聚合物Janus粒子的固/液界面吸附行为及其在分散染料领域的应用

Abstract: The adsorption adlayer of small surfactants at the solid-liquid interface cannot be thick enough in dispersion stability, and the interfacial adsorption efficiency of the amphiphilic copolymers is relatively low due to their kinetically frozen micelles, which results in high consumption of surfactant and serious environmental pollution during polyester dyeing with disperse dyes in dyeing and finishing industry. The frozen kinetics caused by the entanglement of the hydrophobic chain can be avoided through the control of the micro-structure (size, chemical composition, and Janus balance, etc.) of the polymeric Janus particles. In this study, series of triblock polymers will be designed and synthesized, and polymeric Janus particles with different sizes and micro-structure will be prepared by cross-linking of compartments within precisely defined multicompartments micelles (MCMs) through the revelation of their micro-structure regulation mechanism. Common disperse dyes will be selected as the object, the solution behavior and the solid-liquid interfacial adsorption behavior of Janus particles, and their dispersion capacity for disperse dyes will be investigated, to clarify the mechanism of the micro-structure of Janus particles influencing their self-aggregation behavior and adsorption behavior. The structure and performance will be optimized by the establishment of structure-activity-stability relationships about the micro-structure of Janus particles, the adlayer structure, and the dispersion stability. This project will not only provide a new method to enhance the interfacial adsorption efficiency of polymers and solve the environmental problems during polyester dyeing with disperse dyes, but also establish a reliable basis for the enrichment of the polymer interfacial adsorption theory.

分散体系中小分子表面活性剂在固/液界面形成的吸附层薄，双亲共聚物又常因胶束动力学冻结导致界面吸附效率低，在染整工业中表现出分散染料聚酯染色中分散剂用量高、环境压力大等问题。通过控制聚合物Janus粒子微结构（尺寸、化学组成及表面化学分区等），可避免因疏水链缠结引起的胶束冻结。本研究拟选择分散染料为研究对象，设计合成系列三嵌段共聚物，采用多隔段胶束交联法制备具有不同微结构的聚合物Janus粒子，揭示其结构的微观调控机制；通过研究Janus粒子的溶液行为、固/液界面吸附行为以及对分散染料的分散稳定作用，阐明Janus粒子微结构对其聚集行为、吸附行为的影响机制，建立粒子结构－界面吸附层结构－染料分散稳定性间的关系，实现结构与性能的优化。本项目的研究不仅为提高聚合物的界面吸附效率和解决聚酯染色的生态问题提供新思路和新方法，还可为丰富聚合物界面吸附行为理论提供可靠的依据。

鉴于双亲性聚合物Janus粒子较常规表面活性剂具有更高的吸附能，本项目通过研究Janus粒子在水体系中的溶液行为，并以分散染料为载体研究Janus粒子在固/液界面的吸附行为，探究Janus粒子微结构、粒子吸附层结构和染料颗粒稳定性之间的关系，为其在分散染料领域的应用可行性提供理论参考和实验依据。主要研究内容及结果如下：（1）基于Janus粒子前驱体聚合物的分子结构设计，采用连续的原子转移自由基聚合方法结合链段改性手段制得多系列两亲性三嵌段共聚物。（2）研究了不同结构和分子量的三嵌段共聚物在选择性溶剂中的自组装行为，并确立了多隔段胶束的制备条件，表明核-冠胶束尺寸取决于聚合物的分子量；由核-冠胶束进一步自组装得到的多隔段胶束轮廓清晰，相分离明显可见，尺寸和微观结构与其前驱体聚合物的分子量、嵌段比例及溶液pH值相关，可形成多种形貌。（3）通过对其多隔段胶束交联制得具有不同尺寸、微结构和平衡参数的Janus纳米粒子，尺寸为27.5 ~ 79.5 nm不等，平衡参数为0.8 ~ 15.3不等。横向比较了MCD-Janus粒子与其前驱体在水溶液中的自聚集行为及水/空气界面吸附行为，表明MCD-Janus粒子比MCD三嵌段共聚物及MCD多隔段胶束具有更强的表面活性，MCD-Janus粒子在水中的团聚体约由2 ~ 30个Janus粒子组成，在水表面附近的聚集体可以解离成单分散的Janus粒子。纵向比较了四种TCD-Janus粒子在水/空气界面吸附行为及在溶液中的自聚集行为，表明实验范围内四种Janus粒子的表面活性总体随Janus平衡参数的降低而增强。（4）四种TCD-Janus粒子呈球状较均匀地吸附在C.I.分散黄114染料晶体表面，粒子吸附层厚度主要由亲水性半球体积决定，四种Janus粒子层排列疏密性各异。Janus粒子在染料/水界面上的吸附等温线属于Langmuir型，疏水性强的Janus粒子更易稳定地吸附在染料颗粒/水界面。Janus粒子的亲疏水性及分子链长度共同决定了其在染料/水界面的吸附构象。吸附饱和时，Janus粒子可为染料颗粒提供较强的空间位阻，且由于Janus粒子吸附层较厚，预测在分散体系总势能曲线存在引力井的情况下能为体系提供良好的分散稳定性。