiphiles, proteins have an affinity for the other phase if an amphiphile carrying a charge of the same sign partitions to that phase. The hydrophobic effect contributes to protein partitioning if the proteins have significant members of surface hydrophobic amino acid residues. © 1998 Society of Chemical Industry