梳状可降解共聚物PASP-PEG分散亚微米氧化铝水基悬浮液作用机理研究

Based on the preliminary work, comb-like biodegradable polymers PASP-PEG with improved steric hindrance and affinity groups as ceramic dispersant was designed from molecule structure and synthesized to the questions of low solid loadings, poor dispersion of ceramic suspensions and lack of biodegradability of dispersants. PASP as anchor adsorbed on the alumina surface and the side chains PEG extending into the solution provided improved steric repulsion. The adsorption behaviors of PASP-PEG on submicron alumina particles and the rheology of alumina suspensions with PASP-PEG were investigated thoroughly, and the correlation among the structure, adsorption behaviors of PASP-PEG, the rheology of alumina suspensions and the performance of the materials after sintering was established. This project will be of important guiding significance to the design and synthesis of biodegradable ceramic dispersants, reveal the mechanisms of the stable alumina suspenison with high solid loadings and low viscosity, and provide more sufficient scientific basis for the application of colloidal processing.

针对胶态成型中陶瓷水基悬浮液固含量低、粉体分散性差、分散剂不易生物降解等不足，在前期工作基础上，从分子结构角度设计具有较高空间位阻、较高亲和力基团的梳状可降解陶瓷分散剂聚天冬氨酸-聚乙二醇（PASP-PEG）共聚物。其中聚天冬氨酸作为“锚基”吸附在氧化铝颗粒表面，聚乙二醇则以“梳齿”状链段向水中延展，提高体系的空间位阻作用。重点研究该化合物在氧化铝颗粒表面的吸附特性及其分散作用机理，探索PASP-PEG分子结构、吸附特性与氧化铝悬浮液流变性及烧成后陶瓷材料性能的内在相关性规律。本项目研究结果对绿色陶瓷分散剂的设计合成具有理论指导意义，有望揭示高固含量氧化铝稳定悬浮液形成机制，为胶态成型技术的应用提供更充分的科学依据。

针对胶态成型中陶瓷水基悬浮液固含量低、粉体分散性差、分散剂不易生物降解等不足，本项目设计合成了具有较高空间位阻、较高亲和力基团的梳状可降解陶瓷分散剂聚天冬氨酸-聚乙二醇(PASP-PEG)共聚物，PASP-PEG 750、PASP-PEG 1000、PASP-PEG 2000 、PASP-PEG 6000。流变实验结果发现，与PASP相比，PASP-PEG 750和PASP-PEG 1000可较好地改善氧化铝水基悬浮液流变性能的影响，悬浮液呈现“剪切变稀”的特性，最接近于H erschel-Bulkley流变模型。而PASP-PEG 2000和PASP-PEG 6000的效果不明显，流变模型由 Herschel-Bulkley向Bingham模型转变。PASP作为“锚基”吸附在氧化铝颗粒表面，聚乙二醇则以“梳齿”状链段向水中延展，在氧化铝/水界面吸附层厚度增大，提高体系的空间位阻作用。而高分子量的PEG链长较长，容易互相缠绕，引起悬浮液粘度等上升。适合 链长的PEG（750和1000）使得PASP-Al2O3-H2O体系在更高固含量下（≥40 V%），更高的离子强度下（0.06-0.1 M），颗粒团聚减弱，粘度明显降低，并在更宽的pH值范围内具有更好的分散稳定性。本项目研究结果对绿色陶瓷分散剂的设计合成具有理论指导意义，为胶态成型技术的应用提供给更充分的科学依据。