Polymerization of surface-active monomers and applications

The results on radical polymerization and copolymerization of alkyl bromide salts of 2-dimethylaminoethyl methacrylate having a different alkyl chain length in various solvents giving micellar and isotropic solutions are summarized to obtain an insight into micellar polymerization. The monomer micellization of the cationic surface-active monomers at concentrations far above their critical micelle concentration (cmc) leads to great increases in the rate of polymerization and the molecular weight of the resulting polymers for both aqueous and inverse micellar systems and the tendency toward alternation of the copolymerization for aqueous micellar systems, whereas it has little influence on the tacticity of the resulting polymers. Applications of the polimerization and the copolymerization of the surface-active monomer to the polymer encapsulation of silica particles are also reported.     

Micellar Copolymerization:the State of the Arts

Over the past two decades, hydrophobically modified water-soluble polymers (HMWSPs),particularly hydrophobically associating polyacrylamides (HAPAMs), have attracted increased interest owing to their practical and fundamental importance[1]. This system usually consists of a hydrophilic backbone with a small proportion (generally less than 2 mol %) of hydrophobic pendent groups. When dissolved in aqueous solutions, the apolar moieties tend to exclude water and are held together by intra- and intermolecular hydrophobic associations. This leads to a transitional network structure that induces a substantial increase in solution viscosity. Such viscosity-building ability is further elevated upon adding salt or increasing temperature due to the enhanced polarity.Additionally, the dynamic associating junctions can be ruptured upon high shear stress, but re-formed when the force ceases. All these unique properties enable HAPAMs attractiveness to various industrial uses in which the control of fluid theology is required.However, it is a great challenge to synthesize HAPAMs since acrylamide and hydrophobic comonomers are mutually incompatible. After attempts using heterogeneous, inverse emulsion,microemulsion, and precipitation copolymerization processes, the commonly accepted method is micellar free radical copolymerization in which an appropriate surfactant is used to solubilize the hydrophobic comonomer[2].In this paper, the sate of the arts for micellar copolymerization is comprehensively reviewed:1. the mechanism of micellar copolymerization;2. parameters affecting micellar copolymerization, including:(1) nature and level of hydrophobic comonomer;(2) nature and content of surfactant used;(3) initiator and temperature.3. structural characteristics of HAPAMs prepared via micellar copolymerization;4. properties of HAPAMs prepared via micellar copolymerization:(1) dilute solution properties;(2) semi-dilute solution properties.5. applications of micellar copolymerization.In short, the main goal of this review is trying to establish an interrelationship among .synthetic method, structure and properties, so as to give a guideline for "tailoring" the polymer structure to satisfy different specific end use.     

双亲嵌段聚合物的合成与应用

本文介绍了双亲嵌段聚合物的合成方法，包括共溶剂法、聚合后功能化法、胶束聚合法、自由基界面聚合法等，以及双亲嵌段聚合物在乳液聚合、三次采油、医用高分子材料等方面的应用。     

Kinetics of Radical Copolymerization. XII. Investigation of the Rate of Polymerization of the System Styrene-Butyl Acrylate-Benzene

The classical copolymerization rate equation does not describe the copolymerization rate in the styrene-butyl-acrylate-azoiso-butyronitrile-benzene-50°C system appropriately. The cross-termination coefficient (Π), calculated according to the classical rate equation, shows a strong monomer and solvent concentration dependence. The experimental results cannot be interpreted by the diffusion theory, penultimate effect, or the theory of charge transfer complexes. However, Π was found to be constant over the whole concentration range by the hot radical theory. Our kinetic data were consistently described by this theory, and its 13 parameters, characteristic of the copolymerization, were determined.     

基于Maple软件辅助绘制自由基二元共聚曲线的研究

运用数据处理软件(maple)对经典的自由基二元聚合公式进行图形绘制,得到了二元单体之间共聚关系的三组图。一是二元单体的自由基共聚曲线图F1-f1,二是聚合物中单体平均组成(Fp)与投料单体浓度(f1)的关系曲线图,三是聚合物转化率(C)与投料单体(f1)的关系曲线图。通过二组具有代表性的共聚实例,分别是有恒比点的非理想共聚(苯乙烯-丙烯腈共聚物)和非理想非恒比共聚(苯乙烯-乙酸乙烯酯共聚物)展现了绘图步骤和分析了不同竞聚率情况下的聚合物转化过程。     

Synthesis of a polyrotaxane-based macroporous polymer as stationary phase for capillary electrochromatography via host-guest complexation of N,N '-ethylenedianilinediacrylamide with statistically methylated beta-cyclodextrin

A synthetic route to acrylamide-based monolithic stationary phases for CEC with rotaxane-type immobilized derivatized beta-CD was explored. N,N'-Ethylenedianilinediacrylamide was synthesized as the water-insoluble crosslinker forming water-soluble inclusion complexes with statistically methylated beta-CD. Mixed-mode stationary phases were synthesized by free radical copolymerization of the bisacrylamide-CD host-guest complex with water-soluble monomers and an additional water-soluble crosslinker in aqueous solution. Complex formation in solution and inclusion of the pseudorotaxane into the polymeric network (formation of a polyrotaxane architecture) were studied by means of (1)H-NMR chemical shift analysis, CD modified micellar EKC (CD-MEKC), 2D-NOESY spectroscopy, and solid state( 13)C-NMR spectroscopy. The presence of a mixed-mode selectivity of the stationary phase based on hydrophobic and hydrophilic interaction was confirmed by CEC with neutral polar and nonpolar solutes.     

利用大分子单体技术合成接枝共聚物

大分子单体和小分子共单体共聚是合成接枝共聚物的重要途径之一。本文综述了大分子单体通过各种聚合方式(自由基共聚、离子型共聚、配位共聚、基团转移共聚和逐步共聚)和普通小分子单体的共聚反应,详细讨论了大分子单体和小分子单体的自由基共聚反应动力学,并简要介绍了接枝共聚物的应用背景。     

Substituent effect on the emission behavior of thiazolidinedione derivatives in cationic and anionic micellar media

Thiazolidinedione (TZD) derivatives have been found to possess potent immunostimulatory properties as well as antiarthritic, antidiabetic and oncostatic activities. These compounds are free radical scavengers. Photophysical properties of the compounds have been studied in different aqueous micellar environments using steady state and time resolved emission spectroscopy. Appreciable hypsochromic shifts with enhancement in the fluorescence intensities have been observed in the ionic micellar media. The binding constants and energy changes during probe-micelle binding have been evaluated from relevant fluorescence data. Polarity of the microenvironment surrounding the probe molecules has been determined in the micellar systems.     

孪尾疏水缔合水溶性共聚物聚(丙烯酰胺/丙烯酸钠/N,N-二己基丙烯酰胺)/十二烷基硫酸钠水溶液的粘度行为

水溶性三元共聚物;孪尾疏水缔合水溶性共聚物聚(丙烯酰胺/丙烯酸钠/N;N-二己基丙烯酰胺)/十二烷基硫酸钠水溶液的粘度行为     

疏水缔合聚丙烯酰胺在表面活性单体胶束溶液中的制备及其流变特性

配制了表面活性单体2-丙烯酰胺基十二烷磺酸钠(NaAMC12S)与十二烷基硫酸钠(SDS)的胶束溶液,分别测定了强疏水单体N-正十二烷基丙烯酰胺(C12AM)在两种胶束溶液中的增溶性能;在此基础上,于两种胶束溶液中分别进行了丙烯酰胺(AM)与C12AM的胶束共聚合,制备了疏水缔合聚丙烯酰胺(HAPAM),它们分别为二元共聚物C12AM/AM与三元共聚物C12AM/NaAMC12S/AM;测定了两种共聚物的红外光谱;采用荧光探针法与表观粘度法重点研究了它们的疏水缔合性与流变性能.结果表明,在表面活性单体NaAMC12S的胶束溶液中,可顺利地实现AM与疏水单体的胶束共聚合,由于表面活性单体也参与了共聚合,故制得的产物为三元共聚物C12AM/NaAMC12S/AM;与在SDS胶束溶液中制备的二元共聚物C12AM/AM相比,前者的疏水缔合性更强,其强疏水缔合性以强疏水单体C12AM的贡献为主,以表面活性单体NaAMC12S的贡献为辅.     

表面活性含氟单体-丙烯酰胺共聚物溶液性质研究

以异佛尔酮二异氰酸酯(IPDI)、十二氟庚醇(FOH)、烯丙基聚乙二醇(APEG)合成的表面活性含氟单体(FSM)与丙烯酰胺通过水溶液聚合,制备出含氟疏水缔合聚丙烯酰胺(FPAM).用表面张力法研究了FSM的胶束化,用流变仪、动态激光光散射(DLS)和原子力显微镜(AFM)表征了FPAM溶液的流变性能、缔合结构尺寸和形态.结果表明,FSM在25℃下CMC为1.28 g.L-1,表面张力为26.77 mN.m-1.FPAM溶液属于假塑性体系,临界缔合浓度为0.660%,具有一定的耐盐性.DLS和AFM表明,在低于临界缔合浓度时FPAM溶液仍能产生大量的缔合结构,FPAM分子具有很强的疏水缔合性.     

高强度疏水缔合水凝胶的交联网络结构形成机理

高强度疏水缔合水凝胶(HA-gels)是丙烯酰胺(AM)和少量的疏水单体辛基酚聚氧乙烯(4)醚丙烯酸酯(OP-4-AC)在十二烷基硫酸钠(SDS)水溶液中采用胶束共聚的方法制备的.采用胶束共聚理论、橡胶弹性统计理论及Mooney-Rivlin理论,并结合单向拉伸实验数据,对HA-gels的交联网络结构的形成机理进行了探...     

Radical terpolymerization of sulfur dioxide,styrene, and methyl methacrylate

The radical terpolymerization of sulfur dioxide, styrene, and methyl methacrylate in o-dichlorobenzene with 2,2′-azobisisobutyronitrile was carried out in order to clarify the propagation mechanism of the radical copolymerization of sulfur dioxide and styrene, especially as a function of total concentration of sulfur dioxide and styrene. From the analysis of the trigonal composition diagrams it has been definitely shown that the radical copolymerization of sulfur dioxide and styrene proceeds by the propagation of two monomers, but the usual type of copolymerization mechanism, explicable in terms of the Lewis-Mayo equation, is not applicable to this copolymerization. The participation in the propagation of a monomer charge-transfer complex consisting of sulfur dioxide and styrene was also ruled out.     

甲基丙烯酸三丁基锡酯与甲基丙烯酸甲酯共聚合竞聚率的测定和计算

采用红外光谱分析共聚物组成的方法，测定了不同温度下甲基丙烯酸三了基锡酯（ＴｈＴＭ）和甲基丙烯酸甲酯（ＭＭＡ）在甲苯溶液中的自由基共聚合竞聚率．并用Ｆ—Ｒ法、Ｍ—Ｌ法和ＥＶＭ法处理了实验结果，讨论了不同的数据处理的方法对共聚合竞聚率数值的合理性和准确性的影响．随聚合温度的升高，ＴＢＴＭ和ＭＭＡ逐渐倾向于理想共聚合．由共聚温度与ｒ１和Ｒ２的关系得到各温度下最为合理的ｒ１和ｒ２值，并讨论了聚合温度对共聚活性的影响．     

Nitroxide‐mediated free‐radical copolymerization of styrene with butyl acrylate

Controlled free‐radical copolymerization of styrene (S) and butyl acrylate (BA) was achieved by using a second‐generation nitroxide, N‐tert‐butyl‐N‐[1‐diethylphosphono‐(2,2‐dimethylpropyl)] nitroxide (DEPN), and 2,2‐azobisisobutyronitrile (AIBN) at 120 °C. The time‐conversion first‐order plot was linear, and the number‐average molecular weight increased in direct proportion to the ratio of monomer conversion to the initial concentration, providing copolymers with low polydispersity. The monomer reactivity ratios obtained were r_S = 0.74 and r_BA = 0.29, respectively. To analyze the convenience of applying the Mayo–Lewis terminal model, the cumulative copolymer composition against conversion and the individual conversion of each monomer as a function of copolymerization time were studied. The theoretical values of the propagating radical concentration ratio were also examined to investigate the copolymerization rate behavior. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4168–4176, 2004     

Photoreaction of thioxanthone with indolic and phenolic derivatives of biological relevance: magnetic field effect study

The photoinduced reaction of thioxanthone (TX) with various indolic and phenolic derivatives and amino acids like tryptophan and tyrosine has been monitored in sodium dodecyl sulfate micellar medium. Laser flash photolysis and magnetic field effect (MFE) experiments have been used to study the dynamics of the radical pairs. The quenching rate constant with different quenchers in SDS micellar solution has been measured. For indoles the electron-transfer reaction has been found to be followed by proton transfer from the donor molecule, which gives rise to the TX ketyl radical. On the other hand, the electron-transfer reaction in the case of phenols is preceded with formation of a hydrogen-bonded exciplex. The extent of the MFE and magnitude of the magnetic field corresponding to one-half of the saturation value of MFE ( B 1/2) support the fact that hyperfine mechanism plays the primary role. Quenching of MFE in the presence of gadolinium ions confirms that the radical pair is located near the micellar interface. MFE study has been further extended to protein-like bovine serum albumin in micellar solution. The results indicate loss in mobililty of radical pairs in the protein surfactant complex.     

Effects of alcohols on micellization and on the reaction methyl 4‐nitrobenzenesulfonate + Br− in cetyltrimethylammonium bromide aqueous micellar solutions

The effects of n‐hexanol, n‐pentanol, and n‐butanol on the critical micelle concentration (cmc), on the micellar ionization degree (α), and on the rate of the reaction methyl 4‐nitrobenzenesulfonate + Br^? have been investigated in cetyltrimethylammonium bromide (CTAB) aqueous solutions. An increase in the alcohol concentration present in the solution produces a decrease in the cmc and an increase in the micellar ionization degree. Kinetic data show that the observed rate constant decreases as alcohol concentration increases. This result was rationalized by considering variations in the equilibrium binding constant of the methyl 4‐nitrobenzenesulfonate molecules to the micelles, variations in the interfacial bromide ion concentration, and variations in the characteristics of the water–alcohol bulk phase provoked by the presence of alcohols. When these operative factors are considered, kinetic data in this and other works show that the second‐order rate constants in the micellar pseudophases of water–alcohol micellar solutions are quite similar to those estimated in the absence of alcohols. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 634–641, 2004     

Synthesis and solution behavior of hydrophobic association water-soluble polymers containing arylalkyl group

Copolymers of acrylamide (AM) and N-arylalkylacrylamide (AAM) have been synthesized by free radical micellar copolymerization in aqueous solution utilizing sodium dodecyl sulphate (SDS) as the surfactant and ammonium persulfate/sodium bisulfite as the redox initiator. Some factors affecting synthesis, such as the amount of AAM, SDS and 2-acrylamide-2-methylpropane sulfate, are described. Solution behaviors of these polymers were studied. The results show that with the increase of AAM content, the intrinsic viscosity decreases, Huggins constant increases and the viscosification effect increase. The addition of NaCl and CaCl₂ results an increase of solution viscosity, and the addition of surfactant has a significant and complex effect to solution viscosities. The polymers exhibit good temperature tolerance property, shear-thickening and thixotropy behavior.     

Volumes and compressibilities of pentanol in aqueous dodecyltrimethylammonium bromide solutions at 15, 25 and 35°C

Ultrasonic velocities and densities of the water-dodecyltrimethylammonium bromide (DTAB)-pentanol (PentOH) ternary system were measured at 15, 25 and 35°C as a function of the surfactant and alcohol concentrations. The apparent molar volumes and isentropic compressibilities of PentOH were calculated. The standard partial molar volumes increase with surfactant concentration continuously whereas the standard partial molar isentropic compressibilities show sharp changes in slope at about 0.25 mol-kg^–1 DTAB, which can be ascribed to a micellar structural transition. The volume data for alcohol in micellar solutions were treated by a model reported for the distribution of polar additives between aqueous and micellar phases. In the application of the model to compressibility, the contributions due to the pressure effect on the shift of both the micellization equilibrium and the alcohol distribution constant cannot be neglected. This is in contrast to what is found in the case of heat capacity. The distribution constant and the partial molar volumes and compressibilities of PentOH in the micellar phase have been derived by linear regression. Also, the apparent molar volumes and isentropic compressibilities of DTAB in water-pentanol mixed solvents at fixed composition have been calculated. These properties as a function of the surfactant concentration show maxima depending on the temperature and the mixed solvent composition. The decrease beyond the maximum can be attributed to the extraction of PentOH from the aqueous into the micellar phase, where its concentration tends to zero with the progressive increase of the surfactant concentration. As a consequence, by increasing the surfactant concentration, the apparent molar properties of the surfactant in the mixed solvent shifts towards the value in water.     

Micellization and related behavior of binary and ternary surfactant mixtures in aqueous medium: cetyl pyridinium chloride (CPC), cetyl trimethyl ammonium bromide (CTAB), and polyoxyethylene (10) cetyl ether (Brij-56) derived system

Mixed micelles formed with cetyl pyridinium chloride (CPC), cetyl trimethylammonium bromide (CTAB), and polyoxyethylene (10) cetyl ether (Brij-56) mixed in different combinations in aqueous medium have been studied in detail by tensiometric, conductometric, calorimetric, spectrophotometric, and fluorimetric techniques. Different physicochemical properties such as critical micellar concentration (cmc), micellar dissociation, energetic parameters (free energy, enthalpy, and entropy) of micellization, interfacial adsorption, and micellar aggregation number have been determined. The results have been analyzed in terms of the equations of Clint, Motomura, Rosen, Rubingh, Blankschtein et al., and Rubingh and Holland for justification of the experimental cmc, determination of micellar composition parameters, quantification of interaction among the mixed micelle components, and estimation of their activity coefficients.