聚丙烯酰胺类疏水缔合物的增黏因素研究

合成了6种不同修饰度的聚丙烯酰胺疏水聚合物(PAM1~PAM6), 考察了聚合度、 共聚物片段含量及疏水基团大小等内部因素和聚合物的抗剪切能力、 剪切恢复性及抗盐性等外部因素对这些疏水聚合物分子间、 分子内缔合的影响规律.     

Viscosity behavior of silica suspensions flocculated by associating polymers

Associating polymers are hydrophilic long-chain molecules containing a small number of hydrophobic groups, and act as flocculants in aqueous suspensions. The effects of associating and nonassociating polymers on viscosity behavior are studied for silica suspensions. Since flocculation is induced by polymer bridging, the viscosity behavior is converted from Newtonian to shear-thinning profiles. The additions of surfactant cause an increase in viscosity for suspensions prepared with associating polymer, whereas the flow behavior of suspensions with nonassociating polymer is not significantly influenced. In adsorption of associating polymers onto silica particles, the chain may adopt a conformation with a water-soluble backbone attached to the particle surfaces. The hydrophobic groups extending from the chains adsorbed onto different particles can form a micelle by association with surfactant. Therefore, the bridging flocculation is enhanced by surfactant. The cooperative micellar formation between associating polymer and surfactant is responsible for viscosity increase in suspensions.     

疏水缔合型水溶性高分子的合成与表征

本文综述了疏水缔合型水溶性高分子的合成与表征方法，６文中介绿了在合成过程中提高油溶性单体和水溶性单体的混溶性以及疏水基团均匀分布的方法，并了用核磁共振，上光谱等方法测定疏水物含量的方法。     

Effect of associating polymer on the viscosity behavior of suspensions consisting of particles with different surface properties

Associating polymers which consist of water-soluble long-chain molecules containing a small fraction of hydrophobic groups (hydrophobes) behave as flocculants in aqueous suspensions. The effects of associating polymers on the rheological behavior are studied for single suspensions of particles with hydrophilic and hydrophobic surfaces, and their mixtures. For particles with hydrophilic surfaces, the suspensions are highly flocculated by a bridging mechanism, because the water-soluble chains adsorb onto hydrophilic surfaces. On the other hand, the particles with hydrophobic surfaces cannot be dispersed in water without polymer and the additions of a small amount of polymer are required for preparation of homogeneous suspensions. The associating polymer acts as a dispersant at low concentrations. However, further additions of polymer lead to a drastic increase in viscosity. Since the hydrophobes on one end of molecules adsorb onto hydrophobic surfaces and other hydrophobes tending from the particles can form micelles, the particles are connected by linkage of interchain associations. By mixing two suspensions of particles with hydrophilic and hydrophobic surfaces, the viscosity is substantially reduced and the flow becomes nearly Newtonian. The associating polymer in complex suspensions acts as a binder between the hydrophilic and hydrophobic surfaces. The hetero-flocculation which leads to the formation of composite particles may be responsible for the viscosity reduction of complex suspensions.     

疏水缔合水溶性聚合物的合成研究进展

综述了疏水缔合水溶性聚合物的合成的最新研究进展。主要合成方法有非均相共聚、均相共聚、胶束共聚、反相微乳液聚合、无皂乳液聚合、活性阴离子聚合以及超临界二氧化碳介质等。     

疏水缔合水溶性聚合物——P(AM-NaAA-DiAC_8)的合成及其缔合性能

以双烯丙基胺和1-溴代辛烷为原料,合成了疏水单体N,N-双烯丙基辛胺(DiAC8).采取前加碱二元胶束共聚-共水解法合成了三元疏水缔合水溶性聚合物--聚(丙烯酰胺-丙烯酸钠-N,N-双烯丙基辛胺)[P(AM-NaAA-DiAC8)]. DiAC8和P(AM-NaAA-DiAC8)的结构经1H NMR和FT-IR表征.以芘为荧光探针,利用稳态荧光光谱法研究了P(AM-NaAA-DiAC8)在水溶液中的缔合行为,结果表明当r(DiAC8)=0.1%～1.4%时,随聚合物浓度、疏水单体用量的增加,P(AM-NaAA-DiAC8)在二次蒸馏水和1 mol·L-1NaCl水溶液中的Ⅰ1/Ⅰ3值减少.表明P(AM-NaAA-DiAC8)缔合行为取决于聚合物浓度、疏水单体用量及介质的极性.     

Synthesis and Conformations of Dendronized Poly(L-lysine)

Dendronized polymers based on a poly(L-lysine) backbone have been synthesized up to the fourth generation. The hydroxyl-terminated polymers are completely water-soluble, which makes them good candidates for drug delivery applications. The dendronized polypeptide backbones are helical at lower generations, but undergo a dramatic conformational change from alpha-helical to disordered upon increasing the dendron size to the third generation. This conformational change, attributed to steric repulsions between dendrons, is supported by spectroscopic measurements while chain extension upon dendronization is confirmed by scanning force microscopy.     

疏水缔合聚合物稳定乳状液的研究*

本文综述了近年来疏水缔合聚合物稳定乳状液的研究进展。论述了疏水缔合聚合物水溶液的性质,由于其较复杂的分子结构以及其分子主链上疏水基团的缔合作用,使其水溶液增稠的能力比小分子表面活性剂的增稠能力强的多。另外,对疏水缔合聚合物单独稳定乳状液的研究现状进行了介绍,其稳定乳状液的机理与小分子表面活性剂不同。同时讨论了疏水缔合聚合物与表面活性剂的相互作用,此类聚合物可与小分子表面活性剂通过静电和疏水缔合发生强烈的相互作用形成复合体系,并评述了其复配体系稳定乳状液的情况。最后总结了疏水缔合聚合物稳定乳状液的机理。     

Luminescence studies of the conformational behaviour of hydrophobically-modified,water-soluble polymers

A range of hydrophobically-modified water-soluble polymers, based upon acrylic acid and methacrylic acid as hydrophilic components, has been studied using various luminescence techniques. Time-resolved anisotropy measurements, on fluorescently labelled macromolecules, have been used to quantify the extent to which the conformational behaviour of a given polyelectrolyte affects its segmental mobility, and to gauge how such behaviour can be controlled by hydrophobic modification. Room-temperature stabilized phosphorescence from the labels and/or occluded guests and energy transfer experiments have been used to investigate the nature of the hydrophobic domains formed in these polymers. Hydrophobic modification of polyelectrolytes can be used to enhance the scope of water-soluble macromolecules as solubilizing media for photochemical and spectroscopic applications.     

SET-LRP法制备星型疏水缔合水溶性聚合物

采用丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸钠(NaAMPS)以及N-叔丁基丙烯酰胺(NtBA)为共聚单体,以Cu~0粉/三(2-二甲氨基乙基)胺(Me_6-TREN)为催化体系,四氯化碳(CCl_4)为引发剂,利用单电子转移自由基聚合(SET-LRP)方法合成星型疏水缔合水溶性聚合物P(AM/NtBA/NaAMPS)。采用控制变量法分别考察了引发温度、疏水单体含量、AMPS含量、引发剂用量、催化剂铜、单体浓度等因素对聚合物相对分子质量的影响,确定了最佳聚合条件并考察了聚合物的耐温抗盐性能。结果表明,当单体浓度为35%,引发温度为25℃,AM、AMPS、NtBA分别占单体总量的93.6%、5%、1.4%(摩尔比),引发剂质量分数为0.4942%,催化剂铜的质量分数为0.0848%,钝化剂的质量分数为0.1192%时,所得星型疏水缔合水溶性聚合物P(AM/NtBA/NaAMPS)的相对分子质量出现最高值为267万,同时具有一定的耐温抗盐性,其溶液性能与线型化的P(AM/NtBA/NaAMPS)相似,且在相同浓度下CaCl_2对聚合物表观粘度的影响比NaCl大。     

An Alternative Way towards Preparation of Hydrophobically Associating Polyacrylamide:Chemical Post-Modification

Hydrophobically associating polyacrylamides (HAPAMs) are derivatives from polyacrylamides by incorporating a small amount of hydrophobic moieties along the water-soluble mainchain. They are now becoming a class of promising candidates as thickeners or rheology modifiers in the formulations where rheology is necessary to be regulated, such as tertiary oil recovery, drilling fluids, hydraulic fracturing and coatings. Due to association of hydrophobes in nano-domains, their aqueous solutions exhibit very interesting rheological properties and better stability against salts than the unmodified precursor, polyacrylamide.Generally, there are two synthetic routes to introduce hydrophobic portion onto water-soluble polymer chains; i.e., direct copolymerization of hydrophobic and hydrophilic monomers, and post-polymerization functionalization[1]. In the case of HAPAM polymers, a commonly accepted method is micellar copolymerization in which an appropriate surfactant is employed to solubilize both monomers. However, it is widely reported[2] that the obtained polymers via micellar polymerization are characterized by: (i) blocky distribution of the hydrophobes; (ii) compositional inhomogeneity and (iii) strong dependence of solution properties on the block length.In this work, the alternative process, i.e., chemical post-modification, is employed to synthesize HAPAM polymers by direct N-alkylation of parent polyacrylamide (Figure 1) in dimethyl sulfoxide[3,4].PAM HAPAMFig. 1 Schematic route to prepare HAPAM by direct N-alkylation of PAMIt is found that the final incorporation of hydrophobic groups is in good agreement with the feed ratio[4], in contrast with that from micellar copolymerization which always brings about composition drift. Furthermore, unique rheological responses to shear rate, salt, temperature are also evidenced[5].     

水溶性高分子对激光热透镜分析的增强作用

本文研究了水溶性高分子对激光热透镜分析的增强作用。结果表明，水溶性高分子的加入，改变了测定体系的热物理特性和显色体系的微环境。不但提出了热透镜分析的灵敏度，而且增强了显色体系的稳定性。在水溶性高分子存在下，对土壤中水溶性磷及痕量碘进行了高灵敏度的测定。     

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.     

原子转移自由基聚合在制备水溶性聚合物中的应用

水溶性聚合物在工业、农业、医药等领域都有着广泛用途,但随着对水溶性聚合物精细化的要求,寻找新的结构可控的合成方法已成为迫切需求.而利用原子转移自由基聚合(ATRP)则可能得到分子量可控、分子量分布窄的水溶性聚合物.本文主要讨论了利用ATRP合成水溶性聚合物过程中单体、引发剂、催化剂、溶剂、反应温度和时间的影响,并结合聚丙烯酸类、聚丙烯酰胺类以及聚苯乙烯和聚丙烯酸酯的衍生物等具体实例加以了分析.     

Molecular simulation of structure formation and rheological properties of mixtures of telechelic and monofunctional associating polymer

We study the phase behavior, the characteristic times, and the rheological properties under the steady shear flow of the mixtures consisting of telechelic and monofunctional associating polymers by a coarse‐grained molecular dynamics simulation. The mixtures form the transient networks, the closely packed spherical micelles, and the wormlike micelles. We confirm the molecular origins of the several characteristic times of the mixtures. The dependencies of the characteristic times on the composition ratio between telechelic and monofunctional associating polymers show good agreement with reported experimental results. Under the steady shear flow, the mixtures show the shear thinning induced by the change of the spatial configuration of the micelles. The telechelic associating polymers especially play an important role in connecting the micelles at the shear thinning regime and enhance the steady shear viscosity. Furthermore, at the wormlike micellar region, the mixtures show the second shear thinning initiated by the transformation of the association conformation of the telechelic associating polymers.     

Micelle-polymer complexes as studied by the ESR spin probe technique

Complexes between sodium dodecyl sulfate micelles and the water-soluble polymers poly(N-vinylpyrrolidone), poly(ethylene oxide) and a copolymer of poly (vinyl alcohol) and poly(vinyl acetate) have been studied in aqueous solution by the electron spin resonance (ESR) technique using di-tert-butyl nitroxide as a spin probe. The effective rotational correlation times reveal lowering of the critical micelle concentration and decreased headgroup packing in the micelle upon interaction with the polymers.     

水溶性聚合物热稳定性研究进展

水溶性聚合物广泛应用于石油开采、水处理、造纸、印染以及医药等领域,该类聚合物热稳定性问题直接关系到其在高温环境下的应用性能,因此具有重要的研究意义和应用价值。本文选取了几类具有代表性的水溶性聚合物,详细综述了其热稳定性的研究进展,重点分析了不同类型的水溶性聚合物的热降解机理,并探讨了分子结构和外添加剂对热稳定性能的影响,最后对其发展前景进行了展望。     

丙烯酰胺和表面活性大单体共聚物的合成及其性能研究

首先合成表面活性大分子单体丙烯酸聚氧乙烯（２３）－十二烷基酯（ＡＡ－ＰＯＥＬＥ）,再通过与丙烯酰胺共聚合的方法得到在水溶性聚合物聚丙烯酰胺分子结构中引入疏水基团的共聚物改性ＰＡＭ。因ＡＡ－ＯＰＥＬＥ单体具有表面活性,所以共聚合时无需添加乳化剂。当改性ＰＡＭ中疏水基团含量为１．１０ｍｏｌ％时,其水溶液表现出独特的流变性和增稠性,着重讨论了改性ＰＡＭ作为乳胶增稠剂的性能。     

High performance poly(styrene-b-diene-b-styrene) triblock copolymers from a hydrocarbon-soluble and additive-free dicarbanionic initiator

A new hydrocarbon-soluble (additive-free) dicarbanionic organolithium initiator, obtained by a simple halogen-lithium exchange reaction (Gilman's reaction) from a diarylhalide containing a side C15 alkyl chain, has been designed and used to initiate the anionic polymerization of butadiene and styrene. The dilithiated species formed afford well-defined poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymers with a high percentage of 1,4-microstructure polybutadiene (91%) and excellent mechanical properties, such as ultimate tensile strength higher than 30 MPa and elongation at a break of 1000%. This represents a breakthrough in the synthesis of SBS polymers, one of the most used thermoplastic elastomers.     

Viscosity and Electrophysical Characteristics of Solutions Containing Nanocluster Polyoxometalates and Polyvinylpyrrolidone

The physicochemical characteristics of solutions intended for preparing composites that contain a water-soluble polymer, polyvinylpyrrolidone (PVP), and nanocluster polyoxometalates (POMs) based on molybdenum with Keplerate (Mo₁₃₂ and Mo₇₂Fe₃₀) and toroidal structure (Mo₁₃₈) are studied. Concentration dependences of the kinematic viscosity of solutions upon changes in the absolute and relative contents of the polymer component are obtained along with the frequency dependences of the dielectric loss tangents of such solutions that correlate with them. The data allow us to confirm the composition of POM—polymers associates that form, and to estimate the relaxation parameters of ions in solutions.