聚乙烯吡咯烷酮—阴离子表面活性剂形成的拟聚阴离子的研究

发布时间：2018-06-06 00:04

本文选题：拟聚阴离子 + 聚乙烯吡咯烷酮　；参考：《江南大学》2017年博士论文

【摘要】：聚合物与表面活性剂在溶液中能产生协同效应,性能优异,从而广泛应用于制药、涂料、食品、化妆品、石油开采及微纳材料制备等领域。其中,利用聚合物-表面活性剂在溶液中形成的微纳级软模板,研究者已成功合成出各种各样的纳米材料。因此,聚合物-表面活性剂体系的物理化学性能和相互作用机理的研究在过去几十年中一直备受关注并获得很多成果。但关于非离子聚合物-阴离子表面活性剂的研究仍然存在几个问题:(1)前期对该复合体系的黏度、电导率、光散射行为、中子散射行为等研究认为其中形成的缔合物呈现“拟聚电解质”的性质或结构,但这些研究对该“拟聚电解质”的认定主要基于复合物溶液行为或聚合物分子链尺寸发生变化的推测,至今仍缺乏直接的证据证实它的存在及其荷电性;(2)近几十年来,开发各种方法着眼于研究阴离子表面活性剂与非离子聚合物发生缔合相互作用存在双临界浓度—临界聚集浓度(c1)和饱和聚集浓度(c2),发现根据临界浓度划分的不同浓度区间各个物种呈现不同的聚集状态。然而由于该体系是一个热力学平衡体系,鲜有有效的手段能实现其中不同聚集体的分离以及不同浓度阶段物种平衡关系的分析,而大于c2后形成了自由胶束的结论也是主要根据溶液行为推测而得;(3)前期主要以聚乙烯吡咯烷酮(PVP)或聚乙二醇(PEG)与强电离型的表面活性剂如十二烷基硫酸钠(SDS)的复合体系为主要研究对象,通过各种方法研究获得了非离子聚合物与阴离子表面活性剂缔合相互作用的一般规律,然而对于弱电离或多级电离型的阴离子表面活性剂与非离子聚合物相互作用的报道却相对较少,认识浅显,原因归结于该类表面活性剂在溶液中的结构相对复杂且对pH依赖性较强,而对不同类型阴离子表面活性剂与非离子聚合物缔合相互作用的构效关系研究更是缺乏。解决以上关于拟聚电解质认定、物种平衡关系以及缔合作用构效关系等问题对于聚合物-表面活性剂体系研究具有重要的理论指导意义,同时对于优化和拓展该复合体系在不同领域的应用也起着重要的作用。基于以上问题,本实验主要采用毛细管电泳同时联合黏度、表面张力和电导率等测定方法对PVP(PEG)-SDS、PVP(PEG)-十二烷基苯磺酸钠(SDBS)、PVP-十二酸钠(SD)和PVP-十二烷基磷酸酯(MLP)等体系进行了详细的研究。主要研究内容和结论如下:1.拟聚阴离子结构的证明利用乌氏黏度法研究了PVP-SDS和PEG-SDS经典体系中聚合物-SDS缔合物在不同比簇集量([Г])下的溶液比浓黏度特性,结果显示缔合物溶液呈现低浓度下比浓黏度快速上升的“聚电解质效应”,这是SDS以束缚胶束的形式缔合到聚合物链上使其荷电的结果。根据Fuoss方程拟合获得的聚合物链相对扩张量随[Г]的增大而增大,直至SDS束缚胶束在聚合物链上缔合饱和。对于PEG-SDS体系,PEG分子链越长,聚电解质效应越显著,无机盐的加入将屏蔽此效应。PVP(PEG)-SDS缔合物黏度特性的研究为其属于“拟聚电解质”提供了初步证据。作为一种高效、快速、微量且能在水相中实现不同荷电密度物种的分离和分析的有效手段,毛细管电泳法利用PVP的强紫外吸收信号对PVP-SDS的研究直接证实了PVP-SDS缔合物的“拟聚阴离子”结构,同时也证明了PVP-SDBS、PVP-SD和PVP-MLP等体系在特定条件下于c1和c2之间均形成了拟聚阴离子结构的缔合物;毛细管电泳同时利用表面活性剂SDBS的强紫外吸收特征分离检测到了PEG-SDBS拟聚阴离子结构;根据有效电泳淌度(μe)的结果,拟聚阴离子的表面电荷密度随[Г]的增大而增大。2.物种平衡关系的证明利用SDBS相对于SDS在毛细管电泳中可被紫外光谱识别的优势,联合采用毛细管区带电泳(CZE)、胶束电动毛细管色谱(MEKC)和空位亲和毛细管电泳(VACE)三种毛细管电泳分离模式对SDBS、PVP-SDBS和PEG-SDBS三种体系进行对比研究,首次直接证实了大于c2以后形成了自由胶束,根据c1、c2划分的不同SDBS浓度(cSDBS)区间,聚合物相关和表面活性剂相关的物种平衡关系为:cSDBSc1时,SDBS单体与中性聚合物共存,两者无缔合相互作用;c1cSDBSc2时,聚合物-SDBS缔合物与SDBS单体以及有可能一部分未与SDBS发生缔合相互作用的中性聚合物(稍大于c1时)共存;cSDBSc2时,SDBS自由胶束出现,与聚合物-SDBS缔合物、SDBS单体共存。毛细管电泳实验获得的SDBS浓度阈值和物种平衡关系与表面张力法和电导率法获得的结果和推论吻合。3.缔合作用机理与构效关系探讨通过对各个体系在外加盐以及不同pH条件下表面张力、电导率和毛细管电泳的研究,反离子解离度以及缔合物电泳淌度的结果表明外加盐及降低pH均有利于非离子聚合物-阴离子表面活性剂的缔合相互作用,证明阳离子在PVP与SDS、SDBS、SD、MLP等阴离子表面活性剂束缚胶束的缔合相互作用中起着反离子架桥的作用,而与金属阳离子不同的是,氢离子在弱电离的表面活性剂复合体系中同时起着氢键架桥作用。实验结果同时发现,缔合相互作用对氢离子浓度的依赖性基本随表面活性剂pKa的增大而增大。因此本文认为静电相互作用是非离子聚合物与阴离子表面活性剂缔合相互作用的主要驱动力,而疏水作用则加强了表面活性剂分子的聚集行为。有效电泳淌度的研究结果证明,各个体系形成拟聚阴离子的聚电解质性强弱遵循以下顺序:PVP-SDPVP-SDBSPVP-SDSPVP-MLP,这与拟聚阴离子的电离度(α)和比饱和簇集量([Г∞])有关,实验结果和理论分析一致证明μeμα[Г∞]。通过[Г∞]分析不同体系的缔合效率,发现pH低于9.0时的PVP-SD体系由于较强的氢键架桥作用缔合效率高于其他体系,而MLP由于离子头基的位阻效应与PVP的缔合效率最低,且只有在pH7.4时PVP-MLP存在弱缔合相互作用。聚合物的加入降低了表面活性剂形成胶束的浓度(从cmc降至c1),根据降低程度(cmc-c1)/cmc判断聚合物与表面活性剂的缔合效能,发现遵循以下顺序:PVP-MLPPVP-SDSPVP-SDBSPVP-SD。以上的研究结果是不同PVP-阴离子表面活性剂体系在不同外加盐和pH条件下氢键作用、反离子架桥作用、疏水作用以及表面活性剂阴离子头基位阻效应等因素的综合结果,其中对缔合相互作用的影响力大小顺序为位阻效应氢键作用反离子架桥作用。据此本文通过毛细管电泳等方法证明了不是所有的阴离子表面活性剂均能与非离子聚合物发生缔合相互作用,而一旦发生缔合作用则形成非离子聚合物-阴离子表面活性剂拟聚阴离子,且反离子架桥和氢键架桥在其中起着重要的作用。本文的研究不仅对聚合物-表面活性剂体系的研究具有重要的理论意义,而且对可控合成纳米材料有一定的指导作用,不同类型表面活性剂与非离子聚合物缔合作用的pH依赖性研究可以帮助指导该类体系在不同环境中的应用。
[Abstract]:Polymers and surfactants can produce synergistic effects in solutions and have excellent properties, and are widely used in the fields of pharmaceuticals, coatings, food, cosmetics, petroleum mining and micro nano material preparation. Among them, the researchers have successfully synthesized a variety of nanoscale materials by using polymer surface active agents in the solution. Therefore, the research on the physical and chemical properties and interaction mechanism of the polymer surfactant system has attracted much attention and gained a lot of achievements in the past several decades. However, there are still several problems in the study of nonionic polymer anionic surfactants: (1) the viscosity, conductivity and light scattering of the composite system in the previous period For the study of neutron scattering behavior, it is believed that the formation of the association is characterized by the nature or structure of the "polyelectrolyte", but the determination of the "polyelectrolyte" is mainly based on the conjecture of the behavior of the complex solution or the change of the size of the polymer chain, and still lacks direct evidence to confirm its existence and its charge. (2) (2) in recent decades, various methods have been developed to study the interaction of anionic surfactants and nonionic polymers with two critical concentrations, critical concentration (C1) and saturated concentration (C2). Since the system is a thermodynamic equilibrium system, there are few effective methods to analyze the separation of different aggregates and the analysis of species equilibrium in different concentration stages, and the conclusion that the free micelle is formed after more than C2 is mainly based on the solution behavior; (3) polyvinylpyrrolidone (PVP) or poly B is mainly used in the early stage. The main research object is diol (PEG) and the composite system of strong electric dissociated surface active agent, such as twelve alkyl sodium sulfate (SDS). Through various methods, the general law of the interaction of nonionic polymers and anionic surfactants is obtained by various methods. However, the anionic surfactants of weak or multilevel ionization and non ionization are not isolated. There are relatively few reports on the interaction of subpolymers. The reason is simple, because the structure of the surfactants in the solution is relatively complex and has a strong dependence on the pH, but the research on the relationship between different types of anionic surfactants and non ionic polymers is more lacking. The problem of solution quality identification, species balance and association effect relationship are of great theoretical significance for the study of polymer surfactant system, and it also plays an important role in optimizing and expanding the application of the composite system in different fields. PVP (PEG) -SDS, PVP (PEG) - twelve alkyl benzene sulfonate (SDBS), PVP- twelve sodium acid sodium (SD) and PVP- twelve alkyl phosphate (MLP) have been studied in detail by combined viscosity, surface tension and conductivity. The main contents and conclusions are as follows: 1. the proof of the structure of pseudo polyanions is studied by urse viscosity method. The solution of polymer -SDS Association in the PEG-SDS classical system is more viscous than the concentrated viscosity. The results show that the association solution presents a "polyelectrolyte effect" that increases rapidly at a lower concentration than the concentration viscosity. This is the result of the association of SDS in the form of binding micelles to the polymer chain. According to the Fuoss equation. The relative extensor amount of the polymer chain obtained by fitting increases with the increase of the ratio, until the SDS binding micelle is saturated in the polymer chain. For the PEG-SDS system, the longer the PEG molecular chain is, the more significant the polyelectrolyte effect is. The addition of inorganic salts will shield this effect of the viscosity properties of the.PVP (PEG) -SDS Association as a "polyelectrolyte" Preliminary evidence is provided. As an efficient, rapid, micro and effective means for the separation and analysis of species with different charge density in the water phase, capillary electrophoresis has directly confirmed the "polyanionic" structure of the PVP-SDS association by using the strong ultraviolet absorption signal of PVP to PVP-SDS, and also proved PVP-SDBS, PVP- SD and PVP-MLP formed an association of polyanionic structures between C1 and C2 under specific conditions; capillary electrophoresis also detected the structure of PEG-SDBS polyanions by the strong UV absorption characteristics of the surfactant SDBS, and the surface charge density of the polyanions according to the results of the effective electrophoretic mobility (mu E). It is proved that the increase of.2. species balance relationship by SDBS is superior to SDS in capillary electrophoresis, combined with capillary zone electrophoresis (CZE), micellar electrokinetic capillary chromatography (MEKC) and vacancy affinity capillary electrophoresis (VACE) three capillary electrophoresis separation modes for SDBS, PVP-SDBS and PEG-SDBS three A comparative study of the species system has been made for the first time that the free micelle formed after more than C2, according to the different SDBS concentration (cSDBS) interval of C1, C2, and the equilibrium relationship between the polymer related and the surfactant related species is: when cSDBSc1, the SDBS monomer and the neutral polymer coexist and both have no association interaction; when c1cSDBSc2, polymer -SDB S associates with SDBS monomers and some possible neutral polymers (slightly larger than C1) that have not associated with SDBS interaction; cSDBSc2, SDBS free micelles appear, coexist with polymer -SDBS Association, SDBS monomer. The SDBS concentration threshold value and species equilibrium relationship with the surface tension method and electrical conductivity obtained by capillary electrophoresis experiment The results and inferences obtained by the method are consistent with the relationship between the.3. association mechanism and the structure-activity relationship. The results of the surface tension, conductivity and capillary electrophoresis of the various systems under the addition of salt and different pH conditions, the dissolution of the ion and the electrophoretic mobility of the associates show that the addition of salt and the reduction of pH are beneficial to the nonionic polymer - ionization. The association interaction of subsurface active agents shows that cations play an anti ion bridge role in the association interaction of binding micelles of anionic surfactants, such as PVP, SDS, SDBS, SD and MLP. Unlike metal cations, hydrogen ions play the role of hydrogen bonding at the same time in the weakly ionized surfactant composite system. It is also found that the dependence of the association interaction on the concentration of hydrogen ions increases with the increase of the surfactant pKa. Therefore, the electrostatic interaction is the main driving force of the interaction of the nonionic polymers and the anionic surfactants, and the hydrophobic interaction strengthens the aggregation behavior of the surfactant molecules. The results of the effective electrophoretic mobility show that the polyelectrolyte strength of the polyanions in each system follows the following order: PVP-SDPVP-SDBSPVP-SDSPVP-MLP, which is related to the degree of ionization (alpha) and the specific saturation cluster of polyanions. The association efficiency of the system was found to be less than 9 when the PVP-SD system was higher than the other systems because of the strong hydrogen bond bridging effect, while MLP was the lowest associated with PVP because of the steric hindrance effect of the ionic head base, and the PVP-MLP had a weak association interaction only at pH7.4. The addition of polymeric substances reduced the formation of the micelles of the surfactant. The concentration (from CMC to C1), according to the degree of reduction (cmc-c1) /cmc to determine the association efficiency of polymer and surfactant, follows the following order: the results above PVP-MLPPVP-SDSPVP-SDBSPVP-SD. are the hydrogen bond action of different PVP- anionic surfactant systems under the different addition of salt and pH conditions, the anti ion bridge effect, the hydrophobicity. The comprehensive results of factors such as the steric effect of the anionic head base of the surfactant and other factors, in which the influence of the association interaction is the effect of the hydrogen bond on the bridge effect of the hydrogen bond, and it is proved that not all the anionic surfactants can occur with the nonionic polymers by capillary electrophoresis. Association interaction is associated with the formation of non ionic polymer anionic surfactants as a polyanion once the association is associated, and the anti ion bridge and hydrogen bonding bridge play an important role in it. This study not only has a significant theoretical significance for the study of polymer surface active agent system, but also has a great significance in the study of controlled synthetic nanoscale. The material has a certain guiding role. The pH dependence study of the association of different types of surfactants with non ionic polymers can help guide the application of this kind of system in different environments.
【学位授予单位】：江南大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O647.2

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