Hirata Tsuyoshi, Ye Jun, Branicio Paulo, Zheng Jianwei, Lange Alex, Plank Johann, Sullivan Michael
Nippon Shokubai Co., Ltd., Research Division, Suita, 564-0034, Japan.
Institute of High Performance Computing, Materials Science and Engineering, Connexis, 138632, Singapore.
Sci Rep. 2017 Nov 30;7(1):16599. doi: 10.1038/s41598-017-16048-3.
The conformations of polycarboxylate ether (PCE) type superplasticizer polymers adsorbed on the surface of MgO in cement pore solution are simulated by molecular dynamics (MD). Three types of PCEs commonly applied to concrete are simulated, namely a methacrylate type PCE (PCEM-P), an allyl ether type PCE (PCEA-P), and an isoprenyl ether type PCE (PCEI-P) with ethylene oxide (EO) unit numbers (P) of 25, 34 and 25, respectively. It is observed that the adsorbed layer thickness is inversely proportional to the experimentally measured adsorbed amount at the initial paste flow of 26 ± 0.5 cm. Simulation results indicate that the adsorbed layer thickness is sensitive to the initial polymer orientations against the model MgO surface. I.e., polymer molecules initially placed parallel/perpendicularly against the MgO surface gradually forms a train shaped or a loop and tail adsorption profile, respectively. As a result, the loop and tail shaped conformation gives a higher layer thickness.
采用分子动力学（MD）模拟了水泥孔隙溶液中吸附在氧化镁表面的聚羧酸醚（PCE）型高效减水剂聚合物的构象。模拟了常用于混凝土的三种类型的PCE，即甲基丙烯酸酯型PCE（PCEM-P）、烯丙基醚型PCE（PCEA-P）和异戊二烯基醚型PCE（PCEI-P），其环氧乙烷（EO）单元数（P）分别为25、34和25。观察到在初始净浆流动度为26±0.5 cm时，吸附层厚度与实验测量的吸附量成反比。模拟结果表明，吸附层厚度对聚合物相对于模型氧化镁表面的初始取向敏感。也就是说，最初平行/垂直于氧化镁表面放置的聚合物分子分别逐渐形成尾形或环尾吸附轮廓。结果，环尾形构象给出了更高的层厚度。
