【作者】 刘杰；

【导师】 郑利强；

【作者基本信息】 山东大学 ， 胶体与界面化学， 2011， 博士

【摘要】 表面活性剂和高聚物混合水溶液在洗涤剂、食品、感光材料、涂料、化妆品、药物、采矿和采油等诸多领域发挥着重要作用。这类体系同时还可看作是生物过程的简化模型,因此研究该类体系有助于明确生物过程中复杂的相互作用,有利于寻找到新颖的“软”材料,得到在药物缓释、环境保护和人造器官等方面具有重要用途的凝胶。本论文的研究将近年来广泛研究的表面活性离子液体与高分子体系结合起来。通过改变各种影响因素,研究复合体系在水中的聚集行为。结合微量热(ITC)、电导率、表面张力、浊度以及流变等方法,得到表面活性剂和高聚物体系的聚集性质,复合物结构及相应的一些热力学函数。论文内容主要包括以下三个部分：1.对1-十二烷基-3-甲基溴化咪唑(C12mimBr)和羧甲基纤维素钠(NaCMC)水溶液体系复合物形成的研究。研究内容包括两个方面：无机盐NaBr的加入对体系复合物形成的影响；聚电解质浓度对体系复合物形成的影响。研究表明：①在不同盐的浓度下,具有相反电荷的表面活性剂和聚电解质复合物形成的机理不同。当盐的浓度小于某临界值,体系中形成表面活性剂和聚电解质的复合物。其中表面活性剂在高聚物链上的单体绑定为吸热过程,之后胶束状的表面活性剂／聚电解质聚集体开始形成,体系浊度开始上升。继续增加表面活性剂浓度,表面活性剂自由胶束开始形成,量热曲线上出现突然下降的吸热峰,并在表面张力曲线上出现平台。之后浊度曲线上出现最大值意味着表面活性剂在聚电解质链上吸附饱和。当盐的浓度大于某临界值,由于表面活性剂和聚电解质之间的作用被盐完全屏蔽,表面活性剂和聚电解质聚集体不再形成,只能在溶液中形成表面活性剂自由胶束。②在低的表面活性剂浓度下,单体表面活性剂通过静电吸引吸附在聚电解质链上为吸热过程。在稍高的表面活性剂浓度下,表面活性剂单体通过疏水作用在聚电解质链上形成胶束状聚集体为放热过程。流变测定证实在体系中可以形成以高聚物为连接的交联网络结构。继续增加表面活性剂的浓度,更多的复合物形成从而导致相分离。体系中高聚物浓度的增加,导致C12mimBr在NaCMC链上的单体吸附明显增强,而高聚物诱导的胶束状聚集体的形成因此受到影响,CAC变大。2.对两类离子液型表面活性剂1-烷基-3-甲基溴化咪唑(CnmimBr, n=8,10,12,14,16)和N-烷基-N-甲基溴化吡咯(CnMPB,n=12,14,16),与三种高聚物之间的相互作用研究,高聚物包括PEO13-PPO30-PEO13(L64)、PEO79-PPO30-PEO79(F68)以及NaCMC。研究内容包括表面活性剂链长、头基、高聚物类型和疏水链长对复合体系相互作用的影响。研究表明：加入CnmimBr或CnMPB(除了C8mimBr)到L64或者F68溶液中,复合物的形成由表面活性剂单体和PPO链节之间的疏水作用导致,因此表面活性剂和共聚物之间相互作用的强度随着表面活性剂或者共聚物疏水链长的增强而增强,但是表面活性剂头基不同对其影响很小。在NaCMC存在的体系中,CnmimBr或CnMPB(除了C8mimBr)单体通过静电和疏水作用强烈的绑定在NaCMC链上,其相互作用强度强烈依赖于表面活性剂烷基链长度。CnMPB与NaCMC之间的静电绑定作用要强于CnmimBr-NaCMC体系。对于CgmimBr来说,除了能通过静电作用在NaCMC链上单体吸附,胶束状C8mimBr-聚合物聚集体不能形成,在溶液中只有自由胶束形成过程。3.外加盐诱导长链咪唑类离子液体在水中形成蠕虫状胶束的胶束生成热研究。以长链咪唑类离子液体C16mimBr的对甲苯磺酸钠(NaTos)水溶液或者水杨酸钠(NaSal)水溶液为研究体系。研究表明：通过C16mimBr体系中表观摩尔焓随着NaTos或NaSal浓度的变化曲线得到胶束稀释焓以及球状到蠕虫状胶束的转化焓。蠕虫状胶束的形成焓(ΔHW)为球形胶束形成焓(ΔHm)和球形到蠕虫状胶束的转化焓(ΔHtra)之和。C16mimBr/NaTos体系中蠕虫状胶束的形成过程为放热过程,AHw为负值,该过程主要由表面活性剂烷基链之间的疏水作用和C16mim+和Tos离子之间的静电吸引作用共同控制,且为熵焓共驱过程；而C16mimBr/NaSal体系中蠕虫状胶束的形成过程为吸热过程,归结于氢键的破坏和重建,该过程为熵驱过程。而且Sal的平面结构会导致C16mimBr/NaSal蠕虫状胶束体系有更加紧密的结构从而具有较高的黏度。更多还原

【Abstract】 The surfactant/polymer mixed aqueous solution can play important role in detergency, foods, sensitive material, paint, cosmetics, pharmaceuticals, mining and oil recovery, etc. Simultaneously, this kind of system can be regarded as the simplified model of bioprocess which determines the corresponding complicated interaction. Thus this is helpful to find the novel "soft" material to obtain the important gel which has potential applications in drug release, environmental protection and artificial crgan, etc.This dissertation is focused on the interaction of surface active ionic liquid and polymer through changing the various influencing factors. Combining the isothermal titration microcalorimetry (ITC), conductivity, surface tension, turbidity and rheology measurements, the aggregation behaviour, the microstructures of the complexs and the corresponding thermodynamical parameters were obtained. There are three main parts in this dissertation as follows.1. The effect of NaBr and the polyelectrolyte concentration on the complex formation between 1-dodecyl-3-methylimidazolium bromide (C12mimBr) and sodium carboxymethylcellulose (NaCMC) has been studied. Following results were obtained.①The mechanism for surfactant/polyelectrolyte complex formation is found to be different at various salt concentrations. When the salt concentration is lower than the critical value, the surfactant/polyelectrolyte complex can be formed in this system. The binding process corresponding to surfactant monomers to polymer chain is endothermic. Then the micelle-like surfactant/polyelectrolyte aggregates begin to form and the turbidity increases accordingly. Further addition of surfactant, the formation of free micelles induces a second sharp endothermic peak in the enthalpy curves and the beginning of the plateau region of the surface tension curves. Thereafter, the polyelectrolyte chains are saturated with surfactant micelles as determined by the maximum values of the turbidity curve. When the salt concentration is higher than the critical value, no surfactant/polyelectrolyte complex forms in the solution and only surfactant free micelles can be formed due to the complete salt screening.②At the lower surfactant concentration, the monomeric surfactant adsorbs on the polyelectrolyte chains through electrostatic attraction, appearing as endothermic process. While at the higher surfactant concentration, surfactant monomers bind to the NaCMC chains to form micelle-like aggregates through the hydrophobic force and the surfactant micelles behave as a physical cross-linking to bind to polyelectrolyte chains corresponding to exothermic action. The rheological measurement verifies this interpolymer cross-linking network. With further increase of surfactant concentration, more surfactant/polyelectrolyte complexes are formed and lead to the phase separation. Increasing polymer concentration, the interaction of monomeric surfactant binds on the NaCMC chains becomes gradually stronger and the polymer-induced micelle-like aggregates formation is influenced, which resulted in larger CAC.2. The effects of different surfactant headgroup and alkyl chain, and the different polymer type and hydrophobicity on the interaction of a series of cationic surfactants 1-alkyl-3-methylimidazolium bromide (CnmimBr, n=8,10,12,14, 16) and N-alkyl-N-methylpyrrolidinium bromide (CnMPB, n=12,14,16) with nonionic triblock copolymers (PEOnPPOmPEOn) and NaCMC in aqueous solution have been investigated. Following results were obtained.The addition of CnmimBr or CnMPB (except C8mimBr) to L64 or F68 solutions induces the formation of surfactant-copolymer complexes by hydrophobic interaction between the surfactant monomers and the PPO segments. The intensity of surfactant-copolymer interaction increases with the increasing hydrophobicity of the surfactant or copolymer, and it is not affected by the different surfactant headgroup. In the presence of NaCMC, CnmimBr or CnMPB (except C8mimBr) monomers can strongly associate with NaCMC chains due to electrostatic attraction and hydrophobic interaction, but interacting characteristics are strongly dependent on the alkyl chain length of the surfactant. The electrostatic and binding interactions of CnMPB molecules on NaCMC chains are stronger than that of CnmimBr with the same alkyl chain. In the case of CgmimBr, except the monomers can bind to NaCMC chains through electrostatic attraction, the micelle-like surfactant-polymer clusters can not be formed and only surfactant micellization occurs.3. The enthalpy change of salt-induced wormlike micelle formation has been measured. The studied systems include C16mimBr/NaTos and C16mimBr/NaSal. Following results were obtained.The observed molar enthalpies of C16mimBr aqueous solutions as a function of NaTos or NaSal concentration not only allow the determination of the enthalpy of micelle dilution, but also the enthalpy change corresponding to the spherical to wormlike transition. The enthalpy change value of wormlike micelle formation (△Hw) was equal to the sum of the enthalpy of micelle formation (△Hm) and the transformation enthalpy (△Htra).The value of△Hw is negative in C16mimBr/NaTos system, and this exothermic phenomenon in the formation of wormlike micelles is mainly caused by the hydrophobic interaction between surfactant tails and the electrostatic attraction between Tos- and C16mim+; while the wormlike micelle formation is endothermic in the C16mimBr/NaSal system, attributing to the disruption and rebuilding of hydrogen bonds. In addition, the planar structure of Sal- induces the wormlike micelle a more tight structure with higher viscosity.更多还原