新型嵌段结构混凝土超塑化剂的分子构筑及构效关系

The development of modern high performance concrete required superplasticizers with higher performances. However, the performance of conventional polycarboxylic acid (PCE) superplasticizers with random structures has reached a bottleneck. Herein we proposed the synthesis of a series of block-type PCEs with variable chain structures by living radical polymerization. The adsroption and the steric hindrance effect of PCE molecules on the surface of cement particles could be finely tuned to achieve a by the density of functional groups in polymer backbone, length of side chains, and molecular weight. The impact of molecular structure and concentration, type and concentration of salt ions, pH on the solution behavior (e.g. surface tention, conformation, and aggregation state) would be systematically investigated. Furthermore, the impact of molecular structure and dosage of block-type PCE on the adsorption, dispersion, rheology, hydration process of cement at early stages and hydration products would also be systematically studied, in order to figure out the structure-property relationship and action mechanism of block-type PCE, and finally optimise the structure and improve the performance. The project provides new strategies and theoretical basis for the research and development of high performance concrete superplasticizers.

现代高性能混凝土的发展对混凝土超塑化剂提出了更高的性能要求，而传统无规结构聚羧酸超塑化剂的性能提升及功能化已进入瓶颈状态。本项目采用活性聚合技术，通过调整主链吸附基团数量、侧链长度、分子量等，合成系列新型嵌段结构共聚物，使其分子链在水泥颗粒表面具有良好吸附，同时又具有较高的空间位阻作用。系统研究嵌段共聚物的分子链结构与浓度、无机盐离子种类与浓度、pH值等对其溶液行为（表面张力、分子构象、聚集形态等）的影响规律；系统研究嵌段共聚物分子链结构与用量对吸附、分散、流变行为以及水泥早期水化历程、水化产物的影响规律，探明嵌段结构共聚物与水泥颗粒的构效关系与作用机理，实现结构与性能的优化，为高性能混凝土超塑化剂的研究和开发提供新方法和技术应用基础。

嵌段共聚物分子结构清晰明确，序列结构规整可控，其用于混凝土分散剂的研究备受关注。本项目采用ATRP、RAFT两种可控自由基聚合方法，合成了系列序列结构分布明确、PDI较窄的嵌段共聚物，通过调整共聚单体比例、侧链长度和分子量等，调整具有吸附作用基团的数量、具有空间位阻链段的长度，并采用GPC、NMR表征了嵌段共聚物的分子结构信息。系统研究了嵌段共聚物的分子链结构、无机盐离子种类与浓度、pH值等对其溶液行为的影响规律，嵌段共聚物分子构象受离子强度的影响小于无规结构共聚物；系统研究了嵌段共聚物分子链结构与用量对吸附、分散、流变行为以及水泥早期水化历程、水化产物等的影响规律，与无规共聚物相比，嵌段共聚物集中分布的羧基有利于强吸附的发生，吸附速率更快，吸附量更大，且吸附层更厚，硫酸盐敏感性低，能降低水泥浆体的表观粘度，改善其流变性能。初步探明了嵌段结构共聚物与水泥基材料的构效关系与作用机制，实现结构与性能的优化，为高性能混凝土超塑化剂的研究和开发提供新方法和技术应用基础。研究成果在国内外核心学术期刊公开发表论文16篇，其中SCI收录论文13篇，EI收录论文1篇；获授权发明专利5件，新申请发明专利2件。